US2841118A - Control valve mechanism for hydraulic motors - Google Patents

Description

July 1, 1958 E. A. KLEIN 2,341,118

CONTROL VALVE MECHANISM FOR HYDRAULIC MOTORS Filed March 11, 1957 r 4 Sheets-Sheet 1 INVENTOR. EDMUND A. KLEIN AGENT y 1958 E. A. KLEIN 2,841,118

CONTROL VALVE MECHANISM FOR HYDRAULIC MOTORS Filed March 11, 1957 4 Sheets-Sheet 2 INVENTOR. EDMUND A. KLEIN bwkyw AGENT.

E. A. KLEIN 2,841,118

CONTROL VALVE MECHANISM FOR HYDRAULIC MOTORS Filed March 11, 1957 4 Sheets-Sheet 3 July 1, 1958 INVENTOR. EDMUND A. KLEIN BY I M. W

AGENT.

July 1, 1958 E. A. KLEIN 2,841,118

CONTROL VALVE MECHANISM FOR HYDRAULIC MOTORS Filed March 11, 1957 4 Sheets-Sheet 4 INVENTOR. EDMUND A. KLEIN AGENT.

CONTROL VALVE MECHANISM FOR HYDRAULEC MOTOREE Edmund A. Klein, Hilliards, Uhio, assignor to American Brake Shoe Company, New York, N. Y., a corporation of Delaware Application March 11, 1957, Serial No. 645,046

4 Claims. (Cl. 121-38) This invention relates generally to hydraulic apparatus and is particularly directed to mechanism for controlling the operation of hydraulic pressure operated motors, power cylinders and similar mechanisms.

One of the objects of the present invention is to provide an improved hydraulic apparatus or system for controlling the operation of the ram motor of a hydraulic press, for example, which may be controlled either manually or semi-manually.

Another object of the invention is to provide an improved hydraulic apparatus or system having improved means for controlling the speed and timing the phases of the cycle of operation of a hydraulic motor, which motor may, for example, constitute the ram of a hydraulic press.

Another object of the invention is to provide an improved hydraulic apparatus or system including a reversible hydraulic motor which may constitute, for example, the ram of a hydraulic press, and an improved control mechanism for controlling said motor which assures that the motor will exert its full mechanical thrust in one direction and then have its direction of operation reversed.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings where in a preferred form of embodiment of the invention is clearly shown.

In the accompanying drawings:

Fig. l is a diagrammatic view of the hydraulic system of a hydraulic press which includes the features of the invention and in which a control valve mechanism is shown with its parts in the positions which they occupy when the system is idle;

Fig. 2 is a diagrammatic view of the control valve mechanism in which the valve parts are shown in positions which they may occupy when the ram of the press motor controlled, by the valve mechanism is being inched downwardly;

Fig. 3 is a diagrammatic view of the control valve mechanism seen in Fig. 1 in which the valve parts are shown in the positions which they occupy when the press motor controlled thereby is operating in a forward direction at a rapid rate;

Fig. 4 is a diagrammatic view of the control valve mechanism with its parts shown in the positions which they occupy when the press motor is operating in a forward direction at a controlled rate; and

Fig. 5 is a diagrammatic view of the control valve mechanism with its parts shown in the positions occupied when the press motor is operating in a reverse direction.

The hydraulic apparatus and system herein described and claimed includes features which constitute improvements upon the apparatus and system disclosed by Cecil E. Adams in his Patent No. 2,641,228 dated June 9, 1953, for Control Valve Mechanism for Hydraulic Motors.

nitcd States Patent 0 The Adams apparatus and system referred to is capable only of semi-manual operation whereas the present apparatus and system is capable of full manual operation, that is, operation in which the person or operator operating the apparatus has full control of the movement of a hydraulic motor in the system at all times,

and semi-manual operation in which the person or opera-- tor operating the apparatus has full control of the movement of said hydraulic motor only during a portion of a complete cycle of operation of the apparatus or system. The present apparatus also includes structure which operates, when the system is operating undersemi-manual control, to produce more accurate control of the abovementioned motor.

