Abstract: The present invention provides an apparatus for controllably actuating a work implement. The work implement includes at least a first linkage and a second linkage. The apparatus produces a control signal, senses the position and velocity of the first and second linkages and responsively produces position and velocity signals. The apparatus responsively produces a command signal as a function of the control signal and the position and velocity signals. The command signal controls actuation of the first linkage such that dynamic coupling between the first and second linkages is minimized.

Abstract: A device for controlling multiple hydraulic actuators to protect a system from an overpressure caused by increasing the load on an individual actuator. By controlling the supply of hydraulic fluid to a pair of cylinders each associated with a pilot valve so that each cylinder always has enough fluid pressure to operate, the device of the present invention prevents the shutdown of the device caused by too much fluid going to the actuator operating at the maximum pressure. Thus all actuators continue to operate even if one is overpressured.

Abstract: An improvement in a multiple intensifier system having two intensifier units with reciprocating piston assemblies to supply very high pressure water. When one of the piston assemblies travels faster than the other, so that these reached an end stroke position at the same time, there can be an abrupt pressure drop. To alleviate this, a first embodiment isolates the compensator control lines of the pumps of the two intensifier units so as to maximize volumetric flow rates during such pressure drops to give the slower moving piston assembly a boost at the beginning of its subsequent stroke. Another embodiment provides an accumulator in the fluid control line for the compensators, and a further embodiment provides a pressure reference supply pump to alleviate pressure variations in the fluid control line.

Abstract: An apparatus for adjusting the pressure of working fluid provided to the load or user via a hydraulically actuatable control valve is provided. The apparatus includes a comparator that compares a given or desired control pressure for the control valve with the predominant present load pressure. The resulting pressure differential is used to re-adjust the control valve or to re-adjust a pressure compensator positioned upstream of the control valve with respect to the direction of the flow of working fluid flowing to the user.

Abstract: The present invention relates to a valve assembly for the supply of users in hydraulic control systems with pressurized fluid for the load pressure (LS) independent control of several simultaneously actuated hydraulic users wherein the ratio of the partial flows once set is maintained at undersupply of the system with the pressurized fluid. When the demand of the users exceeds the maximum output flow of the variable displacement pump, the (high) priority users receive the demanded quantity whereas the low priority users receive a reduced quantity by switching the control pressure for the low (i.e. no) priority users via a directional control valve and a pressure relief valve to a lower pressure level. Only when undersupply of the entire system occurs, i.e. when the maximum output flow of the variable displacement pump is no more sufficient despite the limitation of the control pressure for the low priority users, then the presently flowing partial flows of all users are reduced proportionally.

Abstract: A plurality of directional control valves (5, 6) respectively disposed between a hydraulic pump (50) and a plurality of actuators (3, 4) each comprises a pump port (9), a pressure chamber (10), a feeder passage (11), actuator ports (12a, 12b), a reservoir port (13), first meter-in variable restrictors (15a, 15b) disposed between the pump port and the pressure chamber, and a pressure compensating valve (16) disposed between the pressure chamber and the feeder passage and having a pair of opposite ends, one of which is subjected to a pressure in the pressure chamber and the other of which is subjected to a maximum load pressure among the plurality of actuators. The hydraulic pump (1) includes a pump flow control device (2) for controlling a delivery rate of the hydraulic pump so that a delivery pressure of the hydraulic pump is held higher by a predetermined value than the maximum pressure obtained, as a load sensing pressure, from load pressures of the plurality of actuators.

Abstract: The displacement of a variable displacement hydraulic pump (1) which is driven by a diesel engine (27) is so controlled as to be set to a first target displacement to keep a pump pressure higher than a load pressure by a predetermined target value, or a second target displacement to limit an input torque on the basis of the pump pressure. Provided is a stand-by flow rate control portion (65) which outputs a third target displacement larger than the minimum value of said first target displacement. The displacement of the pump (1) is controlled so as to be set to the third target displacement when the third target displacement is output from the stand-by flow rate control portion (65).

