Abstract: A differential steering control system and method for a machine includes a motor for steering the machine in a leftwards or a rightwards direction, a continuously variable transmission for moving the machine in a forwards or a backwards direction, and a control unit connected to the motor and the continuously variable transmission. The control unit determines the speed of the continuously variable transmission and based upon the determined speed, modifies a speed of the motor in order to achieve/maintain a desired turn radius for the machine.

Abstract: A steering system for a vehicle wherein the first and second axle shafts are driven by a power shaft powered by an engine. A differential gear is interposed between the power shaft and the first and second axle shafts. The steering system has a first hydraulic unit associated with the first axle shaft, a second hydraulic unit associated with the second axle shaft, a hydraulic circuit connecting an input of the first hydraulic unit to an output of the second hydraulic unit and an output of the first hydraulic unit to an input of said second hydraulic unit. A control unit is connected to the hydraulic circuit for varying a flow rate of hydraulic fluid in the first and second hydraulic units and an actuator associated with the control unit for controlling said control unit. The actuator is responsive to rotation of a steering wheel.

Abstract: An engine-propelled monowheel vehicle comprises two wheels, close together, that circumscribe the remainder of the vehicle. When the vehicle is moving forward, the closely spaced wheels act as a single wheel, and the vehicle turns by leaning the wheels. A single propulsion system provides a drive torque that is shared by the two wheels. A separate steering torque, provided by a steering motor, is added to one wheel while being subtracted from the other wheel, enabling the wheels to rotate in opposite directions for turning the vehicle at zero forward velocity. The vehicle employs attitude sensors, for sensing roll, pitch, and yaw, and an automatic balancing system. A flywheel in the vehicle spins at a high rate around a spin axis, wherein the spin axis is rotatable with respect to the vehicle's frame. The axis angle and flywheel spin speed are continually adjustable to generate torques for automatic balancing.

Abstract: An electric powertrain includes an engine configured to provide mechanical energy and a generator operably coupled to the engine and configured to convert at least a portion of the mechanical energy into electric energy. The electric powertrain further includes at least one electric motor operably coupled to the generator, a plurality of driving members, and at least one power electronics unit configured to control at least one of the engine and the generator. The at least one electric motor is configured to provide torque for the plurality of driving members.

Abstract: A differential steering control system and method for a machine includes a motor for steering the machine in a leftwards or a rightwards direction, a continuously variable transmission for moving the machine in a forwards or a backwards direction, and a control unit connected to the motor and the continuously variable transmission. The control unit determines the speed of the continuously variable transmission and based upon the determined speed, modifies a speed of the motor in order to achieve/maintain a desired turn radius for the machine.

Abstract: A driving force control device for an electric vehicle in which a left wheel is driven by a left in-wheel motor and a right wheel is driven by a right in-wheel motor includes a driving force difference setting section. The driving force difference setting section is configured to set a driving force difference between a driving force outputted from the left in-wheel motor and a driving force outputted from the right in-wheel motor when a lateral acceleration is detected acting on the vehicle, the driving force difference being set to generate a restoring moment against the vehicle corresponding to the lateral acceleration.

Abstract: A method and system are described for calibrating speed controls for a vehicle having a pair of drive means on opposite sides of the vehicle driven by independent speed controls and where relative speed of the drive means is used to direct the vehicle. In one aspect, angular motion of the vehicle is detected using at least one of a gyroscopic angular sensor and a pair of accelerometers to determine a rate of yaw; a speed control output for controlling the relative speed is adjusted so that the rate of yaw is lower than a threshold when speed control inputs for controlling the relative speed are equal; and one or more speed control adjustment parameters are determined and stored for use during operation for controlling the relative speed of the drive means. A microcontroller may be used to receive sensor outputs (e.g. from the gyroscope and/or accelerometers) and speed control inputs and to determine the speed control adjustment.

Abstract: A steering control apparatus is provided, including a steering wheel, steered wheels, a direction varying actuator to operate the steering control wheels, a steering reaction actuator to apply steering reaction torque to the steering wheel and steering controller. The steered wheels are mechanically disconnected from the steering wheel. The steering controller outputs control commands for controlling the direction varying actuator and the steering reaction actuator.

