| 摘要 |
PURPOSE:To ensure the lockup of operating state of a sevice brake, by putting a solenoid shutoff valve for locking up the operating state of the service brake, into or out of operation only when the complete action or release of a parking brake is effected. CONSTITUTION:When a parking brake P is in its initial operating state, a switch 11 is closed by a cam 18 but other switches 13b, 14b are not closed, so that the solenoid 7a of a solenoid shutoff valve 7 for a serivce brake 4 is not energized. When the parking brake P is in its final operating state, a switch 12 is closed by a cam 19 so that a coil 13a is energized to close a contact 13b and the solenoid 7a is energized to lock up the serivce brake 4. At that time, a coil 14a is energized to close a contact 14b. When the release of the parking brake P is started, the switches 12, 13b are opened but the solonoid 7a remains energized because the contact 14b is ketp self-closed. When the parking brake P is completely released, the switch 11 is opened to deenergize the solenoid 7a. |