Abstract: A control device for hydraulic operating cylinders of a tailgate of a vehicle to determine maximum pressures arising in the operation and, particularly, overloading of the tailgate, resulting in excessive pressures. A power-driven hydraulic pump (1) is connected to a reservoir (4) and, via branch lines (8', 8"), with associated gate control valves (10, 13) which include a closing cylinder (14) for the tailgate. A pressure intensifier piston-cylinder unit (15) is connected parallel to the branch pipes. An electric pressure-sensitive switch (16), which is also connected to a counter (17) and to an interrupter switch (18) for the electric pump motor, switches off the pump motor (2) when the predetermined pressure is exceeded. This switch is connected to the closing cylinder (14) for the tailgate.

Abstract: In a hydraulic drilling machine with a boom, arm and bucket as working parts, one or more of the working parts can be vibrated automatically to perform effective drilling with reduced resistance in various types of operations when the soil changes. Adequate vibration can be automatically generated by setting the working mode (Bo, A, Bu, Sk) and vibration mode (L, M, S) according to the soil or operation form beforehand and by setting the automatic vibration mode. Furthermore, since the control input of the working part lever can be added to the automatic vibration, simple and minute repeated operations, such as pressure-shifting, sifting or drilling conducted while the bucket is vibrated, can be performed readily and uniformly without exhausting the operator, and workability can thus be greatly improved.

Abstract: In a controller (229) of a hydraulic control system for construction machines, a valve control signal calculating function (301) works such that when an operation pattern signal (A-I) for actuators (201, 202 . . . ) is outputted, it selects corresponding one of plural output patterns for an auxiliary valve control pressure stored, as a function of a differential pressure signal between a pump delivery pressure and a maximum load pressure, in relation to the operation pattern signals, followed by calculating an auxiliary valve control pressure (Pc) dependent upon the differential pressure signal based on the selected output pattern, and also selects corresponding one of plural sets of rates of change (K . . . , K . . . ) for the auxiliary valve control pressure stored in relation to the operation pattern signals, followed by combining the calculated auxiliary valve control amount with the selected set of speed changes to calculate each of valve control signals (S21-S26).

Abstract: A hydraulic base-load motor (M1) drives a load with the working pressure generated at the motor rising with the load. When the working pressure reaches an upper limit pressure, a hydraulic stand-by motor (M2) is switched on. Since the pressure drops upon switching on the stand-by motor, the control device is designed such that, upon reaching a lower limit pressure, it deactivates the stand-by motor again, the lower limit pressure being less than half the upper limit pressure. This switching hysteresis prevents a repeated switching over of the stand-by motor.

Abstract: When a hydraulic circuit for driving actuators of a construction machine or the like includes a single hydraulic pump and a plurality of direction changeover valves connected to the hydraulic pump for controlling the respective actuators, operation of one of the direction changeover valves may result in undesirable change in the output oil pressure of the other direction changeover valves. The inventive hydraulic circuit includes means for driving a regulator of the hydraulic pump in response to any oil puressure change at the inlets of the direction changeover valves corresponding to the output oil pressure change, thereby compensating for the pressure change.

Abstract: The dual area brake actuation piston mechanism (10, 110) comprises a piston housing (12, 112) having therein a first bore (30, 130) disposed coaxially about a separate second bore (40, 140). A first piston (50, 150) is disposed within the first bore (30, 130) and extends from the first bore (30, (130) to a piston end (70, 170). A second piston (60, 160) is disposed within the second bore (40, 140) and extends to engage the piston end (70, 170). The bores (30, 40; 130, 140) have first and second bore openings (32, 42; 132, 142) for receiving pressurized fluid which displaces the respective pistons (50, 60; 150, 160). The second bore opening (42, 142) includes a valving mechanism (80, 180) to either restrict or prevent lower fluid pressures from actuating the second piston (60, 160).

Abstract: A valve system is provided for the load-independent control of a plurality of simultaneously operated hydraulic consumers, i.e. regardless of variations in load pressure. Fluid flow in a consumer line to each consumer passes across a compensating flow control valve, i.e. a compensator. The valve piston thereof being displaceable to the open position by a pressure downstream of a flowmeter against the opposing resistance offered by a spring and by the respective maximum load pressure of the consumers at a time. The actual highest load pressure is also available at a regulator for the common variable displacement supply pump feeding the consumers.

