CA1076921A - Hydraulic railroad retarder - Google Patents
Hydraulic railroad retarderInfo
- Publication number
- CA1076921A CA1076921A CA332,925A CA332925A CA1076921A CA 1076921 A CA1076921 A CA 1076921A CA 332925 A CA332925 A CA 332925A CA 1076921 A CA1076921 A CA 1076921A
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- CA
- Canada
- Prior art keywords
- pump
- retarders
- pressure
- filter
- unacceptable
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
Abstract of the Disclosure The present invention relates to hydraulic apparatus as used in a railway classification yard having hydraulically operated retarders installed at selected positions along the classification track system. The apparatus includes a plurality of motor-driven pumps at least one being normally active and another one being normally inactive, serving as a reserve pump.
Each pump is provided with a filter unit through which the pump moves fluid under pressure. The pressure drop across each filter may be sensed and the reserve pump may be activated if the pressure drop exceeds a predetermined value indicating unacceptable filter efficiency, the normally active pump being deactivated A signal may be generated when the sensed pressure drop indicates that the filter in question is approaching unacceptable efficiency or that the flow rate of the associated pump is unacceptable.
Thus the invention provides a redundant arrangement of pumps and filters and provides for constant performance monitoring to detect both failing and failure conditions in terms of pump and filter efficiency, enabling remedial action to be timely applied.
Each pump is provided with a filter unit through which the pump moves fluid under pressure. The pressure drop across each filter may be sensed and the reserve pump may be activated if the pressure drop exceeds a predetermined value indicating unacceptable filter efficiency, the normally active pump being deactivated A signal may be generated when the sensed pressure drop indicates that the filter in question is approaching unacceptable efficiency or that the flow rate of the associated pump is unacceptable.
Thus the invention provides a redundant arrangement of pumps and filters and provides for constant performance monitoring to detect both failing and failure conditions in terms of pump and filter efficiency, enabling remedial action to be timely applied.
Description
1~69~
This invention relates to hydraulic apparatus principally intended to supply hydraulic requirements for retarders in a railroad classification yard.
Railroad cars are segregated according to destination in a rallroad classification yard. The cars to be classified or separated according to destination are switched to the various classification tracks. It is customary to slow the cars to a safe coupling speed by means of retarders insta~led at predetermined positions along the classificatior. tracks.
llydraulic controls are usually employed. U.S. patent ~os.
3227246 and 3809188 disclose retarders which employ hydraulic cylinders.
The hydraulic requirements are very extensive since the hydraulic fluid must be transmitted under pressure over a considerable distance. The required force is of considerable magnitude. If there is a pressure failure, the car cannot be brought to a safe speed, in which event the car couplers and the lading as well can be damaged.
The primary object of the present invention is to reduce the possibility of such damage by incorporating in the hydraulic system a redundant arrangement of pumps and related filter units and to constantly monitor performance to detect both failing ~decaying) and failure conditions in terms of pump and filter efficiency, enabling remedial action to be timely applied.
Pnother object of the invention is to incorporate in the - system a reserve unit which is automatically o2erated in the event a failure is detected, while concurrently disabling the failed unit. Another object of the invention is to create warning signals in the event a near failure condition is detectedO
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Specifically, it is an object of the invention to monitor filter efficiency, activating a reserve pump and disabling the active pump ~or pumps) in the event a threshhold of pump l-'ailure is detected or in the event a predetermined level of declining filter efficiency is detected. A further object of the invention in this regard is to employ in redundant relat~on two active pumps and a single reserve pump, together with related filter units, such that in the event both active units are sensed as being in a failed condition, the reserve unit may be relied on for a limited time.
Other objects of the invention are to utilize a flow meter to determine if a pump is either in a failing condition or has failed; to sense the pressure drop across the filter by means of differential pressure switches responsive to co~plete filter failure or a failing (decaying~ filter condition: to enable the failing or failed condition to be remediea by relying on a reserve pump and filter unit; and to enable appropriate signals to be created so that the operator of the classification yard may be aware of the downstream circumstances.
~ reliable and efficient pump operation r~quires clean hydraulic fluid. Contamination results in pump wear and filter inef~iciency. According'y, another object of the invention is to empioy exchange pumps for delivering the unfiltered hydraulic fluid to exchange filter units prior to delivering the return fluid to the reservoir tank which supplies the pressure pumps.
The exchange pumps and the exchange filters preferably incorporate the redundant features imposed on the pressure pumps.
Since contamination particles break up when the fluid is pumped and become smaller in size, it is possible for the clean side of the reservoir to be contaminated with exceedingly fine , ,' ~76~21 but nonetheless destructlve particles which are not captured by the exchange filters. Accordingly, additional objects of the invention are to utilize a silt pump and silt filter at the clean side of the reservoir and to construct a rcservoir which both eliminates turbulence and which accounts for highly efficient transfer of fluid.
This application is a division of Canadian Application Serial No. 265,003 filed November 5, 1976.
The invention as defined in the parent application defined hereinabove provides in a hydraulic system where filtered oil in a reservoir is to be delivered under pressure by a pressure pump to a remote location and returned to the reservoir, reservoir apparatus comprising a first tank for receiving the return oil;
a second tank for containing the oil to be delivered; a pres~ure pump communicating with a pump inlet port in the second tank for delivering oil in the second tank to the remote location; a return conduit terminating at an opening in the first tank for feeding return oil to the first tank; an exchange pump connected with an exchange pump inlet in the first tank for transferring oil from the first tank to the second tank through a transfer conduit having an outlet in the second tank and having a filter interposed between that outlet and the exchange pump; a plurality of baffles interposed between the .~nlet port in the second tank and the outlet in the second tank to remove turbulence from the transfer oil entering the second tank; and a plurality of baffles in the first tank interposed between the opening of the return conduit -and the inlet to the exchange pump to remove turbulence from the oil returned to the first tank.
On the other hand the present invention provides, ln a 10769Zl rallroad classifi.cation yard having hydraulically operated retarders infitslled at selected positions along the classification track system, apparatus for furnishing hydraulic fluid to operate the retarders and co~prising: (a) a plurality of motor-driven pumps, at least one to be a normally active.pump and one to be a normally inactive reserve pump; (b) a plurality of.filter units, one for each pump, and through which the related pump moves fluid under pressure; (c) means to sense the pressure drop across each filter unit and to activate the reserve pump while deactivating the active pump in the event the pressure drop exceeds a predetermined value characterizing unacceptable filter efficiency; and (d) means to sense the pressure drop across each filter unit and to generate a signal when the pressure drop indicates a filter unit is approaching unacceptable efficiency.
Furthermore the present invention may be considered to provide, in a railroad classification yard having hydraulically operated retarders installed at selected positions along the classification track system, apparatus for furnishing hydraulic fluid to.operate th-e retarders and comprising: (a) a plurality of motor-driven pumps, at least one to be a normally act$ve pump and one to be a normally inactive reserve pump; (b) a plurality of filter units, one for each pump, and through which the related pump moves fluid under pressure; (c) means to sense the pressure drop across each filter unit and to activate the reserve pump whlle deactivating the active pump in the event the pressure drop exceeds a predetermined value characterizing unacceptable filter efficiency; and (d) a flow meter to measure the flow of each pump and to generate a signal when the measure indicates a pump is approaching an unacceptable flow rate.
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In the drawing: .
Fig. 1 is a schematic view of a railroad classification yard;
Fig. 2 is a plan view of an oil res~rvoir and Figs. 3, 4 and 5 are sectional views thereof;
Figs. 6 and 7 are sche~.atic views of hydraulic circuitry; and Figs. 8 throush 13 are wiring dia~rams.
1~76~21 ~ i~. 1 of the drawing is a schematic vie~ of a typical retarder installation in a railroad classification yard. The c:lassification tracks are identificd hy reference character 10.
C)n the up-stream side there is a so-called hump (not show?l) where an operator at a console assigns the individual cars to a selected one of the classification tracks. The car to be classified acceleratcs down the grade of the hump, by gravity fall, and is automatically switched to a particular classification track.
The individual retarders are identified by reference character 11. The retarder controls include cylinders, not shown herein but of the character disclosed in patent Nos.
3227246 and 3809188. Hydraulic fluid for the cy~inders is pressurized by accumulators 12 and these accumulators in turn are charged by fluid under pressure furnished by a pump housing 15. The pressure line for charging the accumulat~rs is identified by reference character 16. The exhaust fluid, exhausted from the retarder cylinders after use, is returned to the pump housing through the return conduit 17.
It will be appreciated from what is shown in Fig. 1 that the hydraulic requirements are immense. Huge volumes of fluid under pressure are circulated over a considerable distance, resulting in pump ~?ear seldom encountered elsewhere. The chanees ~or contaminated hydraulic fluid are quite large. Consequently, the factors of pump wear and likelihood of conta?nination drastically effect reliability from the standpoint of sustained operation over a protracted period of time. Under the present invention, as will now be described, pump and filter performance are constantly monitored, not only to give warning of a decline in operating efficiency, but also to maintain aperating efficiency 7692~
in spite of a failcd pump and~or a failed filter unit.
As shown in Fig. 2, a reservoir 20, located at the pump housing, is defined by a pair of adjacent tanks 21 and 22, the construction of which will be described in more detail ~elow.
For the present, it is sufficient to point out that oil returned from the retarder system is delivered to tank 21, filtered and transferred to tank 22 which contains the supply of hydraulic fluid for the pressure pumps.
The pressure pumps and associated filter units are shown in Fig. 6. Three motor operated pumps lPl, lP2 and lP3 are arranged in parallel with three associated filter units, lFl, lF2 and lF3. In normal operation only two of the pumps will be active, say pumps lPl and lP2, while the third pump and its associated filter unit constitute a reserve unit.
Each pump delivers hydraulic fluid under pressure through an outlet 40 and this outlet is branched at 41 and 42 to deliver fluid under pressure to a pair of parallel filter elements 43 and 44, coliectively constituting the filter unit.
