US2004145A - Pumping mechanism - Google Patents

Description

June 11, 1935. w. H. wINEmN 2,004,145

PUMPING MECHANISM Filed Oct. 12, 1931 3 Sheets-Sheet l I l/I/ llllllll RPPROXIMA T: TO?

NORMAL. POSITION 'F P15 ON jiuzea afi' E w'aeman.

June 11, 1935.

w. H. WINEMAN 2,004,145'

PUMPING MECHANISM Filed Oct. 12, 1951 3 Sheets-Sheet 2 Jun1l,l935;. WHWINEM N 2,004,145. I rumrme MECHANISM Filed Oct. 12, 1951 S SheetS-ShB et s Inqzm a? fiwazanam PatentedJune 1 1, 1935 OFFICE,

2,004,145 PUMPING MECHANISM v Wade H. Wineman,

to Sullivan tion of Massachusetts Machinery Company, a

Michigan City, Ind., assignorcorpora- Application October 12, 1931, Serial No. 568,316 26 Claims. ((31.121-47) My invention relates to pumping mechanisms. In certain oil fields it is customary to raise oil which is not under suflicient pressure to rise, without pumping, to the surface, by a pumping plant 5 which includes a central air compressorwith pipes leading out'therefrom to a number of wells. At each of these wells a pump cylinder or pump head connected with a piston type pump in the well is provided. The pump heads are of the single 10 acting reciprocating piston type, with valve mechanisms controlled ton, and the cylinders are commonly supplied with air at high pressure from the central plant, and the air is desirably preheated just before be- 15 ing admitted to the pump cylinders so that the volume of the air is increased. customarily, these pumps operate with aback pressure on the piston on the down stroketo prevent too rapid movements on the down stroke, and the air discharging from the pump cylinder during the down stroke is returned to the intake side of the central compressor and there re-compressed. A suitable make-up device to take care of leakage is commonly provided. Systems of this sort are commonly practically automatic in operation, and it is not customary to maintain an operator at the various pumps. Accordingly, it is important to provide protection for the system which will guard against serious damage in the event of va- 0 rious difficulties arising either at the pump or between the pump and the central compressor plant. It is, moreover, desirable, in view of the high pressures employed and the preheating of the air, to make the valve mechanism, which con- 5 trols the pump cylinders, in such a manner as to minimize wear and cutting of the metal andto reduce as far as'possible the power required to ellect the intermittent valve movements.

Among the objects of my invention is the provision of an improved pumpingmechanism, and particularly an improved pumping mechanism of the character described. Another object of my invention is to provide an improvedsafety mechanism for the protection of pumping mechanisms, and one particularly adapted for the protection of pumping mechanisms of the automatic type. A still further object of my invention is to provide an improved valve mechanism for a pump ing mechanism. Yet another object of my invention is to provide an improved safety mechanism which will protect the pump against injuries whether resulting from breakage in the fluid conducting means connected with its operating motor, damage to the pump proper, or breakage of the connections between the pump and its operating by the movements of the pismotor. Other objects and advantages of the invention will hereinafter more fully appear.

In the accompanying drawings, in which an illustrative embodiment of the invention, together with certain modifications, are shown for purposes of illustration,

Fig. 1 is an elevational view of'a portion of a pumping mechanism arranged at a well which is to be pumped;

Fig. 2 isa fragmentary view, on an enlarged scale and from a like view point, of a portion of the mechanism shown in Fig. 1;

Fig. 3 is a fragmentary view, on an enlarged scale, of the same portion of the pumping mechanism shown in Fig. 2 but view from a. different angle;

Fig. 4 is a central vertical sectional view taken on line 4'4 of Fig. 2 through a portion of an automatic protective device; v

Fig. 5 is a sectional view, substantially at right angles to Fig. 4, and in part on each of two different parallel planes, as indicated by the line 5-5 of Fig. 4, showing a portion of an automatic control mechanism and associated parts;