Abstract: A brake valve (45) is disclosed of the type which permits communication from a source (11) of pressurized fluid to a brake actuator (47) in response to manual movement of a valve spool (57) from a neutral position (FIG. 2) to a power brake position (FIG. 5). In the power brake position, the valve spool permits fluid communication between a work port (53), which communicates with a brake actuator, and a brake load signal chamber (87), the brake load signal controlling the fluid output of the source. As the valve spool moves toward a manual brake position (FIG. 6) communication between the work port and the brake load signal chamber is blocked. In the manual brake position, movement of the valve spool causes a large piston (63) to displace fluid from its piston bore (73) into a piston bore (75) in which is disposed a small piston (61), the small piston being operable in response to movement of the valve spool to build brake pressure in the work port (53).

Abstract: A hydraulic device is furnished for an automatic connection of the pressure means source, either preferably to the primary user or to the secondary user depending on the pressure in the circuit of the primary user. A switching valve can be actuated by way of a precontrol pilot valve for the generation of the connections. An additional restoring second part compression spring (33) with adjustable pretension acts on the precontrol pilot valve (19, 20, 21, 22, 27). A fluid-loadable auxiliary piston (32) serves for a switching-pressure support. The hydraulic device is suitable for applications in hydraulic circuits exhibiting different transport priorities to different ports.

Abstract: A hydraulic drive system comprising a prime mover (21), a hydraulic pump (22) driven by the prime mover, a plurality of hydraulic actuators (23-28) driven by hydraulic fluid supplied from the hydraulic pump, a plurality of flow control valves (29-34) for controlling flow of the hydraulic fluid supplied to the actuators, and a plurality of pressure compensating valve (35-40) for controlling respective differential pressures across the respective flow control valves, in which each of the pressure compensating valves applies a control force (f-F.sub.c) in a valve opening direction for setting a target value of the differential pressure across the flow control valve. There are provided a first detector (60) for detecting the target rotational speed (N.sub.0) of the prime mover (21), and controllers (61, 62, 63) for controlling the control force on the basis of the target rotational speed detected by at least the first detector such that the control force (f-F.sub.

Abstract: A dual servo actuation system is automatically equalized or rigged by electronic control circuits. A static auto rigging bias is applied to one or the other, or both, of a pair of electro hydraulic servo valves that respectively control two hydraulic actuators driving a common member, such as an aircraft control surface. An auto rigging bias, which substantially eliminates force fight, is automatically generated and stored as a fixed quantity prior to use of the system for control of the common member. With a zero commanded output of the two actuators, a difference of differential pressures at the actuators is obtained and caused to change the number in a counter as long as the difference exceeds a threshold. The counter number, while it is above the threshold, is continuously applied as a bias signal to decrease the force fight, and the number in the counter is stored as a fixed bias signal when the force fight indicated by the difference of differential pressures drops below the threshold.

Abstract: A change-over valve including a valve housing defining an inlet port for receiving fluid from a fluid pressure supply, a first outlet port for feeding operating fluid to a first fluid responsive actuator, a second outlet port for feeding operating fluid to a second fluid responsive actuator, and drain port means for draining fluid to a fluid reservoir; and a spool retained by the housing and movable therein between first and second positions, the housing and the spool in its first position providing communication between the inlet port and the first outlet port and preventing communication between the inlet port and the second outlet port, and the housing and the spool in its second position providing communication between the inlet port and the second outlet port, and preventing communication between the inlet port and the first outlet port.

Abstract: There is disclosed a solenoid-operated selector valve adapted for control of hydraulic clutches such as of a tractor. The selector valve has four ports and can assume two positions. The selector valve includes a spool having an axially extending hole. A piston and a sequence valve are held in this hole. The sequence valve can relieve the pressure. The hole is in communication with the outside of the spool via first through third radially extending holes. The pressure inside one cylinder port which is normally connected with the pump port is maintained constant even when the engaged clutch is being switched to the other. This pressure is not reduced down to zero until the pressure inside the other cylinder port reaches a predetermined pressure.

Abstract: A hydraulic driving apparatus has at least one hydraulic pump, a plurality of hydraulic actuators driven by hydraulic fluid discharged from the hydraulic pump, a tank to which return fluid from the plurality of hydraulic actuators is discharged, and a flow control valve associated with each of the plurality of hydraulic actuators. The flow control valve has a first main variable restrictor for controlling flow rate of the hydraulic fluid supplied from the hydraulic pump to the hydraulic actuator, and a second main variable restrictor for controlling flow rate of the return fluid discharged from the hydraulic actuator to the tank. A pump control operative in response to the difference between the discharge pressure of the hydraulic pump and the maximum load pressure of the hydraulic actuators normally controls the discharge rate of the hydraulic pump so that the pump discharge pressure is raised more than the maximum load pressure by a predetermined value.