The present invention is herein shown and described as forming a part of a hydraulic press including a reciprocating type hydraulic power cylinder or motor, but it is to be understood that the scope of the invention is not to be limited to a press since it may be employed with equal facility in other apparatuses which may include any type of reversible motor.

The hydraulic system and its mode of operation under full manual control will now be described. In Fig. l of the drawings, there is shown the hydraulic circuit or system 20 of a hydraulic press which circuit or system includes the features of the invention. This system includes means which form a source 21 of fluid pressure comprised of a reservoir or tank 22, a motor-driven pump 23, an adjustable relief valve 24, a conductor or conduit 25 extending from the reservoir or tank 22 to pump 23 and a pressure delivery conductor or conduit 26 extending from the pump 23. The relief valve 24 is connected between the conduit 26 and tank 22 and functions to predetermine the maximum output pressure of the pressure source 21 which is created in the delivery conduit 26 by the pump 23.

The system 20 also includes a control valve mechanism 27 which receives hydraulic fluid from the pressure source 21 through the delivery conduit 26 and this cont-rol valve mechanism 27 functions to control the operation of a piston 28 and ram 29 in the cylinder 3d of the power cylinder or motor 31 of the press. Valve 27 includes a body 32 in which a pair of spaced parallel bores form valve chambers 33 and 34 which are closed at their opposite ends by top and bottom caps 35 and 36, respectively. Chamber 33 receives a sleeve 37 provided on its exterior with a plurality of circumferential, longitudinally spaced grooves 38 through 43. Groove 38 forms the main inlet groove or port of the valve mechanism 35 and it receives fluid under pressure from the pressure source 21 through the delivery conduit 26 with which it is in constant communication. Groove 39 constitutes the forward motor port of the valve mechanism 27 and it is connected by a conduit or line 44 to a port in the top of the power cylinder or motor 31. Groove 4i constitutes the reverse motor port and it is connected by a conduit or line 45 with the bottom of the power cylinder or motor 31. The mentioned motor ports are usable selectively as an inlet port and an outlet port, depending upon the direction in which the motor 31 is operated. Groove 41 constitutes a first outlet, tank or drain port and it is connected through a conduit or line 46 with tank 22. Groove 42 will be called the second outlet port and its function will be set forth in detail hereinafter. Groove 43 functions merely as a drain port to collect fluid which may seep along the sides of the sleeve 37 and fluid collected by this groove 43 is conducted by conduits 47, 48 and 49 to the first outlet or tank port 41 from which said fluid flows through line 46 to tank 22.

The sleeve 37 slidably receives a main control spool or valve element 50 which is provided with three circumferential, longitudinally spaced grooves 51, 52 andsgpg.

tween spaced lands 54, 55, 56, 57 and which grooves func: tion to establish communication between ports or openings which extend from the grooves 38 through 42 through the side walls of the sleeve 37. When the main control spool 50 is in different longitudinal positions in sleeve 37, various sets of the grooves 38 through 42 will be interconnected through said ports or openings and the grooves 51, 52 and 53 in the spool 56) The bore which forms the valve chamber 34 slidably receives a spool valve element 59 provided with a central bore in which there is a longitudinally movable flow control valve or element 60, and this bore is provided with three annular, longitudinally spaced grooves 61, 62 and 63. The valve element 59 has ports 64, 65, 66 and 67 formed through its side walls. Port 64 connects with or is in register with groove -61, ports 65 connect with a circumferential groove 68 formed in the exterior of valve spool 59 between a center land 69 and a bottom land 70, ports 66v are in register with groove 63, and port 67 connects with a circumferential groove 71 formed in the exterior of the spool 59 between a top land 72 and the center land 69.

The valve element 59 is retained resiliently in its normal position shown in Fig. 1 of the drawings by a spring 73 disposed between its upper end and a socket in the cap 35 and the flow control valve core element 60 is yieldably held in its normal position shown in Fig. 1 by a spring 74 disposed within a socket formed in the core 60. The upper end of spring 74 abuts a plug 75 which is secured in and closes the upper end of the central bore in the valve element 59. The flow control valve spool orelement 68 includes a circumferential groove 76 positioned between a top land 77 and a bottom land '78, the functions of which will be set forth hereinafter.

