US3742971A

US3742971A - Apparatus for controlling direction of movement of a cycling fluid motor

Info

Publication number: US3742971A
Application number: US00263073A
Authority: US
Inventors: W Worthington
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-06-15
Filing date: 1972-06-15
Publication date: 1973-07-03
Anticipated expiration: 1990-07-03

Abstract

The invention relates to a hydraulic valve fluid connected within a pressure system to a remote, reversible fluid motor which in turn is operable to apply a predetermined amount of force in one direction, then to withdraw the force, to apply it again, etc., the valve initially operated manually and then automatically operable to cycle the motor.

Description

United States Patent Worthington APPARATUS FOR CONTROLLING DIRECTION OF MOVEMENT OF A CYCLING FLUID MOTOR [76] Inventor: Wayne H. Worthington, 720

Prospect Boulevard, Waterloo, Iowa [22] Filed: June 15, 1972 I21] Appl. No.: 263,073

[52] US. Cl 137/106, l37/624.27, 137/624.18 [51] Int. Cl. FlSb 11/15, F15b 13/01 [58] Field of Search 137/106, 102, 624.27, 137/624.18, 624.14; 91/356 [56] References Cited UNITED STATES PATENTS 3,650,297 3/1972 Hubbard 137/624.27

July 3, 1973 3,680,583 8/l972 Clair 137/6242? Primary Examiner-Alan Cohan Attorney-H. Robert Henderson et al.

[ 57] ABSTRACT The invention relates to a hydraulic valve fluid connected within a pressure system to a remote, reversible fluid motor which in turn is operable to apply a predetermined amount of force in one direction, then to withdraw the force, to apply it again, etc., the valve initially operated manually and then automatically operable to cycle the motor.

11 Claims, 13 Drawing Figures l m7 54 05 l a 1 4 95 7 7 72 3 103/ 3 //0 37 9g 59 PATENT'ED JUL 3 I975 SHiH 2 OF 6 PATENTEU JUL 3 I975 SHEEF 3 OF 6 PATEN-TEU JUL3 I973 SHEETS 0F 6 PATENTEUJULS ms SHEEI 8 [IF 6 APPARATUS FOR CONTROLLING DIRECTION OF MOVEMENT OF A CYCLING FLUID MOTOR BACKGROUND OF THE INVENTION In a copending application, formerly Ser. No. 54,982 filed July 5, 1970 by Stanley W. Worthington and entitied Apparatus for Controlling Direction of Movement of Refuse Body Compacting and Unloading Blade, a hydraulic valve arrangement wasdisclosed for use with a refuse transporting truck, wherein the valve substantially automated the motor type action of a hydraulic piston and cylinder in reciprocating the compacting and unloading blade within the truck body. The valve arrangement, however, was not fully automated in that operation of the valve depended partially upon mechanical contact between the blade, representing the load, and part of the valve. To the elimination of this mechanical contact is this invention directed.

SUMMARY OF THE INVENTION This invention relates to a new and novel valve for fully controlling the cycle of operation of a reversing fluid motor which comprises changing from a neutral condition to one of applying force to a load until a predetermined resistance, is met, reversing the force until another predetermined resistance is met, returning to the neutral condition, and then repeating the cycle.

It is an object of this invention to provide an improved hydraulic valve for operating a reversing motor, the valve capable of full automatic control, except for the initial manual change from. a neutral condition to an activating condition.

It is another object of this invention to provide a combination of manual andautomatic control means, whereby movement of a reversing fluid motor away from its starting or loading position may beinitiated manually, with automatic control of subsequent movements through the remainder of its working stroke, reversal of direction and return-to starting position.

It is yet another object of this invention to provide a novel control for a reversing fluid motor which will cause it to exert force against an external object until a predetermined force is attained.

A further object of the invention is to provide-a means responsive to the pressure of thehydraulic fluid powering the motor which will cause the direction of movement away from the starting point to be automatically reversed whenever resistance against it reaches a predetermined point.

Still a further object of the invention is to provide a means responsive to the. fluid pressure powering a hydraulic motor, such that whenever the fluid pressure powering the motor reaches a predetermined value, all movement of the motor during its return stroke will cease, and the position of the valve elements controlling said motor and fluid flow conditions within said valve shall be restored to those before movement of the motor and/or the load were manually initiated.

A further object of this inventionis to provide a position responsive means which will automatically arrest the movement of a fluid motor whenever the motor and/or load attains the starting position at the end of its return stroke.