Fig. 6 is a fragmentary view, partially in elevation and partially in horizontal section, of the controlling valve for' the pump operating I motor; the section being taken on the plane of line 6-6 of Fig. 3 I

Fig. 7 is another fragmentary sectional view showing the valve shown in Fig. 6 in a different position;

Fig. 8 is a section through the view of Figs. 6 and 7 on-the plane 88 of Fig. 7;

Fig. 9 is a fragmentary elevational view with parts broken away showing a different form of cylinder mounting;

Fig. 10 is a view, partially in elevation and partially in section, on line Ill-Ill of Fig. 9, showing a detail of the cylinder support, and

Fig. 11 is a horizontal sectional view showing details of the cylinder mounting of the form of Fig. 9.

Fig. 12 is a fragmentary vertical section on the line l2- I2 of Fig. 1, showing the relation of the cylinder, piston, and vent.

Referring to the drawings, and this time particularly to the mechanism as shown in Figs. 1 to 8, inclusive, I is a platform or derrick floor upon which a suitable frame 2 is mounted. The frame 2 at its top carries a mounting plate 3, to which is secured, as by suitable clamp mechanism 4, a vertical pump operating cylinder 5. The cylinder 5 is formed of a cylindrical body portion 6, a lower head Land an upper head 8;

the parts being rigidly held together by tension rods 6 extending between the heads. A suitable piston (not shown) reciprocable within the cylinder 5 is connected to and actuates in one direction a piston rod l6, which is connected through a suitable adjusting mechanism II with a pump rod |2 which extends through a suitable stuffing box |3 into a well head, which includes a pipe l4 through which the oil pump is discharged, a casing head l5, and a gas pipe l6 to conduct away the gas from the well. v

Valve mechanism including an improved valve, later described, is shown in elevationat 26 and is operated by dogs 2|, 22 adj ustably secured by bolts and holes 23 to a valve operating rod 24 which is connected, as at 25, with the piston rod.

Air under pressure from a central compressor plant (not shown) is supplied by a connection 26 to a preheater 21 mounted on the derrick floor and the air in a highly heated, and expanded, condition passes htrough a line 28 to the inlet side of the valve mechanism 20. The exhaust from the valve mechanism 26 is connected by a line 36 with the intake side of'the central'compressor.

20 comprises a valve casing 3| in which a chamber 32 is formed. The valve seat 33 bounds one side of the chamber 32, and the supply connection supplied by the line 28 opens into the chamber 32 at 34 abovethe valve seat, while the return or exhaust connection connected wi'th the intake side of the compressor plant by the line 36 is connected with the valve mechanism at 35 at a point below member 36 which is provided with a bearing bracket 31 at a tative relation to the shaft 4| by a polygonal loose connection 43, as shown, is rotatable through an arc by movements transmitted to the shaft 4| by a lever 44 keyed to the shaft at 45 and a1- ternatively engaged by the dogs 2|, 22.

The valve member 42 is nearly circular but'has a portion of its periphery cut away, as at 46, to

provide an admission port extending completely through the valve. The side of the valve 42 next to the seat is provided with an arcuate groove 41 which extends nearly all the way around the inner surface of the valve and terminates at its opposite ends adjacent the opposite sides of the port or notch 46. The valve seat is traversed by a passage 48 which leads tothe' lower end of the cylinder 6, and this passag'is connected alternativelywith the chamber 32 filledwtih fluid 'at high pressure, through the notch 46 in the valve, or with an exhaust port 46 communl-.

eating with theconnection 35 through the arcu- I ate groove 4i. The end of the shaft 4| opposite the valve rotating connection 43 is engaged by a heavy spring 5| whose compression is controlled by a plug 52 threaded into the bearing bracket 31, the spring engaging at its opposite ends the extremity of the shaft 43 and a ball bearing 53-which is provided to make easier the rotation of the valve and shaft.

