Kubota Corporation

Akio Hattori

Satoshi Machida

Kentaro Nakamura

Toshihiko Takemura

Takashi Yoshii

Tetsu Fukui

Toshiya Fukumoto

Masao Takagi

Masayuki Nakamura

Hidetaka Yoshioka

Muneji Okamoto

Akihisa Okano

A power take-off (PTO) control system for a work vehicle equipped with an implement, comprising a hydraulic multi-plate PTO clutch () whereby power from the work vehicle is interruptibly transmitted to the implement; a control valve () for adjusting an actuating pressure of the PTO clutch; a manually operable clutch operation tool () for sending an operation instruction to the control unit; and a control unit () for switching the PTO clutch from a disengaged state to an engaged state by controlling the control valve on the basis of the target control characteristics in response to the operation instruction of the clutch operation tool (). The target control characteristics are generated and set on the basis of the operational behavior of the clutch operation tool ().

Power take off control system

A hydraulic change speed system for a working vehicle includes a gear type change speed device shiftable by an actuator, a hydraulic clutch connected to a power transmission line including the gear type change speed device, a valve unit for switching operative states of the hydraulic clutch, a controller for controlling the valve unit, and a timer for measuring a shifting time of the gear type change speed device. The valve unit is interlocked to the actuator to be controllable to pressurize the hydraulic clutch rapidly for a predetermined time from a start of engagement of the hydraulic clutch and to pressurize the hydraulic clutch gradually the predetermined time. The controller sets the predetermined time based on the shifting time measured.

Hydraulic change speed system for a working vehicle

In a working vehicle such as an agricultural tractor, a front wheel change speed device for transmitting drive to front wheels includes an equal speed clutch for driving the front wheels substantially at the same speed as rear wheels, and an accelerating clutch for driving the front wheels substantially at a higher speed than the rear wheels. In the front wheel change speed device of this invention, the equal speed clutch and accelerating clutch are arranged coaxially. The front wheel change speed device further includes a shift member axially shiftable for selectively operating the equal speed clutch and accelerating clutch, and an actuator for axially shifting the shift member.

Working vehicle

A tractor has hydraulic cylinders arranged reawardly of a transmission case for swinging lift arms. A plurality of control valves for controlling the hydraulic cylinders are arranged on a lid plate of the transmission case. Oil lines are disposed in the lid plate for intercommunicating the control valves.

Tractor

A friction clutch mounted in a transmission case (25) or the like and connected between a drive shaft (14) for receiving engine power and a driven shaft (15) for receiving power from the drive shaft and transmitting the power to a power takeoff shaft (11). The friction clutch includes a first sleeve (17) connected to the drive shaft, a second sleeve (16) connected to the driven shaft, friction disks (18, 19) disposed between the first sleeve and the second sleeve, the friction disks being switchable between a clutch engaging state to enable power transmission between the first sleeve and the second sleeve, and a clutch disengaging state to disable the power transmission, and a clutch piston (20) movable between a first position to place the friction disks in the clutch engaging state, and a second position to place the friction disks in the clutch disengaging state. The friction clutch further includes a brake mechanism (B) for braking rotation of the driven shaft when the friction disks are in the clutch disengaging state. The brake mechanism includes a first braking member (26) operatively connected to the clutch piston, and a second braking member (24) for contacting the first braking member when the clutch piston is moved to the second position. The second braking member is rotatable through a predetermined range with the first braking member.

Friction clutch having a brake mechanism

A hydraulically operable transmission comprises a hydraulic clutch, a change speed control valve, change speed actuators controllable by the control valve, a pilot oil line for varying pressure states in response to operation of the actuators, an oil supply line extending to the hydraulic clutch, a clutch control valve operable with a pilot pressure applied from the pilot oil line to close the oil supply line, and a pressure buildup device mounted on the oil supply line. The pressure buildup device includes an oil chamber for producing predetermined pressure increase characteristics with a pilot pressure applied from the oil supply line and a spring load, a drain line extending from the oil chamber, and a drain control valve mounted on the drain line for opening and closing the drain line in response to the pilot pressure applied from the pilot oil line.

Hydraulically controllable transmission

A propelling drive control apparatus for a working vehicle comprising hydraulically operable friction clutches, a first clutch control valve for selecting between the friction clutches, and a second clutch control valve connected in series to the first clutch control valve. The second clutch control valve is manually switchable to a declutching position for disengaging the friction clutches, a first clutch engaging position for engaging one of the friction clutches, and a second clutch engaging position intermediate between the declutching position the first clutch engaging position. In this second clutch engaging position one of the friction clutches is operable under a lower hydraulic pressure than in the first clutch engaging position.

Propelling drive control apparatus for working vehicle

A vehicle change-speed control construction for selectively engaging and disengaging a hydraulic clutch of a propelling transmission system according to a change-speed operation. Through maximum simplification and rationalization, the construction has a hydraulic control system comprised of minimized number of components consisting essentially of one pilot pressure controlled selector valve and a plurality of check valves operable in response to a change-speed operation. The improved construction is extremely simple and economical, yet achieves higher operational efficiency without transmission delay.

Change-speed control construction

A speed control structure for a working vehicle comprises a hydraulic clutch, a main change speed device and an auxiliary change speed device mounted in a transmission case. A hydraulic control system includes hydraulic actuators for operating the change speed devices, a speed control valve for controlling the actuators, a pilot operated switch valve operatively connected to the actuators for disengaging the clutch at start of a change speed operation by the actuators, and engaging the clutch upon completion of the change speed operation, and a pilot control valve for controlling a pilot pressure for the switch valve in response to the operation of the actuators. The transmission case defines a lateral opening closed by a lid. The lid carries the actuators mounted on an inside face thereof, the switch valve and the speed control valve mounted on an outside face thereof, and the pilot control valve mounted in an interior thereof.

Growing community of inventors

Osaka, Japan

Akio Hattori