Another object of this invention is to provide a means for automatically unloading the pressure of the fluidv powering the movement of the motor wherever movement of the motor is arrested during its return movement, or upon attaining its starting position at the end of the return stroke.

A still further object of the invention is to provide means whereby the valve controlling the movement of a fluid motor may be manually positioned in any of its three positions, regardless of the position of the load, and mechanically held in the position so selected.

It is still another object of this invention to provide an apparatus capable of accomplishing the above designated objectives which is economical of manufacture, effective in use, efficient in operation, and wherein the valve and its power source can be physically separated from the motor.

These objects, features and advantages will become readily apparent from the following description and appended claims when read in view of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a truck-mounted refuse body, with part of the body cut away, and showing assembled portions of the invention;

FIG. 2 is a reduced side elevational view of the refuse body, with certain parts exposed for clarity of illustration;

FIG. 3 is an enlarged, fragmentary view of the valve apparatus of this invention;

FIG. 4 is a schematic of the hydraulic circuit employed for the invention;

FIG. 5 is an enlarged view of the valve apparatus of FIG. 3, and showing by a longitudinal sectional view the valve apparatus in its neutral position;

FIG. 6 is a partial sectional view of the valve assembly and related-parts at the instant the blade starts its extending stroke;

FIG. 7 is a sectional view taken along the lines 7-7 in FIG. 6;

FIG. 8 is a partial sectional view of the valve and related parts with the blade away from the front wall of the body and-moving in a pack position;

FIG. 9 is a sectional view taken along the lines 9-9 in FIG. 8;

FIG. 10 is a sectional view of the valve and related parts with the valve spool in its blade retracting position with the blade moving toward the front wall;

FIG. 11 is a sectional view taken along lines 11-11 in FIG. 10;

FIG. 12 is a sectional view of the valve and related parts with the valve spool in its blade retracting position, and with the return pressure having activated the cocking piston, the blade near the end of its retracting stroke; and

FIG. 13 is a sectional view taken along the lines l3-l3 in FIG. 12.

DESCRIPTION OF THE PREFERRED EMBODIMENT The blade 11 has a frame consisting of top and bottom cross members 11 and 12 which are joined by upright members l3, l4, l5, l6 and 17. Adjacent the bottom of the blade, a projecting portion is provided, which portion slopes toward the end gate 7 and is built of di

agonal members

18, 19, 20, 21 and 22, the members 18 22 extending from the uprights l3 I7 and terminating in a transverse member 23. The surface 24 (FIG. 2) on the back of the blade serves to contact all refuse being packed. Guides 25 work against the beam 8 support and align the blade 10.

Attached to the front of the blade 10 is a support 32 (FIG. 1) which carries a wrist pin 33 connecting the I piston rod 34 of a conventional double-acting hydraulic cylinder 35. The stationary end of the cylinder 35 is pivotally connected by means of an anchor pin inserted through

suitable anchor brackets

37 and 38 attached to the forward end of the beam 8. Extension and retraction of the cylinder 35 effects a reciprocating movement of the packing blade 10 between its packing and- /or unloading (extending) stroke, and its return or retracting stroke toward the front of the truck body 2.

It is evident that when the end gate 7 is in a raised position, any refuse within the body 2 will be discharged by the rearward movement of the blade 10. When the end gate 7 is closed, rearward movement of the blade 10 serves to compact any refuse between the face 24 of the blade 10 and the end gate 7.

Referring to FIG. 4, the basic components of the hydraulic system for the invention are illustrated. A pressure generating hydraulic pump 39 is powered from the truck transmission (not shown) through a conventional transmission power take-off (not shown). Fluid is drawn by the pump 39 through a suction line 40 from a reservoir 41, and is discharged under pressure through a pressure line 43 to a control valve 42. The control valve 42 is referred to from time to time as the autocycle valve. The valve 42 may be manually operated throughout the full operating cycle of the blade actuating cylinder 35. Subsequent to initial movement of the valve spool, as described hereinafter, to its starting position, all remaining movements of the compacting and return cycle of the blade 10 can also be controlled automatically.

A fluid line 44 connects a related cylinder port of the valve 42 with the rod end of the cylinder 35. A fluid line 45 connects the other cylinder port of valve 42 to the anchor end of the cylinder 35, and is also connected by line 46 to a cocking piston device 47 which is interconnected to one end of the control valve 42 for reasons detailed hereinafter.