Abstract: A hydraulic drive system for a crawler mounted vehicle has a hydraulic pump, a plurality of actuators including a pair of left and right travel motors and at least one other actuator that are driven by hydraulic fluid delivered from the hydraulic pump. The system further contains a plurality of flow control valves for controlling flows of the hydraulic fluid supplied to the respective actuators, and a plurality of distribution compensating valves for controlling differential pressures across the respective flow control valves, the plurality of distribution compensating valves each having drive parts to set a target value of the differential pressure across the associated flow control valve. The hydraulic drive system also has a speed selector for outputting a select signal to change operation speeds of the pair of travel motors, and a controller and a control pressure generator for controlling the drive parts of the distribution compensating valves associated with the pair of travel motors.

Abstract: A hydrostatic steering device is provided with a pump connected with a reservoir, a steering valve, a controlled-volume pump that is capable of being activated by a steering wheel and with a steering cylinder. The steering mechanism has a variable working flow and a constant pilot flow, with the pilot stream flowing through a constant throttle and the pressure drop through the constant throttle serving as a control signal for the conveying flow in a pressure delivery line. The controlled-volume pump is coupled mechanically with an adjustment throttle through which the pilot flows. Between the constant throttle and the adjustment throttle lies a pressure compensator that is controlled by the adjustment throttle's differential pressure. To receive the load signal, a control line branches off between the constant throttle and the pressure compensator and leads to the pump or, in the case of a fixed displacement pump with a rear-position flow-dividing valve, to the flow-dividing valve.

Abstract: A hydraulic system for a construction machine comprising plural hydraulic actuators (23-28) driven by fluid supplied from a pump (22), first and second flow control valves (29-34) for controlling flows of fluid supplied to the first and second actuators, and first and second distribution compensating valves (35-40) for controlling first differential pressure (.DELTA.P v1-.DELTA.P v6) produced between inlets and outlets of the first and second flow control valves. The first and second distribution compensating valves have respective drives (45-50, 35c-40c) for applying control forces (Fc1-Fc2) in accordance with the second differential pressure to the associated distribution compensating valves, to thereby set target values of the first differential pressures. The hydraulic system includes first means (59) for detecting the second differential pressure (.DELTA.

Abstract: A control valve includes a first valve having a cylinder and a piston arranged in the cylinder. The piston defines in the cylinder a pressure receiving chamber and first and second output pressure chambers, and is moved by pilot pressure applied to the pressure receiving chamber to change volumes of the first and second output pressure chambers. The output pressure chambers are connected to each other through a throttle control valve which generates pressure difference corresponding to a rate of change in volumes of the output pressure chambers, between the output pressure chambers. A main valve is connected to the throttle control valve and includes an inlet port, output ports, and a valve member located between the input and output ports. The valve member is moved in accordance with the pressure difference between the first and second output pressure chambers to control hydraulic pressure output from the output ports.

Abstract: A control valve is disclosed for use in controlling flow of hydraulic fluid from a hydraulic pump to a plurality of actuators. The control valve includes a valve housing within which are formed control bores, pressure-compensating bores, a feed passage communicating between the pressure-compensating bores, a selected-load pressure transmitting passage communicating between the pressure-compensating bores, a pair of return passages communicating between the control bores and a reservoir tank, control passages communicating respectively between each of the control bores and each of the pressure-compensating bores, and feeding and exhausting passages, as well as actuator ports, communicating between the control bores and the actuators. Control valve spools are slidably mounted, respectively, in the control bores, and pressure-compensating valves are slidably mounted, respectively, the pressure-compensating bores.

Abstract: A hydraulic control system for driving a plurality of actuators basically includes directional control valves, and pressure compensation valves, and at least one detection valve, the directional valves and the pressure compensation valves both corresponding in number to the actuators. These valves are mounted or incorporated in a body. The body has a plurality of regions corresponding in number to the actuators. Each of the regions of the body has a first hole, and a second hole substantially perpendicularly intersecting the first hole. A load pressure chamber for receiving a load pressure of the corresponding actuator is formed at the intersection between the first and second holes of each region. A spool of the directional control valve is received in the first hole. A balance piston of the pressure compensation valve is received in that portion of the second hole disposed on one side of the load pressure chamber.

