Abstract: A street sweeping vehicle has a chassis supported on travel wheel units. An engine and an operator control compartment are on the chassis. A single hydrostatic transmission is on the chassis and is operatively connected to the engine and travel wheel units. An accelerator pedal located in the compartment is connected to the engine to vary its operating speed. An electronic and hydraulic control system accessible in the control compartment are connected to the transmission to control it and coordinate the operation of the engine and travel wheel units. The control system has a travel mode responsive to engine speed and a work mode independent of engine speed with control components to coordinate the modes and to permit the dual or separate operation thereof. The transmission has a variable displacement hydraulic pump and at least one hydraulic motor, with the control system operatively connected to each.

Abstract: A pneumatic control valve system has a modulating valve and a piston. When the operator depresses the piston, pressure is communicated to a switching piston moving that piston to a switched position so that pressure is communicated to a switching outlet. The switching piston retains this switched position when the first piston is released. When the modulating valve is opened to communicate pressure to a work port, pressure is also communicated to the switching piston in order to move the switching piston back to its unswitched position whereat the switching outlet is vented. The switching piston allows the control of another function.

Abstract: A control system for automatically controlling the operation of a hydraulic system for heavy construction equipment. The system of this invention provides a controller optimally connected to sensors and to control devices on the hydraulic system so that it automatically and optimally preheats the engine coolant and the hydraulic fluid of the heavy construction equipment before a normal starting operation in order to reach to an optimal operating temperature in a relatively short time. The control system automatically checks the operating temperature of the engine coolant and the hydraulic fluid by temperature sensors, and alarms the operator to any overheat condition by an alarm device. The control system also automatically controls the operational mode in order to remove the overheat condition thus preventing the temperature of the engine coolant and the hydraulic fluid from rising above a predetermined temperature.

Abstract: An apparatus controls an electrohydraulic system of a work vehicle. The work vehicle has a engine, at least one fluid circuit having a variable displacement pump driven by the engine, and a plurality of control valves for controllably passing fluid from the variable displacement pump to a plurality of respective work elements. A device produces a signal indicative of a desired velocity of a respective work element. A device senses a load on a work element and producing a signal representative of the actual load in response to the sensed load. A control device receives the desired velocity signal and load signals, and responsively calculates a desired power level for the electrohydraulic system. Responsively, the control device produces an engine speed command signal indicative of an optimum engine speed in response to the desired power level.

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: Hydraulic control of reversible hydraulic motors typically requires several different valves to provide for the various operating parameters. The subject hydraulic control circuit has only a pair of electrohydraulic control valves to provide all the typical operating parameters. Operation of the control valves is controlled by a microprocessor in response to receiving command signals from a manually controlled command signal outputting device which establishes a desired fluid flow rate and direction of flow through the control valves.

Abstract: In a method for operating a drive unit comprised of an internal combustion engine and a hydraulic aggregate group, the amount of fuel supplied to the engine is limited by a proportionally acting RPM regulator. When the engine is overloaded the power absorption of the hydraulic aggregate group is reduced by an electronic maximum load regulator and under no-load operation the engine is shifted from an automatic idling circuit to the idling speed after a specified time and the power absorption of the aggregate group is reduced to a minimum. For partial-load operation, the power absorption of the aggregate group can be limited selectably to a power below the maximum power put out by the engine. In order to render such a process more economical, the engine is operated in the range of the idling control characteristic during partial-load operation.

Abstract: A control system for a fluid operated jack reduces the speed of retraction of a piston rod of the jack to an acceptable rate during a preselected range of operation by adding pressurized fluid flow to the fluid being exhausted from the jack through a restrictor valve to the reservoir. This reduction in speed reduces the potential for damage to the jack and associated componentry without sacrificing efficiency of operation. An implement controller causes fluid flow from a fluid source to be combined with the flow of fluid being exhausted from the jack in response to receiving a position signal from a implement position sensor and subsequent to the implement controller commanding the shifting of a control valve to a position at which fluid flow is passed from the fluid operated jack to the reservoir. The control system is particularly suitable for use on an automatic guided vehicle.