Abstract: The present invention provides a method and apparatus for brake steering a tracked vehicle such as, for example, a military tank. More precisely, the present invention provides independent control of a left brake and a right brake to create a track speed differential and thereby turn the vehicle. The apparatus of the present invention preferably includes a controller, a plurality of circuit selector actuators operatively connected to the controller, and a plurality of brake apply actuators operatively connected to the controller. A plurality of valves are disposed in fluid communication with the plurality of circuit selector actuators. The left brake is in fluid communication with one of the plurality of brake apply actuators, and the right brake is in fluid communication with another of the plurality of brake apply actuators.

Abstract: A steering control system comprises a steering component, a turning component, and a backup mechanism for alternately mechanically separating and linking steering and turning components. A steer-by-wire control unit is provided for executing steer-by-wire control of a turning actuator to a turning angle corresponding to a steering condition and control of a steering reaction force actuator for imparting steering reaction force corresponding to the turning condition. A steering assistance control unit is selectively linked to the backup mechanism to executing steering assistance control for at least one of the steering reaction force actuator and the turning actuator. A control switching unit is provided for controlling a shift, under predetermined conditions, between control by the steer-by-wire control unit and control by the steering assistance control unit.

Abstract: The invention relates to a vehicle with coordinated steering. There is a need for a vehicle wherein Ackerman steered front wheels are coordinated with differentially steered and driven rear wheels. Such a vehicle includes Ackerman steerable front wheels and differentially driven left and right rear wheels. A steered wheel angle sensor is coupled to the front wheels and generates a steered wheel angle value. A front steering unit steers the front wheels and a differential drive unit drives the rear wheels. A control unit is coupled to the steering input sensor, to the steered wheel angle sensor, and to the front steering unit and the differential drive unit. The control unit generates the front steering control signal and the rear drive/steering control signal, and coordinates the steering operation of the front wheels with the differential steering/driving of the rear wheels.

Abstract: A power transmission mechanism of a model vehicle capable of mechanically performing accurate straight running and turning control without relying upon the output characteristic of each drive system in an RC tank having two drive systems. The power transmission mechanism comprises a motor (10) for traveling providing a drive force for traveling, a motor (30) for turning providing a drive force for turning, a left side differential gear (40) and a right side differential gear (50) to which the rotations of the motor (10) for traveling and the motor (30) for turning are transmitted, and a center differential gear (80) to which the rotation of the motor (30) for turning is transmitted. The turning is performed by using the left side differential gear (40), the right side differential gear (50), and the center differential gear (80).

Abstract: A steering system for a vehicle wherein the first and second axle shafts are driven by a power shaft powered by an engine. A differential gear is interposed between the power shaft and the first and second axle shafts. The steering system has a first hydraulic unit associated with the first axle shaft, a second hydraulic unit associated with the second axle shaft, a hydraulic circuit connecting an input of the first hydraulic unit to an output of the second hydraulic unit and an output of the first hydraulic unit to an input of said second hydraulic unit. A control unit is connected to the hydraulic circuit for varying a flow rate of hydraulic fluid in the first and second hydraulic units and an actuator associated with the control unit for controlling said control unit. The actuator is responsive to rotation of a steering wheel.

Abstract: A four wheel drive system for bilaterally symmetric vehicles is characterized by separate drive systems for the front and rear wheels. Each drive system is operable to independently drive each wheel. The rear wheels of the vehicle are steering wheels which are connected with the vehicle frame for independent rotation about a vertical axis. Steering and driving of the wheels is controlled by a controller. The combination of independent steering for the rear wheels and independent powering of all four wheels provides the vehicle with a zero turning radius for improved mobility as well as improved traction on unstable surfaces.

