US1894869A

US1894869A - Pump

Info

Publication number: US1894869A
Application number: US547301A
Authority: US
Inventors: Joseph E Holveck
Original assignee: Individual
Current assignee: Individual
Priority date: 1931-06-27
Filing date: 1931-06-27
Publication date: 1933-01-17
Anticipated expiration: 1950-01-17

Description

Jan. 17, 1933. J. E. HOLVECK PUMP Filed June 27, 1931 3 Sheets-Sheet l INVENTOR NOLLDOS Jan. 17, 1933.

J. E. HOLVECK PUMP Filed June 27, 1931 3 Sheets-Sheet 2 EN \w x .L 4 w R QM INVENTOR Jan. 17, 1933. J. E. HOLVECK 1,394,869

PUMP

Filed June 27, 1931 3 Sheets-Sheet 3 Patented Jan. 17, 1933 UNITED STATES PATENT OFFICE JOSEPH E. HOLVECK, OF PITTSBURGH, PENNSYLVANIA PUMP Application filed June 27,

This invention relates to pumps or compressors, and more particularly to procedure and mechanisms for loading and unloading such apparatus. The invention specifically relates to the loading and unloading of pumps 01' compressors having reciprocating pistons.

The object of my invention is to produce a procedure and a mechanism for loading and unloading pumps which are simpler and more effective than those now in use and known to me.

A further object is to produce a loading and unloading mechanism which is so arranged that the torque on the drive shaft will be more or less gradually increasedas the pump is loaded and will be decreased as the pump is unloaded.

These and other objects, which will be made more apparent throughout the further gradually description of the invention, are accomplished by means of mechanisms embodying the fe-atureshcrein described, and illustrated in the drawings accompanying and forming part hereof. I

In the drawings, Figure 1 is a view partially in section of apparatus embodying my invention. The figure includes a sectional view of the suction chamber of a compressor or pump, such as is here involved. Fig. 2 is a fragmental sectional view along the line .22 of Fig. l, the housing for the shaft illustrated being omitted for convenience of illustration. Fig. 3 is a sectional view along the line 3-8 of Fig. 1, showing the inlet or suction valve in place in the delivery port of the suction chamber. Fig. 4 is a diagrammatic view illustrating the relationship between the crank shaft of the pump and cams forming a part of the unloading mechanism. Fig. 5 is a partial end view of a pump, a portion being shown in section, and illustrates means for motivating the loading and unloading mechanism. Fig. 6 is a fragmental View illustrating. a modified arrangement of the motivating means. Fig. 7 is a diagram illustrating graphically the angular relation of the discharge and suction strokes of a single acting triplex pump. Fig. 7a is, in effect, a continuation of Fig. 7, and illus- 1931. Serial No. 547,301.

trates the relative positions of the operating cams when the cylinders of a triplex single acting pump are unloaded. Fig. 7 b shows the relative positions of such cams when the pump is loaded. Fig. 7c is, in effect, a continuation of Figs. 7a and 7b, and shows the relative positions of the crank pins at the beginning (upper View) and at the end (lower view) of a loading or unloading operation, and Fig. 8 is a view illustrating graphically the effect of the loading and unloading operation of a single acting triple pump.

Throughout the further description I will employ the term pump to include either a compressor or a pump, the understanding, however, being that the term, as herein employed, is limited to include only compressors or pumps having cylinders and reciprocating pistons operating therein. P

In a great many installations of pumps it is customary to drive the pump continuously and to employ some mechanism for automatically unloading the pump when a desired degree of pressure has been obtained, or when the desired amount of fluid has been delivered by the pump to an accumulator. It is also customary to contemplate automatic reloading of the pump. In my Patents 1,316,79 of September 23, 1919 and 1,528,547 of March 3, 1925 I have illustrated and described mechanisms for unloading and loading pumps so that the pump may be continuously operated even under widely varying load conditions. My present invention rer lates broadly to loading and unloading mechanisms such as are covered by my above mentioned patents, but specifically to the particular mechanism here illustrated and the particular procedure here described for loading and unloading the pump. I have not illustrated a complete pump, nor have I illustrated the accumulator or other device for receiving the fluid or liquid pumped, since I have deemed it unnecessary to so complicate the present disclosure and since pumps of the type here involved are well known and their operation well understood. For the same reason I have not illustrated accumulators or other apparatus for receiving the pumped fluid.