Abstract: A housing (50, 52) defines a slide chamber (54) in which a slide member (34) reciprocates between three positions. A coil spring (86) holds the slide member (34) into a center position. In this position, slide member (34) blocks fluid flow through a port (28) and positions an electrical conductor (96) away from electrical contacts (110, 112). A push on the slide member (34) moves the electrical conductor (38) into circuit making contact with the contacts (110, 112). A pull on slide member (34) moves an exhaust passageway (36) in the slide member (34) into communication with the fluid port (28). The switch function activates a compressor which pumps air into an inflatable seat actuator. The valve function exhausts air from the inflatable seat actuator.

Abstract: Control system for a load-sensing hydraulic drive circuit comprising; at least one hydraulic pump; hydraulic actuators driven by the hydraulic pump; and a pressure compensated flow control valve between the pump and each of the actuators, for controlling a flow rate of fluid to each actuator in response to a control signal. The control system has first detection means for detecting a differential pressure between the pump delivery pressure and the maximum load pressure; second detection means for detecting the pump delivery pressure; first means for calculating a differential pressure target pump delivery amount Q.DELTA.p to hold the differential pressure constant; second means for calculating an input limiting target pump delivery amount QT based on at least a pressure signal from the second detection means and an input limiting pump function; third means for selecting one of the differential pressure target delivery amount Q.DELTA.

Abstract: A hydraulic lifting arrangement for a lift assembly on a materials-handling vehicle includes a working piston-cylinder device (17) for raising and lowering the lift assembly, a reversible pump assembly (40) for operating the piston-cylinder device, and an electric motor for driving the pump assembly. The piston-cylinder device (17) is a double-acting device and has two working chambers (28,29), which are connected to the pump assembly by connecting pipes (46,47). The pump assembly comprises a first and a second hydraulic pump (41,42) having fixed displacements. The pumps are so arranged in the system that together they supply hydraulic medium to and receive hydraulic medium from solely the first chamber (28) whereas only the pump motor (41) supplies and receives hydraulic medium to and from the second chamber (29).

Abstract: A drive control system for a hydraulic construction machine, comprises a prime mover driven by a hydraulic pump, at least one hydraulic actuator driven by hydraulic fluid discharge from the hydraulic pump, first rotational speed setting arrangement including a first operating arrangement for setting rotational speed of the prime mover, and a second operating arranngement for controlling operation of the hydraulic actuator (3).

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: An auxiliary coupler pressure relief hydraulic system for off-road vehicles including a battery, an engine, an engine ignition system, a reservoir of hydraulic fluid, and a pump for providing hydraulic fluid under pressure. Quick couplers couple hydraulic fluid to an attachment mounted to the vehicle. An electro-hydraulic spool valve is connected to a source of pilot pressure and controls the flow of hydraulic fluid to the quick couplers in response to valve actuating signals. Forward and reverse auxiliary control switches are coupled to the spool valve and provide valve actuating signals resulting in fluid flow to the quick couplers in forward and reverse directions. Also included is an ignition switch having RUN, OFF and RELIEF positions.

Abstract: Speed regulation of pump drive is set by a pressure-regulating valve providing a constant control pressure for a plurality of normal loads. If a high fluid consumption load such as the lifting cylinder of a forklift truck is to be simultaneously actuated the pump speed and net volumetric displacement must be increased. A higher speed-regulating control pressure from the pressure-regulating valve is required. The control valve for the high consumption load has a spool with an extending inclined cam contacting the biasing spring of the pressure-regulating valve. Upon actuation of this control valve the preload of the biasing spring is increased thereby adjusting the speed-regulating control pressure output of the pressure regulating valve. The pump engine or drive speed and the net volumetric displacement are increased.

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 control device for a drive unit, preferably the drive unit of a power vehicle, is provided having a hydrostatic transmission where the adjusting device of the latter and the adjusting device of the internal combustion engine are controlled by means of a servo piston loaded by control pressure, whereby the internal combustion engine is prevented during reversing from being adjusted to an increased power output through a circuit before the adjusting device of the hydrostatic transmission has passed through the zero-stroke position, and where the circuit has two shut off valves whose outlets are connected with a line, which are connected to the spring-side pressure chamber of the operating cylinder of the internal combustion engine through a multiway valve.