Abstract: An electric power steering apparatus in which, when an abnormality is generated in an electric power steering apparatus, an assist is reduced smaller than normal when a steering burden is estimated to be small; and the assist can be increased to normal and the steering burden can be sufficiently reduced when the steering burden is estimated to be large. When an abnormality is detected, an assist command is set smaller than at a normal time when there is no abnormality in a first range where the steering burden estimated by the steering burden estimation unit is small; the assist command is increased to that at a normal time in a second range where the steering burden estimated by the steering burden estimation unit is larger than the first range; and an assist torque of a motor is controlled in response to the assist command at the abnormal time.

Abstract: A crawler tractor comprises steering mechanisms (44) (45) for rotating a machine body by causing right and left crawler belts (9) to move differentially. The tractor is characterized in that the steering mechanism (44) is connected to a drive system located behind a reverser mechanism (21) that moves the machine body forward and back. Even when the machine body movement direction is changed from forward to back, the direction of the steering wheel (18) and the direction of the rotation of the machine body are kept the same, so that a reversed steering phenomenon is prevented from occurring, and an appropriate operation in forward or back movement is enabled with a simple structure that does not require an additional mechanism such as a reverse-steering preventions mechanism.

Abstract: A steering and driving system (1, 53, 54) for an industrial truck with a driving engine (2), a driving transmission (21), a steering engine (4) and a steering transmission (5, 32, 32?), through that one rotor (23) arranged on a wheel hub (22) could be driven and is swivelable at a vertical axis (V). For the realization of the compact design form as well as lesser manufacturing costs for this steering and driving system is considered, that the driving engine (2), the steering engine (4) and the steering transmission (5, 32, 32?) are arranged co-axially to each other.

Abstract: An electric drive system is provided. The electric drive system includes a first output member, a second output member, and an electric motor that includes an output shaft having an axis of rotation. The output shaft is operatively engaged with the first and second output members to rotate the first and second output members. A differential steering system is disposed between the electric motor and the first and second output members. The differential steering system includes at least one planetary gear assembly that has an axis of rotation that substantially aligns with the axis of rotation of the output shaft. A steering motor is operatively engaged with the at least one planetary gear assembly and is operable to modify the rotational speed of the at least one planetary gear assembly to thereby adjust the rotational speed of one of the first and second output members relative to the other of the first and second output members.

Abstract: A vehicle steering apparatus includes a drive unit for changing a steering angle of a steered wheel. A calculation unit calculates a control target amount of the steering angle based on a vehicle model. A control unit controls the drive unit to change the steering angle based on the control target amount. A determination unit determines whether the absolute value of at least one of yaw rate of the vehicle and lateral acceleration of the vehicle is greater than or equal to a predetermined value when velocity of the vehicle is less than or equal to a predetermined velocity. The control unit refrains from executing the control based on the control target amount when the absolute value is not greater than or equal to the predetermined value.

Abstract: In order to solve a problem that a motor generates a noise so as to deteriorate an environment in a vehicle if a field weakening control is executed to the motor of a electric power steering apparatus, in the case that a vehicle speed is high, the same field weakening control as the conventional one is applied to the motor because a noise generated due to a friction between a tire and a road surface and a wind noise of a vehicle body are large, and in the case that the vehicle speed is low, the field weakening control is weakly applied in comparison with the conventional one because the noise generated by the motor is felt relatively largely. Accordingly, the field weakening control can be executed in response to the vehicle speed in such a manner as to make the motor noise smaller.

Abstract: A crawler tractor comprises steering mechanisms (44) (45) for rotating a machine body by causing right and left crawler belts (9) to move differentially. The tractor is characterized in that the steering mechanism (44) is connected to a drive system located behind a reverser mechanism (21) that moves the machine body forward and back. Even when the machine body movement direction is changed from forward to back, the direction of the steering wheel (18) and the direction of the rotation of the machine body are kept the same, so that a reversed steering phenomenon is prevented from occurring, and an appropriate operation in forward or back movement is enabled with a simple structure that does not require an additional mechanism such as a reverse-steering preventions mechanism.

