Kubota Corporation

Muneji Okamoto

Satoshi Machida

Atsushi Shinkai

Keishiro Nishi

Yasunobu Nakatani

Eiji Nishi

Shigekazu Hasegawa

Akio Hattori

Masayuki Nakamura

Yoichi Sugihara

Yoshimi Ota

A load control structure for a work vehicle comprises: a device for detecting operating position of a manually operated speed change operating element; an engine load detection device for detecting load on an engine of the work vehicle; a swash plate position detecting device for detecting an operating position of a swash plate of a variable displacement pump of a hydrostatic continuously variable speed change device; a pump operating device for steplessly operating the swash plate of the variable displacement pump; a motor operating device for operating a swash plate of a variable displacement motor of the hydrostatic continuously variable speed change device between at least two speed change positions including a higher speed position and a lower speed position; a control device for controlling the operations of the pump operating device and the motor operating device. The control device has a automatic pump swash plate control device for controlling the operation of the pump operating device, based on detected information from the load detection device and detected information from the swash plate position detecting device, such that the greater an engine load is, greater is the extent to which the swash plate of the variable displacement pump is operated to a low speed side; and a motor swash plate control device for controlling the motor operating device so as to change the position of the swash plate of the variable displacement motor between the at least two speed change positions.

Load control structure for work vehicle

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 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

Growing community of inventors

Matsubara, Japan

Muneji Okamoto