Abstract: A hydraulic power system is disclosed which comprises an internal combustion engine having a speed regulator, and which serves to drive a hydraulic system including a pump and a consumer or load. A throttle valve is positioned in the hydraulic system, and the throttle valve is connected to an adjustable controller, such that the volume flow rate to the consumer is proportional to the control signal delivered to the throttle valve by the controller. The same control signal of the controller is also delivered to the speed regulator of the engine. In one disclosed embodiment, the hydraulic system includes a plurality of consumers connected to a common pump, and each consumer includes an associated throttle valve and controller. Also, means are provided for weighting the several control signals from the controllers, and summing the weighted signals so that a composite adjusting signal is delivered to the speed regulator of the engine.

Abstract: The invention relates to a speed regulating device for a hydrostatic drive unit comprising a pump of variable feed volume and a motor in a hydraulic circuit, wherein the pump is driven by a drive motor of variable speed, and there is provided a regulating valve which controls the loading of a hydraulic adjustment device on the pump in dependence on the pressure differential in front of and behind an adjustable throttle arranged in the hydraulic circuit, in such a way that the feed volume is changed in inverse proportion to a speed change in the drive motor. It is the aim of the invention to produce a simple construction for the speed regulating device which can also be easily controlled in reverse operation and can be easily operated.

Abstract: A multi-function valve usable in a hydrostatic transmission and having valve components mounted in a single valve body to provide pressure limiter and high pressure relief functions and with the structure also providing a bypass function and for supply of makeup fluid to the hydrostatic transmission. The multifunction valve has a charge check valve member and a relief valve member in associated relation and movable upon the occurrence of a predetermined pressure differential thereacross to perform control functions. One pressure differential results from a flow through an orifice and with the flow being controlled by a poppet valve member normally held closed by a heavy spring which establishes a system pressure at which the pressure limiter function will occur. With this structure, the pressure limiter function occurs in advance of the high pressure relief function and under the control of a single heavy spring.

Abstract: A hydraulic booster including an input piston adapted to be actuated by a manually operated member such as a brake pedal. The input piston is axially slidable in a power piston which is in turn axially slidable in a booster casing. The power piston divides the inside cavity of the casing into a power chamber and a reservoir chamber. An electrically operated plunger pump is provided and has an outlet port connected with the power chamber and an inlet port. Between the input piston and the power piston, there are defined a first valve and a second valve. The first valve functions to open the power chamber to the reservoir chamber when the pedal is released but to disconnect the power chamber from the reservoir chamber when the input piston is depressed by a first predetermined distance.

Abstract: A hydraulic lifting and lowering system for battery-powered lift trucks includes an electronic control system which reduces or limits operator selected lifting commands in accordance with the current being drawn by an electric motor connected to drive a variable-displacement pump, and in accordance with the state-of-charge of the vehicle battery, to control a proportional valve which meters fluid flow to a lift cylinder.

Abstract: A microprocessor (158) based control for a hydraulic pump motor (26) used to control the operation of a mast assembly (12) on a work vehicle (10). The speed of each function performed by the mast assembly (12) is programmable to one of a plurality of possible speeds. An additional function for performing lifting of the mast (12) produces incremental speed variations relative to incremental movement of a corresponding control lever (14). Each of the functions have a predetermined priority such that attempted operation of multiple functions results in a pump motor speed requested by the function of highest priority.

Abstract: Grinder-mixers include a material infeed device such as a feed table for feeding bales of hay to be ground up and incorporated into livestock feed rations. Due to varying bale density, the bale grinder sometimes lugs down when encountering a dense bale. However, if the feed table continues to feed bales during such a lug down, the grinder may clog and stall. A bypass apparatus solves the feed table problem by providing a bypass valve automatically operable to stop motion of the feed table when a lug down occurs.

Abstract: Disclosed is a compact rotating hydraulic drive comprising (a) a housing, (b) a pumpshaft mounted in the housing for both linear translational and rotational movement, (c) a plurality of pumping units operated by rotational motion of the pumpshaft, (d) a valve spool mounted on the pumpshaft but rotatable relative to the pumpshaft, and (e) means selectively operative upon linear translation of the pumpshaft to rotate the valve spool back and forth between a first angular position in which the output of the pump is directed in one manner and a second angular position in which the output of the pump is directed in another manner.