For the purpose of simplifying the further description of my invention I will briefly describe what I mean by the term pump cycle. Ordinarily the inlet valve to eac pump cylinder-whether the pump is a single or multi-cylinder pump'or is a single acting or' double acting pump-is a suction actuated valve; that is to say the inlet valve opens in response to the diiierence in pres sure of the fluid or liquid moving toward the cylinder and the pressure within the cylinder, and this'difierence in pressure is occasioned by the fact that the pump piston moving away from the inlet port of thecylinder tends to create a vacuum within the cylinder and thereby in effect sucks the fluid or liquid from the so called suction chamher into the cylinder. The inlet valve, having opened in response to the conditions above described, remains open as long as there is a flow of liquid or fluid from the suction chamber into the cylinder, and then closes. From the above it will be apparent that the inlet valve is in efiect a check valve in that it permits a flow through the inlet port to the cylinder, in one directioni. e.,

toward the cylinder but prevents a flow inthe opposite direction and remains closed as long as the pressure within the cylinder exceeds the pressure within the suction chamber. The pump cycle for each cylinder and its cooperating piston is completed by each full reciprocatiou'of the piston, or for each complete revolution of the crank which initiates and completes the suction stroke of the piston in question, and then initiates and completes the discharge stroke of that piston. To further define my meaning of the term pump cycle it may be said that in a single acting pump, the pump cycle starts, for each individual cylinder, as the piston contained within the cylinder starts to move away from the inlet end of the cylinder. Throughout this movement of the piston the cylinder is in effect drawing in a charge of liquid or fluid, and the piston is moving through what has been termed the suction stroke. The piston then comes to rest, it may be for an infinitesimal period of time, and then moves in the reverse direction or back toward its original position, thereby discharging, through the discharge port of the cylinder, the liquid trappedin the cylinder by the closing of the inlet valve at the end of the suction stroke. The discharge port is, of course, provided with an appropriate valve, which like the inlet valve, is ordinarily a pressure responsive and a one way valve. At the end of this return movement of the piston, it momentarily comes to rest, and the pump cycle is completed, since the next movement of the piston will again tend to create a vacuum within the cylinder and thereby occasion the opening of the inlet Lacuna valve and a flow of liquid from the suction chamber into the cylinder.

As in my previous patents, the loading and unloading mechanism effects the operation of the inlet valves of the various cylinders of the pump and each cylinder is unloaded by preventin its inlet valve from closing at the end 0? the suction stroke. Under such conditions fluid drawn into the cylinder by the suction stroke of the associated piston is not trapped, consequently, the return stroke of the piston, instead of completing the pump cycle, merely forces the fluid back through the open inlet port and into the suction chamber with the result that the discharge valve of the cylinder does not open, and the pressure of the fluid-is not increased above the fluid pressure within the suction chamber. That is to say, no effective work is done on the fluid by the particular piston and cylinder involved. As pointed out in my previous patents the unloading operation is accomplished so as to gradually decrease the torque on the shaft.

As described in my revious patents the mechanism for accomplishing the unloading of the pump is so arranged that the cylinders of a multi-cylinder pump are successively unloaded, that is to say, the cylinders are unloaded one after the other. My present invention relates to mechanism for accomplishing this and also for accomplishing a reloadin g of the cylinders so as to gradually increase the torque on the drive shaft of the pump, and in such a way as to prevent a partial loading of any cylinder and the resulting detrimental effect which would be occasioned by -water hammer in case of a hydraulic pump.

In other words, the loading operation is rendered effective for each individual cylinder only at a particular point in the pump cycle, and at such point as'will prevent a partial loading of any cylinder and insure a gradual increase of the load from substantially zero torque to maximum torque.

