| 摘要 |
<p>A full power closed centre hydraulic braking system for vehicle trailer combinations having service (20) and emergency (22) lines, with associated return lines (24), supplying hydraulic fluid from the vehicle through a relay valve (26) on the trailer, to a trailer-mounted accumulator. When the service line (20) is activated by a control on the vehicle or tractor, the relay valve (26) delivers fluid from the accumulator (40) to the trailer service brakes (12). There are spring brake actuators (10) which are connected to the accumulator (40) via a second relay valve (34) triggered by pressure on the emergency line (22), preferably via a park valve (38) which is normally open except when set to a <<park>> position. This second relay valve (34) may be a dual relay valve also triggered by a manoeuvring valve (36) to permit temporary re-energization of the spring brake actuators (10) when the towing vehicle and trailer are uncoupled.</p> |