In turn, the outlets of the filter elements are connected to a common conduit 46 leading to a flow meter lFMl. The outlet of each flow meter is connected to a common manifold 52 representing the pressure line 16 identified in Fig. l.
The filter elements are adapted to filter contaminants of fifteen micron size.or larger.
Efficiency of each filter unit is constantly monitored or sensed by a pair of differential pressure switches lF1-S1 and lFl-52 and to this end the pressure switches are interposed in a conduit 58 connected at its opposit ends respectively to the downstream and upstream conduits 40 and 46.
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~.s the filter elements become co~t~ninated by the filtered I -particles, the pressure rises although the rate of delivery by the pump will remain constant. Pressure switch lFl-Sl is normally open but is pre-set to close when the pressure of the hydraulic fluid being circulatcd rises to a value representative of a marginal filter condition, that is, indicative of a decaying filter of declining effectiveness, approaching a fully inoperative condition, say a 30~ contamination level. l~en switch lFl-Sl closes a warning signal is given, either by lightiny a lamp or sounding a buzzer so that the operator in the hump tower is warned of imminent filter failure.
Switch lFl-S2 on the other hand is pre-set to close ~hen the pressure drop across the filter unit reaches an abnormally high value indicative of an unacceptable filter conditio~, say an 80% contamination level. ~hen switch lFl-52 closes, the motor lMl for driving the associated pump is de-energized to deactivate the pump.
It may be mentioned at this point that the ~onitoring means for each pressure pump is identical and consequently to avoid needless repetition the reference characters are only selectively applied.
When a pump is deac~ivated because of a failed filter, the reserve pump is placed on stream by energizing its motor as will be explained.
-Each flow meter is equipped with three switches: one to identify a failed flow meter tlFMl-s3)~ one to identify that the pump is delivering fluid at a marginal rate, near failure (lF~ Sl), and one to identify that the flow rate is so low that the pump is deemed to be in a wholly ineffective state, switch lFMl-S2.
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The flow meter is of known form and incorporates an element (not shown) for measuring the rate of flow. ~f the element itself fails, switch lFMl-S3 is actuated to preclude needlessly servicing the pump. On the other hand if the metex element which measures flow reflects a flow rate approaching' an unacceptable pump efficiency level (say 80% effective) switch lFMl-S1 closes in response thereto; and if the meter element reflects a flow rate so low that the pump is deemed in a failed condition (say 70~) switch lFMl-S2 closes in response thereto. If either switch lFMl-53 or lFM1-S2 closes in response to a condition deemed "failed", its pump is disabled and the reserve pump is actuated. If switch lF~l-Sl is actuated, a warning is given that the pump is in a near fail state.
The exchange pump and filter system is similar, Pig. 7, but only two pumping units, rather than three, are involved, one for normal operation ~2Pl) and one (2P2) for emergency in case the other fails. The exchange pump units are preferably embodied in tandem pumps as 2Pl-~ and 2Pl-B having a common shaft driven by one motor as 2~1.
Each pump as 2Pl withdraws from tank 21 the fluid returned from the retarder cylinders. This unfiltered fluld is delivered by a pair of separate conduits 60 and 61 first to a pair of related filter units 2Fl and 2F2 (forty micron filter size) and from thence to a filter unit 2F3 having two parallel filter elements 63 and 64 ~fifteen micron size) connected by respective conduits 65 and 66 to the outlets of the pumps 2Pl-A and 2Pl-B.
The fluid filtered at 2F3 is delivered by a conduit 68 to a flow meter 2FMl and from thence to conduits 70 and 71 which feed tank 22 at the pressure side of the pump housing.
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Ffficiency of the filter units 2Fl and 2F2 is monitored b~ vacuum s~itches 2Fl-Sl and 2F2-Sl to detect a failing or marginal condition defined ahove; likewise as to switch 2F3-S~
for filter unit ~F3. '~acuum s~itches 2~1-52, 2F2-S2 and 2F3-52 monitor the filters for a failed condition as defined ahove.
If one of the switches 2Fl-Sl, 2F2-Sl or 2F3-Sl is actuated a warning is given and if one of the switches 2Fl-S2, 2F2-S2 or 2F3-S2 is actuated, the pumping unit 2Pl is disabled and the other pumping unit 2P2 is automatically placed on stream as will be explained.
The flow meter 2FMl monitors pump performance. It is equipped with three switches: one to identify a failed flow meter condition (switch 2FMl-S3), one to identify that the pump is delivering fluid at a marginal rate, near failure ~2FMl-Sl) and one to identify that the flow rate is so low the pump is deemed to be in a failed state, switch 2FMl-S2.
If the measuring element of the flow meter itself fails, switch 2FMl-S3 is actuated to preclude needlessly servicing the pump. If the flow meter reflects a flow rate approaching an unacceptable pump efficiency level switch 2FMl-Sl closes in response thereto; and if the meter reflects a flow rate so low that pump 2Pl is deemed in a failed condition switch 2FMl-S2 closes in response thereto. If either switch 2FMl-S3 or 2FMl-S2 closes in response to a condition deemed ~failed", - pump 2Pl is disabled and the reserve pump 2P2 is actuated.
If switch 2FMl-Sl is actuated, a warning is given that the pump is in a near fail state.
~. , , , ,. : . ., : . , -. . ' ,' '' , ~ ' 1C~769Zl The construction of the reservoir is shown in Figs. 2, 3, 4 and 5. Tank 21 receivcs from return conduit 17 the unfiltered oil returned from the retarder cylinders. The return oil is under a great deal of pressure and is preferabl~
- delivered to a submerqed diffuser 80, inside tank 21, Fig. 2.
The diffuser, constituting the outlet of return conduit 17, has p~rforated hollow sleeves which separate the stream of return fluid into numerous jet sprays within a diffuser outlet chamber 81 of tank 21. Fnergy is thus removed.
The tank 21 is further divided into a plurality of chambers 83, 84 and 85 hy serpentine haffles 86 ~hich reduce turbulence, further reaucing the energy level. There are three baffles and-as shown in Fig. 4 the me2ial one is elevated ahove the bottom ofthe tank to induce a tortuous flow between the chambers defined by the spaced baffles.
Chamber 85 of tank 21 containing the unfi]tered oil is tapped by the conduits as 60 and 61 which feed the exchange pump and filters. The inlets or entry ports of these conauits are isolated from one another by dividers as 88, preventing the formation of interfering vortexes due to the suction effect of the exchange pump leg.
The active exchange pump t2Pl or 2P7, Fig. 2) delivers filtered oil through a transfer conduit 71 whieh terminates in another diffuser 90 (outlet) submerged in the second or pressure tank 22 which constitutes the reservoir for the pressure pump leg. Tanl: 22 is also equipped with serpentine baffles 91 to remove turbulence, and is also equipped with div~der plates 92 which isolate the inlets to the three conduits 93-1, 93-2 and 93-3, Fig. 2, which supply the :
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respective pressure pumps lPl, lP2 and lP3, Fig. 6~ again for the purpose of preventing vortcx overlap.
In order to remove exceedingly fine particles, a silt or slurry pump circuit is employed. This circuit or leg comprises a pu~p lP4, Fig. 2, and related filter unit lF4 ~three micron size), Fiqs. 2 and 6. The silt pump withdraws filtered oil from tank 22 and returns it to tan'- 22 through conduit 97 as shown in Fig. 2.
To maintain a constant interchange between filtered and unfiltered oil, overf~ow pipes 95 are positioned to tap oil at level L2 to tank 22, returning filtered oil to tank 21 having a lower level Ll. The different levels are a manifestation of the requirement that the exchange pump must deliver oil at a rate qreater than the rate of extraction by the pressure pumps.
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- 1~769Zl ELECTRIC~L CONTROL
A. NO~E MODE:
The motor-operated pump control po~er source ~1, Fig. 8, is connected to hand-operated 3-position and 3-pole rotary selector switch E2. This selector switch has three functions:
Local, Off and Remote. Local position is primarily used for pumping system start up and maintenance. The Off position is used to remove all electrical control power from the pumping station. Remote position is used to operate the pumping station from any convenient location.
With switch E2 on Remote position, close switch E3:
energize control relay coil E4; relay contact E5 closes.
Control current flows from power source El through selector switch E2, relay contact E5, normally closed rela~ contacts E6, E7 and E8, selector switch E9 (exchange pump standby selector switch, select any one of two positions) circuit brea~er auxiliary contact E10 (hand operate), and normally closed control relay contacts Ell, E12, E13, E14 and E15.
Exchange pump motor starter thermal overload contacts may be inserted. ~t this point in time, pump motor starter coil F.l9 is energized to close the main motor contactor E20. The motor-operated exchange pump 2Pl begins to operate.
Normally closed auxiliary contact E23 of main contactor E20 and time delay contact E24 are opened, preventing standby motor-operated exchange pump 2P2 from operating.
Control relay coil E25 is enerqized. The contacts of this relay, E25, Fig. 10, are used to control monitoring indicating lights.
Time delay rela~ coil E26 is energized. Delay contact E27 will close at a pre-determined time. The purpose of this . ': ' ~ '' ' : , ' . . , ., , ~ .
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769Zl relay is to prevent the failure detecting circuits from operating until pump speed and hydraulic oil f]ow are normalized. Time delay coil E28 is also energi~ea.
At a pre-determinea time, relay contacts E2~ and E29 will close. Relay contact E29 is shown in Fig. 11 ana so are the other relays, contacts and switches now to be described.
Since remote control relay coil E4 is already energized, relay contact E30 is also closed. Control current flo~7s from control po~er E31 through time delay relav contact E~9, remote control contact E30, control relay contact E32 ana selector switch E33. The latter is the pressure pump standby selector, positioned in any one of three positions. Assume pOsition 1 is selected: control current continues through circuit breaker auxiliary contact E34 (hand operate), and normally closed control relay contact E35, E36 and E37. Pressure pump motor starter thermal overload contacts may be inserted.