The purpose of the counterbalancing features just described is, as indicated above, to make easier the rotation of the shaft 42 and to prevent the latter from pressing so forcibly under the high pressure filling the. chamber 32 upon its seat as to cause cutting. The air in the connection .haust pressure and the of the pump packings.

the valve seat; The valve seat point remote from the valve seat, and the valve seat portion proper and the bearing bracket are traversed by alined bores 39 and .40 through which a valve rotating .shaft 4| extends. A valve 42 secured in non-ro-= 35 is,- as indicated above, preferably maintained at a pressure of about one hundred pounds, and by reason of the formation of the arcuate port 41 an unusually large area of the seat side of the valve is subjected toa pressure which tends to counterbalance the higher pressure acting to force the valve upon its seat. The spring 5| is also so compressed by adjustment of the follower 52 as to diminish the unbalanced pressure which forces the valve 42 upon its seat. To prevent displacement of the valve in the event of failure of the inlet pressure, an adjustable lock nut held abutment screw 54 is positioned adjacent the top of the valve.

It will be evident from the description given that my improved distributing valve is counterbalanced in a very desirable manner and to the necessary extent by a combination of the expressure of the spring 5|; that the valve is accordingly easily moved, though not so easily as to be displaced by mere vibration; and that cutting of the valve or valve seat will be prevented.

In the operation of apparatus of this general nature, it will be appreciated that failures of vari- The improved distributing valve mechanism ous parts of the. systenf may occur, and that in there may be no caretaker at hand when the failures occur, serious damage may result. Some of the troubles which may be encountered may be breakage of either the supply line or the discharge line, breakage of the pump rod, or failure cally of any of these emergencies I have provided improved means which I shall now describe.

Mounted adjacent the lower end of the cylinder 6 isa safety mechanism, generally designated 60,

which comprises a pedestal 6| having a portion in which three cylinder bores 62, 63 and 64 are formed. Bores 62 and 64 are of smaller diameter than the bore 63, and each comprises a larger portion 65 and a smaller portion 66, the junction between these portions being in the form of a beveled seat 61. A piston 68 having a portion 69, beveled to cooperate with the seat 61 in the cylinder 62 is reciprocable in that cylinder, and a correspondingly formed piston 10 is reciprocable in the cylinder bore 64. Thepistons 68 and '16 have rods II and 12, respectively, passing at their lower ends through a yoke member 13 and having nuts or heads 14 adapted to engage ,the lower side of the yoke member and raise the same on upward movement of the pistons. Springs 15 and 16 are arranged in the portions 66 of the cylinder bores 62 and 64, respectively, and normally tend to force the pistons 68 and I0 upwardly and to raise the yoke 13. These springs and the dimensions of the cylinders and pistons are so selected that upon failure of the pressure acting upon the upper surface of either piston the entire system described will move upwardly under the unbalanced spring pressure. The upper end of the cylinder 62 is connected through a line 11 with a T 16 in the exhaust connection 30, and the upper end of the cylinder 64 is connected by a connection 19 with the supply connection 28.

The intermediate cylinder 63 is suitably vented at its upper end and contains a piston 8| connected through a rod 62 and a suitable connection at 63 with the yokemember 13. The space below To take care automatithe piston 8| is connected by afpassage 84 with t but above the upper normal working limit of movement of the piston, with a vent port 85. Prior to the overrunning of the port 85 by upward movement of the motor piston, it will be evident that the upward movement of the latter will be substantially unretarded by air pressure, but were the port 85 passed, the air above the motor pistonwould be trapped and a pressure acting beneath themo-tor pump packing becomes broken,

built up. This pressure, if it occurs, will be transmitted through the connection 84 below the piston 82, and on rapid upward movement of the motor piston a pressure will be built up which, acting upon the lower surface of the piston 8I, will, when added to the pressure exerted by the springs I5, 16, cause the entire system of pistons and the yoke I3 to move upwardly materially before either the pump piston or the motor piston can strike the upper end of its respective cylinder.

