Hydraulic brake system for an off-road vehicle

摘要

A brake system for off-road vehicles of the type including an operator seat, a brake pedal and a hydraulic brake responsive to operator actuation on the brake pedal. The brake system includes a tank for hydraulic fluid, an electric pump hydraulically connected to the tank, a pressure modulating valve actuated by the brake pedal and a flow control valve for controlling the flow of pressurized hydraulic fluid between the pump, pressure modulating valve and brake. During normal braking operation, a switch responsive to operator actuation of the brake pedal causes to provide pressurized hydraulic fluid to the brake through the flow control valve. The return flow of pressurized fluid to the tank is modulated by the pressure modulating valve in response to operator actuation of the brake pedal to control the braking pressure. The flow control valve is responsive to the presence of an operator in the operator compartment, and is coupled to a switch. In the event an unoccupied seat condition is sensed, the switch actuates the pump, and the flow control valve is switched to a flow path which routes all the pressurized fluid to the brake. The brake is thereby automatically actuated when an unoccupied seat condition is sensed. The pressure modulating valve also includes a secondary fail-safe chamber which is actuated by the brake pedal to supply hydraulic fluid to the brake during a fail-safe mode when the pump is not operating.