Operator`s manual

OPERATION
321
Parking Brake/Trailer Supply Valves
Trucks/Tractors may have two air control valves on the instrument
panel:
앫 Trailer Supply (red octagonal knob)
앫 System Park (yellow diamond knob)
The System Park valve knob (yellow) should be pushed in first, after
sufficient air pressure is built up (apply foot brake to prevent vehicle
from rolling). The Trailer Air Supply valve knob may then be pushed in.
The Trailer Air Supply valve knob and System Park valve knob will
automatically pop out if the system pressure (both front and rear
circuits) drops to 170 to 240 kPa (25 to 35 psi). The tractor protection
valve will then close, the tractor spring brakes will apply and the trailer
emergency system will be activated.
vn-vhd.bk Page 321 Tuesday, July 1, 2008 9:44 AM