64
TRACTOR OPERATION
E230 E231
HYDRAULIC TRAILER BRAKES
The control of hydraulic trailer (semi-trailer) brake and the tractor brake is performed
so that their braking effect is synchronized. The oil pressure is created by the oil,
which is drawn from the gear-type disengaging hydraulic pump (1). The brake valve
(2) is installed behind the pump into the circuit.
The brake fluid pressure from master brake cylinders controls the trailer brake valve
in dependence on the force acting on the brake pedal. Pressure in the brake coupling
(3) must be 12 - 15 MPa at maximum depression of the brake pedal. The trailer brake
valve prefers the brake system function to the hydraulic system function. When
bleeding the tractor brakes, do not forget to bleed also the brake valve. In case that
during depression of service brake pedals shocks occur in the piping of the hydraulic
circuit, it is necessary to de-aerate the hose (4) leading from the brake valve (2) to
the quick coupling (3).
Brake pedals must be connected and secured with latch when driving the
tractor with attached trailer or semi-trailer!
When braking with one brake pedal, the hydraulic trailer brakes are not func-
tioning.
CONNECTING AND DISCONNECTING
THE TRAILER HYDRAULIC BRAKE
QUICK COUPLINGS
When connecting and discon-
necting the quick couplings, pay
particular attention to the residual
oil, which remains in a socket or
plug of the quick coupling.
For environmental protection
reasons, it is necessary to wipe
the residual oil after each dis-
connection of quick coupling
using a piece of cloth.
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