The apparatus here illustrated is primarily adapted to be automatically controlled, i. e., by variations in the level of the fluid pumped, or by the pressure resulting from the pumping operation or by both the fluid level and the resulting pressure. For example, where the pump delivers fluid to a hydrostatic accumulator the pumping operation may be controlled by variations in the level of the fluid within the accumulator or by the pneumatic pressure within the accumulator or it may be controlled by a combination of the fluid level and pneumatic pressure within the accumulator. It will, of course, be apparent that where a multi-cylinder pump is employed a change in condition which will effect the control of the pump may occur at any time during the pump cycle of any one of the cylinders and in order to properly load and unload the pump it is therefore necessary to control the'automatic regulation so that it is rendered effective, either to load or unload the various cylinders, at the proper time during the pump cycle of each cylinder. It is, of course, apparent that a separate loading and unloading mechanism maybe employed in connection with each cylinder, and that all of these individual mechanisms may respond either to individual automatic means 10 or to a single automatic means, which, as stated, is rseponsive tothe variations of fluid level or pressure, or both, within the accumulater.

For the sake of simplicity and to reduce 16 the cost of equipment I employ a single mechanism which is so arranged that it accomplishes the loading and unloadng of all the cylinders of a multi-cylinder pump and accomplishes this in such a way as to gradually 20 increase the torque on the drive shaft of the pump during the loading operation, and to gradually decrease the torque during the unloading operation. The mechanism illustrated in the drawings is provided with cam operated fingers which, during the unloading operation, cooperate with the inlet or suction valve of the various cylinders to prevent those Valves from moving to close the inlet ports. In this way each finger, Whenrendered operative as a part of the unloading mechanism, prevents the completion of th e pump cycle in the cylinder with wh ch it is associated. On the other hand, during the loading operat on the fingers move automatically in response to a change of condition so that each inlet valve is relieved of the restraining effect of the finger and is permitted to move to close the inlet port in response to the forces acting on the valve.

One of the features of my invention is, therefore, to provide simple mechanisms which will synchronize the loading and unloading operationsinitiated by automatic means responding to the above mentioned changes in conditions-wit-h the pump cycles in the individual cylinders, so that each operationi. e. loading or unloading-4s accomplished at the desired point in each pump cycle. That is to sav, my invention contemplates a simple mechanism which responds to automatic control, but wh ch will load or unload each cylinder at the proper point during the pump cycle of that cylinder and which will thereby more or less gradually increase the torque on the drive shaft of the pump during the loading operation and more or less gradually decrease it during the unloading operation.

I have illustrated the mechanisms here disclosed as embodying my invention, as applied to a single acting triplex pump. The further description, however, will disclose to those skilled in the art how the invention may be employed in connection with any multi-cylin- 65 der pump whether double or single acting.

In Fig. 1 the apparatus illustrated is associated with a solenoid 7, which, through the agency of mechanisms not here involved and not shown, is automatically energized and deenergized in response to variations in conditions such as level of the liquid pumped or accumulator pressure or both. I have assumed that when the conditions are such as to make it necessary to unload .the pump the solenoid 7 is (lo-energized, thereby permitting its armature 7a to move downwardly in response to gravity as augmented by the weight 7 b. This movement of the armature actuates a bell crank 8, which in turn shifts or tends to shift the position of a detent actuating rod 9, through the agency of a finger 8a, which forms one arm of the bell crank. Y It will, of course, be understood that the finger is bifurcated at its end or otherwise interlocked with the rod 9 so that it is capable of shifting the rod 9one way or the other, dependent upon the direction of the movement of the armature 7a. The rod 9 extends into an axial opening in a shaft 10 on which a pinion 11 is so mounted as to turn freely thereon. Any suitable, well known means may be employed for preventing the gear from moving longitudinally with relation to the shaft 10. This shaft is shown operatively connected to a shaft 12 by means of a coupling 12a. The shaft 12 projects into the suction chamber 13 of a pump (not shown) and is provided with

cams

14, 14 and 14", which effect the loading and unloading operations by cooperating with the inletvalves associated with the various cylinders of the pump.