Abstract: A transmission for speed changing and steering of a vehicle comprises a first HST and a first differential for speed changing and a second HST and a second differential for steering. The first HST is a combination of a hydraulic pump and motor. The pump is driven by an engine and the motor is drivingly changeable by operation of a speed change pedal. Output power from the motor is transmitted into a pair of first differential output shafts as axles through the first differential. The second HST is a combination of a hydraulic pump and motor. The second pump is driven by output power from the first HST and the second motor is drivingly changeable by operation of a steering wheel. A pair of second differential output shafts are rotated in opposite directions by output power of the motor, so that when turning, the first differential output shaft on the opposite side of the turning direction is accelerated.

Abstract: A steering angular velocity computing device detects a change in a steering angle, measures a required time from a time when the steering angle changed until a time when the steering angle next changed, and computes, after the detector has detected a change in the steering angle, the steering angular velocity by dividing an amount of change in the steering angle by the required time corresponding to the amount of change and outputs it. When the steering angular velocity is being reduced, the steering angular velocity computing unit outputs the steering angular velocity during a first extended output period longer than the required period. Thus, the steering angular velocity is outputted with a high accuracy when the steering angular velocity is being reduced.

Abstract: In a displacement-control mechanism for a vehicle hydrostatic transmission system including a traveling hydrostatic transmission (HST) and a steering hydrostatic transmission (HST), a steering link member is extended from a steering displacement-control device of the steering HST, and connected at an end thereof to the traveling-direction switching rotary member interlocking with a traveling manipulator for setting traveling speed and direction of the vehicle or with a traveling displacement-control device of the traveling HST. The traveling-direction switching rotary member is rotatable so as to be switched between a forward-traveling position and a backward-traveling position depending on whether the traveling manipulator is operated for forward traveling or backward traveling.

Abstract: A transmission drive system (TDS) has two AC induction traction motors, each operatively coupled to two semi-independent coaxial traction shafts, and two AC induction steer motors coaxially mounted on a common steer axis parallel to the coaxial traction shafts. A steering gear assembly, preferably between the traction and steering motors, has a common steer input shaft operatively connected to the two AC induction steering motors. Two planetary gear sets have the two traction shafts being operatively connected with one of a two planet gear carriers, or two ring gears, respectively. The other of the planet gear carriers or the ring gears are operatively connected with each other. Two offset gears mounted to the steer input shaft and meshing with two sun gears, respectively, including a reversing idler gear interposed between one of the two offset gears and one of the two sun gears.

Abstract: A work vehicle with a hydrostatic steering system is disclosed which is capable of performing optimum control of the absorption torque of a hydraulic pump according to running load; capable of preferentially ensuring turning performance and implement speed when running load is relatively low; and capable of ensuring desired turning performance even when running load is relatively high. To this end, a bulldozer with a hydrostatic steering system, wherein the power of a hydraulic motor driven by pressure oil fed from a hydraulic pump operated by an engine is transmitted to right and left crawler tracks through a differential steering means composed of planetary gear trains etc., is designed to control the absorption torque of the hydraulic pump according to the speed ratio of a torque converter calculated by a speed ratio operation unit.

Abstract: An electric power steering apparatus includes a booster circuit and a microcomputer. The booster circuit includes a booster coil, a first FET, and a second FET. The booster coil is connected to the first FET, which is grounded. A node a between the booster coil and the first FET is connected to the second FET, which is connected to a drive circuit. The microcomputer drives the first and second FETs such that the first and second FETs are selectively turned on and off, thereby controlling an output voltage of the booster circuit. When application of assisting force to a steering system is stopped, the microcomputer holds the second FETs on until the output voltage of the booster circuit becomes equal to a predetermined voltage.

Abstract: A tracked vehicle has smooth driving and idler wheels (6, 7, 8, 9), which frictionally transmit the tractive force to tracks (3, 4), e.g. rubber tracks, and which are mounted on a frame (3) of the vehicle which carries at least one driving engine (11). To avoid the slipping of the tracks on the driving and idler wheels, both the two front idler wheels (6, 7) and the two rear idler wheels (8, 9) are respectively driven. The front wheels are hydraulically driven, while the rear wheels may be hydraulically or mechanically driven.

