Abstract: A hydraulic circuit for a hydraulically driven vehicle comprising a pair of variable displacement hydraulic pumps, a pair of hydraulic motors each connected with the respective variable displacement pumps in a closed loop, and a straight run compensator valve connected between the respective closed loops for equalizing fluid pressure in both closed loops when the vehicle is set in a straight run thereby assuring a steady straight run of the vehicle irrespective of the difference in displacement of the respective variable displacement pumps.

Abstract: This movement compensation arrangement in one aspect comprises a hydraulic main motor group driven by the pressure difference between two hydropneumatic pressure containers and a hydraulic auxiliary motor group driven by a pump with an effect which can be regulated, and adapted to provide for dynamic compensation. The hydraulic main motor group is adapted to substantially take up the static load. The two motor groups are rotationally coupled to moving means. A control unit in response to input signals controls both motor groups, of which the main motor group has a stepwise and/or continuously variable displacement (FIG. 1).

Abstract: A fuel-saving energy storage vehicle drive system which saves fuel, primarily under stop-and-go driving conditions, by collecting, storing and using energy normally lost in the braking or deceleration of the vehicle, by automatically controlled operation of the engine under certain conditions, and by automatically controlled use of the stored energy and engine respectively as alternative or supplemental prime movers for each other for driving the vehicle. Subsystems for preventing waste of deceleration energy and stored energy are provided, and compact transmission layout and packaging are provided which facilitate installation of the new system in existing vehicles.

Abstract: A hydraulic system comprising a pair of actuators operable to move a single load, each of which has a fluid inlet, a variable displacement pump including means responsive to a pressure for varying the displacement of the pump, a pilot operated meter-in valve associated with each actuator for supplying fluid from the pump to its respective actuator, and means for sensing the pressures between each meter-in valve and its associated actuator and applying an average of said pressures to said responsive means of said pump.

Abstract: An apparatus and method of controlling the input power to a drill feed or other hydraulic system in which the hydraulic power source is obtained from a compressed air supply. Wherein, the flow of air is varied in response to a hydraulic signal controlled by the load demand of the hydraulic system. Low and high mode controls are provided to operate hydraulically actuated mechanisms; and a hydraulic absorbing load is imposed to prevent stall or overspeed of the pump and motor during low load conditions.

Abstract: A hydraulic circuit for a hydraulically driven vehicle comprising a pair of variable displacement pumps each driven by a common engine, a pair of variable displacement motors each connected with the respective variable displacement pumps in a closed loop circuit and driven thereby, a fixed displacement charge pump driven by the engine, and a pair of shuttle valves each connected in parallel with the respective closed loop circuits and has formed therein a neutral position and two offset positions wherein in the neutral positions of the shuttle valves both the closed loop circuits are connected with each other through the shuttle valves.

Abstract: A hopper barge having at least two longitudinal air chambers interconnected pivotally at deck level, which chambers in a loading position bound an upwardly open well and in an unloading position release a discharge opening at the bottom, and comprising at least one control unit for controlling the relative position of the air chambers, with per each control unit two synchronously controlled jack means, which are each pivotally connected with at least one of the air chambers by on the one end a lever arm, which two lever arms are arranged in substantially mirror-symmetrical relationship relative to the median longitudinal plane of the vessel and being interconnected pivotally, and on the other end a hinge fixedly secured to one of the air chambers.

Abstract: PCT No. PCT/US79/00920 Sec. 371 Date Oct. 29, 1979 Sec. 102(e) Date Oct. 29, 1979 PCT Filed Oct. 29, 1979A steering system (36) for vehicles (10) in which a device (90) is provided for circulating fluid through the system when operating in a cold environment. The system includes a hand metering unit (58) which is connected to opposite ends of a pilot operated steering valve (42) through a pair of pilot lines (60,62). A pressure reducing valve (94) maintains a continuous flow of fluid to the pilot lines (60,62) at a first predetermined pressure level. A pressure responsive valve (94) positioned between the hand metering unit (58) and a reservoir (40) intermittently passes pilot control fluid, returned to the hand metering unit (58) from the pilot actuation of the steering valve (42), to the reservoir (40) in response to the pressure of such returned fluid reaching a second slightly higher predetermined pressure level such as occurs when the fluid in the system is cold.