Pump motor starter coil E41 is energized and closes main contactor E42, whercupon motor-operated pressure pump lPl begins to operate.
At the same time control relay coils E44 and F.45 are energized: open normally closed contact E46 to de-energize control relay coil E47, and through relay contact E48 energize the unloader solenoid valve E49. The unloader is shown schematically in Fig. 6. In this manner, there will be zero load on the pressure pump whenever there is a requirçment for the pump to start up.
At a pre-determined time, delay contact E50 is closed, which allows the pressure system to cycle automatically from the unloading mode (solenoid valve E49 energized) to the load-ing mode where solenoid valve ESl is energized.
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Time delay contact ES2 will close at a pre-determined time. This delay closure will prevent the failure detccting circuits from operating until pump speed and hydraulic oil flow are normalized.
Motor-operated silt pump lP4 will start to operate at the same time as pressure pump lPl. Thus, control current flows through Fircuit breaker auxiliary contact E53 and control relay contact E~; starter coil E5~ is energiæed, starting the silt pump.
~hile pressure pump lPl is in operation, time delay relay coil E59 is energized. After a pre-determined time delay, relay contact E60 is closed which permits control current to energize the second pressure pump lP2. Time delay relay coil E62 and its contact E63 are used to prevent operation of the standby pressure pump lP3. The reason for allo~ting only one pump to start at a time, except the silt pump, is to ~eep the starting current demand low.
In normal operation of the system, one of the pressure pumps is de-energized as a standby. To accomplish this, normally closed auxiliary contacts E64 and E65 are held open due to themain contactor coils being energized.
Summary of the normal mode operation is as f~llows:
a) Selector switch E2 on Remote position;
b) Standby exchange pump selector switch E9 in one of two positions. ~For purpose of explanation, position 2P2 is selected, mean-ing exchange pump 2P2 is on standby.
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c) Standby pressure pump selector switch in one of three positions. (For purpose of explanation, position rlo. 1 is selected placing pump lP3 on reserve) d) Turn switch E3 to On position.
e) ~xchange pump 2Pl operates immediately;
standby pump 2P2 remains inoperative.
f) After a time delay, pressure pump lPl and silt pump lP4 automatically begin to operate; pressure pump lP2 and standby pressure pump lP3 remain inoperative.
g) After another time delay, pressure pump lP2 begins to operate; standby pressure pump 1~3 remains inoperative.
h) Loading and unloading cycles are automatically controlled by pressure switches E67 and E68. Switch E67 opens above 800 psi and switch E68 closes below 700 psi.
i) Normally, one exchange pump, two pressure pumps and th~e silt pump are always in operation. In the event of malfunction, the faulty pump will be disabled and the standby pump will be automatically set in operation.
1{~769Z~ -B. W~RNI~G MODE:
Typical ~arnina and failure modcs ~till be descrihed in detail for the exchanae pumps 2Pl and ~P2, Fig. 10. I~'arninq circuits of the same order are employed for the pressure pumn.
lPl, lP2 and lP3, Fig. 13, but will nnt be described in detail since they can be traced on the basis of the detailed explanation now to ~e given for the exchanqe pumps.
Contacts ~25'of relay E25 are closed, Fiq. 8. r~hen filter-operated s~itch 2Fl-Sl, Fig. 10 (and see Fiq. 7) detects a pre-set limit of warning contamination in the leg of pumo 2Pl, switch 2Fl-Sl closes, lighting lamp ~70. Lamo E70 may be at the pump house. Relay coil 71 i.s enersized for remote warning indication which may be located in the hump tower.
lqarning switches for flow meter indication of a failing exchange pump, sw.itch 2FM-Sl for pump 2Pl, Fiq, 10 (and see Fig. 7) establish warnings. The warning circuits do not cause a shift to the standby exchange pump, deemed to be pump 2P2.
The same warninas for filter conta~ination and failinn nump are imposed on the standby exchange pump 2P2, Fig. 8, the silt pump lP4, Fig. 11, and the pressure pumps as shown in Fiq. 8.
Thus e~change oump 2r2, silt pump IP4 and each of the three nressure numps areassociated with a filter conta~ination warninq s~itch (as lFl-Sl for oressure pump IPl, Fiq. 13) and a failing pump ~-arning switch (as lF~l-Sl for oressure pump IPl, Fig. 13).
C. FAILUR~ MODF:
When filter-onerated switch 2Fl-52~ Fiq. 8, cetects a pre-set limit deemed to be a filter failure, the switch closes, .
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energizing control relay coil ~73 which closes relay (holding) contacts E74, Fia. 8, and F75, Fig 10. The related uarninq lamp is thus held lit. ~elay contact ~]1 o~ens, Fig. 8. ~he main contactor coil Elq is de-energized and the e~change num~
2nl ~ill be disahled.
Since main contactor coil ~19 is de-energizea as a result of contacts Ell openina upon energizing relay E73, auxiliary contact E23, Fig. 8, of main ~otor contactor returns to its normal closed position, causing standbv motor-overated e~:chanqe pum~ 2P2 to operate. ~olding contact E74 k~eps rela~ 73 energized and nrevents pump 2Pl from being restarted until after the highly contaminated ~ilter 2~1, Fia. 7, in the leg of pump 2Pl is replaced therehv to de-energize relay coil ~73.
Rela~ contact E75r Fia. 10, is used to liqht ~he related failuxe identification lamP and for rcmote warnina indication.
The other filter failure switch 2F2-~2, Eia. 7, for exchanqe ~ump 2Pl operates in the same ~anner, equally true of the other exchange pumD 2P2.
In the event of pum~ failure tdetected at the flo~r meter) s~ritch 2FMl-S2 is closed, Figs. 7 and 8, energizina relav E78 and closing contacts E79 (holding) and E80. Lamp F81 li~hts for local warnina. Contact~14 controlled ~y relay ~78 opens, de-energizing coil rl9 tQ stop pump 2Pl. Cont~ct ~23 closes, placi~g the stand~y nu~ 2~2 in o~eration. ~?oldinq contact E74 prevents ?ump 2Pl from being restarted (that is, coil E78 is held energized to hold contacts ~14 open) until it is repaired or replaced; reset by switch ~6.
If the flow meter fails, s~itch 2~ 3 ~los~s (see ~i~s.
7 and 8) energizina relay F84. Contacts ~15 o~en, pum~ 2~1 3n is disabled and lamp E85 $s lit.
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~ hesc operations also appl~, to the pressure pump legs in the filtered tan]~ 22: failed filter s~!itch lFl-S2; failed , pump switch lEMl-S2; and failed flo~s mcter s~!itch lFMl~S3.
~ en the fail~re has been corrected in the ].eg reprcsented by pump 2~1, selector s~;itch F9, Fig. 8, is repositioned to posi.tion '.lo. 2 to place pumn 2Pl in automatic standby. r~eset st-itch ~96 is actuated to dro~ out relay R73, e~tinguishing the indicator lam~. ~Jith switch E9 in position ~o. 2, relav El9 ~ill be energized to start ~otor 2?Sl only in the event pumn 2P2 is disabled because of a failure, resulting in a closure of contacts ~97 normally open so lonq as motor 2rl2 is operating.
D SYS?E~l Ft~ILVRR r~DF ()PFI~IO.'~:
~ side from a poter failure, the follo~.~ing conditions are consi.dered as an entire system failure as sho~m in Fig. 10:
a) tt~o e~change pum~as failed (contacts 2~.1 and 2~2);
b) three pressure pumPs failed (contacts lRl, lK2 an~
lY~3); or c) yard pressure failed (see switch PS-3, Fi~. Il) meaning relay 1~,~16 is de-energized, opening contacts lKlG.
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10769Zl . SU~ Y OF ~ r~ Ar7D FATL~D MO~E~:
A11 pumPs (ressure, e~changer and silt or slurrv) deliver through a filter havin~ a sensin~ means in the for~
of a pressure differential switch to detect ~oth a filter condition a~proachinq unaccepta~le contamination (warninq) and a comnletely unacceptable level of filter contaminatiOn.
T~e latter is dee~ed a filter failure. ~hese conditions have been described in detail for the e~change- ~Ump svstem and can be traced for the pressurc pumps.
In the event a failing pumn, detected at the flow meter, warning is also given in the e~change pumP and pressure DUmp leqs.
In the instance of the silt pt~p IP4, it can also he seen in Fia. 13 there is a filter onerated s~-itch lF4-Sl for ~,larning of a near failure an~ as shown in Fig. 11 there is a second filter s-ritch lPA-S2 for sensing a failed filter in the silt pump leg. If this latter switch is operated, relay lR14 is energized; its contacts 1~13, Fig. 13, are closed to light a lamP.
There is no standby silt pump; nor does the silt pump leg include means to detect either a failing pump or a complete ~ump failuxe. On the other hand, if a filter for the operative exchange pump fails ~e.a. 2Pl) or if its motor or 1O~q-meter fails:
a) one of four relays is energized, Fiq. 8:
2K3, 2~4, 2R6 or 2X7;
h) the related relay contacts open to disahle the pump motor, Pig, 8;
c) contacts E23~open when pump motor 2MI is energized) revert to closed position, ~lacing the motor of pump 2D2 in operation;
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7~;9;~
d) the failed con~ition is corrected; and e) s~iritch ~9 is set to ~.lo. 2 position, readyin~
pwnp 2Pl as the stand~v.
Rs for the pressure pum~ sv~tem i.n a faile~ mode, and assuming se]ector s~,ritch P9 (Fi~. 11) set to positi.on .~To. 1 (mhich assi~ns pumr IP3 the standhy role~ motor relay cont~cts ~64 ana E64' ~pump motor lrtl~ are open as ].ona as the motor for pump lP]. is energi~ed, and relav contacts ~65 (motor for pum~ lP2)are also onen.