When the valve core or spool 50 is in its neutral position, as shown in Fig. 1 of the drawings, the motor 31 will be idle and its piston 28 and ram 29 will be held in their up positions in a floating manner. The piston and ram are supported in a floating manner because hydraulic pressure created by pump 23 is conducted through conduit 26, main inlet port 38, groove 52 in spool 50, reverse motor port 40 and conduit 45 to the cylinder 30 below piston 28. This pressure in cylinder 30 supports the piston 28 and ram 29. The volume of fluid being pumped by pump 23 at this time and not supplied to the cylinder 30 flows from conduit 26 through groove 38, past land 55 to groove 51 in spool 50 and through line 46 to tank 22. Also, at this time the top of cylinder 30 is connected to tank 22 through conduit 44, groove 39, groove 51 in spool 56, groove 41 and conduit 46.

The ram 29 and spool 50 are interconnected by an operating linkage, indicated generally by the numeral 79 and described in detail hereinafter, in such manner that when the ram 29 and spool 50 are in the positions shown in Fig. 1 downward movement of ram 29 results in upward movement of spool 50. Upward movement of the spool 50 from the position shown causes the land 55 thereon to restrict the flow of fluid from groove 38 to groove 51 which results in an increased pressure in the grooves and passages connected to the bottom of cylinder 30. This increased pressure in the bottom of cylinder 30 causes the piston 28 and ram 29 to move upwardly and spool 50 to move downwardly until the land 50 restricts the flow of fluid from groove 33 to groove 51 in spool 50 only sufliciently to create the necessary pressure in cylinder 30 to support the piston 28 and ram 29 in a floating manner in the approximate positions seen in Fig. l.

The ram 29 may be inched" downwardly by shifting the spool 50 between the position shown in Fig. 2 and a position, not shown, which is slightly therebelow. When the spool 50 is in the position shown, the fluid from line 26 flows from groove 38 to groove 51in spool 50 and through tank port 41 and conduit 46 to tank 22. However tank port 41 is restricted by land 54 on spool 50 and pressure created in groove 51 by reason of this restriction is reflected to the top of cylinder 30. Piston 28, however, can not move downwardly since lands 55 and 56 on spool 50 block the escape of fluid from the bottom of cylinder 30 at groove 40. Slight downward movement of spool 50 from the position shown will crack the opening between land 56 and the second outlet port or groove 42 to permit the slow escape of fluid from the bottom of cylinder 30 whereby the piston 28 will move downwardly slowly. Ram 29 will stop in any position which it occupies when the spool. 50 is returned to the position shown in which it blocks groove 40.

When the press is to be operated and the ram is to begin a downward stroke, the position of spool 50 is shifted downwardly from the position seen in Fig. 1, through the position seen in Fig. 2, to the position seen in Fig. 3 of the drawings. in this latter position, tank port 41 is blocked by land 54, grooves 33 and 40 are isolated from each other by land 55 and groove 48 is placed in communication with groove 42 through groove 52 in spool 59 and fluid flows from the source 21 of pressure through conduit 26, main inlet port 38, groove 51 in spool 54), forward motor port 39 and line 44 to the top of motor cylinder 30 where it forces the piston 28 downwardly. As piston 28 moves downwardly in cylinder 3%), it displaces fluid from the bottom of the cylinder and this fluid flows through line 45, reverse motor port 40, groove 52 in spool 50 and a conduit 80. to groove 61 in bore 34.

It will be seen that when the valve spool 59 is first shifted to the position seen in Fig. 3 and piston 23 is to begin its downward travel that there is no open path for the flow of exhaust fluid from the bottom of cylinder 30 to tank 22 because the path for fluid through conduit 80, grooves 61, 68 and ports 65 is blocked by the flow control spool 60, which is then in the position shown in Fig. 1. As a consequence of this blocked escape path, hydraulic pressure will be created in the groove 61, port 64 and a chamber 81 within spool valve element 59 and below the flow control spool valve element 66, which pressure will move the flow control spool 6i) upwardly against the force of spring 74 to a position, such as indicated in Fig. 3, wherein its circumferential groove 76 interconnects the ports 65 and 66.

