Kubota Corporation

Akio Inamori

Takeshi Ura

Shigeo Sakamoto

Tetsuo Yamaguchi

Yoshiyuki Katayama

Seiichi Takahashi

Akihiro Asada

Toshinobu Owada

Yoshikazu Aota

Hironobu Kubota

Kazushige Komori

A working vehicle comprises a working implement ( ) supported by the working vehicle to be displaceable by a hydraulic actuator ( ), and a controller ( ) 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&prime;) and a second control characteristic (Qs&Prime;) 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 ( S) 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.

Working vehicle with a working implement displaceable by a hydraulic actuator

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.

Agricultural tractor

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. The drive transmission system includes a shifter mechanism for transmitting a shift command to the main and auxiliary change speed devices; a first controller operable in response to the shift command to operate one of the first control valves to a drain position which was placed in a supply position prior to transmission of the shift command, and to operate to a supply position a different one of the first control valves corresponding to the shift command; and a second controller operable in response to the shift command to operate one of the second control valves to a drain position which was placed in a supply position, and thereafter to operate one of the second control valves gradually to a supply position.

Drive transmission system for working vehicle

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.

Hydraulic clutch operating apparatus

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. The third stage is for fully engaging the hydraulic clutch.

Growing community of inventors

Sakai, Japan

Akio Inamori