.~ No~r if any one of the ~ailure mocle s-ritches in the ].eo of pu~ 1 is actuatcd (lPl-~?. or lF~1-57 or l~Ml-~3) an~
with contacts ~60 and ~63 closed:
a) relay lI'4j lY~5 or lK6 is ener~ized and its contacts o~en;
h) motor relay lMl (~41) is there~y de-enerqized and its contacts are reversed (e.. contacts E64 and ~64' close);
c) contacts P65 are open because it is assumed there is no failure in the leg of pump lP2 but since motor relav lr~l is de-energized its contacts F64 close, placinq pump lP3 on stream;
d) concurrentlv contacts ~64' close an~ the contacts ~66 of the motor relav for the motor of pumn lP3 open, so that e) pumps lP2 and lr3 are on stream.
~he failure in the leg of pump lPl is remeAi.ed and the selector s-ritch may be set to No. 2 position, which readies pump lP2 to he the standby.
: ~, ' :, ' ' - ., ' " ' ' ' ' ~ 769Zl When a predetermincd high temperature ~sa~ 160F) is reached either in the unfiltered tank 21 or filtered tank 22 a related thermal switch F7h (Fiq. 8) located in tank 21 (return oil) or X77 (Fia. 11) located in tan~ 2~ is closecl to enerni~
relay coil ~88 or ~89, openincJ normallv closed contact ~6 or E8, Fig. 8, to disa~]e the exchange pumps. Wonetheless, the pressure ~ums will re~a;n in operation until a low oil 5witch E90, Fig. 11, located in tank 22, is activated to energize reiav coil ~91, openirg relav contact F3?, Fiq. 11. A low oil switch F90 is also located in the unfiltered tank 21, Fig~ 8. From the time a high temperature condition is detected urtil the entire system is shut down is approximately two minutes.
If desired, heat exchanae fans may be used to keep the oil cool h~lt nonetheless the high temperature and low oil sensors will be used.
When a precletermined low te~oerature (sav-20F) is reached either in the unfilterecl tan~ or filtered tank, switch ~92 or ~93, Fig. 8, is closed to eneraize relay coil E94, Piq. 8, openina relay contacts F98 (Fia. 8) and F99 (Fig. 11) to de-activate the filter and flow-meter fault monitoring circuits.
T~is avoi~s faulty indications due to the viscosity of the oil at low te~perature. The exchanae and pressure ~um~s wil] remain in oparation; a warninq light is lit locallv and remotely.
The lamp circuitry shotm in Fiqs. 10 and 13 mav ~e extended to siqnal kich ancl low t~mperatures, low oi] and oil over-fill.
The unloader, FiqO 6~ is employecl to allo~ the pressure pumos to start aaain~t a no-load condition a.s already explained.
At the commencement of start-u~, contacts ~46, F~a. 11, open ~C~7692~
when relay P45 .is energized, de-energi~ing re~av ~7 and al~.owin~
~ts colltact~ ~4~ to revext to the nor~].ly c]os~d condition. As a consc~uence the 4-way unloader va].ve i.~ opened and there is no resistance to the pressure pum~s.
S~!itch ~58 is closed (closed below 700 p5i) 50 ~.~hen the timc delay contActs ESO close, rela~ ~47 is ener~ized and its contacts reverse, energizing solenoid valve F51 to place the 4-way valve in the system loading moae.
It will be seen from the foregoing that oil, used to operate the retarders, is returned to tank 21. Turbulence is removed by the baffles 86 prior to the return oil entering the inlet ports which communicate with th~ exchange pump.
The exchange pump 12Pl or 2P2) sends the oil through a filter (see Fig. 2) and the filtered oil is delivered to an outlet in the second tank hy means of a transfer conduit 71.
Turbulence of oil in the second tank is removed by baffles 91. Very fine particles of contaminant in the oil, not removed by the exchange pump filters, are removed by a filter lF4 servïced by a pump lP4, both interposed in a recirculating conduit 97, Fig. 2.
Oil is pumped from tank 22 by a plurality of activated pressure pumps. To prevent vortex overlap, the inlets to the pressure pumps are isolated from one another by dividers 92, Fig. 2. The same arrangement is employed (dividers 88) for the e~change pump inlets. . .
If a pressure pump ~or exchange pump) fails, the reserve pump is activated and the failed pump is deactivated, automatically. The same automatic switch-over occurs in the ~nstance of a failed flow meter or failed filter in a '.' ' , '' , , '' ' ;,: . ' ' ' :
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10769Zl pressure pump leg or an exchange pump leq.
Such automatic corrections occur as an incident to operation of a sensing means as switch lFMl-52, Fiq. 6, which senses flow rate; switch lF~ 3 ~hich detects failure of the flow meter measuring element; and s~itch lF1-S2 which senses pressure drop across the related filter.
Jf a failed condition is sensed, a relay is energized;
such as relay ~73, Fiq. 8, and a s7arninq is given, e.g. a lamo is lit. .~t the same time, corresponding motor relay contacts such as contacts E20, Fig. 9, are opened to disable the pump and other motor relay contacts are closed to activate the reserve pump.
r~hen a sensing means detects a pumn or filter is nearing failure, a warning is given.
~ eferring to Figs. 10 and lOA, any warning of approaching failure i5 manifest in a lamp as ~70 being lit locally at the pump house (Fig. 10), and remotely as well tFig. lOA) as for instance by a lamp P102 at the control tower where the yard operator is in charqe.
The remote signals,-Fig. lOA, include a lamp E103 identified ~i~h "system failed" and another lamD E104 signifying the system is in a normal mode.
Lamp E103 will be lit ~nd E104 extinguished) as long as relay E106, Fig. lO, is de-energized; lamp E104 will be lit ~and E103 extinguished) if relay E106 is enerqized.
Thus, if the yard pressure is inade~uate, contacts lX16, Fig. 10, will remain open and lamp E103 will remain lit.
If both exchanqe pumps fail, both sets of contacts E108 and E109, Fig. 10, are open; relay E106 is de-energized and lamp E103 is thereunon lit to show a failed svstem; contra if -` 107692~
one exchange pump is workina in the normal mode.
If all three pressure pumps fail, the circuit for relay Elt)6 is open at lKl~ lK3, Fig. 10, and lamp E103 is lit;
~ contra if one pressure pump is in working order.
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This invention relates to hydraulic apparatus principally intended to supply hydraulic requirements for retarders in a railroad classification yard.
Railroad cars are segregated according to destination in a rallroad classification yard. The cars to be classified or separated according to destination are switched to the various classification tracks. It is customary to slow the cars to a safe coupling speed by means of retarders insta~led at predetermined positions along the classificatior. tracks.
llydraulic controls are usually employed. U.S. patent ~os.
3227246 and 3809188 disclose retarders which employ hydraulic cylinders.
The hydraulic requirements are very extensive since the hydraulic fluid must be transmitted under pressure over a considerable distance. The required force is of considerable magnitude. If there is a pressure failure, the car cannot be brought to a safe speed, in which event the car couplers and the lading as well can be damaged.
The primary object of the present invention is to reduce the possibility of such damage by incorporating in the hydraulic system a redundant arrangement of pumps and related filter units and to constantly monitor performance to detect both failing ~decaying) and failure conditions in terms of pump and filter efficiency, enabling remedial action to be timely applied.
Pnother object of the invention is to incorporate in the - system a reserve unit which is automatically o2erated in the event a failure is detected, while concurrently disabling the failed unit. Another object of the invention is to create warning signals in the event a near failure condition is detectedO
10~76921 ,, .
Specifically, it is an object of the invention to monitor filter efficiency, activating a reserve pump and disabling the active pump ~or pumps) in the event a threshhold of pump l-'ailure is detected or in the event a predetermined level of declining filter efficiency is detected. A further object of the invention in this regard is to employ in redundant relat~on two active pumps and a single reserve pump, together with related filter units, such that in the event both active units are sensed as being in a failed condition, the reserve unit may be relied on for a limited time.
Other objects of the invention are to utilize a flow meter to determine if a pump is either in a failing condition or has failed; to sense the pressure drop across the filter by means of differential pressure switches responsive to co~plete filter failure or a failing (decaying~ filter condition: to enable the failing or failed condition to be remediea by relying on a reserve pump and filter unit; and to enable appropriate signals to be created so that the operator of the classification yard may be aware of the downstream circumstances.
~ reliable and efficient pump operation r~quires clean hydraulic fluid. Contamination results in pump wear and filter inef~iciency. According'y, another object of the invention is to empioy exchange pumps for delivering the unfiltered hydraulic fluid to exchange filter units prior to delivering the return fluid to the reservoir tank which supplies the pressure pumps.
The exchange pumps and the exchange filters preferably incorporate the redundant features imposed on the pressure pumps.
Since contamination particles break up when the fluid is pumped and become smaller in size, it is possible for the clean side of the reservoir to be contaminated with exceedingly fine , ,' ~76~21 but nonetheless destructlve particles which are not captured by the exchange filters. Accordingly, additional objects of the invention are to utilize a silt pump and silt filter at the clean side of the reservoir and to construct a rcservoir which both eliminates turbulence and which accounts for highly efficient transfer of fluid.
This application is a division of Canadian Application Serial No. 265,003 filed November 5, 1976.
The invention as defined in the parent application defined hereinabove provides in a hydraulic system where filtered oil in a reservoir is to be delivered under pressure by a pressure pump to a remote location and returned to the reservoir, reservoir apparatus comprising a first tank for receiving the return oil;
a second tank for containing the oil to be delivered; a pres~ure pump communicating with a pump inlet port in the second tank for delivering oil in the second tank to the remote location; a return conduit terminating at an opening in the first tank for feeding return oil to the first tank; an exchange pump connected with an exchange pump inlet in the first tank for transferring oil from the first tank to the second tank through a transfer conduit having an outlet in the second tank and having a filter interposed between that outlet and the exchange pump; a plurality of baffles interposed between the .~nlet port in the second tank and the outlet in the second tank to remove turbulence from the transfer oil entering the second tank; and a plurality of baffles in the first tank interposed between the opening of the return conduit -and the inlet to the exchange pump to remove turbulence from the oil returned to the first tank.