Between the point of connection of the pipe I9 with the supply connection 28 and the valve chest 20, there is arranged an end seating stop valve 81, and between the T 18 and the connection 35, a second stop valve 88 is arranged. These stop valves are generally similar in construction, although that which is to handle the higher pressure may have a longer guide to reduce leakage. Each of these comprises a seat 89, a conical valve 90 cooperating with the seat, and a plunger 9I connected with the valve; and the two plungers 9| are connected to a cross member 92 whose central part is connected with a plunger 93 reciprocable in a bore 94 carried by the member 6|.

' 91 has an end 98 adapted to engage the lower end of the plunger 93 and. raise the latter when the.

outer end 99 ofthe lever is moved downwardly, and a connection I00 is made with the outer end of the lever 99'to permit manual opening of the valves when desired. A latch IIlI pivotally supported at I02 is adapted to engage beneath the plunger 93 when the latter is in raised position, and an arm I03 attached to the latch IOI has a suitable loose connection at I04 with the system of moving parts including thev yoke I3 and the several pistons" which cooperate therewith. The adjustable nut I05 at the lower end of the connection I 04 permits adjustment of the position of the latch as desired.

The mode of operation of this safety mechanism may now be described. The back pressure of one hundred pounds or thereabouts, constantly piston, is desirable to prevent excessively rapid downwardmovement of the parts, and in the event that the connection 30 is broken in any way, the mechanism just described will obviously, upon failure of the pressure above the piston 68, permit upward movement of the three pistons 68, I0, 8|, the yoke I3, and the connection I 04, I05, and the latch IOI will be tripped so that the spring may force downwardly the two valves 90 and shut down the entire system. Similarly, if the connection 28 or 26 is broken, the pressure will fail above the piston I0 andthe spring I6 will then, move the parts upwardly and trip the latch IOI and permit closure of both valves. In themevent that the I or the pump rod breaks, so that the resistance to upward move- 3 ment of the parts is suddenly diminished, the piston inthe cylinder 5 will overrun the port 85 and build up a pressure which will be transmitted through the connection 84 to the lower side of the piston 8I and similarly cause a shut ting down of the entire system. When the necessary repairs have been made and it is desired to restart the pump in operation, traction upon the connection I00 will re-open the valves and re-set the system in operation, and as soon as the pressure builds up in the cylinders 82 and 64 these will be forced downwardly and move the latch IN to hold the plunger 93 in raised position.

vices is highly advantageous in that it will prevent breakage of the mechanism of the pumping device in the event that its supply and discharge connections are broken in any way,.and will, in the event of loss of load due to breakage, or blowing through of packing, or the like, also shut down the system and thereby prevent damage. The

parts are simple and rugged and durable, and

certain in their protective action.

In Figs. 9, l0, and Ila-different form of pumpa heat, with loss of volume of operating medium,

is to be expected. This may be minimized, however, by reducing conduction losses-and instead Clearly, the described system of protective deof supporting the cylinder 5 by a clamp which surrounds the hot portions thereof, it is possible to support the cylinder as indicated in Fig. 9 by a pin and ear connection I06 on a frame I01, and since the upper end of the cylinder does not have the highly heated air enter it at all during normal pumping operation, theconduction losses will be diminished. To steady the cylinder, since it is only pivotally mounted at its upper end, a series of rods I08 provided with turnbuckles I09 may be extended from the lower cylinder head I to the different members of the frame I01.

While I have in this application specifically described one form, with certain modifications,

which my invention may assume in practice, it,

will be understood that the forms shown are illustrated for purposes of illustration only and that the invention may be further modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

-What I claim as new and desire to secure by Letters Patent is:

1. In combination, in a pumping system, a single-acting expansible' fluid pumping motor having a piston, a fluid supply connection therefor, an exhaust, a valve controlling said fluid supply connection, and means operative on interruption of the fluid supply automatically to close said valve, said means including means normally tending to close said valve, means precluding releasing said valve from the control of said means for precluding valve closure.