When the autocycle valve 42 is in its neutral position, as shown schematically in FIG. 4, the ports connecting with

lines

44 and 45 to the anchor and rod ends, respectively, of the cylinder 35 are blocked, preventing the flow of fluid to or from the cylinder 35 and effectively restraining it against movement. When, however, the valve 42 is in the position shown in FIG. 6, wherein the valve 42 has been moved to the left as viewed, fluid delivered under pressure from the pump 39 through line 43 is directed through a line 45 to the anchor end port of the cylinder 35. This results in extending the cylinder. As the piston moves toward the load or rod end, fluid within the rod end of the cylinder is forced through line 44 to the valve 42, from whence the flow is directed through return line 52 to the reservoir .41.

U When the valve 42 is in the position shown in FIG. 10, wherein the valve 42 has been moved to the right as viewed, fluid delivered under pressure from the pump 39 through line 43 is directed through line 44 to the rod end of the cylinder 35, the resulting piston movement forcing fluid from the cylinder anchor end out through line 45 to valve 42, thence through line 52 to sump 41.

To limit the maximum pressure generated by the pump, a relief valve 53 (FIG. 4) is set open at a predetermined pressure, and connects with the pumptovalve line 43 through line 54. When pressure in line 43 exceeds the opening point of relief valve 53, the fluid is discharged through line 55 and back to the reservoir 41.

Referring to FIG. 5, the components of the autocycle valve 42 and related parts are clearly illustrated, with the valve shown in its neutral position, and with the blade 10 in its most forward or retracted position as best shown in FIGS. 2 and 3.

The autocycle valve 42 includes a valve body 56 having a fluid inlet 57 formed therein for connecting a pair of internal ports 58 and 59 with the pressure line 43 from the pump 39. The ports 58 and 59 are cut off from the

adjacent ports

66 and 67 by lands of the valve spool 63, but are in fluid communication with afluid outlet 60 which connects by line 52 to the reservoir 41. The outlet 60 communicates with a pair of

return ports

61 and 62, and it will be noted that external leakage is prevented by a pair of

seals

64 and 69 embracing the spool 63.

The spool 63 is moved longitudinally within the valve body 56 by a manually operated valve handle pivotally connected to an exposed outer end of the valve spool 63 as best illustrated in FIG. 5.

A detent housing 70 is secured adjacent the valve body 56 as best shown in FIG. 5, and includes a detent sleeve 72 slidable in the bore of the housing 70 and having a pair of circular grooves 71 and 73 formed therein longitudinally spaced relation. A detent ball 74 is held against the sleeve 72, being adapted to seat in either

groove

72 or 73, by a plunger 75. The lower end of the plunger 75 has a diameter less than that of the upper end, and forms with a passage 78 a pressure chamber 79. Passage 78 is connected by a line 68 with the inlet valve body pressure port 59.

Seals

76 and 77 are provided on the detent plunger 75 to prevent leakage of fluid outwardly from the pressure chamber '79.

A detent spring body 80 is seated in the housing 70 and houses a spring adjusting screw 83 which contains a detent ball spring 82 for applying adjustable pressure on the detent ball 74. The screw 83 is held by a nut 81 and cap 85, the screw 83 having a slot 84 formed in its upper end for rotation by a screwdriver or the like so as to adjust the compression of the spring 82.

Mounted adjacent the detent housing 70 is another housing 86 which has a bore 98 formed therein for containing a plunger 87. The plunger 87 terminates in a wall 88 adjacent the piston device 47, and moves axially within the bore 98 of the housing 86, which axial movement of the plunger 87 toward the valve body 56 is limited by contact with the face 107 of the detent housing 70.

Travel of the plunger 87 in the opposite direction is limited by the wall 88 striking the housing 89 of the piston device 47. Embracing a spring cup 92 is a major actuating spring 90 which at its inner'end abuts against the face 107 of the detent housing 70, and at its outer end abuts against the upturned flange of the spring cup 92. The cup 92 in turn embraces the reduced section 202 of a spacer 91 and may move axially with respect thereto. This axial movement of the cup 92 is limited in its inward direction by contact of the outer face 108 with the shoulder 203 of the spacer 91.

The axial force of the major actuating spring 90 acts against the spring cup 92 to force it to the right as viewed in FIG. 5, away from the face 103 of the spacer 91. Such outward movement of the cup 92 with respect to the face 103 of the spacer 91 is limited by a retaining washer 93. A screw 94 extends into a threaded hole 109 in the valve spool 63 and acts to clamp the spring cup retaining washer 93, spacer 91, detent sleeve 72, and valve spool 63 into a single functional unit so that all parts move together axially.

When the spring cup 92 is forced by the action of the major spring 90 against the retaining washer 93, any ex ternal force exerted against the cup 92 through contact with the shoulder 95 of the plunger 87, will act to further compress the spring 90 and force the cup 92 axially toward the valve body 56 until the face 108 of the cup 92 engages the shoulder 103 of the spacer 91.

