Kubota Corporation

Satoshi Machida

Akio Hattori

Shigekazu Hasegawa

Masao Takagi

Keishiro Nishi

Masashi Osuga

Yoshimi Oota

Kenji Kato

Muneji Okamoto

Minoru Hiraoka

Tetsu Fukui

Yoshiyuki Katayama

Toshiya Fukumoto

Masayuki Nakamura

Hidetaka Yoshioka

Akihisa Okano

Yoshimi Ota

Naoki Okita

In order to provide a speed change transmission system which can be obtained compactly, while obtaining output at steplessly varied speeds over a large speed change range only by carrying out a simple shifting operation, the speed change transmission system has a hydrostatic stepless transmission to which engine drive is inputted. A planetary transmission device (P) has a plurality of planetary transmission mechanisms, for combining output of the stepless transmission and engine drive not undergoing speed change action by the hydrostatic stepless transmission. A plurality of transmission shafts are provided with a plurality of speed range setting clutches switchable for converting the combined driving force from the planetary transmission device (P) to a driving force in a plurality speed ranges, and transmitting it to an output rotary member. The plurality of transmission shafts are juxtaposed and arranged in parallel.

Speed change transmission system

A work vehicle includes an engine, a PTO shaft driven by power from the engine, an operator's seat, an operator's presence sensor for detecting presence/absence of an operator at the operator's seat, and an automatic engine stop unit operable to automatically stop the engine in response to detection of the operator's absence at the operator's seat. The work vehicle includes a utility member for the vehicle selectively movable between a use position and a non-use position, a non-use state detecting sensor for detecting movement of the utility member to the non-use position, and an override unit operable to override the automatic engine stop function of the automatic engine stop unit, the override unit providing an override signal to the automatic engine stop unit in response to detection by the non-use state detecting sensor of the movement of the utility member to the non-use position.

Work vehicle having overridable automatic engine stop circuit

A work vehicle has an engine (), a PTO shaft () driven by power from the engine, an operator's seat (), an operator's presence sensor () for detecting presence/absence of an operator at the operator's seat, and an automatic engine stop unit () operable to automatically stop the engine in response to detection of the operator's absence at the operator's seat. The work vehicle includes a utility member (A) for the vehicle selectively movable between a use position and a non-use position, a non-use state detecting sensor () for detecting movement of the utility member to the non-use position, and an override unit () operable to override the automatic engine stop function of the automatic engine stop unit, the override unit providing an override signal to the automatic engine stop unit in response to detection by the non-use state detecting sensor of the movement of the utility member to the non-use position.

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 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 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.

Speed control structure

A change speed control structure for a hydraulic transmission comprising a rotary valve for controlling a plurality of hydraulic actuators, a shift lever extending through a crooked guide groove, and a relay assembly for transmitting movements of the shift lever to the rotary valve on a reduced scale. The guide groove includes three straight portions extending parallel to one another in series and offset in a transverse direction thereof, each straight portion including a plurality of change speed positions. An adjacent pair of the straight portions are interconnected end to end by a bight portion.

Change speed control structure for hydraulic transmission

A hydraulic construction for a working vehicle comprising a transmission case housing a hydraulic clutch and defining a lateral opening, and hydraulic control device mounted on an inner face of a cover attached to the transmission case to close the opening, the hydraulic control device acting to control oil flows to the hydraulic clutch. The hydraulic control device is hydraulically connectable to oil passage device connected to the hydraulic clutch when the cover is attached to the transmission case.

Transmission casing including a hydraulic clutch

A hydraulic circuit construction for a power shift transmission having logical operation valves mounted on a pressure oil supply passage connecting a hydraulic clutch to a pressure oil source, the logical operation valves being operable to engage and disengage the hydraulic clutch by opening and closing the pressure oil supply passage in response to a switching operation of a change speed device connected upstream of and in series to the hydraulic clutch. The pressure oil supply passage has mounted thereon a pressure control device including a first valve mechanism, a second valve mechanism and an orifice parallel-connected to the pressure oil supply passage, and an accumulator is mounted between the pressure control device and the hydraulic clutch to assure a speedy and smooth operation of the hydraulic clutch.

Hydraulic circuit construction for power shift transmission

A seated-operator type tractor has a vehicle proper (1), equipped rearwardly thereof with a link mechanism (6) and a scraper (9) for ground-leveling. The vehicle (1) is further provided with: a position-controlling mechanism (34) for controlling up-and-down position of the scraper (9); an automatic control mechanism for maintaining the scraper (9) in its left-and-right horizontal posture, by a sensor (50) therefor; a controlling valve (24) for controlling blade-angle adjustment of the scraper (9); and a manual switch (47) disposed near at hand of the seated operator, for shifting over the vehicle (24).

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Sakai, Japan

Satoshi Machida