Abstract: A hydraulic drive system has first and second flow control valves. Each of the control valves has a main valve of the seat valve type with a valve body for controlling communication between an inlet port and an outlet port which are both connected to a main circuit. Each further have a variable restrictor capable of changing an opening degree thereof in response to displacements of the valve body, and a back pressure chamber communcating with the inlet port through the variable restrictor and producing a control pressure to urge the valve body in the valve-closing direction. A pilot valve is connected to a pilot circuit which is connected between the back pressure chamber and the outlet port of the main valve; and an auxiliary valve is connected to the pilot circuit for controlling a differential pressure between the inlet pressure and the outlet pressure of the pilot valve.

Abstract: In a hydraulic drive system, first and second flow control valves means comprise each: a main valve having a valve body for controlling communication between an inlet port and an outlet port both connected to a main circuit, a variable restrictor capable of changing an opening degree thereof in response to displacements of the valve body, and a back pressure chamber communicating with the outlet port through the variable restrictor and producing a control pressure to urge the valve body in the valve-opening direction; a pilot valve connected to a pilot circuit which is connected between the inlet port of and the back pressure chamber of the main valve; and an auxiliary valve connected to the pilot circuit for controlling a differential pressure between the inlet pressure and the outlet pressure of the pilot valve.

Abstract: Fluid systems for controlling clutch engagement of a vehicle drive train normally have modulating pressure relief valves to aid in smooth clutch engagement. It is desired in such systems to ensure that the system pressure is reduced during a shift so that the load piston of the modulating pressure relief valve is fully reset prior to engagement of the vehicle drive train. In this arrangement, a fluid system is provided which has a plurality of clutches. In order to ensure that the load system is fully reset, a load piston reset control mechanism is provided which establishes a path to vent the pressurized fluid from a load piston pressure chamber of a modulating presure relief valve in response to the pressure of the fluid in one of the clutches being below a predetermined pressure level.

Abstract: A four-wheel steering system of a vehicle includes a power steering device for steering the front wheels, an oil pressure pump for generating an oil pressure in accordance with a travel speed of the vehicle, and a hydraulic actuator for steering the rear wheels. A first control valve is provided between the pump and the actuator so as to operate upon reception of the oil pressure from the power steering device. This valve introduces the oil pressure from the pump to the actuator in accordance with the oil pressure from the power steering device so that the actuator steers the rear wheels in the same direction as the front wheels. A second control valve is provided between the power steering device and the actuator so as to operate in accordance with the oil pressure from the power steering device.

Abstract: A fluid operated circuit for controlling the movement of pistons contained in the drive and idler cylinders of a conventional dual post vehicle lift assembly of the type wherein the cylinders are hydraulically connected in tandem so that movement of the idler cylinder piston is dependent upon movement of the drive cylinder piston and wherein the pistons, while operative to lift and lower movable article supporting structures, are not fixedly connected thereto.

Abstract: Apparatus for automatically monitoring and adjusting the axial thrust acting upon the rotor assembly of a rotating machine having an adjustable balancing mechanism for balancing the axial load acting thereon. A pair of surfaces on the rotor structure and a pair of flow circuits are arranged to direct a pressurized fluid against each surface. The back pressure is each circuit is monitored to determine when the axial forces are unbalanced and the data applied to a control mechanism for automatically balancing the axial forces acting on the rotor structure.

Abstract: A hydrostatic drive assembly with an adjustable pump driven by a primary power source, which acts on several consumers of hydrostatic energy, is disclosed which has a control and regulating device with nominal speed value pickups and adjustable restrictors for each consumer. In order to obtain a control and regulating device at a low production cost, one that operates with a low power loss, it is proposed that the nominal speed value pickup send an electric signal to an electronic control device, that each consumer be provided with an actual speed value pickup, which the control device, and the restrictors assigned to each of the consumers in their connection lines are designed as electromagnetic throttle valves controlled by the electronic control device.

Abstract: A hydraulic control apparatus for a vehicle capable of being significantly simplified in structure and stabilizing its control characteristics. The apparatus includes a variable constriction provided in a first flow passage arranged between a steering pump and a steering cylinder and a steering spool for changing over the first flow passage and controlling the degree of opening of the variable constriction. The apparatus also includes a single flow control valve spool which changes over depending on a variation of pressure on an upstream side of the variable orifice and accomplishes an increase and a decrease in the degree of opening of a second flow passage arranged between a switch pump and an implement circuit corresponding to an increase and a decrease in pressure on the upstream side of the variable constriction.