A minor actuating spring 96 is provided which bottoms at its outer end against the face 111 of the wall 88. The inner end of the spring 96 contacts the outer face of the retaining washer 93, and in this manner exerts a continuing axial. biasing force opposing that of the major spring 90. In all working positions, the axial force of the major spring 90, acting to force the valve spool 63 out of the valve body 56, or to the right as viewed in FIG. 5, is at all times sufficient to overpower the opposing force of the minor spring 96.

The cocking piston device 47, in addition to its housing 89, comprises a chamber 101 fluid connected by line 46 to both the valve chamber 67 (FIG. 5) and the cylinder load end by line 45, and which chamber 101 is in fluid communication with the inner end of a cocking piston 102. The piston 102 is reciprocally movable within a bore 103 formed in the housing 89 axial with the longitudinal axis of the valve housing 86. A quad ring 104 seals the piston 102, the outer end of which is engageable with the plunger wall 88.

For the purposes of this description, the operating cycle of the system is considered as starting with the packing blade cylinder 35 fully retracted (FIG. 2), the packing blade in its extreme forward position, the control valve spool 63 and the control handle 65 stopped in mid-travel, and with hydraulic fluid flowing unimpeded from pump to reservoir through open ports in the valve 42. The positions of the valve spool control handle 65, packing blade 10, and related operating parts are shown in FIG. 5 in their neutral positions.

The automatic operating cycle is started by manually moving the handle 65 to the left, as viewed in FIG. 6, thus bringing the valve spool 63 into its extending position as shown in FIGS. 6 and 7. Thereafter, hydraulic fluid under pressure from the pump is directed to the anchor end of the packing blade cylinder 35, causing it to extend and force the blade 10 rearwardly in the body 2 (FIG. 2). When resistance against such rearward movement causes the hydraulic operating pressure to rise to a predetermined value, the valve spool 63 is caused to automatically move to its retracting position (FIGS. 10 and 12) as described in detail hereinafter. Fluid under pressure is then directed to the rod end of the actuating cylinder 35 (FIG. 10) causing it to retract and return the packing blade 10 to its initial forward position. The valve spool 63 and the hand lever 65 are thereupon automatically returned to their neutral positions as shown in FIG. 5 and as described hereinafter.

The major spring 90, when otherwise unrestrained, exerts sufficient axial force to overpower the minor spring 96 under all operating conditions. The major spring 90 is confined between the face 107 of the detent housing and a flange 110 of the cup 92, and at all times exerts a bias force acting to move the cup 92 and the related washer 93, screw 94, spacer 91, detent sleeve 72 and valve spool 63 as a unit to the right as viewed in FIG. 5. The force of the major spring 90, acting against the cup 92 may be restrained either by the detent ball 74 or the plunger 87 depending upon the relative positions of the valve spool 63 and the plunger 87.

In FIG. 5 the major spring is at its mean working length. This length may be reduced by manually moving the valve spool 63 to the left, and increased by removing restraint from the plunger 87, allowing it to move to the right until restrained by contact of the wall 88 with the inside of the housing 89. The minor spring 96 acts against the retaining washer 93, bringing it into firm contact with the adjacent end of the spacer 91. In this way, the forces of

springs

90 and 96 act to positively position the valve spool 63 in its mid-travel or centered position of FIG. 5.

With the valve spool 63 in the neutral position shown, the hydraulic fluid flows freely from the pump through the line 43, inlet port 57, pressure ports 58 and 59 into

return ports

61 and 62, and then out through the outlet port 60 and line 52 to the reservoir 41. The port 67, connected with the anchor end of the cylinder 35 through line 45, and port 66 connected with the rod end of the cylinder 35 through the line 44 are both blocked by lands forming a part of the valve spool 63. This prevents movement of hydraulic fluid between the cylinder 35 and the valve 42 and effectively locks the piston of the cylinder 35 and the packing blade 10 against movement.

The pressure operated detent unit in housing 70 (FIG. 5), operates to remove restraint holding the valve spool 63 in either extending or retracting positions. Upon removal of such restraint, the position of the plunger 87 is established by the forces of the major actuating spring 90 and the minor actuating spring 96. The detent ball 74 is normally loaded by a spring 82 acting through detent plunger 75. The plunger 75 has two diameters on a common axis. The smaller diameter slides in bore 1 l2 and the larger diameter slides in bore 113. Both diameter sections of the plunger 75 are sealed against fluid pressure by 0

rings

77 and 76, respectively.

