Abstract: The hydraulic system of this invention is for operating a tree processing implement on a work vehicle so that during a first part of an operating cycle the implement is supplied by two hydraulic pumps jointly, while during another part of the operating cycle the implement is supplied by only one of the pumps. The result is that during the first part of the cycle the implement moves rapidly but during the other part it moves slowly.

Abstract: A hydraulic circuit for a self-undecking crane having retractable legs with extendable jacks for elevating and supporting the crane upper. Hydraulic cylinders move the legs between a retracted position and an extended position in which the jacks are engageable with the ground and isolation valve devices in the hydraulic circuit prevent retraction of said legs when the crane upper is supported on the extendable jacks.

Abstract: A multiple consumer hydraulic device is provided having a pump and at least two consumers, where a multiway control valve throttling in the intermediate positions is located in front of each of these consumers and a hydraulically controlled additional valve is located in the line between the pump and this mulitway control valve and is acted upon in the closing direction by the pressure in front of this multiway control valve and is loaded in the opposite direction by the pressure of the assigned consumer in which case, in order to achieve a load-independent proportioning of the pump stream for both pumps with and pumps without load-sensing, the additional multiway valve is provided with two additional control pressure chambers, of which the one acting in the closing direction is acted upon by the pressure of the one of the consumers carrying the highest pressure, and the oppositely acting additional control pressure chamber is acted upon by the pressure in the delivery line of the pump.

Abstract: The carriage lift and mast lift cylinders are sequentially extended and retracted in the reverse order of pressure required to actuate them by a sequencing valve to insure proper sequential movement of the lift carriage and extension of the mast sections.

Abstract: A log debarker having a frame, a stator supported by the frame, a rotor journaled in the stator for rotation about a longitudinal axis of the rotor, a rotating mechanism for rotating the rotor about the longitudinal axis, a plurality of debarking tools attached to the rotor, and a feeding system for feeding logs axially through the rotor. The feeding system includes a plurality of log gripping rollers positioned for rolling contact with the log, and individual hydraulic motors are operatively connected to the log gripping roller for rotating the log gripping roller. Each of the hydraulic motors is adapted to rotate its log gripping roller at different and variable rotation speeds to accommodate logs of uneven surfaces. A hydraulic fluid supply system supplies each of the hydraulic motors with fluid so that the different and variable hydraulic fluid requirements of each of the hydraulic motors necessitated by uneven log surfaces are satisfied.

Abstract: A self-leveling series type hydraulic system with a float position 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 in one position 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 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. The flow divider valve having a second position which bypasses all of the flow from the boom cylinder to reservoir when the boom control valve is in a float position.

Abstract: An hydraulic steering device for a crawler-mounted vehicle, in which a couple of pressure-regulating steering valves controls the rotation direction and speed of two respective rolling trains of the vehicle, is described. Each of the valves is provided with an end chamber having a piston sliding therein in response to a control pressure depending on the pilot pressure regulated by the other steering valve, and each piston is designed to shift respective shouldering means for respective contrast springs of respective shuttles provided on the valves in such a manner that both the rolling trains are stopped whenever both of the valves are activated simultaneously.

Abstract: A power steering apparatus with a pressure supply for additional loads, the steering pump of which has a plurality of feed chambers separate from one another. The additional loads, such as a brake booster and/or a level regulating device, are connected to one of these separate feed chambers. A reversing valve enables a greater supply capacity to the steering gear by shutting off the additional loads.

Abstract: Separate branch conduits extend from a common pump to two fluid power operated systems. One of the branch conduits supplies a relatively low volume of fluid through a pilot flow conduit to a steering control valve in one of the systems to adjust its operating pressure when the steering control valve is displaced from its neutral position. The other branch conduit delivers pressurized fluid directly to the steering control valve on a priority basis. A pressure regulating valve connected between the other branch conduit and the pilot flow conduit isolates the steering system from a higher pressure in the other fluid power operated system and adjusts the operating pressure in the steering system to meet steering load demands.