On the other hand the present invention provides, ln a 10769Zl rallroad classifi.cation yard having hydraulically operated retarders infitslled at selected positions along the classification track system, apparatus for furnishing hydraulic fluid to operate the retarders and co~prising: (a) a plurality of motor-driven pumps, at least one to be a normally active.pump and one to be a normally inactive reserve pump; (b) a plurality of.filter units, one for each pump, and through which the related pump moves fluid under pressure; (c) means to sense the pressure drop across each filter unit and to activate the reserve pump while deactivating the active pump in the event the pressure drop exceeds a predetermined value characterizing unacceptable filter efficiency; and (d) means to sense the pressure drop across each filter unit and to generate a signal when the pressure drop indicates a filter unit is approaching unacceptable efficiency.
Furthermore the present invention may be considered to provide, in a railroad classification yard having hydraulically operated retarders installed at selected positions along the classification track system, apparatus for furnishing hydraulic fluid to.operate th-e retarders and comprising: (a) a plurality of motor-driven pumps, at least one to be a normally act$ve pump and one to be a normally inactive reserve pump; (b) a plurality of filter units, one for each pump, and through which the related pump moves fluid under pressure; (c) means to sense the pressure drop across each filter unit and to activate the reserve pump whlle deactivating the active pump in the event the pressure drop exceeds a predetermined value characterizing unacceptable filter efficiency; and (d) a flow meter to measure the flow of each pump and to generate a signal when the measure indicates a pump is approaching an unacceptable flow rate.
- 3a -769Z~
In the drawing: .
Fig. 1 is a schematic view of a railroad classification yard;
Fig. 2 is a plan view of an oil res~rvoir and Figs. 3, 4 and 5 are sectional views thereof;
Figs. 6 and 7 are sche~.atic views of hydraulic circuitry; and Figs. 8 throush 13 are wiring dia~rams.
1~76~21 ~ i~. 1 of the drawing is a schematic vie~ of a typical retarder installation in a railroad classification yard. The c:lassification tracks are identificd hy reference character 10.
C)n the up-stream side there is a so-called hump (not show?l) where an operator at a console assigns the individual cars to a selected one of the classification tracks. The car to be classified acceleratcs down the grade of the hump, by gravity fall, and is automatically switched to a particular classification track.
The individual retarders are identified by reference character 11. The retarder controls include cylinders, not shown herein but of the character disclosed in patent Nos.
3227246 and 3809188. Hydraulic fluid for the cy~inders is pressurized by accumulators 12 and these accumulators in turn are charged by fluid under pressure furnished by a pump housing 15. The pressure line for charging the accumulat~rs is identified by reference character 16. The exhaust fluid, exhausted from the retarder cylinders after use, is returned to the pump housing through the return conduit 17.
It will be appreciated from what is shown in Fig. 1 that the hydraulic requirements are immense. Huge volumes of fluid under pressure are circulated over a considerable distance, resulting in pump ~?ear seldom encountered elsewhere. The chanees ~or contaminated hydraulic fluid are quite large. Consequently, the factors of pump wear and likelihood of conta?nination drastically effect reliability from the standpoint of sustained operation over a protracted period of time. Under the present invention, as will now be described, pump and filter performance are constantly monitored, not only to give warning of a decline in operating efficiency, but also to maintain aperating efficiency 7692~
in spite of a failcd pump and~or a failed filter unit.
As shown in Fig. 2, a reservoir 20, located at the pump housing, is defined by a pair of adjacent tanks 21 and 22, the construction of which will be described in more detail ~elow.
For the present, it is sufficient to point out that oil returned from the retarder system is delivered to tank 21, filtered and transferred to tank 22 which contains the supply of hydraulic fluid for the pressure pumps.
The pressure pumps and associated filter units are shown in Fig. 6. Three motor operated pumps lPl, lP2 and lP3 are arranged in parallel with three associated filter units, lFl, lF2 and lF3. In normal operation only two of the pumps will be active, say pumps lPl and lP2, while the third pump and its associated filter unit constitute a reserve unit.
Each pump delivers hydraulic fluid under pressure through an outlet 40 and this outlet is branched at 41 and 42 to deliver fluid under pressure to a pair of parallel filter elements 43 and 44, coliectively constituting the filter unit.
In turn, the outlets of the filter elements are connected to a common conduit 46 leading to a flow meter lFMl. The outlet of each flow meter is connected to a common manifold 52 representing the pressure line 16 identified in Fig. l.
The filter elements are adapted to filter contaminants of fifteen micron size.or larger.
Efficiency of each filter unit is constantly monitored or sensed by a pair of differential pressure switches lF1-S1 and lFl-52 and to this end the pressure switches are interposed in a conduit 58 connected at its opposit ends respectively to the downstream and upstream conduits 40 and 46.
,.
1~76~2~
~.s the filter elements become co~t~ninated by the filtered I -particles, the pressure rises although the rate of delivery by the pump will remain constant. Pressure switch lFl-Sl is normally open but is pre-set to close when the pressure of the hydraulic fluid being circulatcd rises to a value representative of a marginal filter condition, that is, indicative of a decaying filter of declining effectiveness, approaching a fully inoperative condition, say a 30~ contamination level. l~en switch lFl-Sl closes a warning signal is given, either by lightiny a lamp or sounding a buzzer so that the operator in the hump tower is warned of imminent filter failure.
Switch lFl-S2 on the other hand is pre-set to close ~hen the pressure drop across the filter unit reaches an abnormally high value indicative of an unacceptable filter conditio~, say an 80% contamination level. ~hen switch lFl-52 closes, the motor lMl for driving the associated pump is de-energized to deactivate the pump.
It may be mentioned at this point that the ~onitoring means for each pressure pump is identical and consequently to avoid needless repetition the reference characters are only selectively applied.
When a pump is deac~ivated because of a failed filter, the reserve pump is placed on stream by energizing its motor as will be explained.
-Each flow meter is equipped with three switches: one to identify a failed flow meter tlFMl-s3)~ one to identify that the pump is delivering fluid at a marginal rate, near failure (lF~ Sl), and one to identify that the flow rate is so low that the pump is deemed to be in a wholly ineffective state, switch lFMl-S2.
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~0'769Z~
The flow meter is of known form and incorporates an element (not shown) for measuring the rate of flow. ~f the element itself fails, switch lFMl-S3 is actuated to preclude needlessly servicing the pump. On the other hand if the metex element which measures flow reflects a flow rate approaching' an unacceptable pump efficiency level (say 80% effective) switch lFMl-S1 closes in response thereto; and if the meter element reflects a flow rate so low that the pump is deemed in a failed condition (say 70~) switch lFMl-S2 closes in response thereto. If either switch lFMl-53 or lFM1-S2 closes in response to a condition deemed "failed", its pump is disabled and the reserve pump is actuated. If switch lF~l-Sl is actuated, a warning is given that the pump is in a near fail state.
The exchange pump and filter system is similar, Pig. 7, but only two pumping units, rather than three, are involved, one for normal operation ~2Pl) and one (2P2) for emergency in case the other fails. The exchange pump units are preferably embodied in tandem pumps as 2Pl-~ and 2Pl-B having a common shaft driven by one motor as 2~1.
Each pump as 2Pl withdraws from tank 21 the fluid returned from the retarder cylinders. This unfiltered fluld is delivered by a pair of separate conduits 60 and 61 first to a pair of related filter units 2Fl and 2F2 (forty micron filter size) and from thence to a filter unit 2F3 having two parallel filter elements 63 and 64 ~fifteen micron size) connected by respective conduits 65 and 66 to the outlets of the pumps 2Pl-A and 2Pl-B.
The fluid filtered at 2F3 is delivered by a conduit 68 to a flow meter 2FMl and from thence to conduits 70 and 71 which feed tank 22 at the pressure side of the pump housing.
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Ffficiency of the filter units 2Fl and 2F2 is monitored b~ vacuum s~itches 2Fl-Sl and 2F2-Sl to detect a failing or marginal condition defined ahove; likewise as to switch 2F3-S~
for filter unit ~F3. '~acuum s~itches 2~1-52, 2F2-S2 and 2F3-52 monitor the filters for a failed condition as defined ahove.
If one of the switches 2Fl-Sl, 2F2-Sl or 2F3-Sl is actuated a warning is given and if one of the switches 2Fl-S2, 2F2-S2 or 2F3-S2 is actuated, the pumping unit 2Pl is disabled and the other pumping unit 2P2 is automatically placed on stream as will be explained.
The flow meter 2FMl monitors pump performance. It is equipped with three switches: one to identify a failed flow meter condition (switch 2FMl-S3), one to identify that the pump is delivering fluid at a marginal rate, near failure ~2FMl-Sl) and one to identify that the flow rate is so low the pump is deemed to be in a failed state, switch 2FMl-S2.
If the measuring element of the flow meter itself fails, switch 2FMl-S3 is actuated to preclude needlessly servicing the pump. If the flow meter reflects a flow rate approaching an unacceptable pump efficiency level switch 2FMl-Sl closes in response thereto; and if the meter reflects a flow rate so low that pump 2Pl is deemed in a failed condition switch 2FMl-S2 closes in response thereto. If either switch 2FMl-S3 or 2FMl-S2 closes in response to a condition deemed ~failed", - pump 2Pl is disabled and the reserve pump 2P2 is actuated.
If switch 2FMl-Sl is actuated, a warning is given that the pump is in a near fail state.
