PRONAR T680, Operator'S Manual, Page: 58 / 147

Pronar T680 SECTION 2
3.12
in case of an inadvertent disconnection of the conduit between the trailer and the tractor, the
control valve will automatically activate the trailer's brakes. Valve used in the system is
equipped with a circuit causing the brakes to be applied when trailer is disconnected from the
tractor, compare with figure (3.8). When compressed air conduit is connected to the tractor,
the device automatically applying the brakes changes its position to allow normal brake
operation.
FIGURE 3.8 Control valve and braking force regulator
(1) control valve, (2) braking force regulator, (3) trailer parking brake release button, (4) work
selection regulator lever, (A) position "NO LOAD”, (B) position "HALF LOAD”, (C) position
"FULL LOAD”
Three-step brake force regulator (2)- figure (3.8), adjusts braking force depending on setting.
Switching to a suitable working mode is done manually by the machine operator using the
lever (4) prior to moving off. Three working positions are available: A - "no load”, B - "half
load” and C - "full load”.
Valve used in the system is equipped with the button causing the brakes to be applied when
trailer is disconnected from the tractor - see figure (3.9). Brakes are applied as a result of
reduction of pressure in the trailer's braking system.The brakes can operate normally after