Abstract: A transmission for speed changing and steering of a vehicle comprises a first HST and a first differential for speed changing and a second HST and a second differential for steering. The first HST is a combination of a hydraulic pump and motor. The pump is driven by an engine and the motor is drivingly changeable by operation of a speed change pedal. Output power from the motor is transmitted into a pair of first differential output shafts as axles through the first differential. The second HST is a combination of a hydraulic pump and motor. The second pump is driven by output power from the first HST and the second motor is drivingly changeable by operation of a steering wheel. A pair of second differential output shafts are rotated in opposite directions by output power of the motor, so that when turning, the first differential output shaft on the opposite side of the turning direction is accelerated.

Abstract: An electric drive configuration for a tracked vehicle comprises a pair of propulsion motors (1a, 1b) each in operable communication with one of a first pair of track drive sprockets (3a, 3b) for driving a pair of tracks (4a, 4b) of the tracked vehicles; a steer motor (5) in driveable communication with a controlled differential steer gear unit (6) positioned centrally of a pair of steering cross-shafts (7a, 7b) and in driveable communication with each shaft, the opposing ends of the steering cross-shafts (7a, 7b) being each in operable communication with one of a second pair of track drive sprockets (9a, 9b) for controlling the relative speeds of the two track to steer the tracked vehicle; the first pair of track drive sprockets (3a, 3b) being engageable with the tracks (4a, 4b) at a first end of a tracked vehicle and the second pair of track drive sprockets (9a, 9b) being engageable with the tracks at a second end of the tracked vehicle.

Abstract: A rear-engine type riding lawn tractor having a frame, an engine carried on the frame, a cutting mower driven the engine, a seat set on the frame, a caster wheel supported on the front frame, a pair of drive wheels supported on the rear frame, axles connected with the pair of drive wheels, a HST for drive and a HST for steering included in the transmission, a transmission case arranged on the left and right direction in the frame, a drive belt transmitting power to the cutting mower from the engine over the axle.

Abstract: An electric drive system is provided. The electric drive system includes a first output member, a second output member, and an electric motor that includes an output shaft having an axis of rotation. The output shaft is operatively engaged with the first and second output members to rotate the first and second output members. A differential steering system is disposed between the electric motor and the first and second output members. The differential steering system includes at least one planetary gear assembly that has an axis of rotation that substantially aligns with the axis of rotation of the output shaft. A steering motor is operatively engaged with the at least one planetary gear assembly and is operable to modify the rotational speed of the at least one planetary gear assembly to thereby adjust the rotational speed of one of the first and second output members relative to the other of the first and second output members.

Abstract: An electrical system for increasing the amount of voltage available to an electric power steering motor under high demand conditions includes a vehicle speed sensor that ascertains the speed of the vehicle, a steering wheel sensor that ascertains the rotational speed of the vehicle steering wheel, and a steering voltage controller that receives the signals provided by the vehicle speed sensor and the steering wheel sensor and processes these input signals to increase the voltage furnished to the power steering system by causing at least one component that consumes electrical power in the vehicle to reduce power consumption, or by causing a component that produces electrical power to increase power output, or by a combination of reducing power consumption and increasing power production.

Abstract: An axle driving apparatus of the invention is available for an economical vehicle having a belt type stepless transmission. The axle driving apparatus includes a pair of axles connected to respective drive wheels, a propelling transmission mechanism, and a steering transmission mechanism. The propelling transmission mechanism is drivingly connected to said prime mover through said belt type stepless transmission so as to transmit speed-variable output rotation of said belt type stepless transmission to both said axles, thereby rotating said axles together at various speeds in a common direction selected from two opposite directions for forward and backward traveling of said vehicle. The steering transmission mechanism is drivingly connected to said prime mover so as to transmit two oppositely directive output rotations to said respective axles, thereby differentially rotating said axles at various differences of rotational speed between said axles.

Abstract: A transmission for speed changing and steering of a vehicle comprises a first HST and a first differential for speed changing and a second HST and a second differential for steering. The first HST is a combination of a hydraulic pump and motor. The pump is driven by an engine and the motor is drivingly changeable by operation of a speed change pedal. Output power from the motor is transmitted into a pair of first differential output shafts as axles through the first differential. The second HST is a combination of a hydraulic pump and motor. The second pump is driven by output power from the first HST and the second motor is drivingly changeable by operation of a steering wheel. A pair of second differential output shafts are rotated in opposite directions by output power of the motor, so that when turning, the first differential output shaft on the opposite side of the turning direction is accelerated.

