| 摘要 |
<p>880,894. Valves. BENDIX-WESTING- HOUSE AUTOMOTIVE AIR BRAKE CO. Dec. 4, 1959 [Jan. 30, 1959], No. 41297/59. Class 135. [Also in Group XXXIV] A control valve mechanism 22, for a vehicle braking system, supplies to an outlet port 26 a pressure reduced with respect to pressure at inlet port 20 whenever pressure at port 26 exceeds the pressure at a control port 32 connected to an air suspension spring or springs 36 of the vehicle, and includes a movable element 46 having an area exposed to port 32 equal in size to the difference between second and third areas exposed to ports 20, 26, respectively, and being operatively connected to valve means 62, 64, 66 which connect or disconnect ports 20, 26 depending on whether the force exerted on the third area is greater or less than the combined force on the first and second areas. Valves ports 20, 26, 54 are connected respectively to drivers control valve 10, brake cylinders 30 and atmosphere. Normally with the brakes released, the element 46 is lowered by pressure in cham- .ber 56, exhaust port 54 being closed and valve 60, 64 opened. On braking, should the air pressure delivered from the brake valve 10 to the brake cylinders 30 be greater than the air spring pressure (controlled automatically according to load) then the forces on element 46 cause closure of both valves 60, 64 and 54, 56. The brake cylinder pressure being less than the pressure in chamber 50 by an amount depending on the air spring pressure and hence the load. Should the air spring pressure be greater than the pressure delivered from the brake valve, then element 46 remains in the lower position and full pressure is applied to the rear brakes as if the valve did not exist. On reduction of pressure in chamber 50, element 46 rises to open exhaust valve 54, 66 and release the brakes; the pressure in chambers 50, 52 also equalizes via spring-biased valve 74 should the resultant downward force on element 46 cause valve 54, 66 to close before complete brake release. The front brakes may be applied directly from the brake valve or via a pressure-reducing valve as above.</p> |