Abstract: PCT No. PCT/US79/00968 Sec. 371 Date Nov. 8, 1979 Sec. 102(e) Date Nov. 8, 1979, PCT Filed Nov. 8, 1979An improved load resolver (41) is provided of the type which receives a pair of generally unequal pressure signals (32, 34), and which resolves the pair of pressure signals (32, 34) by blocking the lesser and transmitting the greater. Each pressure signal (32, 34) is sent to the load resolver (41) by a respective control valve (18, 20) in a hydraulic system (10). Prior load resolver structures have required angled or intersecting holes therein or special porting therearound. The improved load resolver (41) comprises a first member (58) having a first, axially extending hole (64) and a second member (72) having second and third axially extending holes (78, 104). The members (58, 72) are fitted within a bore (48) of a control valve body (19).

Abstract: The steerable wheels of a hydraulically driven vehicle are provided with fixed displacement type auxiliary motors which are connected in parallel both with each other and with the motor which powers the main drive wheels. A selector valve permits the motors for the steerable wheels to be optionally connected and disconnected from the reversible, variable displacement main pump. Flow dividers in the hydraulic lines limit the maximum flow of fluid to any one auxiliary drive motor. To prevent large power losses when the steerable wheel assist mode is not being utilized, the selector valves are placed in close proximity to each fixed displacement motor. This allows the motors to circulate large quantities of fluid around a closed loop at minimum pressure drop.

Abstract: The steerable wheels of a hydraulically driven vehicle are provided with auxiliary motors which are connected in parallel both with each other and with the motor which powers the main drive wheels. A selector valve permits the motors for the steerable wheels to be optionally connected and disconnected from the reversible, variable displacement main pump. Flow dividers in the hydraulic lines limit the maximum flow of fluid to any one hydraulic motor. The auxiliary motors are of the variable displacement type, enabling them to be destroked to neutral when disconnected from the main pump. Destroking to neutral eliminates energy loss due to the pumping of large quantities of hydraulic fluid through a closed loop when the motors are driven by the wheels.

Abstract: An electro-hydraulic auxiliary drive system providing power to the non-driven steerable wheels of an agricultural tractor utilizing hydraulic power in a parallel circuit from a pressure compensated pump which varies torque supplied to the auxiliary system by sensing the relative speed between the front and rear wheels and increases the torque to the auxiliary system when a set percentage of slip is determined between the front and rear wheels. The steerable wheels are driven by hydraulic motors connected in parallel through a flow divider valve and supplied by a variable displacement pressure compensated pump. When the electronic control receives an indication of slip from the main drive wheels it energizes a solenoid causing the pressure compensation level of the variable displacement pump to increase the torque output of the auxiliary drive system, with the percentage of slip being proportional to the increased torque.

Abstract: A hydraulically driven utility vehicle comprising hydraulically operated, reversible propulsion means on each side of said vehicle, a source of hydraulic fluid contained on said vehicle, a first hydraulic flow control valve coupled between said hydraulic source and said propulsion means on one side of said vehicle, a second hydraulic flow control valve coupled between said hydraulic source and said propulsion means on the other side of said vehicle, and a control stick hydraulically coupled to said first and second flow control valves for controlling vehicle speed and direction by selectively positioning said first and second control valves whereby movement of said stick causes said flow control valves to direct hydraulic fluid from said source to said propulsion means to control speed and steering of said vehicle.