The lengths of the bores 112 and 113 and the lands on plunger 75 are such that an annular fluid chamber 79 is formed around the smaller land 75. This chamber 79 connects with the valve pressure port 59 by passages 68 in the

valve body

56 and 78 in the detent housing 70. Through these communicating passages, the hydraulic pressure in the chamber 79 approximates that of the fluid entering the valve body 56 from tthe pump. This pressure acts on a differential area numerically equal to that of the larger diameter of the plunger 75 minus that of the smaller diameter and always acts against the force exerted by the detent spring 82 against the ball 74.

The detent ball 74 under loading of the detent spring 82 is forced into an extending groove 73 or a retracting groove 71, and thereby holds the valve spool 63 in either respective position withstanding the axial forces resulting from the major spring 90 and the minor spring 96. Since the bias of the spring 82 opposes that resulting from the pressure of hydraulic fluid against the differential pressure area of the plunger 75, the pressure at which the plunger 75 will unload the detent ball 74 and thereby remove restraint from the axial movement of the valve spool 63 may be readily changed by adjusting the working length of the spring 82. This may be accomplished by turning the adjusting screw 83 to the right or left as desired, employing the slot 84 for that purpose. The lock nut 81 may be subsequently tightened to prevent loosening of the screw 83 and thereby preserve the desired adjustment. The nut 85 serves to prevent fluid leakage.

It will be seen that whenever the valve spool 63 is moved into either the extending or the retracting position, either manually or automatically through the forces of the major and

minor springs

90 and 96 respectively, it is restrained by the detent ball 74. Sufficient manual effort may be applied to the handle 65 to overpower the restraint imposed by the ball 74 and actuating springs 90 and 96, and bring the valve spool 63 into either its extending or retracting position. In this manner, manual control of the blade may be taken over at any point of the operating cycle. With the blade 10 fully retracted, and all valve and related parts in the re spective positions shown in FIG. 5, automatic cycling of the motor 35 may be started by moving the operating handle 65 away from the valve body 56 as shown in FIG. 6.

As a result, the spool 63 is moved from its mid position to the left, as viewed in FIGS. 6 and 7; the pressure port 59 opens into the cylinder port 67 allowing hydraulic fluid under pressure from the pump to flow through the line 45 to the cylinder 35, causing it to extend; the cylinder port 66 opens into the return port 61, allowing hydraulic fluid to flow freely from the rod end of the cylinder 35 through the cylinder port 66 into the return port 61, and outwardly through the outlet 60 to the reservoir 41; and the forced movement of the spring cup 92 toward the detent housing 70 creates a gap between the flange 110 of the cup 92 and the shoulder 95 of the plunger 87, reducing the working height of the major spring 90 by an equal amount and correspondingly increasing its axial compressive force to a maximum. The working height of the spring 96 has been increased an equal amount and its axial force likewise reduced. Under the force of the detent spring 82, the ball 74 has dropped into the extending detent groove 73, holding the valve spool 63 in the extending position against the bias forces exerted by the

springs

90 and 96.

As the packer blade 10 moves rearwardly away from the front wall 4 (FIG. I), changes effected in the positions of the parts are best illustrated in FIG. 8. With fluid flowing freely out line 44, line 46 also feeds the chamber 101 in the piston housing 89, such that the piston 102 is freely movable. The axial force of the minor spring 96 has forced the plunger 87 away from the detent housing until stopped by the wall 88 striking the piston housing side 100. The gap between the cup flange 110 and the shoulder 95 of the plunger 87 has increased until it equals the travel of the spool 63 from the extending to the retracting position. With the outward movement of the plunger 87, or movement from the left to the right as viewed in FIGS. 6 and 8, the minor spring 96 has attained maximum working height and its axial force is minimal.

Under the operating force of the extending cylinder 35, the packer blade 10 continues its packing stroke until either a pre-determined resistance is encountered or the cylinder 35 reaches the end of its extending stroke. In either case, the hydraulic pressure operating the cylinder increases. When a predetermined working pressure is attained, it is transmitted through the pressure passages 68 and 78 (FIG. 8) into the annular pressure chamber 79 and acts to raise the detent plunger and release the ball 74 from the detent groove 73. Unrestrained by the ball 74, the axial force of the major spring overpowers the minor actuating spring 96 and forces the valve spool 63 outward or to the right in FIG. 8, until stopped by contact of the cup face 110 with the shoulder of the sleeve 87.

