| 摘要 |
The control device has a key valve (7) with a differential piston (13) and a scanning arm (18) that can be moved by it. The differential piston (13) is charged on its smaller surface (12) by a first brake pressure emitted by the brake control valve (2), and on its larger surface (14) by a reduced second brake pressure derived from the first brake pressure by means of a reduction valve (23, 26), which can be opened by the differential piston (13) only by a motion of a scanning arm (18), corresponding to a vehicle when unloaded, by means of a stop (24). The second brake pressure charges a switching piston whcih shifts the closing point of the reduction valve (23, 26) in the direction of motion of the differential piston (13) for lifting the scanning arm, and switches a shuttle valve (10, 35, 38) which charges a brake cylinder (44) either with the first or the second brake pressure. The volume of the spaces conducting the second brake pressure is increased by an air container (42). The key valve (7) has a very simple construction and, after an initial scanning touch, again lifts the scanning arm (18) during braking of an unloaded vehicle from its abutment (21'), which prevents unnecessary wear and tear. |