Abstract: A fluid power assisted vehicle steering system which is switched between manual and automatic control by an operational mode selector, and switched from automatic to manual control without the intervention of the mode selector by an override action in response to operation of the manual steering control. Once switched to manual control, the steering system remains in the manual control mode of operation until switched by the mode selector to automatic control. Automatic control is also prevented until various safety conditions are satisfied.

Abstract: Priority valve system with pressure-flow compensation and signal control having first, a restricted orifice which can be satisfied when flow requirements therethrough are sufficiently large in combination with, second, a closed center primary control valve equipped with an hydraulic detent unlatch mechanism and hydraulically disposed downstream of the orifice to receive the flow directed thereto by the orifice, all to provide appropriate signals controlling the priority valve.Through this intervening, novel two component control combination, the priority valve is controlled to supply flow to a priority load and, in addition, has an auxiliary outlet chamber connected to an auxiliary motor with the purpose to cut off the auxiliary chamber flow whenever the priority flow is sufficient to satisfy only the restricted orifice.

Abstract: An agricultural tractor is provided with a hitch and draft control system hydraulically related to a plurality of other hydraulic functions. The hydraulic fluid distribution is preferenced by a priority valve including a variable orifice in series with the hitch and draft control system. The variable orifice acts as a raise rate control device and also as a controlling member for a load sensing variable displacement pump.

Abstract: A variable displacement pump is compensated to provide a relatively constant predetermined flow of hydraulic fluid under pressure to an open-center hydrostatic steering system, as the speed of the engine driving the pump varies, and a relief valve by-passes the steering system whenever the steering system would normally reduce the flow to hydraulic apparatus connected in series with and downstream of the steering system.

Abstract: A fluid system (10, 10A, 10B) which supplies two work systems (26, 38) with respective different fluid flow rates, including a pressure-flow compensated pump (12), a first control valve (18) for delivering the fluid to one of the work systems, a second control valve (28) for receiving the fluid from the first control valve and delivering the fluid to the other of the work systems (38), a first device ([20,42,50] or [20,56,58] or [20,90,96]) coupled between the pump output and the first control valve, for providing one control signal causing the pump to produce one flow rate of fluid for activating the one work system (26), and a second device ([20,40,44,46,50] or [22,58,66,72,78] or [22,88,92,96,102]) for overriding the first device for providing another control signal causing the pump to produce another flow rate of fluid for actuating the other work system.

Abstract: The inflow of fluid from a motor driven pump is divided into two flow streams at a flow rate ratio selectively adjusted through a manually actuated flow divider valve. The adjusted flow rate ratio is maintained constant by a pressure control device within two outflow conduits interconnected by secondary throttling branches to regulate pressure as a function of outflow rates.

Abstract: A grapple tong system has first and second hydraulic lines for closing and raising the grapple tongs, respectively. A hydraulic system is provided for automatically, controllably passing fluid from the second to the first line in response to a preselected pressure in the first line and a higher pressure in the second line for automatically, controllably urging the grapples to a closed position.

Abstract: A load sensing hydraulic system is disclosed of the type in which a load signal is communicated from downstream of a main flow control orifice to a device which is operable to vary the fluid delivery rate in response to changes in the load signal. Disposed in the load signal conduit is a load signal modulating valve which, in one position, communicates the load signal, substantially unchanged, to the variable fluid source. In another position of the modulating valve, the load signal chamber of the variable fluid source is drained to tank, while in intermediate positions of the modulating valve, a portion of the load signal is communicated to the variable fluid source, and a portion is bled to tank. Modulation of a load signal permits flow control in an hydraulic system, independent of the position or movement of the main spool valve. The input to the modulating valve may be manual or electric, and if electric, may be remote, or may be automatic in response to certain predetermined system conditions.