The valve spool 63 (FIG. 10) and the handle 65 are now in their respective retracting positions. The pressure port 58 connects with the rod end cylinder port 66, allowing hydraulic fluid from the pump 39 to flow through the line 43, valve inlet 57, pressure port 58, cylinder port 66 and line 44 to the rod end of cylinder 35, causing it to retract and to return the packing blade 10 to its forward position. Simultaneously, the anchor end cylinder port 67 is opened to the return port 62, allowing fluid to freely flow from the anchor end of the cylinder 35 through line 45, cylinder port 67, return port 62, outlet 60 and return line 52 to the reservoir 41 (FIG. 8).

The detent ball 74 is forced into the retracting detent groove 71 by the force of the spring 82 and thereby positions the valve spool 63 in its retracting position. The plunger 87 is in its outer position with the wall 88 against the shoulder of the housing 89. The retaining washer 93 is in contact with the face 108 of the cup 92. The bias force of the minor spring 96 is overpowered by the controlling greater force of the major spring 90. The gap between the shoulder 203 on the spacer 91 and the inner face 122 of the cup 92 is equal to the axial movement of the valve spool 63 from retracting to extending positions.

It is under these conditions that the blade 10 continues its retracting movement. As it nears the end of its retracting movement, pressure from the line 44 (FIG. 10) to the cylinder 35 is also transmitted through line 46 to the chamber 101 in the piston housing 89. There, at a predetermined pressure value set slightly below the operating pressure for the detent unit, the piston 102 is moved from right to left as viewed in FIGS. 10 and 12. This movement forces the plunger 87 also toward the detent housing 70 until its inner end 105 strikes the housing 70. In so doing, the shoulder 95 carries the spring cup 92 with the plunger 87, sliding the cup 92 over the intermediate portion 204 of the spacer 91, compressing the major spring 90 to its normal length (FIG. 12), while leaving the minor spring 96 attempting to force the valve spool 63 to the left as viewed, but which bias is overcome by the hold of the detent unit on the valve spool 63 via the ball 74.

When the blade operating cylinder 35 reaches the end of its retracting stroke, all movement stops and the operating pressure rises until the detent ball is allowed to disengage from the detent groove 71, removing all restraint against axial movement of the valve spool 63. Thus free from restraint, the bias force of the compressed minor spring 96 forces the valve spool 63 into its mid-travel, or neutral position as shown in FIG. 5, the force of the major spring 90 preventing the spool 63 from moving into the extending position of FIG. 6.

The major spring 90, the minor spring 96, and the detent ball spring 82 may be manually overpowered by moving the operating handle 65 as desired. In this manner, movement of the cylinder 35 and the blade 10 is under the operators control at all times. After stopping the blade 10 at any point of its extending or retracting movements by manually moving the handle 65 to its neutral position, further movement of the blade 10 in either direction may be initiated by moving the handle 65 into its appropriate retracting or extending positions. When the spool 63 is so moved, it will thereafter be retained by the detent ball 74 in cooperation with the grooves 71 or 73. Should the extending movement of the blade 10 be so initiated at any point between its extremes of travel, it will automatically continue throughout the unexpired portion of its cycle and eventually be brought to a stop at the end of its retracted stroke, at which time the valve spool 63 will be automatically returned to its neutral position as previously described.

It will be seen that whenever the valve spool 63 is so positioned that the detent ball 74 engages neither the groove 71 nor 73, and the plunger 87 is free of restraint from the cocking piston 102, the

springs

90 and 96 will cause the valve spool 63 to assume the retracting position shown in FIG. 10. In order to avoid this condition, a manually operated means is provided to hold the operating handle 65 and the valve spool 63 in their respective neutral positions. Referring to FIG. 5, a hinge 1 18 is attached to any suitable anchoring point 128 and may be brought into its full line position such that the flip bar 119 engages a suitable detent shoulder 120 formed in the handle 65, and restrains the handle against any clockwise rotary movement resulting from the loading imposed by the major spring 90 acting through the valve spool 63. In this way, the handle 65 and the valve spool 63 are both effectively held in their mid-travel or neutral positions, and movement of the cylinder 35 and the blade 10 are hydraulically locked. The holding effect of the hinge 118 and the flip bar 1 19 may be eliminated by moving them to their dotted line position as shown. It has also been found that use of the bar 119 to latch the handle 65 in a neutral position eliminates a slow hunting of the spool 63 which may occur over a long period of time when the pump 39 is operating, but with the cylinder 35 at rest.

