| 摘要 |
<p>1,253,696. Brakes. KELSEY-HAYES CO. 26 Feb., 1969 [4 March, 1968], No. 10421/69. Headings F2E and F2F. In a vehicle brake system having front and rear braking systems there is an indicating system 34 providing a signal if the pressure in either system is lost and remaining in the signalling condition even when the brakes are released but being reset by actuation of the brakes with restoration of normal pressure. This is achieved by a detent piston 306 which slides in a bore 300 between the rear-brake pressure fed from bore 36 of a proportioning valve 28 at its right-hand end, and pressure from a front-brake metering valve assembly 30 at its left-hand end. If one of these pressures fails, the other pressure drives the piston along the bore 300 and in doing so, deflects a plunger 310 out of groove 308 in the piston to actuate an alarm switch 312. The piston is restored to its central position by virtue of the bushings 316, 332 which add to the effective area of the piston on the side that engages them. When the front brake system fails, leftward movement of the piston, causes 0-ring 328 to open port 400 to a by-pass valve 32 which by-passes the proportioning valve 28 to apply full pressure to the rear brakes. The front and rear brakes are separately fed from a dual master cylinder 10, feeding pressure at entries 16, 20. A single housing 16 contains the alarm unit 34, a rear-pressure proportioning valve 28 which cuts off the rear-braking force on heavy braking, and a front-pressure metering valve assembly 30 which accommodates the differential spring-rate between the front and rear shoes.</p> |