Abstract: A vehicle drive system including a rotary output, variable displacement, hydraulic motor (22) adapted to drive a wheel or the like, a pump (10) for providing hydraulic fluid under pressure to the motor, a pressure control valve (30) connected to the motor for regulating the displacement thereof to achieve a desired system pressure and having a pressure responsive surface (34) receiving a signal representative of system pressure and a biasing spring (36) acting in opposition thereto. The invention contemplates the improvement wherein a variable, settable, pressure reducing device (60,106) is connected to the pump and to the pressure control valve to apply hydraulic fluid under reduced pressure to the pressure control valve in bucking relation to the system pressure signal.

Abstract: A fluid control system includes a directional control valve assembly adapted for use in either an open-center or a closed-center configuration. The system is capable of incorporating one or more control sections, each with a manual control valve and its own individually variable flow control mechanism. Each flow control mechanism is independently responsive to section load pressure, and is capable of controlling the flow rate delivered to its section when the control valve spool is biased to a full power position. Each section contains a kickout mechanism for returning the control valve spool to its neutral position at a predetermined pressure.

Abstract: An improvement to a priority valve which provides priority flow to a priority function, not only directly from a fluid power source, but also from an accumulator when the priority demand exceeds the output of the fluid power source. This priority flow valve also provides flow to one or more secondary functions when the priority flow requirements are satisfied or when the priority flow path is blocked.

Abstract: A motor displacement control system (10) has a variable displacement drive motor (38), an auxiliary motor (30), a source (12) of fluid under pressure for operating the motors (30, 38), a first valve (50) for controlling the displacement of the drive motor (38) and maintaining at least a first pressure level thereto, and a second valve (98) for controlling the displacement of the drive motor (38) in response to operation of the auxiliary motor (30) at a second pressure level and overriding the first valve (50). The system is particularly useful on a motor grader.

Abstract: A vehicle engine accessory drive system is disclosed including a hydraulic fan motor (41) and a power steering gear mechanism SG in series flow relationship. The vehicle power steering pump P is the sole source of fluid for the system and has its flow control setting at a flow rate X, which is substantially greater than the flow rate Z required by the power steering gear SG. The motor-valve apparatus includes a valve portion (43), including a bypass valve portion (43), including a bypass valve piston (113) connected in parallel across the fan motor (41), and operable to permit fluid flow from the inlet passage (83) to the outlet passage (91) at a flow rate which is at least a portion of X. The bypass valve piston (113) is biased toward the bypass position by the fluid pressure in the inlet passage (83), and is biased toward the closed position by fluid pressure in a signal chamber (115).

Abstract: A vehicle drive and work performing system including a rotary output, variable displacement, hydraulic drive motor (22) adapted to drive a vehicle, at least one hydraulic implement motor (14,16 and 18) adapted to power a work performing implement, a hydraulic pump (10) providing hydraulic fluid under pressure to the motors, a flow control valve (12) for controlling the fluid flow from the pump to at least the drive motor, and a pressure control valve (30) for controlling the displacement of the drive motor to achieve a desired fluid pressure level at the drive motor, and including the improvement wherein a load sensor (60,62) is connected to the implement motor for providing a signal representing the load thereon and a piston (54) is responsive to the signal for causing the pressure control valve to change the displacement of the drive motor to thereby change the fluid pressure level thereat to a value different from the desired fluid pressure level.

Abstract: A fluid power system (10) for a lift truck (18) has a movable steering device (12) and a valve (14) which moves in response to movement of the steering device (12) a preselected amount to supply fluid power for steering the lift truck (18). Apparatus (30) is provided for controllably supplying fluid power to the valve (14) prior to the valve (14) moving to supply fluid power for steering. The apparatus (30) eliminates delay between the moving of the valve (14) and the availability of fluid power at the valve (14) to insure quick, responsive steering.

Abstract: Two fluid circuits respectively supply pressurized fluid from engine driven and vehicle pumps to separate servomotors in a vehicle steering system for steering operation during vehicle travel. Both fluid circuits are connected to the engine driven pump alone during vehicle standstill by a reversing valve which is shifted to a travel position by pressure output of the vehicle driven pump.

