Assertion: relay's output | /r/HasProperty | directed through the tractor-protection valve
Facets:
value: in order to control the trailer service brakes
type: PURPOSE
Source sentences:
text: In order to control the trailer service brakes, the merged outputs (i.e., merged via 2 two-way check valves connected in-series to give three inputs) of the foot-valve and trailer-hand-valve (if applicable) are directed through the tractor-protection valve, and onward towards the trailer relay valve via the blue service line.