GILLIG LOW FLOOR, Руководство по обслуживанию

Страница: 169 / 506

69
Suspension
Caster
Caster is the inclination of the kingpins toward the front or rear of the vehicle (see Figure 5-9). Caster is
described as “negative” when the kingpin is angled with its top closer than the bottom to the front of the
vehicle. A vehicle is said to have “positive” caster when the kingpin is angled with its bottom closer than
the top to the front of the vehicle. The coach axle beams have a +3 degree caster angle machined into
the beam.
Caster variations may be caused by a bent axle, worn
torque rod end bushings, or sagging of torque rod tower
assemblies. Precision gauges must be used to determine
caster when the axle is on the coach.
Caster is adjusted by changing the length of the torque
rods. Loosen the upper rod end clamps and rotate the tube,
using a pipe wrench if necessary, to set the caster to 3
degrees. When the correct setting is obtained, tighten the
clamp nuts to the specified torque. When tightening the
clamp nuts you must:
1. Tighten the torque rod clamps at the nut end only.
2. Install the clamp within 1/4" from the end of the
torque rod tube.
3. Place the mouth of the clamp over a slot in the rod.
Always adjust the torque rods as a pair, either upper or lower, and in
the same amount for each torque rod . If you are unable to adjust both
sides equally to 3 degrees, the axle is bent, torque rod end bushings are
worn, or rod tower assemblies are sagging.
Caster adjustment should be made using the upper pair of torque rods. If sufficient travel is not avail -
able in the upper pair, the lower pair and upper pair must be adjusted together to obtain the specified
caster setting. The lower pair of torque rods are adjusted by loosening the two bolts in the center clamp,
spreading the clamp with a chisel, and turning the clamp itself to obtain adjustment to the length of the
torque rod. When the correct setting is reached, tighten the clamp nuts to the specified torque.
When the axle is removed from the coach, the caster can be checked on a bench. Place two uniform
blocks on a level surface. Turn the axle upside down and rest the suspension support pads on the blocks.
Use a shop protractor to determine the caster angle. If this angle is ± .5 degrees off from 3 degrees, the
axle beam is twisted and must be replaced.
Figure 5-9, Caster
A
Positive Caster
Forward