~. , , , ,. : . ., : . , -. . ' ,' '' , ~ ' 1C~769Zl The construction of the reservoir is shown in Figs. 2, 3, 4 and 5. Tank 21 receivcs from return conduit 17 the unfiltered oil returned from the retarder cylinders. The return oil is under a great deal of pressure and is preferabl~
- delivered to a submerqed diffuser 80, inside tank 21, Fig. 2.
The diffuser, constituting the outlet of return conduit 17, has p~rforated hollow sleeves which separate the stream of return fluid into numerous jet sprays within a diffuser outlet chamber 81 of tank 21. Fnergy is thus removed.
The tank 21 is further divided into a plurality of chambers 83, 84 and 85 hy serpentine haffles 86 ~hich reduce turbulence, further reaucing the energy level. There are three baffles and-as shown in Fig. 4 the me2ial one is elevated ahove the bottom ofthe tank to induce a tortuous flow between the chambers defined by the spaced baffles.
Chamber 85 of tank 21 containing the unfi]tered oil is tapped by the conduits as 60 and 61 which feed the exchange pump and filters. The inlets or entry ports of these conauits are isolated from one another by dividers as 88, preventing the formation of interfering vortexes due to the suction effect of the exchange pump leg.
The active exchange pump t2Pl or 2P7, Fig. 2) delivers filtered oil through a transfer conduit 71 whieh terminates in another diffuser 90 (outlet) submerged in the second or pressure tank 22 which constitutes the reservoir for the pressure pump leg. Tanl: 22 is also equipped with serpentine baffles 91 to remove turbulence, and is also equipped with div~der plates 92 which isolate the inlets to the three conduits 93-1, 93-2 and 93-3, Fig. 2, which supply the :
: , 1~7692~
respective pressure pumps lPl, lP2 and lP3, Fig. 6~ again for the purpose of preventing vortcx overlap.
In order to remove exceedingly fine particles, a silt or slurry pump circuit is employed. This circuit or leg comprises a pu~p lP4, Fig. 2, and related filter unit lF4 ~three micron size), Fiqs. 2 and 6. The silt pump withdraws filtered oil from tank 22 and returns it to tan'- 22 through conduit 97 as shown in Fig. 2.
To maintain a constant interchange between filtered and unfiltered oil, overf~ow pipes 95 are positioned to tap oil at level L2 to tank 22, returning filtered oil to tank 21 having a lower level Ll. The different levels are a manifestation of the requirement that the exchange pump must deliver oil at a rate qreater than the rate of extraction by the pressure pumps.
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- 1~769Zl ELECTRIC~L CONTROL
A. NO~E MODE:
The motor-operated pump control po~er source ~1, Fig. 8, is connected to hand-operated 3-position and 3-pole rotary selector switch E2. This selector switch has three functions:
Local, Off and Remote. Local position is primarily used for pumping system start up and maintenance. The Off position is used to remove all electrical control power from the pumping station. Remote position is used to operate the pumping station from any convenient location.
With switch E2 on Remote position, close switch E3:
energize control relay coil E4; relay contact E5 closes.
Control current flows from power source El through selector switch E2, relay contact E5, normally closed rela~ contacts E6, E7 and E8, selector switch E9 (exchange pump standby selector switch, select any one of two positions) circuit brea~er auxiliary contact E10 (hand operate), and normally closed control relay contacts Ell, E12, E13, E14 and E15.
Exchange pump motor starter thermal overload contacts may be inserted. ~t this point in time, pump motor starter coil F.l9 is energized to close the main motor contactor E20. The motor-operated exchange pump 2Pl begins to operate.
Normally closed auxiliary contact E23 of main contactor E20 and time delay contact E24 are opened, preventing standby motor-operated exchange pump 2P2 from operating.
Control relay coil E25 is enerqized. The contacts of this relay, E25, Fig. 10, are used to control monitoring indicating lights.
Time delay rela~ coil E26 is energized. Delay contact E27 will close at a pre-determined time. The purpose of this . ': ' ~ '' ' : , ' . . , ., , ~ .
.
769Zl relay is to prevent the failure detecting circuits from operating until pump speed and hydraulic oil f]ow are normalized. Time delay coil E28 is also energi~ea.
At a pre-determinea time, relay contacts E2~ and E29 will close. Relay contact E29 is shown in Fig. 11 ana so are the other relays, contacts and switches now to be described.
Since remote control relay coil E4 is already energized, relay contact E30 is also closed. Control current flo~7s from control po~er E31 through time delay relav contact E~9, remote control contact E30, control relay contact E32 ana selector switch E33. The latter is the pressure pump standby selector, positioned in any one of three positions. Assume pOsition 1 is selected: control current continues through circuit breaker auxiliary contact E34 (hand operate), and normally closed control relay contact E35, E36 and E37. Pressure pump motor starter thermal overload contacts may be inserted.
Pump motor starter coil E41 is energized and closes main contactor E42, whercupon motor-operated pressure pump lPl begins to operate.
At the same time control relay coils E44 and F.45 are energized: open normally closed contact E46 to de-energize control relay coil E47, and through relay contact E48 energize the unloader solenoid valve E49. The unloader is shown schematically in Fig. 6. In this manner, there will be zero load on the pressure pump whenever there is a requirçment for the pump to start up.
At a pre-determined time, delay contact E50 is closed, which allows the pressure system to cycle automatically from the unloading mode (solenoid valve E49 energized) to the load-ing mode where solenoid valve ESl is energized.
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1(~7692~
Time delay contact ES2 will close at a pre-determined time. This delay closure will prevent the failure detccting circuits from operating until pump speed and hydraulic oil flow are normalized.
Motor-operated silt pump lP4 will start to operate at the same time as pressure pump lPl. Thus, control current flows through Fircuit breaker auxiliary contact E53 and control relay contact E~; starter coil E5~ is energiæed, starting the silt pump.
~hile pressure pump lPl is in operation, time delay relay coil E59 is energized. After a pre-determined time delay, relay contact E60 is closed which permits control current to energize the second pressure pump lP2. Time delay relay coil E62 and its contact E63 are used to prevent operation of the standby pressure pump lP3. The reason for allo~ting only one pump to start at a time, except the silt pump, is to ~eep the starting current demand low.
In normal operation of the system, one of the pressure pumps is de-energized as a standby. To accomplish this, normally closed auxiliary contacts E64 and E65 are held open due to themain contactor coils being energized.
Summary of the normal mode operation is as f~llows:
a) Selector switch E2 on Remote position;
b) Standby exchange pump selector switch E9 in one of two positions. ~For purpose of explanation, position 2P2 is selected, mean-ing exchange pump 2P2 is on standby.
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10~692~
c) Standby pressure pump selector switch in one of three positions. (For purpose of explanation, position rlo. 1 is selected placing pump lP3 on reserve) d) Turn switch E3 to On position.
e) ~xchange pump 2Pl operates immediately;
standby pump 2P2 remains inoperative.
f) After a time delay, pressure pump lPl and silt pump lP4 automatically begin to operate; pressure pump lP2 and standby pressure pump lP3 remain inoperative.
g) After another time delay, pressure pump lP2 begins to operate; standby pressure pump 1~3 remains inoperative.
h) Loading and unloading cycles are automatically controlled by pressure switches E67 and E68. Switch E67 opens above 800 psi and switch E68 closes below 700 psi.
i) Normally, one exchange pump, two pressure pumps and th~e silt pump are always in operation. In the event of malfunction, the faulty pump will be disabled and the standby pump will be automatically set in operation.
1{~769Z~ -B. W~RNI~G MODE:
Typical ~arnina and failure modcs ~till be descrihed in detail for the exchanae pumps 2Pl and ~P2, Fig. 10. I~'arninq circuits of the same order are employed for the pressure pumn.
lPl, lP2 and lP3, Fig. 13, but will nnt be described in detail since they can be traced on the basis of the detailed explanation now to ~e given for the exchanqe pumps.
Contacts ~25'of relay E25 are closed, Fiq. 8. r~hen filter-operated s~itch 2Fl-Sl, Fig. 10 (and see Fiq. 7) detects a pre-set limit of warning contamination in the leg of pumo 2Pl, switch 2Fl-Sl closes, lighting lamp ~70. Lamo E70 may be at the pump house. Relay coil 71 i.s enersized for remote warning indication which may be located in the hump tower.
lqarning switches for flow meter indication of a failing exchange pump, sw.itch 2FM-Sl for pump 2Pl, Fiq, 10 (and see Fig. 7) establish warnings. The warning circuits do not cause a shift to the standby exchange pump, deemed to be pump 2P2.
The same warninas for filter conta~ination and failinn nump are imposed on the standby exchange pump 2P2, Fig. 8, the silt pump lP4, Fig. 11, and the pressure pumps as shown in Fiq. 8.
Thus e~change oump 2r2, silt pump IP4 and each of the three nressure numps areassociated with a filter conta~ination warninq s~itch (as lFl-Sl for oressure pump IPl, Fiq. 13) and a failing pump ~-arning switch (as lF~l-Sl for oressure pump IPl, Fig. 13).
C. FAILUR~ MODF:
When filter-onerated switch 2Fl-52~ Fiq. 8, cetects a pre-set limit deemed to be a filter failure, the switch closes, .
, '. ' . : ' "' - " ~ ' .: '' .: . : ~ : .:
1~769~
energizing control relay coil ~73 which closes relay (holding) contacts E74, Fia. 8, and F75, Fig 10. The related uarninq lamp is thus held lit. ~elay contact ~]1 o~ens, Fig. 8. ~he main contactor coil Elq is de-energized and the e~change num~
2nl ~ill be disahled.
Since main contactor coil ~19 is de-energizea as a result of contacts Ell openina upon energizing relay E73, auxiliary contact E23, Fig. 8, of main ~otor contactor returns to its normal closed position, causing standbv motor-overated e~:chanqe pum~ 2P2 to operate. ~olding contact E74 k~eps rela~ 73 energized and nrevents pump 2Pl from being restarted until after the highly contaminated ~ilter 2~1, Fia. 7, in the leg of pump 2Pl is replaced therehv to de-energize relay coil ~73.
