6
CF65/75/85 series
Description of components
OPERATION OF BRAKE COMPONENTS
2-31
PARKING BRAKE VALVE WITH
TRAILER CONNECTION WITHOUT
TEST POSITION
Note:
Application depends on the country of use.
Purpose
The parking brake valve enables simultaneous,
controlled operation of both the parking brake
system of the truck and the trailer vehicle
brakes.
Operation
The parking brake valve has 2 positions:
1.
driving
2.
parking
R600095
2
7
3
4
5
6
1
3
2
a
Driving
With the handle in the driving position, there is a
through connection in the valve for the supply
pressure (connection point 1) to the connection
points for spring brake cylinders 21 and trailer
vehicle 22. The vent is now closed.
The output pressure at connection points 21 and
22 is now approx. 8.5 bar (see graph).
Emergency braking
If the handle is pulled a little backwards against
the spring pressure, tappet 3 will move
downwards via eccentric 2. The chamber at
connection point 21 can now be vented and as a
result the pressure at connection point 21 will
drop. Via the bore in valve 10 the pressure at
connection point 22 will also drop. Spring 4
forces piston 5 down until valve 6 comes into
contact with the seal collar of tappet 3. A state
of equilibrium has now been achieved.
When the handle is moved against stop 7, the
vent will remain open, so that the spring brakes
and the trailer vehicle brakes will be applied to
their maximum (max. emergency-brake
position).
4
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