| 摘要 |
<p>A valve arrangement positionable between the brake pedal (600) and the brake actuators (700) in an air braking system provides for the automatic response to braking pressures to produce intermittent on/off braking above a predetermined braking threshold. It operates solely from the air braking line (1) pressure controlled by the brake pedal (600) by means of a reciprocating shuttle piston (80,90) that intermittently produces braking pressures within a braking chamber (165). A sliding rod (80) controls by flange (80 min ) exhaust to atmosphere through ports (155) as the shuttle piston reciprocates, when a threshold sensing plunger (135) is urged into position to intercept and urge the shuttle piston toward a main valve (35) passing the braking pressure into the chamber (165). The shuttle piston returns with the same braking pressure in chambers (165 and 170) on opposite ends thereof because of different areas on the opposite ends of the piston. As the braking pressure increases, the threshold plunger (135) shortens the reciprocating stroke of the shuttle piston and increases the on/off frequency of the braking.</p> |