When the flow control spool 60 has moved upwardly sufficiently to interconnect ports 65 and 66, fluid being displaced from the bottom of cylinder 30 will flow through the grooves 61 and 68, port 65, groove 76 in spool 6 Port 66, groove 63, and a conduit 82 to groove 39 in bore 33 where it is merged with the fluid being delivered from the source 21 of pressure through the conduit 26. it will thus be seen that at this time all of the fluid being delivered from the source 21 of pressure through conduit 26 and all of the fluid being exhausted from the bottom of the cylinder 30 are merged and delivered to the top of cylinder 30 from the groove 39 through the conduit 44.

When the total volume of fluid being pumped by pump 23 is merged with fluid being exhausted from the bottom of cylinder 30 and the merged fluid is delivered to the top of cylinder 30, the ram 29 will be travelling ownwardly at its greatest rate of speed, and this is because the area of the top of piston 28 is greater than the area of the bottom thereof by an amount equal to the area of the top of the piston less an area equal to the cross-sectional area of the ram 29. Therefore, an area on the top of the piston equal to the area of the bottom thereof and the area of the bottom thereof will be hydraulically balanced by the fluid which is displaced from the bottom of cylinder St! to the top thereof whereby the total volume of fluid supplied to the top of cylinder 39 from the source 2.? of fluid pressure will be caused to act upon an area of the top of the piston 28 equal to the cross-sectional area of the ram 29.

The spool valve element 50 was, of course, shifted manually from the position shown in Fig. l to the position shown in Fig. 3 by means of the operating linkage 79. This linkage 79 includes a pivotally mounted operating lever 83 having an operating extremity 84 which is depressed manually to cause the opposite end thereof to elevate a shipper rod 85. The upper end of shipper rod 85 is connected through a lost motion connector 86 to a pivotally mounted lever 87 which, in turn, pulls the core or spool 59 downwardly. After the ram 29 has been projected from the cylinder 39 of motor 31 a distance predetermined by the position of a collar 88 which is adjustably positioned on a second shipper rod 89, a cross head 90 carried by the ram 29 sets a weight 91 on the collar 88 and continued downward movement of the ram 29 causes the weight 91 to shift the shipper rod 89 to the position seen in Fig. 4 of the drawings, whereupon the spool 59 is shifted upwardly to the position seen in Fig. 4, by a pivoted lever 92 which interconnects the shipper rod 89 and an abutment 93 on the spool 59 and when the spool 59 is in this position the rate of travel of the ram 29 is slowed down. In other words, the ram 29 advances at its greatest rate of speed until the weight 91 causes the spool 59 to be shifted upwardly whereupon the rate of travel of the ram is slowed. The position of the ram when this action occurs may be predetermined by adjusting the position of the collar 88 on the shipper rod 89.

When the spool 59 is shifted to the position shown in Fig. 4, the connection between its groove 68 and the annular groove 61 in body 32 is severed and fluid being exhausted from the bottom of motor cylinder 30 can no longer flow to the groove 39 to be merged with the fluid pumped by the source 21 of fluid pressure, but must flow from the groove 61 through a conduit or passage 94 and an adjustable throttling, restrictor valve or orifice 95 to reach the groove 68 in spool 59. Groove 68 is now connected through groove 62, a conduit 96 including an orifice 97, conduits 48 and 49, groove 41 and conduit 46 to tank 22 and the flow control valve 66 begins to function as a pressure differential operated valve, that is, its position in the spool 59 will be changed by differences in pressure existing at its opposite ends and in the chamber 81 at its bottom and a chamber 98 at its top. The pressure obtaining in the chamber 98 is derived from the low pressure or downstream side of the orifice valve 95 through port 67, groove 71, a conduit 99, conduit 96, and grooves 62 and 68 while the pressure obtaining in the chamber 31 is taken from the high pressure or upstream side of valve 95 through port 64.

