Abstract: A hydraulic flow divider has first and second (147, 148) flow control valves each dividing its inflow into two flows. The constant orifice first flow control valve (147) divides flow to outlets (151) and (153). Flow from outlet (151) is then divided by the second valve (148). One of the output flows of the second valve is generated by a constant orifice and directed to a power steering cylinder. Any secondary output from the second valve is generated by a pressure relief valve (152), joins flow from outlet (153), and passes to a hydraulic lift cylinder. The arrangement secures a significant flow rate for lift cylinder operation at low pump drive engine speeds at which pump output flow is low.

Abstract: A pump supplies a plurality of consumers each via a directional control valve with pressure balance. When the pump delivery is not adequate, manifesting itself in a dropping of the pump pressure, the pressure balance of the consumer with the highest load pressure is displaced out of the end position of its regulating position into a further control position in which a control pressure line is connected via a throttle point to a discharge so that by means of the throttle point a control pressure is generated which is used for equiproportional reduction of the supply flow to the consumers. This is done either by reducing the stroke of the directional control valves or by acting on the pressure balances in the closure direction.

Abstract: A single supply line feeds hydraulic fluid under pressure to a hydraulic percussive machine with a percussion motor and a rotation motor. A constant flow device is positioned between the supply line and the rotation motor.

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 hydraulic-control system for a hydraulic press utilizes a main power unit consisting of a pump and a flywheel which delivers the energy necessary for a working stroke to at least one cylinder of the press. An auxiliary power unit consisting of an electric motor and another pump driven thereby is connected to the hydraulic network to drive the first mentioned pump as a motor and rotate the flywheel to increase the energy stored therein.

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: A bidirectional flow communication passageway is provided by the present invention in a multiple-circuit fluid pressure responsive system on a motor vehicle to allow a gradual reduction of pressure in a parking brake circuit which is a part of such system. The passageway is restricted to limit such bidirectional flow to a predetermined level. The pressure reduction permitted is sufficient to activate a parking brake valve in such parking brake circuit when a defect occurs in an operating service brake circuit which is also a part of such system.

Abstract: A bidirectional flow communication passageway is provided by the present invention in a multiple-circuit fluid pressure responsive system on a motor vehicle to allow a gradual reduction of pressure in a parking brake circuit which is a part of such system. The passageway is restricted to limit such bidirectional flow to a predetermined level. The pressure reduction permitted is sufficient to activate a parking brake valve in such parking brake circuit when a defect occurs in an operating service brake circuit which is also a part of such system.

Abstract: A master cylinder includes a hydraulic pressure control valve having a valve member mounted in a valve body and normally held apart from a valve seat by a valve spring. The valve member is seated on the valve seat when a pressure in a pressure chamber of a housing of the master cylinder reaches a predetermined level. A control device includes a body received in the bore and having one end portion of a convex shape. The body of the control device is urged by a spring in such a manner that the one end portion projects through a port of the housing into the pressure chamber.

Abstract: Level lifting and lowering of a working implement in combination with a hydraulic boom is provided through a hydraulic circuit and valve including a shuttle check valve, a rotary flow divider and a counterbalance valve. Selective operation results in the working implement being raised or lowered in a level displacement relative to the ground.

Abstract: The sweeping roller of a sweeping machine is held on the ground in sweeping operation by two hydraulic cylinders in such a manner that the degree of wear is small. For this purpose in each cylinder a static and different holding pressure must be set. The higher pressure is set at a pressure-limiting valve and the lower pressure at the series circuit parallel thereto of a nozzle with an adjustable throttle.

Abstract: In a working vehicle comprising a hydraulic power steering cylinder (25) and hydraulic lift cylinder (31), a novel hydraulic system is employed which comprises first and second flow control valve means (47, 48; 147, 148; 247, 248; 347, 348), each dividing its inflow into two flows. These valve means are connected in a fashion such that output flow of a single pump (43) driven by engine (10) is first divided into two output flows one of which is then divided by the second valve means. Further, one of the output flows of the second valve means is directed towards the steering cylinder whereas the other of output flows of the both valve means are directed towards the lift cylinder.The connection is such that, while a predetermined constant flow is secured for the steering cylinder at the normal engine speeds, a flow is necessarily secured for a relatively quick operation of the lift cylinder already at a low engine speed.