Abstract: A system reduces force fight between hydraulic actuators (22, 24) operated on independent hydraulic circuits (29, 49) which position a control surface (20) of an aircraft. Each circuit includes a hydraulic supply (30, 50). A pressure equalization valve (70) is connected to first sides (42, 62) of the actuators. In the event of a pressure imbalance, a spool (82) shifts in the pressure equalization valve. Movement of the spool enables fluid from the circuit supply to be delivered through the equalization valve to the actuator at the lower pressure, rapidly eliminating the imbalance.

Abstract: Valve device for controlling the delivery of pressurized fluid from a common pump to two hydrostatic working motors, one of which is subjected to a load dependent on the speed of the other motor. A volume flow regulator is disposed in the flow path between an inlet port of the valve device connected to the pump and an outlet port connected to the other working motor and varies the volume flow rate in this flow path in inverse proportion to the pressure in the inlet port to keep that pressure substantially constant.

Abstract: An improved hydraulic circuit for automatically sequencing a pair of hydraulic cylinders through alternate extension and retraction cycles. A manually operated control valve initiates addition and withdrawal of fluid within the circuit and a logic valve determines which cylinder will be in communication with the control valve. The circuit uses an improved flow restrictor arrangement for creating the pressure drop which automatically shifts the logic valve. The restrictor consists of an orifice, a simple check valve and a constant pressure relief valve, all arranged in parallel. The functions of these various restrictor elements can all be performed by a single multifunction valve disclosed herein.

Abstract: A fluid servomechanism has a first actuator driven by fluid, a second actuator, and a pressure generator for generating pressure corresponding to the difference in displacement between output shafts of the first and the second actuators. Therefore, a compact-size finger facilitating angularly free movement and having a highly elaborate human-like function can be attained.

Abstract: An automatic, hydraulically actuated, sequencing valve for use with a pair of hydraulic acutators (e.g. double acting hydraulic cylinders) includes a valve body having a cylindrical bore therein. Cam members at either end of the bore are engaged by pins on the ends of a cylindrical spool, thereby rotating the spool 30.degree. each time it engages one of the cam members. A third cam member incorporated into the spool alternately locks open one of a pair of check valves as said spool is pressure shifted between the two bore cam members. The third cam member operates a locking system which permits only one of the two hydraulic cylinders to operate at a time and in sequence.

Abstract: The thread winding machine includes a piston and cylinder unit, comprising a cylinder housing with first and second chambers and a dividing structure between said first and second chambers. A piston is movable longitudinally in the first chamber and a piston extension projects from said piston towards the second chamber. A port in the dividing structure receives the piston extension when the piston is near the dividing structure, thereby separating said first and second chambers. A thread guide is connected to the piston of the piston and cylinder unit for movement in combination therewith.

Abstract: A pump supplies via in each case a directional valve a plurality of consumers with fluid, a pressure balance for load-independent division of the pump displacement being provided between each branch line branching off the pump delivery line and the directional valve. In a pressure regulating valve common to all pressure balances a control pressure is generated from the pressure difference between the pump pressure and the respective highest consumer pressure and is applied to all the pressure balances so that when the pump power is inadequate a proportional quantity reduction at all consumers is achieved.

Abstract: A self-leveling series type hydraulic system including boom and bucket valves which separately control boom and bucket cylinders and a flow divider valve positioned in the exhaust flow path from the rod end of the boom cylinder. The flow divider valve splits the flow sending a portion of it to the cap end of the bucket cylinder so as to maintain the bucket in a level condition during raising of the boom with the remaining flow returning to the control valve downstream of the boom valve along with the return flow from the rod end of the bucket cylinder which is also returned to the control valve downstream of the boom valve whereby the bucket valve can be separately actuated concurrent with the boom valve and supplied with oil so as to override the self-leveling function if desired.