It will be obvious from the foregoing that the throttling or orifice valve 95 may be adjusted to provide more or less resistance to exhaust fluid flowing therethrough and that this resistance will cause a pressure to be created in the chamber 51 at the lower end of the flow control spool 60 which will function to move the spool 60 in opposition to its spring 74 and the pressure in chamber 98 derived from the downstream side of valve 95 to a position wherein its annular groove 76 will establish a connection between ports 65 and 66. When the connection between ports'65 and 66 is established, some fluid bein supplied to the top of cylinder 35 by the source 21 of pressure is diverted from the cylinder and flows from the forward motor port 39 through conduit 82, groove 63, port 66, groove 76 in spool 69, port 65, groove 62, conduit 96, restrictor 97, conduits 48 and 49, groove 41 and conduit 46 to tank 22.

It will be seen that all of the exhaust fluid from the bottom of cylinder 30 flows to tank 22 after the spool 59 has been shifted to the position seen in Fig. 4 of the drawings and that this in itself will cause slowing of the rate of travel of the ram since this exhaust fluid was formerly directed to the top of cylinder 30. Some of this fluid will flow to tank 22 by passing from groove 61 through the valve chamber 34 to a conduit or line 109, a restrictor or bleed orifice 191, conduits 4S and 49, tank port 41 and conduit 46 and the remainder of this fluid will flow to in when orifice valve 95 is closed, and a result of dividing the path of the exhaust fluid in the manner set forth above, that is, through the fixed orifice 191 and the adjustable orifice valve 95, is the causing of orifice 101 to predetermine the minimum rate at which the ram 29 can descend after the spool 59 has been shifted to the position seen in Fig. 4 and permitting the adjustable orifice valve 95 to be employed to determine the rate of speed of the ram after the spool 59 has shifted, down to the minimum predetermined by the fixed orifice 101. It will, of course, be seen that when the flow of exhaust fluid is restricted by the adjustable orifice valve 95 that the fluid pressure created on the high pressure side of the valve is employed to determine the quantity of hydraulic fluid being supplied by the source 21 of fluid pressure which will be by-passed from the groove 39 to tank 22 thereby to control the rate of travel of the ram 29.

When the apparatus is operated under full manual control, a needle type shut-ofl valve 162 is opened and a needle type shut-ofl valve 103 is closed. When these valves are so adjusted, a path for fluid is established from the chamber 104 above the valve 59 through a conduit 105, the valve 102 in a conduit 106, a chamber 167 above the valve core or spool 59, a drain conduit 1%, conduit 49, tank port 41 and conduit 46 to tank 22. Because of this path, fluid will not be trapped in the chamber 194 and the position of spool 50 may be changed manually.

When the operating extremity 84 of lever '79 is held depressed after the spools 59 and 61D have been shifted to the positions seen in Fig. 4 and the ram 29 engages work on the press which slows its rate of travel and finally stops it, the volume of fluid being exhausted from the bottom of cylinder 30 will diminish and as this volume is reduced the flow control spool 60 will be forced downwardly by its spring 74 and pressure in chamber 9% and port 66 in spool 59 will be closed. After port 66 is closed, the maximum pressure created by the source 21 of pressure will be conducted to the top of cylinder 36 and the flow of fluid from conduit 26 will be through the adjustable relief valve 24 to tank 22.

The above-mentioned action occurs because the pressure of the fluid flowing through the above-enumerated path in advance of orifice 97 is conducted from conduit 96 through conduit 99 to the top of flow control spool 6 in the chamber 98 and because the chamber 51 at the bottom of the spool 60 is connected to tank 22 through orifice 191 when the fluid pressure in chamber 31 is reduced by the slowing or stopping of the flow of the extank 22 through the adjustable restrictor or orifice valve haust fluid from the bottom of the cylinder 36 to a pressure less than necessary to overcome the pressure in chamber 93 and the force of spring 74 the spool 61? will be moved downwardly from the position shown in Fig. 4 toblock the flow of fluid from conduit 82 to conduit 96 and the entire output volume of the source 21 of pressure is directed to the top of cylinder 30.