3. In combination, in a pumping system, a single-acting expansible fluid pumping motor having a piston, fluid supply and exhaust connections therefor, valve means controlling said connections, said motor exhausting against a substantial back pressure, and. means operative on breakage of either the fluid supply or exhaust connections automatically to close said valve means, said second mentioned means including means normally tending to close said valve means, means for holding the same open continuously during normal motor operation, and controlling means therefor including a plurality of cylinders,

plungers in said cylinders and having end seating engagement with their respective cylinders, and means for transmitting to said cylinders supply and exhaust pressures respectively.

4. In a pumping system, in combination, a single-acting pumping motor having a piston, a load carried thereby, fluid connections leading to said motor, controlling means for said connections, and means controlled by a pressure built up at the non-working side of said piston due to abnormally rapid motion of the latter upon loss of the load on said pumping motor during a working stroke and operative automatically to cause said controlling means to close completely, prior to the start of the next succeeding opposite stroke, said connections.

5. In a pumping system, in combination, a single-acting pumping motor, a load carried thereby, fluid connections leading to said motor, controlling means for said connections, and means controlled by compression pressure built up in said motor at the non-working end thereof upon an abnormally long pass of the load carrying element thereof, and operative on loss of the load on said pumping motor, automatically to close completely said connections, to shut down the motor.

6 In a pumping system, in combination, a single-acting pumping motor, a load .carried thereby, fluid connections leading to said motor, controlling means for said connections, and means operative on loss of the'load on said pumping motor automatically to close said connections, said second mentioned means including means normally tending to close said connections, and means for rendering said last mentioned means operative including a piston governed by abnormal pressure conditions in the non-working end of the pumping motor.

'7. In a pumping motor, a cylinder, a singleacting piston reciprocable therein, a fluid supply connection for said motor, a controlling valve for said supply connection, a member movable to control the position of said controlling valve, and

means including said piston operative on an abnormally long stroke of said piston in a working direction to produce a pressure and means operative to sub ect said controlling member to such pressure to eifect complete closure of said con-- trolling valve thereby to shut down the motor.

8. In combination, a controlling valve, means for moving the same to open position, a latch for retaining the same in open position when moved thereto, a single-acting motor controlled by said valve, and means for controlling the position of said latch maintained inoperative during continued supply of fluid to said valve but operative automatically on interruption of said supply to cause said latch to release said valve to effect closing thereof and auxiliary means for controlling said latch controlled automatically by said motor upon too rapid operation of the latter in either direction.

9. In combination, in a pumping system, a single-acting pumping motor having an exhaust, a fluid supply connection for said motor, a valve for controlling said fluid supply connection, controlling means for said valve automatically operative to effect closure of the latter upon failure of supply pressure, and controlling means for said valve automatically operative to effect closure of the latter upon disconnection of the pumping load from the motor.

10. In combination, ina pumping system, a fluid supply, a single-acting pumping motor connectible thereto, a fluid exhaust connection for exhaust pressure, and

operative to efiect closure of the latter upon failure of supply pressure, controlling means for said valves automatically operative to effect closure of the latter upon failure of exhaust pressure, and controlling means for said valves automatically operative to eiiect closure of the latter upon disconnection of .the pumping load from the motor.

12. In a system comprising asingle-acting motor and fluid supply and exhaust means for said motor, a controlling device for the fluid connections of the motor including fluid connection controlling valve means, and controlling means for said last mentioned means including parallel cylinders, pistons therein, means for connecting one of said cylinders toa fluid connection for the motor, and means for connecting another of said cylinders to a space within said motor in which the pressure substantially exceeds atmospheric pressure only when the motor loses its load.