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: There is provided an improved fluidic drive circuit for a fluid powered vehicle arranged to limit flow to an unloaded drive wheel. A restricting orifice is mounted in parallel with a pressure sensitive control valve to provide fluid power to the motor. A trickle flow is provided through the restricting orifice to maintain a minimum pressure to the fluid motor. The control valve, sensitive to pressure at the fluid motor, provides full flow only when the pressure in the fluid motor is sufficient.

Abstract: A pumping system for producing uniform discharge and suction rates includes a pump connected to a supply of hydraulic fluid to deliver hydraulic control fluid at a selectable flow rate to a proportioning valve. The proportioning valve divides the flow of hydraulic fluid into two resulting flows, each of which is utilized via a four-way valve to drive a piston within a hydraulic cylinder. The positions of the pistons within the cylinders are detected and used to control the proportioning valve such that each piston is imparted with a velocity that varies in a sinusoidal manner in response to the hydraulic fluid delivered to it by the porportioning valve. Sensing of the piston positions and control of the proportioning valve may be accomplished mechanically by a system of cams driven by the pistons, or electronically by a microprocessor receiving signals from transducers coupled to the pistons.

Abstract: A hydraulic feed control system for log debarkers having three infeed and three outfeed rolls. Each roll is driven by its own hydraulic motor. Each infeed motor is connected in series with a corresponding outfeed motor whereby three pairs of motors are defined. The hydraulic fluid is pumped through a three way flow divider which divides the fluid equally to each of these pairs. Each of the motors has a special crossover relief with a directional flow control that will prevent the excessive pressure that may be created by one of the motors in the series from effecting the pressure to the other motors. The special relief is also provided with a direct line into the oil reservoir which if needed either of the motors in series may siphon oil from the reservoir through the directional flow control valve without affecting the other motor. The return line from the outfeed (down flow) motor joins a common return which is separate from the relief return to tank.

Abstract: In a vehicle hydraulic system of the open center kind, hydraulic fluid for operating vehicle services is circulated continuously, normally by an engine-driven pump. A closed center booster which requires a substantially constant pressure differential to operate it, is included in the open center system, the pressure differential being provided by a fixed restriction. The fixed restriction may be operative when the pump is operative, or only when the booster is operative. The booster is arranged so that in operation, high pressure fluid entering a boost chamber displaces an equal volume of fluid from a forward chamber into the system. The booster may also include a one-way valve allowing flow of fluid from the forward chamber to the boost chamber.

Abstract: A hydraulic apparatus for a vehicle having a propulsion engine comprises a control valve, a flow dividing valve, pumps driven by the engine for delivering fluid to the valves, and steering and implement circuit operatively connected to the control and flow dividing valves. The control valve includes plunger provided with orifices having variable degrees of openings and a spool connected to the plunger and the flow dividing valve includes a spool. With the hydraulic apparatus this constructed, fluid having an amount necessary for operating the steering circuit is always fed thereinto by operatively connecting the spools of the control and flow dividing valves and sharing the fluid into the steering and implement circuit by controlling the fluid dividing valve in accordance with pressure difference between the upstream and downstream portions of the orifices in the control valve.

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: A control system has two fixed-displacement pumps for supplying pressurized fluid to a pair of steering cylinders via a steering valve and to a pair of implement cylinders via an implement valve. Connected next to the pumps is a demand valve which is pilot operated to deliver to the steering cylinder pair the pressurized fluid from only one pump upon slight displacement of the steering valve and the pressurized fluid from both pumps upon greater displacement of the steering valve. The demand valve is further pilot operated to deliver to the implement cylinder pair the pressurized fluid from only one pump when the implement valve is actuated in a direction to lower the implement assembly, and the pressurized fluid from both pumps when the implement valve is actuated in a direction to raise the implement assembly.

Abstract: A hydraulic fan control for controlling air ventilation in a building having a plurality of fans operated by associated hydraulic motors which are connected in parallel and driven by a single pump and electric motor unit through a hydraulic fluid circuit. The speed of the fans is proportional to the volume of fluid flowing through the associated hydraulic motors per unit time, i.e., the rate of fluid flow. The volume of fluid is regulated by a shunt flow divider valve included in the hydraulic circuit and connected in parallel with the hydraulic motors. The shunt flow divider valve is in turn controlled by an electrical drive circuit responsive to variations in the ambient temperature of the air in the building.