When the lever 83 is released by the person operating the press, the spool 50 is moved to its full up position shown in Fig. 5 by a spring 109 which surrounds the spool and abuts the cap 36 and a spring abutment in the form of a washer 110. When spool 50 is in this position, fluid flowing from the source 21 of pressure flows through conduit 26, main inlet port 38, groove 52 in spool 5%, reverse motor port 40 and conduit 45 to the bottom of cylinder 30. This fluid forces the piston 23 upwardly in the cylinder 30 and fluid therein above the piston will be expelled to tank 22 through conduit 44, forward motor port 39, groove 51 in spool 513, tank port 41 and conduit 46. As the ram 29 is retracted or raised in the manner set forth, the cross head 90 picks up the weight 91 and the valve spools 59 and 69 are lowered to the positions seen in Figs. 5 and 1, and as the ram continues to travel up wardly the cross head 99 engages a collar 111 on shipper rod whereby the spool 50 is returned to the position seen in Fig. 1 of the drawings before the piston 28 reaches the top of cylinder 30.

The control valve mechanism 27 also includes a conduit or passage 112 which leads from the bottom of the valve chamber 34 to the needle valve 103 and a conduit 113 which connects with a check valve 114 that permits fluid to flow from the conduit 113 to the conduit 105. Check valve 114 is by-passed by a conduit 115 including a restrictor or orifice 116. Fluid flows through these last-mentioned passages and valves only when the circuit or system is being operated under semi-manual control.

When the system 20 is to be operated under semi-manual control, the needle valve 102 is closed to block the free flow of fluid from the chamber 104 to tank 22 and valve 103 is opened to establish a connection whereby there will be free flow of fluid from tank 22 to chamber 104 while the spool 50 is being lowered and whereby there will be a restricted flow of fluid from the chamber 104 While the spool 50 is being elevated by spring 109. The purpose of this restricted flow of fluid from chamber 104 while the spool is being elevated is to predetermine the time required for the spool 50 to return from its full down position seen in Fig. 4 to its full up position seen in Fig. 5. The reason for this delayed or slow upward movement of spool 50 is set forth hereinafter.

In semi-manual operation, the operation of system 20 is exactly as previously described until spool 59 is shifted to the position seen in Fig. 4 by the weight 91. When the spool 59 shifts to this position, the operator loses control of the motion of the ram and upon his releasing of the operating lever 83 the circuit 20 completes the cycle of operation of the ram automatically. When the spool 59 is shifted to the position shown in Fig. 4, the ram is approaching the work and the only variation in the operation of the control mechanism 27 over that described in connection with its manual operation is that a connection is established from circuit 80 through groove 61 and valve chamber 34 to conduit 112, valve 193, conduit 113, check valve 114 and conduit 105 to chamber 104 and the pressure of the fluid being exhausted from cylinder 3% holds spool 50 down, as shown in Fig. 4, until exhaust fluid from cylinder 30 ceases to flow. When exhaust fluid ceases to flow, the pressure below spool 59 and in chamber 61 below spool 60 dissipates through orifice 1&1 and orifice valve 95 and, as the pressure in chamber 81 dissipates, a reduced pressure is reached in chamber 31 at which pressure in chamber as and spring 74 will force spool 61} downwardly to block the connection between conduits 32 and 96. When the connection between conduits 82 and 96 is severed, the full output volume of the source 21 of pressure is directed to the top of cylinder 39.

Upon further dissipation of the pressure below spool 59 and in chambers S1 and 104, spring 109 will force spool 50 to its full up position seen in Fig. independently of the shipper rod 85 because of the presence of the lost-motion connector 86, and as spool 50 moves to its full up position, the fluid in chamber 104 flows through conduit 105, conduit 115, orifice 116, conduit 113, needle valve 103, conduit 112, bore 34 below spool 59 and to tank 22 through the divided path described in cluding the orifice 101 and orifice valve 95. Orifice 116 determines the rate of speed or time which will be required for the spool 50 to move from its full down position to its full up position and during which time the pump 23 will build pressure in the top of motor cylinder 3% equal to the opening pressure of the relief valve 2 -2.

After spool 50 has moved to its full up position, the ram 29 is retracted in a manner identical to that described in connection with the manual operation of the system 20 and Fig. 5 of the drawings.

The function of orifice 97 is to insure that sufficient pressure will. be created in chamber 104 to cause spool 50 to operate in the manner described when the adjustable orifice valve 95 is fully open and is not causing a build up of pressure in the chamber 194.