' As shown in Fig. 3, the suction chamber is provided with three ports, each of which is adapted to receive an inlet valve 37 for one of the pump cylinders. As there illustrated, each inlet valve is yieldingly held against its seat or in the closed position by means of a spring 38, and is enclosed within a suitable housing 36. Each of the

cams

14, 14', and 14 is associated with a finger 41, which is pivotally mounted on a pin 42 carried by the casing of the suction chamber 13 and is operatively associated with a pin 39, guided by a way 40, which is supported by a spider 40a spanning the port of the suction chamber. The rod 39 is slidable through the way 40 and is screw'threaded at its upper end so as to provide for-a cap 39a which is screwed thereon and is therefore capable of being adjusted for the purpose of increasing or decreasing the effective length of the rod 39. The lower end of the rod rests on the finger 41 and is axially aligned with the stem of the inlet valve 37 so that when the finger is lifted by the associated cam (14) thecap 39a or the upper end of the rod prevents the valve -37 from moving to a closed position. The

cam 14, like the other two cams designated by related reference numerals, is rigidly secured in place on the shaft 12 and each such cam is so arranged that it supports the free end of the associated fin er 41 and thereby supports the associatethro 39.

In Fig. 7a I have shown the. cams in the positions they occupy while the pump is un-' loaded. Fig. 7 b shows the positions of the cams when the pump is loaded. It will be noted that the cams are all of similar contour, but that they are so placed on the "shaft 12 that their lobes move into and out of cooperative relation with the associated fingers 41 at different times during the rotation of the shaft 12. The shaft is rotated by means of the pinion 11, which, as has been said, is rotatably mounted on the shaft 10. Figs. 7a and 7?) make it apparent that a rotation of the shaft 12 through an arc of approximately 180 degrees-,will shift the cams from the loading to the unloading position (Fig.

7a) or from the unloading to the loading position (Fig. 7b).

In order that this shifting of the cams may take place at the proper point during the cycle of operation of the pump, the pinion 11 is actuated-in synchronisin with the rotation of the crank shaft of the pump. In the illustrated embodiment of the invention I have shown means for oscillating the pinion through an arc of about 180. degrees, and as illustrated in Fig. 5 the pinion moves through both swings or phasesof its oscillatory movement, once during each revolution of 'the drive shaft-i. e., crank shaftof the pump. As shown, a crank disc ll?) is mounted on the end of the crank shaft 46 of the pump adjacent the flywheel 47. This disc carries a pin 48 on which a connecting rod 44 is journaled. The lower end of the connecting rod carries a rack 44a, which meshes with the pinion 11. As shown in Fig. 5, the rack ll may be held in meshing engagement with the pinion by means of a roller 45, which is suitably journaled on the housing 43 of the pinion. If desired, the rack may be adjustably mounted on the connecting rod so as to facilitate the positioning of the pinion with relation to the shaft 10 and the detents carried thereby. I have shown a simple and well known form of such an adjustment at 440.

With the arrangementillustrated i:. will be apparent that the pinion oscillates about the shaft 10 as the crank shaft rotates. and, as has been said, it first moves through about 180 degrees in one direction and then back in the opposite direction to its original position, and that both these movements take place during a revolution of the crank shaft,

or. more properly siated. during one complete cycleof the multi-cylinder pump. It is, therefore, apparent that the pinion starts its oscillatory cycle at a particular time during each revolution of the crank shaft, or, more strictly speaking, at a particular time during the complete cycle of operation of the nausea v pump. I employthis oscillating pinion to render the movements of the automatically responsive device (the armature effective edge so that the jaw gradually increases in 7 width. circumferentially of the pinion, toward its detent-engaging-face. The shaft 10, besides receiving the rod 9, is slotted asat 15 to receive and guide the

detents

10a and 10?). These detents are located on opposite sides of the pinion and 180 degrees apart with relation to the shaft 10. As shown, each detent extends through a suitable aperture provided in the rod 9 and they are so located that when the rod is moved to its inner position, as shown in Fig. 1, the detent 10b is in position to be engaged by the jaw 11?), whereas the detent 10a is moved, longitudinally of the shaft 10, to such a position that it clears the jaw 110.. using the oscillations of the pinion. The arrangement is also such that when the rod 9 s moved to its outermost positon by the bell crank 8, the detent 10a is moved to position to be engaged by the jaw 11a..whereas the detent 10b is moved to such the rod 9 and the shaft 10 by a ring 16 which engages the detent and encircles the shaft, but which permits free movement of the detent along the shaft and in the slots 15. Each ring is held in place on its corresponding detent by a set screw 16a.