Abstract: A wheel cylinder assembly has telescoping brake actuating pistons with a brake pressure proportioner in the larger actuating piston to proportion brake actuating pressure.

Abstract: In a hydrostatic auxiliary power steering apparatus, a short-circuit passage of a control valve establishes a restricted flow path from a pump pressure line to a reservoir return line in the neutral position of the control valve wherein all other flow paths are blocked. A fixed flow restrictor in the pump pressure line conducts a continuous flow from one of two pumps connected to the pressure line for regulation of the fluid power steering circuit by the pressure drop across the flow restrictor. If one of the pumps is of the variable volume type, the pressure downstream of the flow restrictor is utilized to regulate pump flow adjustment. If fluid under operating pressure is supplied to both the fluid power steering circuit and another fluid operating circuit, a flow dividing valve controlled by the pressure differential across the flow restrictor distributes pressurized fluid between the two fluid circuits.

Abstract: An electrohydraulic control system which includes first and second electrically controlled fully variable hydraulic pumps adapted to be driven by the vehicle engine. In the specific embodiment of the invention herein disclosed, the first pump is coupled to the steering and braking control valves, and the second pump is coupled to the bucket and hoist control valves. An electrically controlled poppet valve selectively interconnects the respective pump outputs. Operator-responsive controllers, namely a bucket/hoist joy-stick controller, a vehicle propulsion controller and a steering controller, provide associated electrical signals as respective functions of operator demand. Electrically operated valves control application of hydraulic fluid to the bucket and hoist drive mechanisms, and pressure and position sensors are connected to such valves and actuating mechanisms.

Abstract: Refuse apparatus, e.g.

Abstract: A log debarker of the hollow-head type having a rotor journaled in a stator for rotation about a longitudinal axis of the rotor. A plurality of debarking tools are attached to the rotor for debarking a log being moved axially through the rotating rotor. Three independently and hydraulically-powered infeed spiked rollers are positioned on the infeed end of the stator for feeding logs into the rotor and three independently and hydraulically-powered outfeed spiked rollers are positioned on the outfeed end. The rollers are powered at differing rotational speeds to accommodate logs of uneven surfaces. An air-operated tensioning system including a quick release valve adjusts the position of the infeed and the outfeed rollers urging them towards the longitudinal axis and automatically jogs the rollers open when they are unable to mount a log. A lubricating system having lubricant filtering and flow control capabilities lubricate and flushes the bearings for the rotating rotor.

Abstract: An apparatus for synchronizing a plurality of actuators, comprising a pressure fluid source 15 associated with a setting device 6, with transmitters 10 of the movements of the operating members 5, and also with multichamber adding elements 17 equal in number to the actuators 4 to be synchronized.

Abstract: A remote controlled hydraulic circuit of the type comprising a source of pressurized fluid, a number of hydraulic motors connectible to the source of pressurized fluid, and control means for connecting the source of pressurized fluid to the hydraulic motors, the control means being remotely piloted by a series of pressure signals each of which corresponds to the opening of the connection between the source of pressurized fluid and a respective hydraulic motor. The hydraulic circuit according to the invention includes selector means for establishing priority for supplying pressurized fluid to one or more preferential hydraulic motors. These selector means are intended to detect, when operatively active, pressure signals corresponding to the supply of pressurized fluid to the preferential hydraulic motors and, in this condition, to render inoperative the control means associated with the other hydraulic motors, should they already have been activated to effect the supply of these other hydraulic motors.

Abstract: A safety circuit for preventing uncontrolled descent of a hydraulically supported load, in the event of a leak, comprises parallel hydraulic pressure feed lines, control valves in these, and means responsive to a difference in pressure between the lines and arranged to close the valves when such a pressure difference is detected. The valves are provided adjacent to a lifting cylinder or cylinders and close to the pressure source, so as to prevent spillage of hydraulic fluid as well as to prevent descent of the supported load.

