Abstract: A locking differential gear mechanism of the type which can operate in either a manual mode or an automatic mode. The mechanism includes a gear case (11), and differential gearing including a side gear (23). The side gear (23) includes a flange portion (43) having a set of gear teeth (45), and adjacent thereto is a locking member (47), also having a set of gear teeth (49), disposed to engage the gear teeth on the flange portion. A ball ramp actuator is disposed adjacent the locking member (47), which is preferably integral with an inner actuating plate (57). There is an outer actuating plate (59), preferably disposed outside the gear case (11), and a set of cam balls (73) operable with the actuating plates (57,59) to cause ramp-up, and engagement of the gear teeth (45,49). An electromagnetic coil assembly (75) is disposed adjacent the ball ramp actuator, and is operable to retard rotation of the outer actuating plate (59), and initiate ramp-up, in response to an electrical input signal.

Abstract: A full fluid-linked steering system, especially for use in on-highway steering, in which the system includes a fluid controller (21) including a fluid meter (65) operable to provide follow-up movement to controller valving (87,89), in response to the flow of fluid through the meter. The controller (21) includes a centering or biasing spring assembly (75) which provides sufficient torque that, upon rotation of the steering wheel (W), fluid is communicated to the steering actuator (19) without relative displacement of the valving, thus providing driver with the desired road feel. The system includes an EHC valve assembly (23) which controls flow to or from the actuator (19) in response to appropriate input signals (113,115) to maintain steered wheel to steering wheel registry.

Abstract: A torsion isolator (34) for transmitting torque and dampening torsionals in a driveline. The isolator includes a composite c-shaped spring (48) disposed in an annular chamber (44) of a housing (38,40) filled with torque converter fluid. The spring transmits driveline torque and attenuates torsionals. The spring also functions as a fluid displacement piston by dividing the chamber into radially inner and outer volumes (44a,44b) which vary inversely in volume in response to torque changes flexing the spring. Rapid flexing of the spring increases the fluid pressure in the decreasing volume and thereby dampens or reduces the rate of spring flexing or rebound.

Abstract: A steering control unit having a gerotor gear set (15) including a ring member (35) and a star member (37) which orbits and rotates within the ring. Adjacent the rearward surface (49) of the star (37) is and end cap (17). The invention provides an improved sealed star arrangement, in which the star defines an annular groove (51) in which are disposed a seal ring (55) and a backup ring (57). In accordance with the invention, the inside diameter (61) of the backup ring (57) is less than the diameter of the inner surface (59) of the groove, such that there is a radial squeeze on the backup ring (57). The axial dimension of the seal ring (55) and backup ring (57) together is less than the axial dimension of the groove (51), so there is no axial squeeze on the rings, thus eliminating the binding of the gerotor star which has been common with prior art sealed star arrangements.

Abstract: A variable displacement axial piston pump (11) including a housing (19 and a back plate (25), with a cylinder barrel (29) rotating therein, and defining a plurality of cylinders (31), and a piston (33) reciprocably disposed in each one. There is a tiltable swashplate (37) whereby the displacement of the pump can be varied. In one embodiment, an open center shuttle assembly (71) is disposed in the swashplate (37), and interconnects the high and low pressure paths of the pump to provide a wide neutral band. When the pump is displaced intentionally, the resulting pressure in the high pressure path biases the shuttle to a closed position, permitting normal operation of the pump. In a second embodiment, the shuttle assembly (71) is disposed in the back plate (25), and is accompanied by a load holding valve assembly (105), which insures that, when the vehicle is on an incline, the fluid pumped by the propel motors won't flow through the shuttle assembly (71).

Abstract: A two speed gerotor motor in which the rotary disk valve (47) and the balancing ring (67) cooperate with a control valve assembly (87) to define four different fluid zones arranged within a housing (21) in a generally concentric pattern to provide a relatively compact arrangement. Among the four fluid zones one (95) is always connected to an inlet (51) while another (101) is always connected to an outlet (53). The middle two zones (97, 99) communicate with each other in the high speed, low torque mode. Operatively associated with the control valve assembly (87) is a shuttle valve (103) such that high pressure is always communicated to the middle two zones, such that high pressure is always circulated within the gerotor gear set (17) in the high speed, low torque mode. The control valve (87) includes a spool valve (107) including dampening passages (123, 125, 127) which dampen or cushion the shifting of the spool valve between the high speed and low speed conditions.