Assume that a change in conditions has been encountered wh ch occasions a movement of the automatic control mechanism (armature 7a) to the position shown in Fig. 1. Under such conditions the detent 10b is moved into the path of travel of the jaw 11?) with the result that the detent is picked up by the jaw as it starts its oscillatory movement with 1 he pinion and consequently moves with the pinion throughout one phase of the pinion movement. This

turnsthe shafts

10 and 12 and the

cams

14, 14', and 14" through 180 degrees. The next phase of the pinion movement causes the jaw 11?) to move back away from the detent- 10?) and since the pinion 11 is free to rotate on the shaft 10 the subsequent oscillations of the pinion therefore do not affect or change the position of either of the

shafts

10 or 12. f If now, the conditions controlling the solenoid 7 change so that the energizing current of the solenoid is interrupted, the armature 7a will drop, thereby moving the rod 9 to its outermost position and moving the detent 10a into the line of travel of the oscillating jaw 11a.

If this movement, or any'movement of the armature 7 41. takes place after the pinion has moved from its initial position the movement of the pinion will haveno effect on the detent in question, since that detent will merely ride the bevel face of the associated jaw until such time as the pinion returns to its initial position, when the detent will then drop into place in front of the detent-engaging-face of the jaw and the shaft 10 will then be turned through 180 degrees and in the same direction as the previous turning of the shaft. From this it will be apparent that both

shafts

10 and 12 move as a unit and have but two fixed positions, which are 180 degrees apart. It will also be apparent that each movement of the shaft 12, and consequently of the

cams

14, 14 and 14", takes place at a fixed point during the cycle of operation of the pump, or at a fixed point with relation to the pump cycle of each individual cylinder.

Fig. 7 is a diagram illustratin the pum piston movements durin the period that the pinion 11 moves on the first phasei. e., the

I operative phaseof its oscillatory motion and consequently during the period that a cam shifting operation takes place. Fig. 7a illustrates the relative positions of the various cams 14 at the completion of the cam shifting operation wherein the cams are moved from the loading to the unloading position. It will also be apparent that this view incidentally illustrates the positions of the cams at the start of the cam shifting operation, which moves them from the unloading to the loading position. Fig. 7 b illustrates the positions of the cams at the completion of the cam shifting operation which moves them from the unloading to the loading position. The top view of Fig. 7 c illustrates the positions of the crank pins A, B, and C of the pump crankshaft 46 at the start of the first, or operative phase of the oscil latory motion of the pinion l1; and the bottom view illustrates the positions of the crank pins as this phase of the pinion motion is completed.

It will be apparent from an inspection of these views that each cylinder is either loading or unloading during the operative phase of the pinion movement. A reference to Figs. 7 and 7 c discloses that at the beginning of the operative phase of the pinion 11, the piston operating in the cylinder associated with the crank pin A and with the cam 14 is moving on its suction stroke and must move through 60 degrees of crank pin travel in order to complete that stroke. The cam 14 must therefore be so positioned on the shaft and its operating lobe must be so proportioned that it will position the parts (finger 41 and pin 39) to unload or load that cylinder as the piston completes the suction stroke and before it starts on the discharge stroke.

This positioning of the cam and proportion-.

loading to the unloading position, or vice versa, must take place at the end of this stroke and prior to the beginning of the discharge stroke. The positioning and the proportioning of the cams 14 to accomplish this is illustrated in Figs. 7a and 7b. The piston operating within the cylinder associated with the crank pin C and with which the cam 14" is associated, is moving through the discharge stroke and must move through 120 degrees of cran'k pin travel before the stroke is completed. It is therefore apparent that the loading or unloading operation initiated by the pinion 11 must be deferred for 120 degrees of crank pin travel, and the cam 14" is so positioned on the shaft 12 and is so proportioned as to its cam lobe to accomplish either the loading 'or the unloading at the proper time during the stroke of the associated piston, i. e., at the beginning of a suction stroke.