Abstract: Grinder-mixers include a material infeed device such as a feed table for feeding bales of hay to be ground up and incorporated into livestock feed rations. Due to varying bale density, the bale grinder sometimes lugs down when encountering a dense bale. However, if the feed table continues to feed bales during such a lug down, the grinder may clog and stall. A bypass apparatus solves the feed table problem by providing a bypass valve automatically operable to stop motion of the feed table when a lug down occurs.

Abstract: A control system is disclosed for use with pressure-driven loads, such as reversible motors. The system allows the loads to be driven at varying speeds and also allows the loads to be reversed. However, the system is so designed that an operator cannot subject the loads to pressure shock caused by abrupt changes in pressure by adjusting the system too rapidly. The system disclosed is suitable for use with either hydraulic or pneumatic loads.

Abstract: A control valve for a hydraulic booster steering system provides gradual control of inlet flow to the system pump to complete cut off of output, or by throttling of inlet flow to effect a pilot stream through the pressure pump. This occurs in the neutral position of the control valve during straight ahead steering. Where flow through the pump intake feed means is thus impeded, the pump simply cavitates in a known manner and to be of a type which is suction regulated, having a check valve means at the pressure outlet side. The advantage of cutting off inlet flow to the pump during straight ahead steering, or at least throttling of such inlet flow by a constantly open throttle passage, is to save energy otherwise wasted in heating the fluid.

Abstract: A fluid control circuit includes a source of pressurized fluid (10) adapted for connection to a hydrostatic transmission (23) upon actuation of a vent control valve (16). The vent control valve (16) is connected to a control and preconditioning valve (17) which functions to ensure that a control lever (14) is in its "vent" position upon starting of an engine and provides for the continuous preconditioning of the control circuit subsequent to such start-up. The control circuit is relatively non-complex in structure and function and does not require positioning of the control lever (14) in a special reset position upon shifting thereof between its "run" and "vent" positions.

Abstract: An engine for operating a hydraulic motor. Opposed pistons, joined by a common connecting rod operating between two cylinders and between internal combustion valving and ignition components, are used to drive fluid under pressure through a series of cross-over valves to and from a hydraulic motor. Hydraulic fluid is stored and maintained under pressure within the engine cylinders on the other side of the pistons forming an internal combustion engine. A series of embediments within the common connecting rod actuate a matched set of proximity detectors. The proximity detectors, in turn, time the operation of the engines and the operation of the cross-over valves without mechanical linkages. A hydraulic pump is used to start the engine. A blower is used to mix the fuel and air within the engine and to exhaust combustion gasses. The hydraulic motor drives a flywheel to store energy and to dampen the pulsations resulting from the shifting of the cross-over valves and the reciprocating action of the pistons.

Abstract: A hydrostatic transmission includes a reversible, variable displacement pump having a swashplate actuator controlled by a pilot-operated displacement control valve. A manually operated displacement control lever is manipulated to opposite sides of a neutral position to effect command signals for causing pilot operation of the displacement control valve to control movement of the swashplate in accordance with the command. A neutral control valve is coupled to the displacement control lever and is operated thereby to a neutral position, wherein it connects the swashplate actuator to sump, when the lever is moved to its neutral position.

Abstract: More specifically, the invention includes a single lever control mechanism for controlling the operation of hydraulic cylinders and including a control housing, a manually operable lever, and a support member housed in the control housing and having a supporting surface. The single lever control mechanism also includes a pivot member rigidly connected to the lower end of the lever and supported on the supporting surface of the support member for rocking movement from a neutral position in a first pivotal direction and in a second pivotal direction transverse to the first direction. The control mechanism also includes a first cable attached to one side of the pivot member and being adapted to be operably connected to a first hydraulic cylinder for actuating that hydraulic cylinder in response to pivotal movement of the lever and the pivot member in the first direction.