Abstract: A hydraulic control valve provides controlled fluid supply for two hydraulic services having different flow and pressure requirements, as for example a lift service of a lift truck for lifting loads vertically and a tilting service for tilting loads forwardly and rearwardly. Two landed spools operate in parallel adjacent bores each joining a plurality of chambers and connected to fluid pressure supply and tank service ports. The supply to port communicating with one of the bores through two of the chambers, so that flow area is increased and the pressure drop of fluid flowing through them is reduced, and is connected through the bore and chambers to the tank port when the respective spool is in a neutral position and selectively to the service ports by movement of the spool.

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 hydraulic control for a folding tool bar which has a transport width less than half the field working width. Restrictors are added in series in the right-hand folding lines to cause the left-hand outrigger to fold to the transport position first. A one-way plunger operated ball check valve located in the hinge area between the main frame and an outrigger frame bypasses the restrictors for the first five degrees of fold and for the complete unfold cycle. The outriggers can therefore be lifted together at the start of the fold cycle during turns in the headlands. For complete folding to the transport position the left-hand outrigger folds first with the end of the right-hand outrigger positioned above it. The ball check valve causes the right-hand outrigger to unfold out of the path of the left-hand outrigger during the unfolding cycle.

Abstract: The present invention is a pressure limiter for a hydraulic booster. The pressure limiter adjusts and limits the pressure generated between a pumping means and a restricting gap in a gain valve by limiting the size of the gap in response to sensed system pressure. A pressure limiter piston responds to system pressure to act against a gain valve piston and control the size of the gain valve gap.

Abstract: A tree harvesting machine is disclosed in which a grappling arm functions to reach behind a tree and draw the machine forwardly to force a shearing blade through the tree close to the ground. The harvester frame holds the severed tree and includes spring-loaded holders which allow the tree to enter the collecting space but prevent its escape once severed. The grappling or draw arm is operated by two piston/cylinder devices connected mechanically in parallel but which are hydraulically actuated in a particular sequence and fashion which assures quick closing of the draw arm upon a tree, slow but powerful shearing action, and quick opening of the draw arm.

Abstract: A programmed valve system for positioning control having a first two stage valve assembly operable for raising a load and a second two stage valve assembly for lowering the load. Each of the second stages has a poppet with a parabolic contour which is dimensioned with orifice parameters to provide substantially linear flow rate change for minimized shock when one of the second stage poppets closes and the other opens. In the raise assembly, the pilot stage outlet orifice has a cross-sectional area substantially larger than that of the inlet orifice so that the second stage poppet opens much more rapidly than the closing thereof thereby to minimize overshoot when the pilot stage is actuated to the open position.

Abstract: A vehicular power steering system including a primary hydraulic circuit for operating the steered wheels and a secondary hydraulic circuit for operating auxiliary equipment such as an implement or the like which may be attached to the vehicle. The system includes a fluid controller for controlling the flow of pressurized fluid from a pump to the primary or steering circuit and the implement or secondary circuit. The fluid controller includes a valve mechanism which is constructed and arranged to provide the primary hydraulic circuit with pressurized fluid in the amount necessary to produce the desired steering maneuver while furnishing the secondary hydraulic circuit with the excess pressurized fluid supplied by the power pump. Thus the requirements of the primary hydraulic circuit may be always satisfied and have priority over the requirements of the secondary circuit in all modes of operation.

Abstract: A stacked parallel valve assembly adapted for use on a highway dump truck or the like where primary hydraulic cylinders are actuated by shifting valves in the assembly and pressure fluid flowing through the assembly is continuously available to power a downstream hydraulic accessory or accessories such as an auger, spreader or cylinder.

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 ratio between flow rates of divided flow streams established by a flow divider valve is selectively changed through a manually adjustable control valve to establish in adjusted ratio that is maintained constant for any adjusted position of the control valve. The relative flow areas of throttling passages are adjusted by the control valve to establish a predetermined pressure differential causing a corresponding change in restricted flow areas through which the divided flow streams are conducted under the constant flow rate ratio.

Abstract: A hydraulic control system having a pump and circuits connecting the pump to a pair of hydraulic motors through first and second circuits is provided with a priority valve system operative to provide a priority of fluid pressure to the first motor up to a predetermined minimum pressure and thereafter to maintain the pressure in the first circuit and simultaneously supply fluid to the second motor of the second circuit. The priority valve system is also responsive to a load on a second motor to split the flow of fluid between the two motors above the predetermined minimum pressure up to a second pressure after which the second predetermined pressure is maintained in the first circuit while fluid is being supplied to the second conduit.