When travel of the actuating cylinder 35 and the packing blade 10 is arrested at any point by holding the control handle 65 and the valve spool 63 in their respective neutral positions, with the axial position of the plunger 87 not determined by 'the cocking piston 102, the remaining valve operating parts are positioned as follows: hydraulic fluid circulates freely from the pump to the reservoir through the valve 42, the detent ball 74 bears against the outer cylindrical surface of the detent sleeve 72 at a point midway between the grooves 71 and 73, the bias force of the minor spring 96 forces the plunger 87 outwardly until restrained by contact of the wall 88 with the housing 89, and the gap between the face 110 of the cup 92 and the shoulder 95 of the plunger 87 is equal to one half the total travel of the valve spool 63.

Telescoping cylinders employing multiple pistons of different sizes are commonly made so that the volume of the hydraulic fluid necessary to extend the cylinder may be much greater than that required to retract it. With hydraulic fluid delivered to such a cylinder maintained at a given rate, the retracting speed will therefore be considerably greater than that of extending. This results in substantially increasing the rate of hydraulic fluid return flow from the anchor end of the cylinder as compared with that from the rod end thereof. Such a high rate of return flow has been found to significantly increase the back pressure acting against the piston, so that for a given external resistance to piston travel, the operating pressure is comparably higher to a point where it may adversely affect the operation of the hydraulic detent in a valve of the type covered by this invention.

To effect dependable operation of such a valve, it may become advisable to limit the rate of hydraulic fluid flow to the rod end of the cylinder by means of a flow divider. Such divider may be adjusted so that the rate of flow from the anchor end of the cylinder during the retracting stroke remains at a rate which will not seriously affect the operation of the valve. Such flow dividers are well known in this art and can be depended to deliver fluid to the primary outlet (cylinder) at a fixed rate, with all excess fluid delivered back to the reservoir, but their use for the purposes described is believed new to this art.

It has been found under certain conditions with use of a cylinder 35 of the telescoping type, that during the return stroke thereof the back pressure generated in the line 43 is so much higher than that in line 44 that a premature release of the holding detent 74 is effected. To prevent such a premature release, the flow divider FD (FIG. 4) arrangement is included in the hydraulic circuit. With the valve 42 in the retracting position of FIG. 10, operation of a check valve 50 (FIG. 4) diverts flow from

lines

44 and 49 toward the rod or load end of the cylinder 35 to a flow divider FD via line 50a. The divider FD permits a limited volume of fluid to pass through line 47 to line 49 and then to the cylinder, delivering the excess through line 48 to the reservoir 41. By this arrangement, the pressure and flow rate of fluid pumped into the valve 42 are substantially equal that discharged therefrom, thereby preventing premature release of the detent mechanism.

I claim: 1. Apparatus for controlling the operation of a reversing fluid motor operating through a cycle of changing from a first condition applying force in one direction, to a second condition applying force in another direction, then returning to the first condition, etc., the apparatus comprising:

a fluid pressure system; valve means in communication with said fluid and having a neutral position where fluid is not directed to the motor, a second position where fluid is di' rected through said system to the motor to effect the first condition thereof, and a third position where fluid is directed through said system to the motor to effect the second condition thereof;

means for positioning said valve means into at least one of said positions; I

detent means for releasably holding said valve means in either said second position or said third position;

positioning means relatively movable with said valve means and having a first placement and a second placement;

piston means engageable with said positioning means and responsive to a predetermined pressure in said system prior to the motor changing from the first condition to the second condition to move said positioning means from its second placement to its first placement;

biasing means tending to maintain said valve means in its neutral position, said biasing means operable to move said positioning means from its first placement to its second placement in response to movement of said valve means to its second position, said biasing means further operable to move said valve means from its second position to its third position upon release of said valve means by said detent means, said biasing means operable in conjunction with said positioning means to move said valve means from its third position to its neutral condition upon release of said valve means by said detent means; and

fluid pressure means in said system fluid associated with said detent means for releasing the hold of said detent means on said valve means, said hold overcoming the bias of said biasing means on said valve means, according to the pressure of said system reaching a predetermined value in response to a load being applied to said motor.

2. Apparatus as defined in claim 1, and wherein the pressure necessary to activate said piston means to move said positioning means is less than the said predetermined pressure value necessary for releasing said detent means hold on said valve means.

3. Apparatus as defined in claim 2, and wherein said biasing means comprises a major operating spring and a minor centering spring, said major spring having a strength of expansion greater than that of said minor spring when both are compressed, said major spring operable to move said valve means from said second position to said third position upon release of said valve means by said detent means, and wherein said minor spring tends to move said valve body to said neutral position.