Abstract: A system and method of calibrating a differential steering system in a vehicle is provided. An initiation signal is received. At least one operating condition of the vehicle is monitored. A variable activation signal is applied to an actuation device operable to initiate a flow of pressurized fluid to a steering motor when the at least one operating condition is within a predetermined range. The rotation of the steering motor is monitored. A data point indicative of the value of the variable activation signal applied to the actuation device is captured when the steering motor begins to rotate in response to energization of the actuation device.

Abstract: A safety redundant drive by wire system includes a plurality of first control members to which control signals may be communicated and a plurality of device controllers adapted to deliver control signals to a respective first control member. Each device controller includes a first microprocessor for communicating control signals to the first control member and all other device controllers. Each device controller further includes a second microprocessor for redundantly communicating control signals to all other device controllers and for communicating with the first microprocessor. The system includes a dual redundant communication channel system having a first communication channel controlled by the first microprocessor of each device controller and a second communication channel controlled by the second microprocessor of each device controller.

Abstract: A method of synchronizing first and second steering arrangements is provided to control the steering of a machine. The first steering arrangement has steerable wheels that turn in response to a steer input. The second steering arrangement has non-steerable wheels or drive units in which steering is provided by changing the relative speed of right and left drive units. An electronic controller senses and controls the angle of steer of each of the first and second steering arrangements in order to synchronize their respective outputs. If the second steering arrangement cannot provide the needed angle of steer, an independently controlled brake is proportionally applied to the appropriate drive unit in order to assist the second steering arrangement.

Abstract: A hybrid steer-by-wire and mechanical steering system for a vehicle includes two subsystems. The first subsystem connects a steering wheel with a mechanical link adapted to turn a first wheel of the vehicle. The second subsystem has an electro-mechanical actuator adapted to turn a second wheel of the vehicle. An electronic controller adapted to receive information indicative of the positions of the steering wheel and the first wheel controls the electromechanical actuator to thereby control the position of the second wheel.

Abstract: An object is to provide a steering system for a tracklaying vehicle which is capable of preventing overrun of a motor during a pivot turn irrespective of the load of the road surface and does not cause a shortage of power during a turn. The steering system is comprised of a pair of brakes for right and left output shafts and designed to transmit the driving force of a hydraulic motor to the output shafts through a planetary gear mechanism. A transmission of a driving force from the hydraulic motor to the planetary gear mechanism is interrupted after concurrently carrying out actuation of a brake for either one of the right and left output shafts and a transmission of a driving force from the hydraulic motor to the planetary gear mechanism for a specified period of time, when the vehicle carries out a pivot turn. During a pivot turn of the vehicle, the engine is controlled such that a vehicle body speed obtained by a bevel shaft rotational speed detector becomes equal to a specified value.

Abstract: A system for monitoring the charge flow in a hydrostatic system. The system provides a sharp edge orifice restriction in the drain from the hydrostatic pump, creating a back pressure in the drain that is proportional to the fluid flow through the drain. A pressure switch mounted in the pump case, or in the drain, detects the back pressure in the drain. The pressure switch is designed to be activated at a back pressure that corresponds to the intended charge flow at a specific engine speed. During operation, if the back pressure is not sufficient to cause the pressure switch to be activated at the predetermined engine speed or at a faster engine speed, the charge flow is not sufficient and a warning signal is generated.

Abstract: The planetary steering differential includes first and second interconnected gear trains. First and second gear trains are used for rotating output members in the same direction at the same speed in response to rotating solely a first input and holding a second input stationary. Rotation solely the second input arrangement and holding the first input arrangement stationary the output members are rotated in opposite directions at the same speed. The first input arrangement is driven by a transmission, and the second input arrangement is driven by a reversible steering motor.