Abstract: A control device for the sequential control of an advancing mine-roof support comprising pressure-controlled directional control valves alternately connectable to a high pressure line and to a return line in order to convert a pressure pulse into a switching step at the main control unit of the advancing mine-roof support and for transmitting an answering pressure pulse signalling the completion of the workstage for continuing the sequence.

Abstract: A hydrostatic power steering control system with variable feedback compensation employing a unique compensating valve. The steering control system includes first and second hydraulic cylinders, each having two internal chambers denoted as head and feedback chambers. A piston is movably retained in each of the cylinders and is attached to a piston rod which extends outwards. The pair of piston rods are connected to a pair of steerable wheels by a mechanical linkage. Fluid contained in a reservoir is pressurized by a supply pump and is selectively passed to a head chamber of one of the cylinders by a control valve. The control valve is actuated by pressure differences in two interconnected fluid passages which connect to the feedback chambers of the two cylinders. A pressure difference in these passages is created by manually operating a steering wheel which actuates a metering pump positioned across the fluid passages.

Abstract: A fluid control system (10) has a first fluid pump (12) for supplying pressurized fluid in interrupted series to first and second work elements (14,16). The first work element (14) in the series has priority which prevents simultaneous full power operation of the first and second work elements (14,16). A second fluid pump (24) is capable of supplying pressurized fluid to the second work element (16) only upon receiving a signal indicating that pressurized fluid from the first pump (12) is being directed to the first work element (14). The subject fluid control system (10) is especially useful with a tree harvesting machine where it is beneficial to propel the machine and at the same time rotate the upper structure.

Abstract: A hydraulic press has lowering and lifting cylinders, a controlled pressure-limiting valve connected to the high-pressure hydraulic supply, and a shuttle valve with its operating inlets connected respectively to the hydraulic supply and to the lifting cylinders and its outlet connected to the pressure-limiting valve to control it. Further valves responsive to a disturbance of hydraulic equilibrium in the hydraulic circuit operate switches controlling the hydraulic fluid supply.

Abstract: A single hydraulic supply line feeds fluid under pressure to a hydraulic percussive machine with a percussion motor and a rotation motor. The feed passes through two valves of the constant volume priority flow dividing type. The first valve gives priority to the percussion motor to the extent of establishing idling speed. The second valve in the bypass of the first valve gives priority to the rotation motor while its bypass reaches the percussion motor. Working speed of the percussion motor can only be obtained after the rotation motor is up to speed and control of the feed above the priorities controls the percussion motor speed only.

Abstract: A fluid powered actuator system has first and second piston actuators, the fluid flows to and from which pass through first and second flow paths which include respective first and second valve devices, the valve devices being coupled for operation in unison and being responsive to the flow levels therethrough, so that the valve devices operate to equalize these flows and thereby to equalize the rates of movement of the piston actuators. A further valve is responsive to a predetermined level of difference between the flows in the first and second paths to apply a servo actuating pressure which urges the first and second valve devices to a position in which flow to or from the piston actuators is prevented.

Abstract: A mowing machine comprises a plurality of cutting units (4) powered by a parallel hydraulic system with distributing means (30). The cutting units (4) are each powered by a hydromotor (16), all hydromotors (16) being driven by a central hydraulic pump (P). The hydromotors (16) are fed in a parallel relationship by the pump (P). Ahead of the hydromotor (16) in each circuit, is a distributing means (30) with an inlet (26) from the pump (P), and two outlets, (31) back to the supply tank (V), and (33) to the corresponding hydromotor (16). When a hydromotor (16) is deactivated, distributing means (30) automatically diverts the fluid normally flowing through the deactivated hydromotor back to the supply tank (V). This diversion of fluid prevents changing the speed of the remaining hydromotors as a result of increased flow or pressure available due to the deactivated hydromotor.