Abstract: A control mechanism for controlling a reversible pump that selectively supplies fluid to two different motors forming separate functions includes a control lever pivoted about a fixed axis and having said pump connected thereto. A control console is located adjacent the control lever and cooperates therewith to define a plurality of distinct operating positions on opposite sides of a neutral position for said control lever. The control lever and control console also have releasable interlock means defining the neutral position for the control lever and the pump.

Abstract: A vehicle includes a variable displacement fluid pump and a variable displacement hydrostatic motor for driving the tracks of the vehicle. An auxiliary reversible motor may be actuated in one and the other directions to provide steering of the vehicle through planetary drives associated with the tracks of the vehicle.

Abstract: A transfer system having a transfer mechanism which is located directly on or adjacent the production machine. The transfer mechanism comprises a reciprocating workpiece shuttle driven by a hydraulic driving unit, specifically a hydraulic transfer cylinder. The latter is connected to a remote hydraulic cycloidal drive unit by long conduits which may be positioned overhead. The remote hydraulic cycloidal drive unit employs a pumping cylinder having an elongated stationary piston rod on which the cylinder housing is slidably supported, with the pressure fluid from the pumping cylinder being supplied through the conduits to the transfer cylinder. The housing of the pumping cylinder is reciprocated by a crank associated with a cycloidal mechanical drive. This crank is connected to and rotates with a gear which is rotatably supported on a slide and reacts with a stationary rack so that reciprocation of the slide causes alternate rotation of the gear.

Abstract: The carriage of a fork lift truck is actuated by the action of hydraulic fluid controllably supplied through a manually operated control system from a pump driven by an internal combustion engine having a carburetor. The throttle valve of the carburetor is partially opened in response to the operation of the control system in order to increase the discharge amount of the hydraulic fluid of the pump during idling of the engine.

Abstract: A control system for hydraulic lifts is characterized by a low pressure air circuit for controlling a high pressure closed center hydraulic circuit for operating hydraulic cylinders of the lift.In the disclosed embodiment the control system is for operating a hydraulic bucket lift, and the air circuit has a plurality of air switches which are actuable to provide compressed air at outlets from the circuit. The hydraulic circuit includes fluid valves operated by the compressed air at the outlets from the air circuit, and a fluid pump which operates only upon actuation of the circuit to move the cylinder, yet which maintains full hydraulic pressure at all other times for rapid system response. Adjustable metering valves control the volume flow of fluid to the cylinders to smooth and control the speed of operation thereof, and therefore of the lift.

Abstract: An integrated transmission-engine control for a transmission, such as a hydrostatic transmission having a variable displacement unit connectable to an engine and a second displacement unit connected to an output shaft, including fluid pressure-operated ratio governor means for the transmission, fluid pressure-operated means for controlling the supply of fuel to an engine, a power demand valve for converting a particular power demand to a particular fluid pressure primary control signal. The primary control signal is applied to the ratio governor means in opposition to a signal representing engine speed to set the transmission ratio for a desired engine speed and also applied to the fuel supply controlling means to establish a fuel setting to match engine horsepower to engine speed for minimum fuel consumption.

Abstract: An electronic control for hydraulic operation of forks on a lift truck wherein in the motor and pump speed can be matched to the particular flow requirements of each hydraulic ram and wherein a smoothly variable speed of the motor and pump is obtained for operation of the lift ram by the degree of manipulation of the lift lever.

Abstract: An improved pressure sensitive valving arrangement is provided for a power steering unit for a lift truck, and in particular for a battery powered lift truck. To the conventional implement valve is added an accumulator charging means which includes an additional valve, herein called a "blocking or control valve", which additional valve is downstream from the implement valve and which additional valve, when actuated, blocks the flow of fluid through the implement valve to thereby build up pressure for charging an accumulator. The blocking valve includes a blocking spool which operates against a pressure-actuated pilot plunger such that when the pressure in the accumulator reaches or exceeds a predetermined amount, the pilot plunger shifts the blocking spool to permit the fluid to again flow through the implement valve.