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: A simplified overall hydraulic control system is provided for dual systems comprising a booster steering power cylinder and the power cylinder of an accessory of a work vehicle pressurized from a common engine driven hydraulic pump. The system utilizes conventionally constructed multiway valves for steering and accessory control and comprises flow dividing means effecting a constant minimum flow rate at all operational times for steering and variable flow rates for accessory power and additionally for steering dependent upon demand, essentially under vehicle operator control.A main steering flow to the steering control valve can connect with the minimum steering flow through a one way valve when steering is effected, less such flow as may be directed for accessory power by operation of the accessory control valve.

Abstract: A directional change-over valve which has a valve body having connecting surfaces at both sides thereof, a spool slidably inserted into the valve body, a check valve replaceable depending upon utilities thereof, wherein the valve body has a plurality of valve chambers, the central valve chamber is communicated with the hole for mounting the check valve for removably mounting the check valve, passages are provided opening at the connecting surfaces of the valve body in the respective valve chambers, another passages are provided for connecting the interior of the check valve to the both side valve chambers to form parallel, tandem and series circuits. Thus, this invention simplifies the structure and circuits to provide a compact directional change-over valve device as a whole.

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 power brake valve and a related braking system are disclosed. The valve comprises a housing defining a first bore of large diameter and a second bore of smaller diameter, and annular pistons are slidably disposed within each bore. A biended rod, also slidable within the bores, carries reaction pistons which are radially extended to cover the annular flow space of the adjacent, associated annular pistons. When the rod is pulled in a power mode of operation, each annular piston moves toward the associated annular piston to restrict and halt the normal flow of fluid through the annular piston and create a movable end wall. As pressure rises within the chambers, pressurized fluid is discharged from the valve to brake units to cause braking action. In a manual mode of operation, pulling action on the rod causes a relatively large quantity of relatively low pressure fluid to be discharged from the first chamber so as to quickly and effectively take up systemic clearances within the brake system.

Abstract: A hydraulic system for a vehicle having an open center type braking booster and the other hydraulic operating system e.g. power steering having open center type valve mechanism, both being in fluid communication with a discharging port of an engine driven pump for receiving input fluid flow through a flow divider.The invention provides, at an early stage of the braking operation, means for fluid communication between the discharge port of the power steering system and the inlet port of the booster other than communication between the discharging port of the flow divider and the inlet port of the booster.

Abstract: A device for distributing pressurized fluid to first and second movable consumers while maintaining a fixed ration between the fluid flows to the consumers, including rotary flow value gauges for directing a return flow from each consumer to an associated gauge, a comparator interconnecting the gauges without one gauge being dependent on the other gauge as to the rotation of the gauges and sensing differences between the output flow of the gauges, inlet valves activated by the comparator to regulate the flow to each consumer for maintaining the fixed flow ratio, and throttle valves for the return flow from each consumer and activated by the comparator to throttle the return flow from a consumer to slow down such consumer.

Abstract: an open center hydraulic system in which a pair of flow divider valves is connected in series with the system's hydraulic pump to create a parasitic pressure upstream of these flow valves and the feeder and separator clutches are controlled remotely by simple solenoid actuated two-position valves. The cylinders actuating the clutches are of sufficient size upon application of the minimum parasitic pressure to hold the clutches in a given position so that no center neutral position is necessary on the two-position valves.

Abstract: A vehicular power steering system including a primary hydraulic circuit for operating the steered wheels and a secondary hydraulic circuit for operating auxiliary equipment such as an implement or the like which may be attached to the vehicle. The system includes a fluid controller for controlling the flow of pressurized fluid from a power pump to the primary or steering circuit and the implement or secondary circuit. The fluid controller includes a valve mechanism which is constructed and arranged to provide the primary hydraulic circuit with pressurized fluid in the amount necessary to produce the desired steering maneuver while furnishing the secondary hydraulic circuit with the excess pressurized fluid supplied by the power pump. Thus the requirements of the primary hydraulic circuit may be always satisfied and have priority over the requirements of the secondary circuit in all modes of operation. .Iadd.