Abstract: A control mechanism (48) is provided to controllably maintain a constant force on an actuator (18) and provide fluid flow to a downstream control valve (24) by controlling a pilot differential pressure between first and second ends (38,40) of a pilot operated control valve (14). A two position valve (56,66) acting in response to a predetermined pressure level in the actuator (18) modulatably controls the flow of pressurized pilot fluid to the pilot operated control valve (14) to position the pilot operated control valve (14). This maintains the pressure in the actuator (18) at the predetermined pressure level and passes the excess flow of fluid from a source (12) to the downstream control valve (24).

Abstract: A power assisted steering gear assembly having a first fluid system 5 comprising a first pressure operated device such as a double acting piston and cylinder, a first valve for controlling fluid flow to the first pressure operated means in response to a steering input in shaft 2 and a first fluid pump 7. The first pressure operated means can be a conventional power assisted steering gear 1 imparting rotation to a drop arm 8. A second fluid system 20 comprises second valve means controlling fluid flow from a second pump 26 to a second piston and cylinder device incorporated in a ram unit 12. The second valve in the ram unit 12 is responsive to displacement of the drop arm 8 and reacts to determine power assistance provided by the system 20 to a steering maneuver, such power assistance being additional to that provided by the system 5. Displacement of the ram unit 12 controls movement of a steering linkage through drag link 38.

Abstract: An excavator including a boom pivotally moved by boom cylinders, an arm pivotally moved by an arm cylinder and a bucket pivotally moved by bucket cylinders further includes a boom detecting device detecting a pivotal displacement of the boom and producing a first pilot pressure substantially proportional to the pivotal displacement of the boom and a bucket detecting device detecting a pivotal displacement of the bucket and producing a second pilot pressure substantially proportional to the pivotal displacement of the bucket. The first pilot pressure is supplied via a first conduit to a first valve switching pilot pressure port of a control valve device, and the second pilot pressure is supplied via a second conduit to a second valve switching pilot pressure port of the control valve device. The control valve device is connected to the bucket cylinders in such a manner that a piston side of the bucket cylinders can be drained.

Abstract: A circuit for controlling pitch and tilt of a dozer blade in which two cylinders are connected between the dozer blade and the dozer push arms. One cylinder only is extended and retracted to achieve tilt, and both cylinders are operated in unison to achieve pitch with divider valves assuring that equal volumes of hydraulic fluid reach each cylinder and are expelled from each cylinder. Extension and retraction is selectively determined by a directional control valve, while a selector valve determines whether both cylinders or only one cylinder is connected with the directional control valve.

Abstract: A lifting and dumping apparatus for use with a front end loading refuse vehicle. The apparatus includes a pair of lift arms which extend forward of the cab of the vehicle and which are pivotally secured to the sides of the vehicle. A rotatable front tube extends between the front ends of the left arms, and a pair of fork arms are pivotally connected to the front tube. The fork arms can pivot between an open position and a closed position. In the open position the fork arms extend forward of the lift arms, generally perpendicular to the front tube for engagement with a detachable refuse container, and in the closed position the fork arms are generally parallel to the front tube so that their projection forward of the left arms is eliminated. Hydraulic cylinders are provided for pivoting the fork arms, and a hydraulic circuit is provided with a sequencing valve to close the fork arms one at a time.

Abstract: A fast acting hydraulically actuated ram (10) especially suitable for use in the punch head of a press uses a first ram area (28) to advance the ram until the load thereon increases, which occurs when punching is about to take place. Then a pressure actuated valve (22), which is responsive to the increase in hydraulic pressure acting upon the first ram area, places pressure on a large area (36) of the ram for a time sufficient to enable penetration of the work. An electrohydraulically controlled valve (20, 98) responsive to the ram position, switches hydraulic pressure which is applied to the first ram area so as to operate the ram under electrical control to provide the desired cycle time and frequency.