Fig. 8 is a diagram corresponding to Fig. 7, but graphically illustrating the effect of the loading or unloading operation in connec tion with a triplex pump. In this dia ram I have employed the same letters, as in ig. 7, to designate the different curves which indicate conditions within the cylinders associated with the correspondingly lettered crank pins, diagrammatically illustrated in Figs. 7c. The lower diagram is a continuation of the upper diagram, but is shown as if an intervening portion between the two diagrams were omitted. The top portion of the view illustrates the effect of the unloading operation on the various cylinders of the pump, whereas the bottom portion illustrates the eil'ect of the loading operation on the various cylinders, and the two views together disclose the fact that the unloading cycle and the loading cycle each take place as the crank shaft moves through approximately 180 degrees, and that the various pistons occupy the same relative positions at the beginning of the loading cycle as they do at the beginning of the unloading cycle. The curves designated a, b, and 0 indicate suction stroke intakes; the curves a, b and 0' illustrate discharge stroke displacements; and the curves (1, b" and 0"each of which is shown dotted-indicate unloaded stroke displacements.

This combined chart discloses the fact that while the unloading operation is in effect accomplished during a particular 180 degrees of crank shaft travel, that it is in fact retroactive insofar as one cylinder of the pump is concerned. For example, the cylinder corresponding to the curve a is in effect unloaded at the beginning of its suction stroke, since prior to the termination of that stroke its suction valve is put under the restraint of the unloading mechanism with the result that the cylinder does not load or does not pass, as in normal operation, from a suction to a discharge stroke. The piston, in moving through what would normally be the discharge stroke, merely displaces the fluid drawn in by the preceding suction stroke as is shown by the curve a. The chart also discloses that, from the standpoint of crank shaft torque, the unloading is in effect accomplished on one cylinder with the result that the load on the crank shaft gradually decreases from maximum to minimum torque. The particular cylinder in question is the one corresponding to the curve (*0 of the upper view. The cylinder corresponding to the curve bb completes one pump cycle and starts the next pump cycle, in that its piston draws in a charge, but prior to the completion of this ortion of the pump cycle the inlet valve oi that cylinder is restrained so that the next movement of the corresponding iston merely displaces the water so drawn 1n, as shown bythe curve b", and does not force it through the discharge port of the cylinder. 4

The lower view also indicates that the loading operation is to some extent retroactive with relation to the operation of the loading and unloadingmechanism. That is to say, the cylinder corresponding to the curve aa is receiving a charge at the time the loading and unloading mechanism becomes effective. This portion of the pump cycle of this particular cylinder is completed and the inlet valve then closes, thereby leading the cylinder with the result that theload on the pump gradually increases from minimum to maximum torque as the corresponding piston moves through that portion of its stroke dur ing which its movement is accelerated. It will also be apparent that the cylinder corresponding to the curve bb is not loaded until after the piston in the cylinder corresponding to aa, is moving through the decelerating portion of its stroke, with the result that the gradually increasing torque occasioned by the cylinder b?) is compensated for by the gradually decreasing torque occasioned by the cylinder aa', as its piston decelerates. The chart also discloses that the cylinder corresponding to the curve 0-0 is in effect unloaded, so far as crank shaft torque is concerned, for 120 degreesafter the loading cycle of the loading and the unloading mechanism, is completed.

In connection with these Figs. 7-70, it must be remembered that the pinion starts each phase of its motion from rest and is gradually accelerated to its maximum speed of travel and then is gradually decele'rated until it again comes to. rest. This is also important in connection with the engagement of the pinion with one or the other of the detents 10a or .106, since'the shaft 10, and consequently the shaft 12 starts from rest with the pinion and is first accelerated and then decelerated as it moves to shift the cams, with the result that the first part of each cam motion is a gradually accelerated motion, whereas the cam motion is gradually decelerated as the cams move to their final position.

I have stated that each phase of the pinions oscillatory motion is through an arc of approximately 180 degrees and I have found that with the apparatus illustrated it is desirable that each throw or each phase of the pinion movement should be through an arc of about 185 degrees in order to provide the desired clearance.

In Fig. 6 I have illustrated a modification of the mechanism for motivating the pinion in that I have shown the connecting rod 44 actuated by a gear driven eccentric 50. The eccentric pin 50', to which the connecting rod 44 is operatively connected, is, in effect, carried by a gear 52 which is driven by a pinion 51 operatively coupled to the crank shaft. The gear and pinion are so proportioned that the pinion moves through two revolutions while the gear moves through one revolution. With this arrangement the operative phase of the pinion 11 extends through a complete revolution of the crank shaft, consequently a longer period of time, from the standpoint of crank shaft rotation, is obtained in which to load or unload the cylinders.