Abstract: Two hydraulic brakes or clutches being primary users, are alternately, delayedly, hydraulically energized from a constant volumetric flow rate pump feeding also a secondary user via a pressure controller with a differential piston operated by feedback ducts from the primary users via a throttle valve. The latter valve is bypassed through a check valve for undelayed de-energization. A selector valve is disposed between the branch point for the secondary user and upstream as to energizing fluid from the feedback connection to the primary user. The pressure controller is described further as to several structural details.

Abstract: A vehicle engine accessory drive system is disclosed including a hydraulic fan motor and a power steering gear mechanism in series flow relationship. The vehicle power steering pump is the sole source of fluid for the system and has its flow control setting at a flow rate X, which is substantially greater than the flow rate Z required by the power steering gear. A temperature responsive bypass valve is connected in parallel across the fan motor and the bypass flow and motor outlet f1ow recombine, then flow to a steering gear flow control which communicates a flow rate Z to the steering gear mechanism and all fluid in excess of Z bypasses the steering gear, recombining with the output flow from the steering gear and returning to the pump inlet. This system provides a flow to the fan motor resulting in a fan speed-versus-engine speed similar to a "viscous curve".

Abstract: A steering control system is disclosed for use on a dual path, hydrostatic drive vehicle. The steering control system includes a steering signal generator, the steering signal representing commanded steering ratio and direction. The system senses vehicle direction and steering direction and generates an electrical switch signal having a first or second condition, depending upon which transmission must have its speed reduced to achieve the desired vehicle orientation. The steering signal and the main speed command signal are multiplied to generate a speed modification signal and an electrical switch transmits the modification signal to one transmission or the other depending upon whether the switch signal is in the first or second condition. The disclosed steering system permits use of a T-handle control, for both speed and steering, such that vehicle orientation may be maintained generally perpendicular to handle orientation for both forward and reverse vehicle travel.

Abstract: A control apparatus is disclosed for permitting simultaneous actuation of a plurality of fluid motors whose combined flow capacity exceeds the available flow rate. The plurality of fluid motors are actuated by a corresponding plurality of open center, pressure-compensated, pneumatically actuated control valves which are connected in series flow arrangement with a fluid supply having a fixed minimum flow output and a maximum flow rate output. A device is provided to sense the rate of flow for hydraulic fluid exhausting from the series of control valves. The rate of flow sensing device controls a pneumatic pressure regulator that provides a corresponding pressure change in the pneumatic supply pressure provided to a plurality of control valves.

Abstract: A hydrostatic vehicle transmission and control for automatically controlling vehicle operation in accordance with pre-selected operator settings. The hydrostatic transmission automatically adjusts to operational conditions of the vehicle to obtain the pre-selected function and automatically adjusts the vehicle transmission until the preselected operational conditions can be obtained.

Abstract: A fluid circuit connects a first pump to a first motor and has a control valve for controlling fluid flow to the first motor. The control valve is movable between a first position at which the first pump is blocked from communication with the first motor, a second position at which fluid flow to the motor is controllably modulated and a third position at which substantially the full output of the first pump is directed to the first motor. A valve device connects a second pump to the fluid circuit and is movable between a first position at which the second pump is in communication with a tank and a second position at which the output of the second pump is combined with the output of the first pump. The valve device is moved to the second position in response to the control valve being moved from said second position toward said third position.

Abstract: A simple load sensitive hydraulic system having a variable displacement pump, a priority dependent work circuit, at least one secondary work circuit, priority means preferencing fluid flow to the priority dependent work circuit over the secondary work circuit, flow and pressure compensating means responsive to requirements of either work circuit for controlling displacement of the variable displacement pump and a relief valve which when overridden allows fluid flow to the secondary work circuit.