Abstract: The invention relates to hydraulic steering apparatus of the type having valve gear for selectively directing pressurized fluid to and from opposite sides of a servomotor connected to vehicle wheels to be steered. This type of steering apparatus only requires pressurized fluid when actuated and may provide an auxiliary circuit with pressured fluid at times when it is not being actuated. Priority valves give priority to the steering apparatus. During extended intervals when pressured fluid is supplied to an auxiliary circuit, parts of the steering apparatus are subjected to substantial cooling. Then when the priority valve diverts hot pressurized fluid from the auxiliary circuit to the cooled steering apparatus the temperature differential causes an adverse effect on the steering apparatus by creating a tendency for binding of parts due to the unequal expansion of valve sleeves.

Abstract: The heretofore known transmission control systems providing automatic sequential engagement of the fluid clutches have valves directly controlled by the operator and are not readily convertible to be pilot operated. The present invention has a selector valve (31) movable between first and second positions for communicating a supply line (19) with first and second fluid clutches (11,12) respectively. A fluid actuated valve (44) is moved to a first position communicating a third fluid clutch (13) with a drain line (18) when the fluid pressure in a fluid chamber (61) thereof drops below a preselected value and to a second position communicating the supply line (19) with the third fluid clutch (13) when the fluid pressure in the fluid chamber (61) exceeds the preselected value. A dump valve (76) drops the fluid pressure in the chamber (61) below the preselected value in response to a momentary pressure drop in the supply line (19) upon moving the selector valve (31) between the first and second positions.

Abstract: The valve includes an input port and two output ports and an arrangement to cause fluid pulses to appear at the output ports as a result of the appearance of fluid pulses alternately at the inlet port. The fluid pulses fed to the inlet port directly appears at the outlet ports and directly causes the valve to pass at least through three successive positions for every two successive pulses at the inlet port. This valve controls the operation of a pneumatic control circuit of a wire cutting, skinning and wrapping tool which is mounted in the handgrip of the tool.

Abstract: A hydraulic circuit (10) has a fluid supply source (12) to a work element, such as a control valve (14) for a work implement, connected by a first fluid pathway (18). A second work element (16), such as a master cylinder reservoir of a brake system, has a fluid level (36) which is desirably maintained against leakage in the system to prevent problems in using the brake system. The master cylinder reservoir (16) is associated with the hydraulic circuit (10) by apparatus (38,42) which initiate pressure conditions in fluid pathways (22,24) positioned in fluid communication with the master cylinder reservoir (16) to maintain the desired fluid level. The pressure conditions create a pressure differential which initiates or induces a fluid flow from the hydraulic circuit (10) to the master cylinder reservoir (16) to maintain the reservoir fluid level and substantially prevent undesirable braking characteristics which can result from an improper fluid level.

Abstract: There is disclosed a new and improved hydraulic sequencing valve of the type which includes a movable valve spool within the body to sequence operation of the valve. An aperture through one spool or chamber is arranged for direct fluid communication with a tank port upon initial movement of the spool to increase the differential fluid pressure across the chambers and accelerate the sequencing movement of the spool.

Abstract: For work vehicles, for example, cold weather can be a problem. Disengaging the vehicle clutch (26) aids starting by reducing engine loads during starting. Where the clutch (26) is hydraulically actuated, it can be disengaged by keeping fluid pressures below required engagement pressure when supplying other elements common to the clutch hydraulic circuit. Apparatus is provided which during starting directs fluid to, for example, pump drive bearings (20) at less than clutch engagement pressure. An input signal to the apparatus from the vehicle operator after engine start-up then builds pressure to activate the clutch (26) while continuing to supply the pump drive bearings (20) for lubrication. Upon a preselected fluid flow to the apparatus, such as at engine shutdown, the apparatus automatically returns to the condition at which available pressure levels are less than required for clutch engagement.