Abstract: A method of controlling a vehicle hydraulic drive system of the type including a plurality of fluid pressure actuated wheel motors (13,15) connected in a parallel circuit with a source (17) of pressure. A flow restrictor valve (65) is disposed in a downstream conduit (27) of each of the wheel motors (13,15). The method involves determining the theoretical fluid flow for each motor, the actual fluid flow through each motor, and generating an error signal (107) which is then used to bias the restrictor valve (65) toward a flow restriction position. The disclosed method can be used to achieve steering at greater than kinematic, by scrubbing the inside front wheel, or can be used to prevent wheel slip of propulsion wheels, or can be used to prevent scrubbing of a wheel during hydrostatic braking, or can even be used to achieve vehicle steering.

Abstract: A fluid pressure motor of the type including a gerotor gear set (15) including a star member (31) which orbits and rotates. The motor includes valving (41) which is disposed forwardly of the gerotor gear set, and an end cap assembly (21;111) disposed rearwardly of the gerotor gear set. The star member (31) defines a central opening (89;127) at the rearward end thereof, which may be defined by a separate insert member (125). Within the end cap assembly (21;111) is a lock piston (75;133) biased by a pair of Belleville washers (85,87;121) toward an engaged position (FIG. 1; FIG. 4) in which a lock portion (79) has its beveled portion (91;135) in engagement with the central opening (89;127) of the star (31), thus preventing any further orbital motion of the star, and serving as a parking lock. The lock piston (75;133) and end cap assembly (21;111) define a pressure chamber (99;119) which may be pressurized by an external signal (95) to move the lock piston to its disengaged position (FIG.

Abstract: A gerotor motor (11) of the spool valve type, in which the spool valve (45) includes a central sealing land (85), effectively separating a high pressure region (87) from a low pressure region (89), when the motor is operating in the normal low-speed, high-torque mode. This separation of high and low pressure involves having two separate commutating openings (81,83) associated with each of the passages (79) communicating with the volume chambers (25,27) of the gerotor gear set (17). The present invention also includes an improved two-speed capability in which, in the high-speed, low-torque mode of operation, high pressure fluid is recirculated to certain of the contracting volume chambers (27), thus eliminating cavitation in the high-speed, low-torque mode.

Abstract: A compact and inexpensive fluid pressure operated torque amplifier and a power steering system incorporating such torque amplifier to eliminate the need for a separate return fluid conduit. The power steering system (10) includes a fluid pressure operated torque amplifier (12), a reduction gear unit (16) disposed within a cavity (53) of a transmission casing (14), and a steering linkage (20) for wheels. The torque amplifier includes a control valve assembly (24) disposed in a housing (22), a torque amplifier unit (32), a high torque drive shaft (58) and an output shaft (54). The output shaft of the torque amplifier serves as an input member of the reduction gear unit. The torque amplifier also includes a pressurized fluid inlet (78) provided in the housing and a return fluid outlet (61) provided in the output shaft (54), both the inlet and outlet being in communication with the cavity of the transmission casing.

Abstract: A gerotor motor (11) of the type having a spool valve (45) disposed opposite a main drive shaft (35). The motor also includes a set of brake discs (104) in engagement with an extension (45e) of the spool valve (45), and a set of brake discs (106) in engagement with internal splines (108) defined by an end cap (41). A piston (109) operable to engage the brake discs (104,106) is disposed in a chamber defined by the valve housing section (19), disposed adjacent the end cap (41). A valve drive shaft (57) having splines (53) engaging the main drive shaft (35) at its rotating end (33), also has splines (55) engaging the spool valve (45) to transmit the pure rotation of the drive shaft (35) to the spool valve (45). The result is a very compact valve drive and brake arrangement.

Abstract: A variable displacement pump assembly (11) of the type including a tiltable swashplate (29) to vary the pump displacement. The assembly includes a main control valve (43) having a housing (44). The assembly includes an input section (65) disposed between the valve housing (44) and the pump housing (61). The input section (65) defines a cylinder bore (77, 79) in which a piston member (81) is disposed and is connected by a mechanical input (59) to a valve spool (51) of the main control valve. The piston defines first (87) and second (89) piston chambers and a solenoid valve (105) is responsive to a remote electrical input signal (111, 113) to control the fluid pressure in the piston chambers, and therefore, the position of the valve spool (51).

Abstract: A fluid coupling device in which the input coupling member (11) includes a plate-like member (29) defining a first inlet port (63), and a second inlet port (67) disposed radially outward of the first inlet port. The device includes a valve member (43) having a disengaged position (FIG. 4) blocking flow through both inlet ports. As the valve member (43) moves from the disengaged position toward a first operating position (FIG. 5) the first inlet port (63) is uncovered, while the second inlet port (67) remains covered. Continued movement of the valve member results in progressive uncovering of the second inlet port (67). Finally, there is a third inlet port (73), radially outward from the second inlet port (67), and further movement of the valve member (43) eventually uncovers the third inlet port.