It will be apparent that the variation in conditions which initiates the loading or the unloading of the pump or, which in the present embodiment, occasions the energizing or the de-energizing of the solenoid 7, may take place at any time during the oscillatory motion of the pinion 11. That is to say, the rod 9 may tend to shift the position of the

de tents

10a and 10?) after the pinion 11 has started on what I have termed the first, or operative phase of its movement, or as the pinion 11 is moving back or is in the second phase of its movement. It will, however, be apparent that any such movement of the detents will be ineffective, insofar as the cam shaft 12'is concerned, since the friction (friction of rest) of that shaft and associated parts will resist any such movement, and the jaws 11a and 11?) are so designed that each detent will merely ride on the inclined face of the associated jaw until the jaw has moved to such a position that the detent is capable of dropping in front of its detent-engaging face. It is the purpose of ensuring this one direction,

movement of the cams the cam shaft 12 may be equipped with a ratchet and pawl or a suitabledetent for preventing a reverse movement, although Thave found that such a device is unnecessary.

I have found it convenient to enclose the inion 11 in a housing, such as illustrated in ig. 1, and to mount the solenoid 7 on a bracket formed on the closure for the housing. 15 This, in effect, makes the pinion 11, and its associated apparatus, including the solenoid, a unit which may be readily installed with any pump. With such an arrangement it is also convenient to mount the shaft 10 in suitable bearin s carried by the housing and to provide oi rings for sealing the joint between the shaft and the housing so that the shaft may be submerged or partially submerged in a lubricating liquid. Any suitable means may be employed for mounting the shaft 12, but it is desirable to provide the shaft with gaskets for preventing the leakage of liquid around the shaft and between it and the walls of the suction chamber 13.

While I have described what I now consider to be the preferred embodiment of my invention it will be apparent that various changes, additions and omissf ons may be made without departing from the spirit and scope of the invention as defined by the appended claims.

What I claim is: i i

1. The combination with a multi-cylinder pump having a suction chamber provided with a series of inlet valves, one for each cylinder of the pump, of devices for holding said inlet valves open durng the operation of the pump, to thereby unload the pump, an instrumentality moving in synchronism with the cycle of operation of the pump, and means for rendering said instrumentality effective in moving all said devices to an inoperative position with relation to said inlet valves.

2. The combination with a multi-cylinder pump having a suction chamber provided with a series of inlet valves, of a separate devicefor holding the inlet valve of each cylinder of the pump open during discharge periods of such cylinder to thereby unload the pump, an instrumentality moving in synchronism with the cycle of operation of the pump, and means rendering sa'd instrumentality effective in moving all said devices to release said inlet valves and to thereby load each cylinder of the pump at thebeginning of the discharge stroke of each such cylinder.

3. The comb'nation with a multi-cylinder pump having a series of inlet valves, of an oscillatory member, means for oscillating said member in synchronism with the cycle of op- 65 eration of the pump, devicesfor controlling of such valves, an oscillatory member operstrumentality eifective in actuatingsaid cam the operation of saidinlet valves, .an'dmeans for rendering said oscillatory member eflective to actuate saiddevices andload or'unload each cylinder of the pump.

4. The combina-tionwith a multicylinder pump, and its inlet valves, of a-se arate device for controlling the operation 0 each such inlet valve, an instrumentalityoperating in synchronism with said pump foractuating each such device to load the corresponding 7 cylinder of the pump at the end of the suction stroke of the piston of such cylinder.

' 5. The combination with a pump having inlet valves, of means for controlling said valves to load and unload the pump, and an instrumcntality operating in synchronism with the drive shaft of the pump to actuate saidmeans to load or unload the pump at predetermined points in its cycle of operation.

6. The combination with a multi-cylinder pump having a series of inlet valves, of an instrlunentality operating in synchronism with the pump shaft, a separate device for controlling each said inlet valve, and means actuated by said instrumentality for actuating each such device to load the corresponding pump cylinder at the beginning of the discharge stroke of thepiston of such cylinder.