13. In a system comprising a single-acting motor and fluid supply and exhaust means for said motor, a controlling device for the fluid connections of the motor including fluid connection controlling valve means, and controlling means for said last mentioned means including three parallel cylinders, pistons therein, means for connecting two of said cylinders to fluid connections for the motor, and means for connecting the third of said cylinders to a space within said motor in which the pressure substantially exceeds atmospheric pressure only when the motor loses its load.

14. In a; pumping system, a pumping motor comprising a cylinder having a single-acting piston reciprocable therein, fluid supply and exhaust connections for said cylinder, a distributingvalve for controlling communication of the working end of said cylinder alternately with said supply and exhaust connections, said supply and exhaust connections including fluid supply and exhaust conduits leading to said distributing valve, and a safety control means for said motor comprising a valve controlling the flow of pressure fluid through said fluid supply conduit to said distributing valve, and meansautomatically operative and controlled by the pressure in said inlet conduit for closing said latter valve when the supply of fluid to said conduit is interrupted.

15. In a pumping system, a pumping motor comprising a cylinder having a single-acting piston reciprocable therein, fluid supply and exhaust connections for said cylinder, a distributing valve for controlling communication of the working end of said cylinder alternately with said supply and exhaust connections, said supply and exhaust connections including fluid supply and exhaust conduits leading to said distributing valve, and a safety control means for said motor comprising a valve controlling the flow of exhaust pressure from said distributing valve through said exhaust conduit, and means automatically operative and controlled by the pressure in said exhaust conduit for closing said latter valve upon breakage of said exhaust conduit.

16. In a pumping system, apumping motor comprising a cylinder having a single-acting piston reciprocable therein, fluid supply and exhaust connections for said cylinder, a distributing valve for controlling communication of the working end of said cylinder alternately with said supply and exhaust connections, said supply and exhaust connections including fluid supply and exhaust conduits leading to said distributing valve, and a safety control means for said motor comprising valve means controlling the flow of fluid through saidsupply and exhaust conduits respectively towards and from said distributing valve, and means automatically operative and controlled by the pressures in said conduits for closing said valve means in the event of breakage of said conduits. 1'7. In a pumping system, a pumping motor comprising a cylinder having a single-acting piston reciprocable therein, fluid supply and exhaust connections for said cylinder, a distributing valve for controlling communication of the working end of said cylinder alternately with said supply and exhaust connections, said supply and exhaust connections including fluid supply and exhaust conduits leading to said distributing valve, means controlled by movement of the piston for automatically controlling said distributing valve, and a safety control means for said motor comprising a valve controlling the flow of pressure fluid through said fluid supply conduit to said distributing valve and closing in the direction of such flow, and means automatically operative and controlled by the pressure in said supply conduit for closing said latter valve when the supply of fluid to said conduit is interrupted.

18. In a pumping system, a pumping motor comprising a cylinder having a single-acting piston reciprocable therein, fluid supply and exhaust connections for said cylinder, a distributing valve for controlling communication of the working end of said cylinder alternately with said supply and exhaust connections, said supply and exhaust connections including fluid supply and exhaust conduits leading to said distributing valve, means controlled by movement of the piston for automatically controlling said distributing valve, and a safety control means for said motor comprising a valve controlling the flow of exhaust pressure through said exhaust" conduit from said distributingvalve, and means automatically operative and controlled by the pressure in said exhaust conduit for closing said latter valve upon breakage of said exhaust conduit.

19. In a pumping system, a pumping motor comprising a cylinder having a single-acting piston reciprocable therein, fluid supply and exhaust connections for said cylinder, a distributing valve for controlling communication of the working end of said cylinder alternately with said supply and exhaust connections, said supply and exhaust connections including fluid supply and exhaust conduits leading to said distributing valve, means controlled by movement of the piston for automatically controlling said distributing valve, and a safety control means for said motor comprising valve means controlling the flow of fluid through said supply and exhaust conduits respectively towards and from said distributing valve, and means automatically operative and controlled by the pressures in said conduits for closing said valve means in the event of breakage of said conduits.