Abstract: A fluid coupling assembly (11) in which the fluid coupling (43) is disposed within a coolant cavity (C) defined by an engine block (B) of an internal combustion engine. The fluid coupling includes an input coupling assembly (45) and disposed therein is an output coupling member (55), the input and output cooperating to define forward (61,65) and rearward (63,67) viscous shear areas to optimize torque capacity of the coupling. The input coupling assembly (45) includes a rearward body member (49) disposed within the cavity (C) and which includes impeller blades (73), such that the member (49) also serves as the water pump for the engine.

Abstract: A coupling arrangement (63;107;229) for use in a fluid pressure device including a gerotor gear set (15;83;205). The gerotor gear set includes an orbiting and rotating star (21;95;209). In a motor embodiment (FIGS. 1-4 and FIG. 6), the coupling (63;229) transmits the orbital and rotational movement of the star (21;209) to an output shaft (29;203). In a steering unit embodiment (FIG. 5) the orbital and rotational movement of the star (95) is transmitted as rotational follow-up movement to a sleeve valve (101). In either case, the invention eliminates the need for the conventional solid dogbone arrangement, thus making the device much less expensive and more compact, and giving the designer greater flexibility with regard to various options, such as the provision of thru-shaft capability for a motor.

Abstract: A torsion isolator (34) for transmitting torque and dampening torsionals in a driveline. The isolator includes a composite c-shaped spring (48) disposed in an annular chamber (44) of a housing (38,40) filled with torque converter fluid. The spring transmits driveline torque and attenuates torsionals. The spring also functions as a fluid displacement piston by dividing the chamber into radially inner and outer volumes (44a,44b) which vary inversely in volume in response to torque changes flexing the spring. Rapid flexing of the spring increases the fluid pressure in the decreasing volume and thereby dampens or reduces the rate of spring flexing or rebound.

Abstract: A fluid coupling device of the type including an external bimetal coil (45) operable to move a valve arm (41) from a closed position (FIG. 4) toward an open position (FIG. 5) as the external temperature increases. An internal bimetal coil (61) is provided within the fluid reservoir chamber (35), having an inner end (65) fixed to a disc-like member (63) which rotates with the valve shaft (39), and an outer end (67) fixed to the valve arm (41). The internal coil (61) is preloaded such that, when the internal fluid temperature increases, the preload is relieved, and the valve arm (41) rotates from its open position (FIG. 5) back toward a closed position (FIG. 6), thus protecting the fluid from overheating and being damaged.

Abstract: A pump assembly (33) including a cartridge valve assembly (39) having a poppet member (69) biased toward a closed position (FIG. 4) when a pilot portion (51) is closed, under the influence of an electromagnetic actuator (53), so that flow entering an inlet port (65) flows out an outlet opening (61). When the actuator (53) is not energized (FIG. 1), a pilot poppet (89) and armature (93) are biased to an open position (FIG. 5) by a pilot spring (94), so that fluid in the inlet port (65) flows through an orifice (71) in the poppet member (69) and through the pilot portion (51) to a system reservoir (R), creating a pressure differential across the poppet member (69), and opening a tank port (67). Flow is then from the inlet port (65) to the tank port (67), thus operating in a "bypass" mode. Under excessive inlet pressure, the pilot portion (51) also serves a pressure relief function.

Abstract: A spool valve assembly (11) including a valve spool (33) defining a Raise position (R) operable to provide fluid communication from an inlet port (21) to a work port (25), and a Neutral position (N) blocking such flow. The spool valve (33) has a Lower position (L) in which return flow from the work port (25) flows past a pilot operated check valve (77) is then metered by a metering notch (75) defined by the valve spool. The valve spool (33) also has a separate Float position (F) in which the inlet port (21), the work port (25) and the return port (23) are interconnected. In the Float position (F), fluid at the valve spool (33) is in communication with the return port (23) through a back-pressure valve (59), which may be manually adjusted to control the back-pressure on a work implement (15) as it is permitted to "float".

Abstract: A fluid controller (15) of the type which controls the flow of fluid to an unequal area steering cylinder (25), wherein the controller is of the load reaction type. The controller (15) includes valving (27) which, when it is in neutral (FIGS. 1 and 5), defines a load reaction fluid path (LR) permitting fluid communication between the control fluid ports (21, and 23) through the fluid meter (29) in response to an external load imposed on the cylinder (25). In accordance with the invention, the valving (27) includes a fluid path (97,95,99,71,75) between the load reaction fluid path (LR) and the return port (19), when the valving is in neutral. When the rod end chamber (A) is contracting, fluid is drawn from the return port into the load reaction fluid path (LR), preventing cavitation, and when the head end chamber (B) is contracting, fluid flows from the load reaction fluid path (LR) to the return port (19), preventing pressure intensification.