Rela~ contact E75r Fia. 10, is used to liqht ~he related failuxe identification lamP and for rcmote warnina indication.
The other filter failure switch 2F2-~2, Eia. 7, for exchanqe ~ump 2Pl operates in the same ~anner, equally true of the other exchange pumD 2P2.
In the event of pum~ failure tdetected at the flo~r meter) s~ritch 2FMl-S2 is closed, Figs. 7 and 8, energizina relav E78 and closing contacts E79 (holding) and E80. Lamp F81 li~hts for local warnina. Contact~14 controlled ~y relay ~78 opens, de-energizing coil rl9 tQ stop pump 2Pl. Cont~ct ~23 closes, placi~g the stand~y nu~ 2~2 in o~eration. ~?oldinq contact E74 prevents ?ump 2Pl from being restarted (that is, coil E78 is held energized to hold contacts ~14 open) until it is repaired or replaced; reset by switch ~6.
If the flow meter fails, s~itch 2~ 3 ~los~s (see ~i~s.
7 and 8) energizina relay F84. Contacts ~15 o~en, pum~ 2~1 3n is disabled and lamp E85 $s lit.
:. ~
~(~769Z~
~ hesc operations also appl~, to the pressure pump legs in the filtered tan]~ 22: failed filter s~!itch lFl-S2; failed , pump switch lEMl-S2; and failed flo~s mcter s~!itch lFMl~S3.
~ en the fail~re has been corrected in the ].eg reprcsented by pump 2~1, selector s~;itch F9, Fig. 8, is repositioned to posi.tion '.lo. 2 to place pumn 2Pl in automatic standby. r~eset st-itch ~96 is actuated to dro~ out relay R73, e~tinguishing the indicator lam~. ~Jith switch E9 in position ~o. 2, relav El9 ~ill be energized to start ~otor 2?Sl only in the event pumn 2P2 is disabled because of a failure, resulting in a closure of contacts ~97 normally open so lonq as motor 2rl2 is operating.
D SYS?E~l Ft~ILVRR r~DF ()PFI~IO.'~:
~ side from a poter failure, the follo~.~ing conditions are consi.dered as an entire system failure as sho~m in Fig. 10:
a) tt~o e~change pum~as failed (contacts 2~.1 and 2~2);
b) three pressure pumPs failed (contacts lRl, lK2 an~
lY~3); or c) yard pressure failed (see switch PS-3, Fi~. Il) meaning relay 1~,~16 is de-energized, opening contacts lKlG.
' -18-.
:
.- ' ~ ,. - ,:.
. " ,:
10769Zl . SU~ Y OF ~ r~ Ar7D FATL~D MO~E~:
A11 pumPs (ressure, e~changer and silt or slurrv) deliver through a filter havin~ a sensin~ means in the for~
of a pressure differential switch to detect ~oth a filter condition a~proachinq unaccepta~le contamination (warninq) and a comnletely unacceptable level of filter contaminatiOn.
T~e latter is dee~ed a filter failure. ~hese conditions have been described in detail for the e~change- ~Ump svstem and can be traced for the pressurc pumps.
In the event a failing pumn, detected at the flow meter, warning is also given in the e~change pumP and pressure DUmp leqs.
In the instance of the silt pt~p IP4, it can also he seen in Fia. 13 there is a filter onerated s~-itch lF4-Sl for ~,larning of a near failure an~ as shown in Fig. 11 there is a second filter s-ritch lPA-S2 for sensing a failed filter in the silt pump leg. If this latter switch is operated, relay lR14 is energized; its contacts 1~13, Fig. 13, are closed to light a lamP.
There is no standby silt pump; nor does the silt pump leg include means to detect either a failing pump or a complete ~ump failuxe. On the other hand, if a filter for the operative exchange pump fails ~e.a. 2Pl) or if its motor or 1O~q-meter fails:
a) one of four relays is energized, Fiq. 8:
2K3, 2~4, 2R6 or 2X7;
h) the related relay contacts open to disahle the pump motor, Pig, 8;
c) contacts E23~open when pump motor 2MI is energized) revert to closed position, ~lacing the motor of pump 2D2 in operation;
.
7~;9;~
d) the failed con~ition is corrected; and e) s~iritch ~9 is set to ~.lo. 2 position, readyin~
pwnp 2Pl as the stand~v.
Rs for the pressure pum~ sv~tem i.n a faile~ mode, and assuming se]ector s~,ritch P9 (Fi~. 11) set to positi.on .~To. 1 (mhich assi~ns pumr IP3 the standhy role~ motor relay cont~cts ~64 ana E64' ~pump motor lrtl~ are open as ].ona as the motor for pump lP]. is energi~ed, and relav contacts ~65 (motor for pum~ lP2)are also onen.
.~ No~r if any one of the ~ailure mocle s-ritches in the ].eo of pu~ 1 is actuatcd (lPl-~?. or lF~1-57 or l~Ml-~3) an~
with contacts ~60 and ~63 closed:
a) relay lI'4j lY~5 or lK6 is ener~ized and its contacts o~en;
h) motor relay lMl (~41) is there~y de-enerqized and its contacts are reversed (e.. contacts E64 and ~64' close);
c) contacts P65 are open because it is assumed there is no failure in the leg of pump lP2 but since motor relav lr~l is de-energized its contacts F64 close, placinq pump lP3 on stream;
d) concurrentlv contacts ~64' close an~ the contacts ~66 of the motor relav for the motor of pumn lP3 open, so that e) pumps lP2 and lr3 are on stream.
~he failure in the leg of pump lPl is remeAi.ed and the selector s-ritch may be set to No. 2 position, which readies pump lP2 to he the standby.
: ~, ' :, ' ' - ., ' " ' ' ' ' ~ 769Zl When a predetermincd high temperature ~sa~ 160F) is reached either in the unfiltered tank 21 or filtered tank 22 a related thermal switch F7h (Fiq. 8) located in tank 21 (return oil) or X77 (Fia. 11) located in tan~ 2~ is closecl to enerni~
relay coil ~88 or ~89, openincJ normallv closed contact ~6 or E8, Fig. 8, to disa~]e the exchange pumps. Wonetheless, the pressure ~ums will re~a;n in operation until a low oil 5witch E90, Fig. 11, located in tank 22, is activated to energize reiav coil ~91, openirg relav contact F3?, Fiq. 11. A low oil switch F90 is also located in the unfiltered tank 21, Fig~ 8. From the time a high temperature condition is detected urtil the entire system is shut down is approximately two minutes.
If desired, heat exchanae fans may be used to keep the oil cool h~lt nonetheless the high temperature and low oil sensors will be used.
When a precletermined low te~oerature (sav-20F) is reached either in the unfilterecl tan~ or filtered tank, switch ~92 or ~93, Fig. 8, is closed to eneraize relay coil E94, Piq. 8, openina relay contacts F98 (Fia. 8) and F99 (Fig. 11) to de-activate the filter and flow-meter fault monitoring circuits.
T~is avoi~s faulty indications due to the viscosity of the oil at low te~perature. The exchanae and pressure ~um~s wil] remain in oparation; a warninq light is lit locallv and remotely.
The lamp circuitry shotm in Fiqs. 10 and 13 mav ~e extended to siqnal kich ancl low t~mperatures, low oi] and oil over-fill.
The unloader, FiqO 6~ is employecl to allo~ the pressure pumos to start aaain~t a no-load condition a.s already explained.
At the commencement of start-u~, contacts ~46, F~a. 11, open ~C~7692~
when relay P45 .is energized, de-energi~ing re~av ~7 and al~.owin~
~ts colltact~ ~4~ to revext to the nor~].ly c]os~d condition. As a consc~uence the 4-way unloader va].ve i.~ opened and there is no resistance to the pressure pum~s.
S~!itch ~58 is closed (closed below 700 p5i) 50 ~.~hen the timc delay contActs ESO close, rela~ ~47 is ener~ized and its contacts reverse, energizing solenoid valve F51 to place the 4-way valve in the system loading moae.
It will be seen from the foregoing that oil, used to operate the retarders, is returned to tank 21. Turbulence is removed by the baffles 86 prior to the return oil entering the inlet ports which communicate with th~ exchange pump.
The exchange pump 12Pl or 2P2) sends the oil through a filter (see Fig. 2) and the filtered oil is delivered to an outlet in the second tank hy means of a transfer conduit 71.
Turbulence of oil in the second tank is removed by baffles 91. Very fine particles of contaminant in the oil, not removed by the exchange pump filters, are removed by a filter lF4 servïced by a pump lP4, both interposed in a recirculating conduit 97, Fig. 2.
Oil is pumped from tank 22 by a plurality of activated pressure pumps. To prevent vortex overlap, the inlets to the pressure pumps are isolated from one another by dividers 92, Fig. 2. The same arrangement is employed (dividers 88) for the e~change pump inlets. . .
If a pressure pump ~or exchange pump) fails, the reserve pump is activated and the failed pump is deactivated, automatically. The same automatic switch-over occurs in the ~nstance of a failed flow meter or failed filter in a '.' ' , '' , , '' ' ;,: . ' ' ' :
.
:: .
10769Zl pressure pump leg or an exchange pump leq.
Such automatic corrections occur as an incident to operation of a sensing means as switch lFMl-52, Fiq. 6, which senses flow rate; switch lF~ 3 ~hich detects failure of the flow meter measuring element; and s~itch lF1-S2 which senses pressure drop across the related filter.
Jf a failed condition is sensed, a relay is energized;
such as relay ~73, Fiq. 8, and a s7arninq is given, e.g. a lamo is lit. .~t the same time, corresponding motor relay contacts such as contacts E20, Fig. 9, are opened to disable the pump and other motor relay contacts are closed to activate the reserve pump.
r~hen a sensing means detects a pumn or filter is nearing failure, a warning is given.