Abstract: A system is disclosed for controlling the flow of fluid from a pair of pumps (15,15') to a steering system (11) and a pair of auxiliary load circuits (13,13'). The steering system includes valving (43) defining a variable flow control orifice (45), and the steering system normally operates with a pressure differential X across the variable orifice, and provides load pressure signals (47,49,49',53,53') representative of demand for fluid by the steering system. Fluid flow from the pumps is controlled by a pair of priority flow control valves (21,21') including a pair of valve members (27,27') each of which is biased by a spring (29,29') toward a position permitting flow to the steering system. The spring (29) exerts a biasing force equivalent to the pressure differential X while the spring (29') exerts a biasing force equivalent to a pressure differential Y, which is less than X.

Abstract: A priority flow divider is disclosed for dividing hydraulic fluid flow between a steering circuit and an auxiliary circuit thereby providing better efficiency and greater productivity for the auxiliary circuit. The priority flow divider includes a cylindrical housing having a slidable spool valve therein, and the housing further includes an inlet port connected to the steering pump in the steering circuit, a discharge port connected to the steering valve, in the steering circuit, and a discharge port connected to the auxiliary hydraulic circuit. The spool valve has enlarged cylindrical portions which are connected by recessed connecting portions of a reduced diameter.

Abstract: A pressure-compensated directional control valve assembly suitable for use in hydraulic power steering systems of off-highway working vehicles. The valve assembly integrally comprises a control valve for controlling communication between two engine-driven pumps and a steering cylinder, and a pressure compensator valve for controlling the fluid pressure delivered from the pumps to the control valve. Constantly comparing its outgoing fluid pressure with the fluid pressure at control ports of the control valve, the pressure compensator valve delivers to the control valve the pressurized fluid from one or both of the pumps. Any excess of the pressurized fluid is directed from the pressure compensator valve to, for example, an implement hoist cylinder of the work vehicle.

Abstract: The invention relates to apparatus for supplying pressurized fluid to various controlled members (16,30,34). A problem with prior apparatus is the need for a plurality of separate apparatuses to supply the controlled members. The invention solves this problem through the use of a single valve (25) that controls the supply of pressurized fluid from a fluid source to first (34), second (16) and third (30) controlled members, in which the single valve (25) has a first relief valve segment (46) to relieve the pressure of fluid flowing from the source to the first controlled member (34), a second relief valve segment (100) to relieve the pressure of fluid relieved by the first relief valve segment (46), and a third valve segment (138) to direct the fluid relieved by the first relief valve segment (46) to the second (16) and third (30) controlled members. A movable lever (26) is connected to the third valve segment (138) to shift this valve segment (138) and control the direction of the fluid.

Abstract: A wheel cylinder comprises a bore closed by two pistons which define a pressure chamber therebetween. The pressure chamber is divided into two compartments by a partition member placed in the bore and which comprises a passage communicating the two compartments. One of the compartments is connected to a source of pressurized fluid and a control valve is mounted in the passage for controlling the pressure in the other compartment as a function of the pressure in the one compartment, whereby the wheel cylinder acts as a proportioning valve.

Abstract: An automatic, hydraulically actuated, sequencing valve for use with a pair of hydraulic actuators (e.g. double acting hydraulic cylinders). The valve includes a valve body, a bore therein, and a valve spool axially shiftable in the bore. The valve spool shifts automatically due to creation of a differential in hydraulic pressures on opposite ends of the valve spool during each admission of hydraulic fluid under actuating pressure to the valve.

Abstract: A flow control valve assembly for controlling first and second reversible fluid motors for series or parallel operation has a direction control secton and a torque control section provided in a single valve body. The valve body has first, second, and third supply ports selectively pressurizeable by the direction control section and connected to a torque control bore in the torque control section. First and third function passages extend from the torque control bore and are connectible to the first fluid motor, and second and fourth function passages extend therefrom and are connectible to the second fluid motor. A grooved, torque control spool is disposed in the torque control bore for sliding from a series operating position wherein the grooves connect the first port to the first function passage, the second function passage to the third function passage, and the fourth function passage to the second and third ports.

