PRONAR PT512, Operator'S Manual

Page: 108 / 139

Pronar PT512 CHAPTER 5
5.12
Adjustment should be conducted separately for each wheel. Expander arm (1) should be
moved by one notch in the selected direction. If the extent of cylinder action is still incorrect,
move the lever again. After proper brake adjustment, at full braking the axle shaft expander
should create an angle of 90
0
with the cylinder piston, and the stroke should be equal to
approximately half the length of the total stroke of the piston. When the brake is released,
expander arms may not be supported on any structural elements, because too small
withdrawal of a piston may cause abrasion of brake shoes in drum and result in overheating
the trailer brakes. Expander arms must be positioned in parallel with regard to each other at
full braking. If they are not, adjust the position of the lever which has the longer stroke.
TABLE 5.2 POSITION OF PIN IN EXPANDER ARMS
TYPE OF BRAKING SYSTEM
PIN POSITION –
FRONT AXLE [mm] (C)
PIN POSITION – REAR
AXLE [mm] (D)
Twin-line system
Twin-line system ALB
Hydraulic system
Single-line system
150
150
150
150
200
200
200
200
5.2.8 REPLACEMENT OF PARKING BRAKE CABLE AND ADJUSTMENT OF
CABLE TENSION
Proper operation of the parking brake depends on efficiency of drive axle brakes and proper
tension of brake cables.
Replacement of parking brake cable
Hitch the trailer to a tractor. Park the trailer and a tractor on level surface.
Insert the chocks under the trailer's wheel.
Unscrew maximally the bolt of brake crank mechanism (1).
Remove shackles and pins of guiding rollers (4).
Unsecure and remove pin of crank mechanism (1).
Loosen nuts of cable clamps (2).
Dismount the cable (3).