20. In a pumping system, a pumping motor comprising a cylinder having a single-acting piston reciprocable therein, fluid supply and exhaust connections for said cylinder, a distributing valve for controlling communication of the working end of said cylinder alternately with said supply and exhaust connections, automatic controlling means for said distributing valve for connecting said cylinder alternatively to supply and exhaust, and a safety control means for said motor comprising a valve controlling the flow of pressure fluid through said supply connection towards said distributing valve and closing in the direction of such flow, and means automatically operative and controlled by the pressure in said fluid supply connection for closing said latter valve when the supply of fluid to said supply connection is interrupted.

21. In a pumping system, a pumping motor comprising a cylinder having a single-acting piston reciprocable therein and having a normal working stroke, fluid supply and exhaust connections for said cylinder, a distributing valve for controlling said supply and exhaust connections, means including said piston automatically operative upon breakage of said supply and exhaust connections for closing communication of the latter with said cylinder, and means automatically operative upon abnormally long movement of said piston in said cylinder for interrupting communication of said supply and exhaust connections with said cylinder, said two latter means comprising common valve actuating means for controlling said supply and exhaust connections.

22. In a pumping system, a pumping motor comprising a cylinder having a single-acting piston reciprocable therein, fluidsupply and exhaust connections for said cylinder, distributing valve means for controlling said supply and exhaust trolling member one of said elements movable by pressure fluid relative to the other and having a normal working stroke, a fluid supply connection for said motor, a controlling valve for said supply connection, a

member movable to control the position. of said controlling valve, means including said pressure fluid movable motor element operative on an abnormally long stroke of said element in a working direction to produce an excessive pressure within said cylinder, and means for subjecting said conto said pressure to eflect complete closure of said controllin valve and operative to eilect such closure prior to the next succeeding stroke of said pressure fluid movable element.

24. In a pumping system, a pumping motor comprising a cylinder having a single-acting piston reciprocable therein, said motor having a normal working stroke, means for supplying pressure fluid to and exhausting fluid from said cylin-.

der, said cylinder exhausting against a back pressure sufficient to retard relative movement between said cylinder and said piston in one direction, and means controlled automatically by an excessive pressure within the opposite end of said cylinder caused by an abnormally long relative movement between said cylinder and of said piston due to abnormal operation of said motor for interrupting communication of said fluid supply connection with said cylinder.

25. .In a pumping system, a pumping motor comprising a cylinder having a single-acting piston therein, said motor having a normal working stroke, means for supplying pressure fluid to and exhausting fluid from said cylinder, said cylinder exhausting against a back pressure suflicient to retard relative movement between said cylinder and said piston in one direction, and means controlled automatically by an excessive pressure within the opposite end of said cylinder caused by an abnormally long relative movement between said cylinder and said piston due to abnormal operation of said motor for interrupting communication of said exhaust connection with said cylinder.

26. In a pumping system, a pumping motor comprising a cylinder having a single-acting piston reciprocable therein and having anormal working stroke, means for supplying pressure fluid to and exhausting fluid from said cylinder, said cylinder exhausting against a back pressure sufficient to retard movement'of said piston in one direction, and means controlled automatically by an excessive pressure within the opposite end of said cylinder caused by an abnormally long movement of said piston due to abnormal operation of said motor for interrupting communication of said fluid supply and exhaust connection with said cylinder.

WADE H. WINEMAN.

CERTIFICATE OF CORRECTION.

Patent No; 2,004,145. I June 11. 1935.

WADE H. WINEMAN.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, first column, line 2l-, for "htrohgh" read through; page 6, first column, line 18, claim 24, strike out the word "reciprocable"; and line 27; same claim, strike out the word "of"; andthat the said Letters Patent shouid be read with these corrections therein that the same may conform to the record of the casein the Patent Office.

Signed and sealed this 6th day of August, A. D. 1935.

Leslie Frazer Acting Commissioner-wot Patents.

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