Kabushiki Kaisha Toyota Jidoshokki

Nishina Industrial Co., Ltd.

Other

Yasuhiro Maeda

Tetsuya Goto

Keinosuke Ichikawa

Kazuo Kobayashi

Shigeto Nakajima

Takeharu Matsuzaki

Hiroyuki Horiuchi

A main spool is located in a bypass line connecting a pump line to a return line. The main spool moves in an axial direction according to the pressure in a spring chamber and the pressure in a pilot chamber, thereby adjusting the opening degree of the bypass line. A pilot switching valve is located in a pressure control passage connecting the spring chamber to the return line. The pilot switching valve controls the flow rate of hydraulic oil that flows from the spring chamber to the return line in accordance with the load pressure of a hydraulic actuator, thereby adjusting the pressure of hydraulic oil in the spring chamber. As a result, the range of the flow rate of hydraulic oil supplied to the hydraulic actuator, which range precludes the influence of the load pressure of the hydraulic actuator, is expanded.

Hydraulic control device and industrial vehicle with hydraulic control device

A hydraulic parking brake device is selectively switched between a braking state and a non-braking state. A braking force decreases as a pressure in the control oil chamber increases and increases as the pressure in the control oil chamber decreases. The device includes a discharged oil restrictor located in a discharge passage and an accumulator connected to the control oil chamber. The accumulator is capable of releasing hydraulic oil to the control oil chamber when the braking force is greater than that at the time when the parking brake device is switched from the non-braking state to the braking state and the braking force can further be increased during the braking state of the parking brake device. Thus, the parking brake device can gradually brake the vehicle from the running state.

Parking brake device of vehicle

A main passage communicated to a pump passage or a tank passage by switching operation of a spool valve is provided with an operation check valve permitting communication only to a cylinder. A puppet in the operation check valve is provided with an orifice communicating the main passage with a pilot chamber of the operation check valve. The pilot chamber is communicated with the main passage through an electromagnetic on/off valve. Further, the pilot chamber in the operation check valve is communicated through a bypass passage with the main passage, and the bypass passage is provided with a manually operable opening/closing valve.

Cylinder control device

Growing community of inventors

Nagano-ken, Japan

Yasuhiro Maeda