It is to be noted that the control chamber 81 of the reversing valve 50 receives fluid pressure from the upstream side of the restrictor or orifice valve 95 and that chamber 81 is in constant, though restricted, communication with tank 22 through the fixed orifice 101. These features result in controlling accurately the rate of movement of the spools 50 and 60 and thereby overcome the problem of ram reversal before full pump output pressure is built up in the top of cylinder 30 and/ or a long dwell period of the ram 29 without full pressure being built up in the top of cylinder 30.

While the form of embodiment of the present invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follows:

1 claim:

1. In a hydraulic system, a source of fluid pressure; a tank for fluid; a reversible fluid motor; control valve mechanism between said pressure source and said motor, said mechanism including means forming a body; a pair of bores in said body forming a pair of valve chambers; a main motor reversing control spool in the first of said bores cooperating with ports therein to form a four-way valve, said ports including an inlet port con nected to receive fluid from said source of pressure, forward and reverse motor ports connected with said motor, a tank port connected with said tank and an outlet port, said main control spool being movable from one position in said bore wherein sets of said ports are connected to cause operation of said motor in one direction to another position wherein other sets of said ports are connected to cause operation of said motor in the opposite direction; means forming a pressure chamber at one end of said main control spool; passage means including a valve for connecting said chamber with said tank port; passage means in said body extending from said tank port, said outlet port and said forward motor port to ports in the second of said valve bores; first and second valve spools in said second valve bore, said second valve spool being within said first valve spool and both of said spools being movable to relatively different positions to connect said ports in said second bore in different sets, said first and second valve spools being normally disposed to prevent fluid flow from said outlet port to any other of said ports in said second bore, and said second valve spool operates in response to pressure in said outlet port to connect it with said forward motor port; linkage means operated by said fluid motor for moving said first valve spool from its normal position to a second position wherein said connection between said outlet port and said forward motor port is broken; passage means leading from said second bore to said tank port including a bleed orifice connecting said outlet port to said tank port when said first spool is shifted to said second position; a port in said second bore; passage means including a restriction connecting said last-mentioned port to said tank port; passage means including an adjustable orifice connecting said outlet port to said last-mentioned port in said second bore; passage means for conducting fluid pressure from said inlet port to one end of said second spool when said first spool is moved from its said normal position whereby difierences between said pressure and the pressure in said outlet port cause said first and second spools to function as a pressure operated flow control valve for controlling the flow of fluid from said inlet port through said passage means and orifice to said tank port; passage means connecting said chamber at one end of said main control spool with said tank port in advance of said adjustable orifice through said bleed orifice; a check valve in said last-mentioned passage means arranged to permit the free flow of fluid to said chamber; passage means including an orifice arranged to by-pass said check valve to permit a restricted flow of fluid from said chamber, and a shut-off valve in said last-named passage.

2. In a hydraulic system, a source of fluid pressure; a tank for fluid; a reversible fluid motor; control valve mechanism between said pressure source and said motor, said mechanism including means forming a body; a pair of bores in said body forming a pair of valve chambers; a main motor reversing control spool in the first of said bores cooperating with ports therein to form a four-way valve, said ports including an inlet port connected to receive fluid from said source of pressure, forward and reverse motor ports connected with said m-otor, a tank port connected with said tank and an outlet port, said main control spool being movable from one position in said bore wherein sets of said ports are connected to cause operation of said motor in one direction to another position wherein other sets of said ports are connected to cause operation of said motor in the opposite direction; means forming a pressure chamber at one end of said main control spool; passage means in said body extending from said tank port, said outlet port and said forward motor port to ports in the second of said valve bores; first and second valve spools in said second valve bore, said second valve spool being within said first valve spool and both of said spools being movable to relatively diflerent positions to connect said ports in said second bore in different sets, said first and second valve spools being normally disposed to prevent fluid flow from said outlet port to any other of said ports in said second bore, and said second valve spool operates in response to pressure in said outlet port to connect it with said forward mot-or port; linkage means operated by said fluid motor for moving said first valve spool from its normal position to a second position wherein said connection between said outlet port and said forward motor port is broken; passage means leading from said second bore to said tank port including a bleed orifice connecting said outlet port to said tank port when said first spool is shifted to said second position; a port in said second bore; passage means including a restriction connecting said last-mentioned port to said tank port; passage means including an adjustable orifice connecting said outlet port to said last-mentioned port in said second bore; passage means for conducting fluid pressure from said inlet port to one end of said second spool when said first spool is moved from its said normal position whereby differences between said pressure and the pressure in said outlet port cause said first and second spools to function as a pressure operated flow control valve for controlling the flow of fluid from said inlet port through said passage means and orifice to said tank port; passage means connecting said chamber at one end of said main control spool with said tank port in advance of said adjustable orifice through said bleed orifice; a check valve in said last-mentioned passage means arranged to permit the free flow of fluid to said chamber; and passage means including an orifice arranged to by-pass said check valve to permit a restricted flow of fluid from said chamber.

