Abstract: A working vehicle comprises a working implement (20) supported by the working vehicle to be displaceable by a hydraulic actuator (1), and a controller (16) for generating a control output signal for controlling a position of the working implement in response to a control input signal, with reference to predetermined control characteristics. The control characteristics include at least a first control characteristic (Qs′) and a second control characteristic (Qs″) different from each other. The controller refers to the second control characteristic for generating the control output signal when the control input signal results from a variation in a set signal from a setter (15; 17S) for setting a target level of the working implement, and refers to the second control characteristic for generating the control output signal when the control input signal results from a variation in a detection signal from a displacement detecting sensor for detecting a displacement of the working implement.

Abstract: A working vehicle comprises a working implement (20) supported by the working vehicle to be displaceable by a hydraulic actuator (1), and a controller (16) for generating a control output signal for controlling a position of the working implement in response to a control input signal, with reference to predetermined control characteristics. The control characteristics include at least a first control characteristic (Qs′) and a second control characteristic (Qs″) different from each other. The controller refers to the second control characteristic for generating the control output signal when the control input signal results from a variation in a set signal from a setter (15; 17S) for setting a target level of the working implement, and refers to the second control characteristic for generating the control output signal when the control input signal results from a variation in a detection signal from a displacement detecting sensor for detecting a displacement of the working implement.

Abstract: This invention relates to controls of an agricultural tractor having a rotary cultivating mode and a draft control mode for performing a plowing operation. A conventional tractor has a controller for accelerating front wheels to be faster than rear wheels when the front wheels are steered to a predetermined reference angle. Such control is effected only in the rotary cultivating mode. In the agricultural tractor according to this invention, different reference angles are automatically set for the rotary cultivating mode and draft control mode. In addition, different reference speeds are set for the rotary cultivating mode and draft control mode. When the tractor runs faster than the reference speeds, the front wheels are prevented from becoming faster than the rear wheels even if the front wheels are steered to the reference angles.

Abstract: A drive transmission system for a working vehicle for transmitting power of an engine to running devices through a main clutch, a main change speed device and an auxiliary change speed device is disclosed. The main change speed device includes a first group of hydraulic clutches and a group of control valves for operating these clutches. The auxiliary change speed device includes a second group of hydraulic clutches and control valves for operating these clutches. Pressure oil is supplied to selected clutches of the first and second groups of hydraulic clutches to obtain the desired speed.

Abstract: A hydraulic operating apparatus includes a release hub for supporting a release bearing, a piston formed separately from the release hub, and an abutting plate disposed between the piston and release hub as a power transmission relay member for absorbing shocks. The abutting plate may itself be formed of an elastic material or may include an elastic element to suppress shocks transmitted between the piston and release hub. The release hub and piston are formed annular, and the release hub is supported slidable on an outer surface of an outer wall section of a cylinder defining an annular piston chamber. The release hub includes a supporting surface having a smaller diameter than the outer wall section for supporting the release bearing.

Abstract: A propelling clutch apparatus for a working vehicle comprises a friction type hydraulic clutch mounted on a propelling line, a valve for adjusting an oil pressure applied to the hydraulic clutch, a sensor for detecting angular acceleration of a rotary shaft included in the propelling line, and a control unit for controlling the hydraulic clutch in response to a change in a vehicle running state. The control unit effects controls in three stages. The first stage includes a preliminary step of narrowing spaces between friction disks of the hydraulic clutch by applying the oil pressure at a maximum level to the hydraulic clutch for a predetermined time from receipt of a clutch engaging command, and a subsequent main step of applying the oil pressure with predetermined characteristics. The second stage is for maintaining the hydraulic clutch in a half-clutch state when the angular acceleration in an accelerating direction or a decelerating direction reaches a predetermined value.

Abstract: A four wheel drive vehicle comprising an engine, a transmission connected to the engine, a front wheel drive line, a rear wheel drive line, and an automatic switch mechanism for operatively connecting the front wheel and rear wheel drive lines to the transmission to selectively provides a two wheel drive mode and a four wheel drive mode. The front wheel drive line and the rear wheel drive lines are constructed such that front wheels are driven at a lower speed than rear wheels. The automatic switch mechanism includes an input portion connected to the transmission, a first output portion connected to the front wheel drive line, a second output portion connected to the rear wheel drive line, and a clutch for connecting the first and second output portions to the input portion. The clutch is operable to disconnect the first output portion from the input portion upon receipt of a torque exceeding a predetermined value.

Abstract: Hydraulic control system including a bypass provided in an intermediate portion of an oil passage extending from a position control valve to a hydraulic actuator for raising and lowering a working implement. A draft control valve disposed in the bypass controls the pressure of oil flowing into the bypass, in response to the displacement of a member for sensing the draft force of the working implement.