7. The combination with a pump, of an oscillating instrumentality moving in synchronism with the cycle of operation of the pump, and means actuated by said instruinentality for loading the pump at the bei ginning of a discharge stroke.

8. The combination in a multi-cylinder pump, having a series of inlet valves, of a separate lifting finger for holding open each ated in synchronism with the cycle of operation of said pump and means for rendering said oscillating member effective to actuate said lifting fingers and to control the operati on of each inlet valve and unload each cylinder of the pump during a suction stroke of the piston of each such cylinder.

9. The combination with a multi-cylinder pump and its inlet valves, of a separate device for controlling each such valve to load and unload the corresponding cylinder, and means operating in synchronism with the cycle of operation of the pump for actuating said devices to load each cylinder of the pump at the beginning of the discharge stroke of the piston of such pump.

10. Thecombination with a multi-cylinder pump having an inlet valve leading to each cylinder, of a separate device for controlling each such valve to load and unload the corresponding cylinder of the pump, a camshaft for operating each of said devices in timed relation, an instrulnentality oscillated in synchronism with the cycle of operation of the pump, and means for rendering said inshaft to load each cylinder of the pump at the beginning'of the discharge stroke of the pump piston operating in such cylinder.

11. The combination with a multi-cylinder pump having an inlet valve leading to each cylinder of the pump, of a separate device for controlling the operation of each inlet valve to load and unload the corresponding cylinder of the ump, a shaft having cams thereon for operating each of said devices, an instrumentality oscillated in timed relation with the cycle of operation of the pump, and means for rendering said instrumentality effective in actuating said cam shaft.

12. The combination with a multi-cylinder pump having a suction valve leading 'to each of the cylinders thereof, of a separate device for lifting each of said valves, a shaft having "a series of cams thereon for operating each of said devices and means for oscillating said cam shaft including a shaft connected to said cam shaft, a member freely mounted on said shaft, means for oscillating said member in timed relation to the pump shaft and means for rendering said oscillatory member effective to turn said shaft and the cam shaft connected thereto.

- 13. The combination with a multi-cylinder pump having an inlet valve leading to each of the cylinders thereof, of a lifting finger for each of said valves, a cam shaft for actuating said lifting fingers, a shaft connected to said cam shaft, a pinion freely mounted .on said last mentioned shaftmeans for oscillating said pinion about said shaft in synchronism with the cycle of operation of the pump and means for making said pinion effective to turn said shaft and associated cam shaft to load or unload said pump.

14. The combination with a multi-cylinder pump having a suction valve for each of the cylinders thereof, of a shaft, a member rotatably mounted on said shaft, means for oscillating said member in timed relation with the drive shaft of said pump, meansv for ren dering said oscillatory member effective to turn said shaft, and means actuated by the turning of said shaft for loading each cylinder of the pump at the beginning of the discharge stroke.

15. The combination with a multi-cylinder pump having a suction valve for each of the said oscillating member to make it e ective to turn said cam shaft and load or unload the pump.

17. The combination with a multi-cylinder pump having a series of inlet valves, of a separate device for controlling the operation of each of such valves, means for actuating each of said devices, an oscillatory member, means for oscillating said member first in one direction and then in the opposite directien during each cycle of operation of the pump, and means for rendering said oscillatory member effective to operate said device actuating means and load or unload each cylinder of the pump.

18. The combination of a multi-cylinder pump having a suction chamber and an inletvalve for each cylinder of the pump, of a separate device for holding each of said valves open to unload the pump, and means for actuating each of said devices at the beginning of the suction stroke in each cylinder, said means lncludlng a cam shaft having a series of cams thereon one for operating one of said devices, a shaft connected to said cam shaft, :1 pinion mounted on said shaft and rosaid pinion through an arc of 180 in synchronism with the pump shaft and means associated with the shaft for engaging said pinion to make it effective to turn said cam shaft through an arc of 180, the cams on said cam shaft being disposed so that each time the cam shaft is turned 180 each of the devices will be operated.

In testimony whereof, I have hereunto subscribed my name this 25th day of June, 1931.

JOSEPH E. HOLVECK.

.tatable relative thereto means for oscillating