~ eferring to Figs. 10 and lOA, any warning of approaching failure i5 manifest in a lamp as ~70 being lit locally at the pump house (Fig. 10), and remotely as well tFig. lOA) as for instance by a lamp P102 at the control tower where the yard operator is in charqe.
The remote signals,-Fig. lOA, include a lamp E103 identified ~i~h "system failed" and another lamD E104 signifying the system is in a normal mode.
Lamp E103 will be lit ~nd E104 extinguished) as long as relay E106, Fig. lO, is de-energized; lamp E104 will be lit ~and E103 extinguished) if relay E106 is enerqized.
Thus, if the yard pressure is inade~uate, contacts lX16, Fig. 10, will remain open and lamp E103 will remain lit.
If both exchanqe pumps fail, both sets of contacts E108 and E109, Fig. 10, are open; relay E106 is de-energized and lamp E103 is thereunon lit to show a failed svstem; contra if -` 107692~
one exchange pump is workina in the normal mode.
If all three pressure pumps fail, the circuit for relay Elt)6 is open at lKl~ lK3, Fig. 10, and lamp E103 is lit;
~ contra if one pressure pump is in working order.
':' ' :
.- . . : . :: : ~ :
:. : : : . : .
: ~ . ' ~. ' .,,: ,, ~ ' '
Claims (22)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a railroad classification yard having hydrauli-cally operated retarders installed at selected positions along the classification track system, apparatus for furnishing hydraulic fluid to operate the retarders and comprising:
a) a plurality of motor-driven pumps, at least one to be a normally active pump and one to be a normally inactive reserve pump;
b) a plurality of filter units, one for each pump, and through which the related pump moves fluid under pressure;
c) means to sense the pressure drop across each filter unit and to activate the reserve pump while deactivating the active pump in the event the pressure drop exceeds a predetermined value characterizing unacceptable filter efficiency; and d) means to sense the pressure drop across each filter unit and to generate a signal when the pressure drops indicates a filter unit is approaching unacceptable efficiency.
a) a plurality of motor-driven pumps, at least one to be a normally active pump and one to be a normally inactive reserve pump;
b) a plurality of filter units, one for each pump, and through which the related pump moves fluid under pressure;
c) means to sense the pressure drop across each filter unit and to activate the reserve pump while deactivating the active pump in the event the pressure drop exceeds a predetermined value characterizing unacceptable filter efficiency; and d) means to sense the pressure drop across each filter unit and to generate a signal when the pressure drops indicates a filter unit is approaching unacceptable efficiency.
2. Apparatus according to claim 1 including a flow meter to measure the flow rate of each pump, means responsive to insufficient flow rate to activate the reserve pump and deactivate the active pump, and means to establish a signal that the active pump has been deactivated.
3. Apparatus according to claim 2 including a flow meter to measure the flow of each pump and to generate a signal when the measure indicates a pump approaching unacceptable flow rate.
4. Apparatus according to claim 3 including means to generate a signal when there is a failed flow meter.
5. Apparatus according to claim 2 including means responsive to a failed flow meter to activate the reserve pump and deactivate the active pump.
6. Apparatus according to claim 5 in which (a), (b) and (c) are duplicated in a pressure supply system which services the retarders and in a return system which returns fluid from the retarders.
7. In a railroad classification yard having hydrauli-cally operated retarders installed at selected positions along the classification track system, apparatus for furnishing hydraulic fluid to operate the retarders and comprising:
a) a plurality of motor-driven pumps, at least one to be a normally active pump and one to be a normally inactive reserve pump;
b) a plurality of filter units, one for each pump, and through which the related pump moves fluid under pressure;
c) means to sense the pressure drop across each filter unit and to activate the reserve pump while deactivating the active pump in the event the pressure drop exceeds a predetermined value characterizing unacceptable filter efficiency;
t) a flow meter to measure the flow rate of each pump, means responsive to insufficient flow rate to activate the reserve pump and deactivate the active pump, and means to establish a a signal that the active pump has been deactivated;
e) and means to generate a signal when the measure indicates a pump is approaching an unacceptable flow rate.
a) a plurality of motor-driven pumps, at least one to be a normally active pump and one to be a normally inactive reserve pump;
b) a plurality of filter units, one for each pump, and through which the related pump moves fluid under pressure;
c) means to sense the pressure drop across each filter unit and to activate the reserve pump while deactivating the active pump in the event the pressure drop exceeds a predetermined value characterizing unacceptable filter efficiency;
t) a flow meter to measure the flow rate of each pump, means responsive to insufficient flow rate to activate the reserve pump and deactivate the active pump, and means to establish a a signal that the active pump has been deactivated;
e) and means to generate a signal when the measure indicates a pump is approaching an unacceptable flow rate.
8. Apparatus according to claim 7 including means responsive to a failed flow meter to activate the. reserve pump and deactivate the active pump.
9. Apparatus according to claim 8 including means to generate a signal when there is a failed flow meter.
10. Apparatus according to claim 9 in which (a), (b) and (c) are duplicated in a pressure supply system which services the retarders and in a return system which returns fluid from the retarders.
11. In a railroad classification yard having hydrauli-cally operated retarders installed at selected positions along the classification track system, apparatus for furnishing hydraulic fluid to operate the retarders and comprising:
a) a plurality of motor-driven pumps, at least one to be a normally active pump and one to be a normally inactive reserve pump;
b) a plurality of filter units, one for each pump, and through which the related pump moves fluid under pressure;
c) means to sense the pressure drop across each filter unit and to activate the reserve pump while deactivating the active pump in the event the pressure drop exceeds a predetermined value characterizing unacceptable filter efficiency; and d) a flow meter to measure the flow of each pump and to generate a signal when the measure indicates a pump is approaching an unacceptable flow rate.
a) a plurality of motor-driven pumps, at least one to be a normally active pump and one to be a normally inactive reserve pump;
b) a plurality of filter units, one for each pump, and through which the related pump moves fluid under pressure;
c) means to sense the pressure drop across each filter unit and to activate the reserve pump while deactivating the active pump in the event the pressure drop exceeds a predetermined value characterizing unacceptable filter efficiency; and d) a flow meter to measure the flow of each pump and to generate a signal when the measure indicates a pump is approaching an unacceptable flow rate.
12. Apparatus according to claim 11 including means responsive to a failed flow meter to activate the reserve pump and deactivate the active pump.
13. Apparatus according to claim 12 including means to generate a signal when there is a failed flow meter.
14. Apparatus according to claim 13 in which (a), (b), (c) and (d) are duplicated in a pressure supply system which services the retarders and in a return system which returns fluid from the retarders.
15. In a railroad classification yard having hydrauli-cally operated retarders installed at selected positions along the classification track system, apparatus for furnishing hydraulic fluid to operate the retarders and comprising:
a) a plurality of motor-driven pumps, at least one to be a normally active pump and one to be a normally inactive reserve pump;
b) a plurality of filter units, one for each pump, and through which the related pump moves fluid under pressure;
c) and a pair of differential pressure switches to sense the pressure drop across each filter unit, one switch for activating the reserve pump while deactivating the active pump in the event the pressure drop exceeds a predetermined value characterizing unacceptable filter efficiency, and a second switch for originating a warning signal when the pressure drop indicates a filter unit is approaching unacceptable efficiency.
a) a plurality of motor-driven pumps, at least one to be a normally active pump and one to be a normally inactive reserve pump;
b) a plurality of filter units, one for each pump, and through which the related pump moves fluid under pressure;
c) and a pair of differential pressure switches to sense the pressure drop across each filter unit, one switch for activating the reserve pump while deactivating the active pump in the event the pressure drop exceeds a predetermined value characterizing unacceptable filter efficiency, and a second switch for originating a warning signal when the pressure drop indicates a filter unit is approaching unacceptable efficiency.
16. Apparatus according to claim 15 including a plurality of sensing switches responsive to the flow rate of each pump for:
activating the reserve pump and deactiving the active pump when the flow rate is deemed unacceptable, and establishing a warning signal when the flow rate is approaching the unacceptable rate.
activating the reserve pump and deactiving the active pump when the flow rate is deemed unacceptable, and establishing a warning signal when the flow rate is approaching the unacceptable rate.
17. Apparatus according to claim 16 in which the sensing switches sense flow through a flow meter and in which means are provided to disable the active pump and activate the reserve pump in the event of flow meter failure
18. Apparatus according to claim 17 including means to generate a signal when there is flow meter failure.
19. Apparatus according to claim 18 in which (a), (b) and (c) are duplicated in a pressure system servicing the retarders and in a return system which returns fluid from the retarders.
20. Apparatus according to claim 17 in which (a), (b) and (c) are duplicated in-a pressure system servicing the retarders and in a return system which returns fluid from the retarders.
21. Apparatus according to claim 16 in which (a), (b) and (c) are duplicated in a pressure system servicing the retarders and in a return system which returns fluid from the retarders.
22. Apparatus according to claim 15 in which (a), (b) and (c) are duplicated in a pressure system servicing the retarders and in a return system which returns fluid from the retarders.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA332,925A CA1076921A (en) | 1975-11-10 | 1979-07-31 | Hydraulic railroad retarder |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/630,155 US4027595A (en) | 1975-11-10 | 1975-11-10 | Hydraulic apparatus |
| CA265,003A CA1076000A (en) | 1975-11-10 | 1976-11-05 | Hydraulic apparatus |
| CA332,925A CA1076921A (en) | 1975-11-10 | 1979-07-31 | Hydraulic railroad retarder |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1076921A true CA1076921A (en) | 1980-05-06 |
Family
ID=27164750
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA332,925A Expired CA1076921A (en) | 1975-11-10 | 1979-07-31 | Hydraulic railroad retarder |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1076921A (en) |
-
1979
- 1979-07-31 CA CA332,925A patent/CA1076921A/en not_active Expired
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