PRONAR T680, Operator'S Manual, Page: 113 / 147

SECTION 5 Pronar T680
5.15
Make a line (A) on the brake cylinder piston (1) to indicate the position of the
maximum withdrawal of the brake cylinder piston rod when the trailer's brakes
are released.
Press the tractor brake pedal and mark the position of the maximum extension
of the brake cylinder piston rod with a line (B).
Measure the distance between lines (A) and (B). If the brake cylinder rod
stroke is outside the proper operating range, adjust the expander arm.
Dismantle brake cylinder fork pin.
Remember or mark the original position of pin (6) of brake cylinder fork (5) in
expander arm opening (3) – figure (5.6).
Check if the brake cylinder piston rod moves freely and within the whole
nominal range.
Check if the brake cylinder vent holes are not blocked with impurities and that
there is no water or ice inside the brake cylinder. Check if the brake cylinder is
correctly installed.
Clean the brake cylinder. If necessary, defrost the brake cylinder and drain
water through the unblocked vent holes. Replace damaged brake cylinder with
a new one. When installing the brake cylinder, maintain its original position
with regard to bracket (7).
Rotate adjustment bolt (4) to align the marked expander arm opening with the
brake cylinder fork opening.
During adjustment, membrane (2) must rest on the rear wall of the
brake cylinder – compare figure (5.6).
Install the brake cylinder fork pin and washers and secure the pin with cotter
pins.
Rotate adjustment bolt (4) to the right until one or two clicking sounds are
heard in the expander arm regulating mechanism.
Repeat adjustment activities for the other brake cylinder on the same axle.
Engage the brake.