| 摘要 |
PURPOSE:To prevent an excessively high pressure in a wheel cylinder of a brake system caused by decrease in a shoe clearance of a brake drum by providing a circuit which connects an oil pressure source and the wheel cylinder to each other and integrating a pressure control valve in the circuit. CONSTITUTION:A hydraulic brake circuit is made up by connecting a wheel cylinder 2b of a drum brake device 2 by a piping 3 to a master cylinder 1 to which an accumulator ACC of an oil pressure source PU and a tank T are connected. Said accumulator ACC and a wheel cylinder 2b are connected by a circuit 4, in which a pressure control valve 5 is integrated. When a brake drum 2a is thermally expanded due to repetition of the braking effect to decrease a shoe clearance 1' a pedal 12 is operated, as similar before the decreasing, to increase an oil pressure in the wheel cylinder 2b. A valve 5, at this time, connects the cylinder 2b and the accumulator ACC to each other, preventing an excessively high pressure from acting in the cylinder 2b. |