Abstract: Fluid pressure operable remote control apparatus for a marine vessel equipped with a dual shaft and propeller propulsion system and fluid pressure operable operator controllers for coordinating operation respective valve devices and servo-positioners, whereby the desired operating disposition of the shafts and propellers, relative to each other, is effected for providing the desired speed and directional movement of the vessel.

Abstract: A hydraulic drive circuit for tracked vehicles is provided in the form of two hydrostatic transmissions, one for each track with a control system for one track acting as a master control and the other transmission control following as a slave unit, except as modified by the signal from a manual steering control.

Abstract: A direction flow control valve for control of positive and negative loads equipped with a load responsive control which automatically blocks the pump flow to the motor while controlling negative load, providing the motor inlet with fluid from the motor exhaust.

Abstract: A hydraulic flow dividing and proportioning system is provided for use in conjunction with a multi-function mining vehicle. In a preferred embodiment of the invention, the hydraulic system is employed for powering a roof bolting vehicle having the power requiring functions of drill rotation, drill thrusting and vehicle tramming. The system, utilizing a single hydraulic pump, provides for the efficient and selective pumping of hydraulic fluid to those power requiring elements when necessary. The system additionally includes a hydraulic flow proportioner which provides for a smooth and even tramming transition from a stop condition to full drive condition.

Abstract: The shiftably supported, rotatable feed rolls on a forage harvester or other material processing machine are operably coupled to a control lever on the hydraulic pump regulating the feed roll drive motor such that the angular velocity of the rolls is increased in response to shifting movement of the rolls away from one another, thereby enabling the rolls to readily rid themselves of a larger-than-normal slug of material should the same be encountered during harvesting. An additional control lever of a second hydraulic pump regulating another drive motor for the standing crop cutter and gathering elements of the harvester is operably coupled to the first control lever by a lost motion connection that permits the control levers to be shifted simultaneously for in unison manual operation of the motors, yet the first lever may be actuated independently by the feed rolls to control the first drive motor in response to relative shifting movement between the rolls.

Abstract: A power steering system is disclosed which selectively controls the flow of fluid to a steering motor and an auxiliary device, and may have as its source of pressurized fluid either a fixed displacement pump, a variable displacement pump, or a load sensing pump. The system includes a steering control valve disposed between the pump and the steering motor, and an externally pilot operated flow control valve, specifically, a priority valve, disposed between the pump and the steering control valve, such that the entire system flow enters the priority valve.

Abstract: A hydrostatic transmission system is provided which is particularly well adapted for use in driving vehicles employing skid-steer drives. In the system disclosed two independent hydrostatic transmissions, each employing a variable displacement motor are utilized; and a pressure responsive valve is employed to sense the magnitude of the load on each of the motors and to permit shifting the motors from minimum displacement toward maximum upon the sensing of a load in excess of a predetermined valve. The variable displacement motors of the system are configured to create forces during operation tending to urge the motors to maximum displacement, and the pressure responsive valve operates to bias the motors to minimum displacement when they are loaded at a magnitude less than the predetermined valve.

Abstract: A load responsive fluid power multiple load control system using load responsive direction and flow control valves in combination with pump control responding to highest system load. Each direction flow control valve is equipped with a load responsive positive load control which automatically regulates valve inlet pressure to maintain a relatively constant pressure differential between pump inlet pressure and load pressure at a first level and a load responsive negative load control which automatically regulates valve inlet pressure to maintain a relatively constant pressure differential between pump inlet pressure and load pressure at a second higher level. The load responsive control of each direction control valve blocks the pump flow to the motor while controlling negative load, providing the motor inlet with fluid from the motor exhaust.

