| 摘要 |
A motor drives a pump to provide fluid under pressure in a closed hydraulic circuit through a pilot valve to a change speed clutch valve and a directional valve of a multi-speed transmission for an electrically powered vehicle, such as a mine haulage vehicle. The multi-speed transmission is connected by an output shaft to the driven wheels of the vehicle. A braking force is applied to the driven wheels by a hydraulically operated service brake to effect routine stopping of the vehicle. Under emergency conditions an emergency brake applies a braking force to the driven wheels by operation of a panic bar positioned in the operator's compartment. A brake valve connected to the panic bar maintains a preselected fluid pressure in the hydraulic circuit of the emergency brake to retain the brake in a released position. The hydraulic circuit is interlocked through the pilot valve to the transmission clutch and direction valves. Depressing the panic bar actuates the brake valve to engage the emergency brake and simultaneously actuate the pilot valve to interrupt fluid flow to the respective valves of the transmission. Transmission of power to the driven wheels is terminated, and the vehicle is stopped. Actuation of the brake valve also opens the main contactors of the electrical controller that supplies electrical power to the traction motors to stop the motors. A safety brake valve is connected to the hydraulic circuit in series with the brake valve and is operable when the traction motors are stopped routinely or by application of the emergency brake to prevent restarting the traction motors and moving the vehicle until the emergency brake is manually disengaged. |