Abstract: A lawn tractor vehicle having a front mounted engine and a drive and steer type of transmission having vehicle components supported by the vehicle frame in such a manner to establish a weight distribution between the front and rear pairs of wheels that allows the effective use of a drive and steer type of transmission with a lawn tractor having a front mounted engine, and which enhances the performance, stability and handling of the vehicle.

Abstract: In a steering device for vehicle, the movement of a steering actuator, which is driven in accordance with the rotating operation of an operating member, is transmitted to the vehicle wheels such that the steering angle changes without mechanically coupling the operating member to the wheels. A target yaw rate, which accords with a load torque, that is sum of the control torque generated by an operating actuator and driver operating torque, and an operating angle of the operating member resulting from the functioning of this load torque, are computed. The steering actuator is controlled such that the vehicle yaw rate follows the target yaw rate. The operating actuator is controlled such that the operating angle follows a target operating angle of the operating member corresponding to a behavior index value comprising at least yaw rate of the vehicle.

Abstract: A transmission in a power machine includes an axle having an inboard and outboard end. The outboard end is coupled to a wheel through a universal joint. The inboard end is coupled, through a sprocket assembly and chain drive linkage to a hydraulic motor. The axle is supported at its inboard end by a single spherical bearing.

Abstract: A hydraulic power steering apparatus for a vehicle is provided with a main control valve in which a valve opening degree is controlled on the basis of a relative movement between an input shaft interlocking with a steering wheel and an output shaft interlocking with a steering mechanism for turning a steered wheel, a power cylinder mechanism generating a steering assist force, a pump apparatus discharging a fixed flow amount of working oil, a first flow passage including a supply passage communicated with the main control valve, and a control unit controlling an assist control valve. The main control valve controls a supply amount of the working oil in the first flow passage to the power steering apparatus, and the assist control valve controlling a flow amount of a part of the working oil discharged from the pump apparatus is controlled to a set valve opening degree set on the basis of a vehicle speed and an oil pressure of the working oil in the first flow passage, by the control unit.

Abstract: A four-wheel vehicle equipped with a space saving, relatively simple turning mechanism capable of turning a vehicle body with a sufficiently reduced turning radius. One of front and rear pairs of left and right wheels, to which a running torque produced by a driving force is not transmitted, are arranged for rotation concerning respective axes perpendicular to the ground. For turning the vehicle body, the one pair of left and right wheels are fixed at respective angular positions along tangential directions of an arc which passes the axes perpendicular to the ground of the one pair of left and right wheels and has the center near the center point of a rotating axle for running the vehicle of the other pair of left and right wheels.

Abstract: A tracked vehicle has an electrohydraulic drive/steering system having an engine driven variable displacement hydraulic steering pump which drives a hydraulic steering motor which is coupled to a differential track drive mechanism via a transmission with multiple gear ratios. A steering wheel is coupled to a variable friction device which produces a variable friction force which resists rotation of the steering wheel. A control system is responsive to a position of the steering wheel and controls the steering pump displacement and controls the friction device. The control system sets the variable friction device to its high friction level when a limit of the steering pump displacement is reached when the transmission is in a higher one of its gear ratios.

Abstract: A power assist motor drive unit includes an H-bridge circuit, current detecting means, and current control means for carrying out a PI feed back control according to a difference between the absolute values of a command current value and a actual motor current, thereby controlling the H-bridge circuit. The current control means includes PI operation control means and compensation-term-operation means for resetting a integral compensation term to a suitable value when operation of the power assist motor is changed from one state to another.

Abstract: This is a connecting device (7) to be interposed between left and right wheels (5L, 5R) of a vehicle. There are provided: a differential gear (8) having a first rotational element (8a), and second and third rotational elements (8b, 8c). The third rotational element (8c) is coupled to one (5R) of the rear wheels via the first power transmission system (10), and the second rotational element (8b) is coupled to the other (5L) of the rear wheels via second and third power transmission systems (11, 12). The gear ratios of both the first and second power transmission systems (10, 11) are identically set, and the gear ratio of the third power transmission system (12) is set so as to be opposite in direction to, but be equal in absolute value to, the above-mentioned gear ratio.