Abstract: A hydraulic drive system for counterweight dolly in a counterbalance type crane, including dolly driving wheels supported vertically movably through wheel supporting hydraulic cylinders at the lower portion of the counterweight dolly which is connected to the rear portion of a crane body; a wheel driving hydraulic motor connected to each of the wheels; a support pressure detecting mechanism for detecting a support pressure for each wheel supporting hydraulic cylinder, the support pressure detecting mechanism being provided in a drive circuit for the cylinder; and a mechanism for controlling the driving pressure for the wheel driving hydraulic motor in accordance with a detected value provided from the detecting mechanism.

Abstract: The invention contemplates a hydraulically operated twin-cable suspension for a clamshell or the like load-handling device. In a preferred embodiment, a charged accumulator is effectively a counterweight and is the source of all hydraulic fluid needed for the full range of actuation of two traction cylinders, one for each of the respective cables. Both cables automatically share the load, without slack, in any elevational situation, and simple hydraulic control circuitry selectively enables (a) an automated closing dig into loadable material and (b) a quick opening for load discharge. A single power integrator is interposed between the accumulator and the two traction cylinders for directionally controlling hydraulic-fluid displacement between the accumulator and the traction cylinders, as needed for all cable displacements.

Abstract: Apparatus for controlling the compaction of refuse in a refuse collection truck, and for controlling the operation of an ejection panel of the refuse collection truck, so as to provide for uniform compression of refuse in the truck. A hydraulic cylinder supports the ejection panel, and a combination sequence-relief valve is provided to vent hydraulic fluid from the cylinder when the fluid pressure output of the hydraulic pump exceeds a predetermined pressure and when the fluid pressure in the packing cylinder exceeds a selected pressure.

Abstract: The invention contemplates a hydraulically operated twin-cable suspension for a clamshell or the like load-handling device. In a preferred embodiment, a charged accumulator is effectively a counterweight and is the source of all hydraulic fluid needed for the full range of actuation of two traction cylinders, one for each of the respective cables. Two power integrators are employed: one is interposed between the accumulator and one of the traction cylinders, and the other is interposed between the accumulator and the other traction cylinder; hydraulic control interconnections between the respective integrator circuits enable load sharing by both cables and simplified single-lever control of plural clamshell functions, including (a) an automated closing dig into loadable material and (b) a quick opening for load discharge.

Abstract: A reversing and adjustment mechanism, especially for a reversible plough adapted for hydraulically adjustable furrow width and hydraulic reversing of the plough, wherein the reversing and adjustment mechanism comprises a hydraulic cylinder (8) with a "hydraulic memory" for adjustment of the furrow width. The oil chambers on both sides of the ordinary piston (15) in the adjustment cylinder (8) communicate with a reservoir (24) via two pilot-controlled check valves (26, 25) with open passage toward the adjustment cylinder (8) and a second direction-control valve (10). The chamber (31) in the adjustment cylinder (8) between the rear head and a freely movable piston (17) communicates on the one hand with a hydraulic cylinder (7) for reversing the plough, preferably with the rod end thereof, via a first check valve (14) with open passage toward the reversing cylinder (7), and on the other hand communicates with the reservoir (24) via a flow-control valve (28) and a first direction-control valve (9).

Abstract: A hydraulic control system is provided, including first and second bidirectional fluid actuated motors adapted to travel a predetermined amount in each direction. A directional control valve is placed in fluid communication with a supply of high pressure, hydraulic fluid and a reservoir and has a first operating position for directing the supply of fluid to the motors in a first direction of flow and a second operating position for directing the supply of fluid to the motors in a direction of flow opposite to the first direction of flow. A combination sequence and regeneration valve is in continuous fluid communication with the supply and the second motor for preventing the operation of the second motor until the first motor has reached its limit of travel and for regenerating fluid from one side of the second motor to the other side when the first motor has reached its limit of travel and the control valve is in its second operating position.

Abstract: An apparatus for disabling an obstructed lift mechanism having at least two hydraulic cylinders for controllably lifting and lowering a load includes a pair of valves, each arranged for sensing the differential pressure between a first sensing line and a second sensing line. The first valve is movable to a position for preventing the flow of hydraulic fluid from a first cylinder when the pressure in the second sensing line exceeds that in the first sensing line by a first predetermined value. The second value is movable to a position for preventing the flow of hydraulic fluid from the first cylinder when the pressure in the first sensing line exceeds that in the second sensing line by a second predetermined value. If the flow of hydraulic fluid from the first cylinder is prevented by the movement of either the first valve or the second valve, the operator is required to lift the load slightly to remove the obstruction.