Abstract: A hydraulic pumping unit for vertically actuating a downhole pump including first and second hydraulic piston and cylinder assemblies. The first assembly is connected to the downhole pump and the second assembly is connected to a counterweight. A hydraulic line is connected between the first and second assemblies so that the counterweight counterbalances the downhole pumping equipment. A hydraulic pump is connected to the first and second assemblies through switching means for alternately supplying hydraulic fluid to and from the first and second assemblies. A check valve is provided between the hydraulic pump and the hydraulic line for replenishing the assemblies with fluid. A safety valve is connected between the first assembly and the hydraulic line for preventing the first assembly dropping in the event of a hydraulic line failure. A return valve in parallel with an orifice closes in the event the hydraulic pump stops for preventing free fall of the first assembly.

Abstract: A vehicle hydraulic system is disclosed of the type including a steering control valve (29), a brake system (31), and an auxiliary load circuit (65). Fluid flow to these load circuits is controlled by a flow control valve assembly (11) including a priority spool valve (85) which controls the flow of fluid from the inlet port (13) to the priority fluid chamber (75). Fluid flows from the priority fluid chamber to the steering control valve and the brake load system, in parallel, and at equal levels of priority. A shuttle valve assembly (83) receives a steering load signal by means of a load signal line (44) and a brake load signal from the load signal chamber (111), and transmits the higher of the two load signals into the load signal chamber (93) which biases the priority spool valve toward a position to permit a greater flow of fluid into the priority fluid chamber.

Abstract: Two circuit breakers or circuit breaker modules are actuated by hydraulic jacks fed by supply and drain valves operated by a single closing-operation control unit. A differential pressure detector is subjected to the pressure of the two jacks. In the event of a relative variation in the jack-operating times, the free piston of the detector actuates a switching device which connects the supply and drain valves to the drain tank, thus preventing the complete performance of any non-simultaneous operation of the circuit breakers.

Abstract: A spring brake actuator has a quick release clutch for deactivating the brake in absence of fluid pressure and a governing device operating the clutch in response to the relative pressures prevailing at the service brake and spring brake cylinders. The governing device comprises a biased pilot valve and a signal valve which permit alternate operation of the brake release clutch manually or automatically.

Abstract: An actuator device for actuating ejector of a scraper comprising a first actuator having a long stroke, a second actuator having a short stroke, said first and second actuators being connected and fixedly secured in series so that the piston rod of said second actuator can be brought into contact with the piston of said first actuator, and valve means which normally permits the communication between the delivery side of a hydraulic pump and a pressure chamber of said first actuator and which also permits the communication between the delivery side of said pump and the pressure chamber of said second actuator when the pressure within the pressure chamber of said first actuator has increased beyond a predetermined value.

Abstract: A priority system has a valve assembly which has an inlet, first and second outlets, and apparatus for controllably limiting fluid pressure at the first outlet to a preselected maximum value by controllably communicating the second outlet with the inlet. The priority system has a fluid reservoir, a work element and control apparatus connected to the work element, second outlet and reservoir which receives fluid from the second outlet and passes the fluid to the fluid reservoir or work element.

Abstract: A power piston apparatus, comprising two or more double acting hydraulic piston drive means in which the cross-sectional areas of the pistons are identical and the cylinder spaces or chambers of which are hydraulically interconnected in crossed fashion above and below the pistons in the case of two cylinders, while being connected in series in the case of more than two cylinders having separately closed oil spaces of identical volumes, with each such oil space being connected to a positive-pressure oil supply through check valves for replenishing the leakage oil, and wherein said piston drive means have associated therewith metering cylinders with a coaxial and/or parallel direction of stroke, i.e. with mechanical connections between the ends of the piston rods.