Abstract: The present invention relates to an apparatus providing for the co-ordinated driving of a towing vehicle and a towed vehicle equipped with a hydrostatic driving system of its own. The respective driving wheels of the towed vehicle are each driven by a separate hydrostatic transmission and a variable output hydraulic pump coupled to a hydraulic motor which can be driven by output of said hydraulic pump and can be engaged with a driving wheel. The apparatus includes for each respective transmission control circuits having a control device mounted on the towing vehicle. The invention is particularly useful for a cross-country towing vehicle and a towed vehicle in the form of a heavy field artillery gun which for purposes of operating the hydrostatic transmissions is equipped with a reciprocating engine, for instance a gasoline engine, which actuates said transmissions via a dividing gear box.

Abstract: A load sensitive hydraulic circuit for material handling equipment is energized by a prime mover. The hydraulic circuit includes variable displacement pumps coupled to the prime mover and having pressure and flow compensating control means for varying the volumetric output. Each pump is connected to a valve bank which controls various hydraulic actuators of the material handling equipment. Load pressure feedback is provided to the pump compensators for establishing pump flows to operate the actuators at a fixed pressure differential in excess of load pressure. The valve banks contain pressure compensated valves for providing desired fluid flow rates and speeds in the hydraulic actuators. Means are provided to sense reductions in the prime mover speed resulting from excessive hydraulic loads.

Abstract: A hydraulic motor maintains its speed substantially constant in spite of changes of hydraulic fluid pressure and flow. The motor comprises a rotor to which hydraulic fluid is delivered through a nozzle arrangement from an inlet port and exhausted from the rotor to an exit port. A by-pass duct interconnects the passageway for the incoming fluid with the passageway for the outgoing fluid, to by-pass the rotor. A spring-loaded piston is situated in relation to the entrance to the by-pass duct so that when the incoming fluid pressure is relatively high the piston is retracted to expose the by-pass duct to permit some of the hydraulic fluid to by-pass the rotor, and when the fluid pressure and flow rate decrease, the spring moves the piston to close up the entrance to the by-pass duct to reduce or even stop the flow through the by-pass. A manual diverter valve is situated to divert incoming fluid away from the rotor so that all the fluid is diverted directly out of the motor housing.

Abstract: A rock drilling apparatus comprises a hydraulically rotated drill, a percussion motor having a piston which transfers impact energy to the drill, the piston defining together with the machine housing first and second pressure chambers for receiving pressure liquid to move the piston, the percussion motor having a hydraulic circuit including a high pressure side and a low pressure side, a pressure liquid distributing valve having a control input for receiving a control pressure, the distributing valve being located in the hydraulic circuit of the percussion motor for alternately connecting at least one of the pressure chambers to the high pressure side and low pressure side, respectively, of the hydraulic circuit in response to the control pressure, the hydraulic circuit for rotating the drill being separate from the hydraulic circuit of the percussion motor and including a high pressure side and a low pressure side separate from the high and low pressure sides of the percussion motor, a control valve for cont

Abstract: The novel arrangement of prime movers and associated driven pumps in cooperation with a hydraulic summating system disclosed in this application consists of a plurality of prime movers, each of which is connected to drive a group of interconnected fixed displacement pumps. Separate sets of pumps are formed with one pump of each driven group connected in parallel to supply fluid under pressure to separate systems containing various hydraulically operated functions. The summating system includes a valve arrangement whereby the total engine power generated by the prime mover of each group of pumps is available for one or all pumps in the group and thus any one or all of the hydraulically operated functions in each system has available all or a portion of the prime movers' total engine power up to the maximum available.

Abstract: Two adjustable-stroke pumps are driven off a common drive shaft and supply fluid to respective consumers via respective control valves settable by the user of the system. Each pump is provided with its own pressure regulator operative for regulating the output pressure of the respective pump by automatically adjusting the setting of the stroke-adjustment member of the pump. Transducers generate first signals indicative of the settings of the stroke adjustment members and second signals indicative of the settings of the control valves. A control arrangement maintains the settings of the volume-adjustment members in correspondence with the settings of the control valves by automatically altering the operation of the pressure regulators in response to discrepancies between the settings indicated by the first and second signals.