3. In a hydraulic system, a source of fluid pressure; a tank for fluid; a reversible fluid motor having a pair of ports usable selectively as an inlet port and an exhaust;

control mechanism for said motor connected between it and said source of fluid pressure, said control mechanism including reversing valve means connected to said ports to cause said motor to be operated in forward and reverse directions; manually operated means for operating said valve; pressure operated means for operating said valve means; pressure operated valve means responsive to pressure in the exhaust port of said motor when the latter is being operated in its forward direction for directing the exhaust fluid from the exhaust port of said motor to the inlet port thereof; a pressure dilferential operated valve operated by differences in pressure between the pressures at said inlet and exhaust ports for directing fluid from said source of pressure to said tank; an adjustable orifice and a fixed orifice for bleeding exhaust fluid from said pressure differential operated valve to control the operation or" the latter; a manually operated valve means for connecting said pressure operated reversing valve operating means to said tank; a normally closed valve for connecting said pressure operated reversing valve operating means directly with said exhaust port; a manually operated valve between said last-mentioned valve and said reversing valve operating means; means operated by forward operation of said motor for rendering said pressure operated inlet and exhaust port connecting valve means inoperative, placing said pressure differential operated valve in operation, and opening said valve between said pressure operated reversing valve operating means and said exhaust port; a check valve between said lastmentioned valve means and said pressure operated reversing valve operating means for admitting fluid freely into the latter; bleed restrictor means for bleeding pressure from said pressure differential operated valve for permitting the latter to close when the pressure of said exhaust fluid dissipates to close the connection between said motor inlet port and said tank, and restrictor means for controlling the rate of flow of fluid from said pressure operated reversing valve operating means.

4. In a hydraulic system, a source of fluid pressure; a tank for fluid, a reversible fluid motor having a pair of ports usable selectively as an inlet port and an exhaust; control mechanism for said motor connected between it and said source of fluid pressure, said control mechanism including reversing valve means connected to said ports to cause said motor to be operated in forward and reverse directions; manually operated means for operating said valve; pressure operated means for operating said valve means; pressure operated valve means responsive to pressure in the exhaust port of said motor when the latter is being operated in its forward direction for directing the exhaust fluid from the exhaust port of said motor to the inlet port thereof; a pressure differential operated valve operated by diflerences in pressure between the pressures at said inlet and exhaust ports for directing fluid from said source of pressure to said tank; an adjustable orifice and a fixed orifice for bleeding exhaust fluid from said pressure differential operated valve to control the operation of the latter; a normally closed valve for connecting said pressure operated reversing valve operating means directly with said exhaust port; means operated by forward operation of said motor for rendering said pressure operated inlet and exhaust port connecting valve means inoperative, placing said pressure diiferential operated valve in operation, and opening said valve between said pressure operated reversing valve operating means and said exhaust port; a check valve between said last-mentioned valve means and said pressure operated reversing valve operating means for admitting fluid freely into the latter; bleed restrictor means for bleeding pressure from said pressure differential operated valve for permitting the latter to close when the pressure of said exhaust fluid dissipates to close the connection between said motor inlet port and said tank, and restrictor means for controlling the rate of flow of fluid from said pressure operated reversing valve operating means.

No references cited.

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