4. Apparatus as described in claim 3, and wherein said major spring is capable, when fully extended, to simultaneously move said valve body from said second position to said third position while overcoming the expansion force of said minor spring in its fully compressed condition.

5. Apparatus as described in claim 4, and wherein the force of said major spring holding said valve means in said third position is removed by action of said positioning means, whereupon said minor spring is operable alone to return said valve means to said neutral position upon release of said valve body by said detent element.

6. Apparatus as described in claim 1, and wherein said piston means includes a housing having a fluid chamber formed therein in fluid communication with said fluid pressure means, and having further a piston element reciprocally mounted therein, one end of said element responsive to said fluid pressure and the other end engageable with said positioning means.

7. Apparatus for controlling the direction of movement of a load movably mounted for longitudinal movement, and including further a fluid operated device operably connected with the load for reciprocating the load between two positions, the apparatus comprising:

a fluid pressure system;

valve means in said system in fluid communication with said device, and having a neutral position, a device force applying position, and a device force released position;

means for positioning said valve means into any one of said positions; detent means interposed in said fluid pressure system and operatively engaged with said valve means for releasably holding said valve means in either said force applying position or said force released position, said detent means releasing its hold on said valve means in response to the pressure in said system reaching a predetermined value;

positioning means relatively movable with said valve means and having a first position and a second position; piston means interposed in said fluid pressure system and operatively engaged with said positioning means, said piston means operable in response to the pressure within said system reaching a predetermined value to move said positioning means from its second position to its first position; and

biasing means for biasing said valve means into the neutral position when said positioning means is in said first position, said biasing means operable to bias said valve means from the device force applying position to the device force released position when said positioning means is in its second position.

8. Apparatus as defined in claim 7, and wherein said detent means predetermined pressure value is greater than said piston means predetermined pressure value.

9. Apparatus as defined in claim 7, and wherein said piston means is non-resistant to movement of said positioning means from its first position to its second position.

10. Apparatus as defined in claim 7, and wherein said pressure values are determined by the resistance of the load to movement thereof by the fluid operated device, which device is reversibly actuated by said value means to automatically reciprocate the load between its alternate positions.

11. Apparatus as defined in claim 7, and including further means for latching said means for positioning said valve means into its neutral position.

i l i I l

Claims

1. Apparatus for controlling the operation of a reversing fluid motor operating through a cycle of changing from a first condition applying force in one direction, to a second condition applying force in another direction, then returning to the first condition, etc., the apparatus comprising: a fluid pressure system; valve means in communication with said fluid and having a neutral position where fluid is not directed to the motor, a second position where fluid is directed through said system to the motor to effect the first condition thereof, and a third position where fluid is directed through said system to the motor to effect the second condition thereof; means for positioning said valve means into at least one of said positions; detent means for releasably holding said valve means in either said second position or said third position; positioning means relatively movable with said valve means and having a first placement and a second placement; piston means engageable with said positioning means and responsive to a predetermined pressure in said system prior to the motor changing from the first condition to the second condition to move said positioning means from its second placement to its first placement; biasing means tending to maintain said valve means in its neutral position, said biasing means operable to move said positioning means from its first placement to its second placement in response to movement of said valve means to its second position, said biasing means further operable to move said valve means from its second position to its third position upon release of said valve means by said detent means, said biasing means operable in conjunction With said positioning means to move said valve means from its third position to its neutral condition upon release of said valve means by said detent means; and fluid pressure means in said system fluid associated with said detent means for releasing the hold of said detent means on said valve means, said hold overcoming the bias of said biasing means on said valve means, according to the pressure of said system reaching a predetermined value in response to a load being applied to said motor.

7. Apparatus for controlling the direction of movement of a load movably mounted for longitudinal movement, and including further a fluid operated device operably connected with the load for reciprocating the load between two positions, the apparatus comprising: a fluid pressure system; valve means in said system in fluid communication with said device, and having a neutral position, a device force applying position, and a device force released position; means for positioning said valve means into any one of said positions; detent means interposed in said fluid pressure system and operatively engaged with said valve means for releasably holding said valve means in either said force applying position or said force released position, said detent means releasing its hold on said valve means in response to the pressure in said system reaching a predetermined value; positioning means relatively movable with said valve means and having a first position and a second position; piston means interposed in said fluid pressure system and operatively engaged with said positioning means, said piston means operable in response to the pressure within said system reaching a predetermined value to move said positioning means from its second position to its first position; and biasing means for biasing said valve means into the neutral position when said positioning means is in said first position, said biasing means operable to bias said valve means from the device force applying position to the device force released position when said positioning means is in its second position.