Abstract: A hydraulic fluid supply system for providing pressurized fluid to fluid actuated components on a refuse collection vehicle, generally including a fluid tank, a pump operatively connected to the crankshaft of the refuse vehicle engine for continuous operation and having an inlet communicating with the tank, a diversion valve having an inlet communicating with the outlet of the pump and having an outlet selectively communicating with the tank and the fluid actuated components on the refuse collection vehicle, means for increasing the idle speed of the engine to a predetermined actuation idle speed when the diversion valve outlet is communicating with the fluid actuated components, and means for preventing the engine from exceeding a predetermined override speed when the outlet of the diversion valve is communicating with the fluid actuated components thereby preventing damage to the pump if an operator accidentally depresses the accelerator pedal in the vehicle.

Abstract: An improved valving arrangement and actuator is provided for a power steering unit for a lift truck, and in particular for a battery powered lift truck. To the conventional implement valve is added an accumulator charging means which includes an additional valve, herein called a "blocking valve," which additional valve is downstream from the implement valve and which additional valve, when actuated, blocks the flow of fluid through the implement valve to thereby build up pressure for charging an accumulator. The blocking valve includes a blocking spool which operates against a pressure-actuated pilot plunger such that when the pressure in the accumulator reaches or exceeds a predetermined amount, the pilot plunger shifts the blocking spool to permit the fluid to again flow through the implement valve.

Abstract: A valve having a body with two ports and a bore, a sleeve selectively movable within said bore and having two radially extending passages adapted for sequential communication with one of said ports upon movement of said sleeve, and a spool selectively movable within said sleeve and including a land to restrict fluid flow in said passages. The valve is used as a variable pressure control valve in a closed loop hydrostatic circuit to control the displacement of a variable displacement pump. The spool is actuated in response to a pressure difference between the high pressure and the low pressure lines of the circuit. The sleeve is manually movable. A charge pump is provided to provide control fluid to one of the ports of the valve whereby movement of the sleeve and spool within the body will result in the flow of fluid from the charge pump to one servo of the variable displacement pump and from the other servo to drain.

Abstract: A hydraulic system and control valve assembly therefor characterized in that it provides a two wheel pressure compensated hydraulic drive for mobile equipment in forward or rearward direction at any speed up to maximum as determined by the operation of the control valve assembly. Said control valve assembly is further characterized in that it incorporates an override for the pressure compensating means to achieve steering control by decreasing the rate of flow of fluid to either wheel motor or to achieve braking action in conjunction with a counterbalance valve in the motor return circuit by decreasing the rate of flow of fluid to both wheel motors.

Abstract: The operation of a 4-way, open-center, three position hydraulic valve is coordinated with the operation of the pump for the hydraulic system in which the valve is controlling flow. As the valve is moving from its open-center position to either one of its other two operative positions, a switch maintains the power circuit for the pump open and closes that circuit to activate the pump after the valve has assumed one of the other two positions.

Abstract: A power steering system for electric vehicles in which an electric drive motor for the supply pump of a power steering system is controlled by a motor control which is in turn controlled by the steering demand of the operator. The motor and pump are operated only during steering operations and only at the power level required for any steering demand.

Abstract: A hydraulic circuit including a single pump and a plurality of control valves for communicating actuating fluid to the separate hydraulic motors from the single pump includes a synchronizing unit for initiating and terminating operation of the pump in response to operation of any of the control valves, the synchronizing unit including a pivotable gang plate adjustably mounting cam shoes separately associated with synchronizing levers connected to actuating elements for each of the control valves, the single gang plate thus being movable in response to operation of any one of the valves in order to initiate or terminate operation of the pump in closely synchronized relation to positioning of any one of the control valves to communicate the pump with one of the motors.

Abstract: Coordinated control of engine speed, transmission drive ratio and drive direction is provided for with a single foot pedal and a compact economical linkage arrangement for coupling the pedal to a vehicle engine and hydrostatic transmission. Forward rocking of the pedal from a neutral position progressively increases transmission drive ratio in the forward direction while backward rocking of the pedal from the neutral position progressively increases the drive ratio in the reverse direction. The pedal linkage further produces a unidirectional progressive motion of the engine speed control upon being rocked in either the forward or backward direction and this engine speed control motion may be continued by additional pedal movement after the transmission control member has reached the maximum possible movement in either direction.