Figure 11-8.-Carrier rollers.
The carrier rollers are mounted on brackets that
extend above the track frame (fig. 11-8). Two of these
rollers are on each side of the dozer. The single flange
on the rollers extends upward between the links of the
track chain and keeps the chain in alignment between
the drive sprocket and the front idler.
The track rollers support the weight of the dozer and
ensure the track chain is in alignment with the truck
frame, as it passes under the rollers (fig. 11-9). Track
rollers, both single and double flanged, are installed
Figure 11-9.Track rollers in position in track frame.
alternately. In the normal arrangement, a double-flanged
roller is positioned directly in front of the rear drive
sprocket, followed by a single-flanged roller. The rollers
alternate forward to the front idler.
FRONT IDLER. The front idler, as shown in
figure 11-9, serves as a guiding support for the track
chain. The idler is spring-loaded and mounted on slides,
or guides, that allow it to move back and forth inside the
track frame, as the dozer passes over uneven ground.
The spring-loading effect causes the idler to maintain
the desired tension regardless of operating conditions.
RECOIL SPRING. The recoil spring is a large
coil spring placed in the track frame in a way that
enables the spring to absorb shock from the front idler.
The spring is compressed before installation and held in
place by stops or spacers. The track adjusting
mechanism, by pressing against the spring stop,
maintains the desired tension on the track assembly by
holding the idler and yoke in the forward position. The
operation of the coil spring depends on the amount of
tension on the truck.
TRACK ADJUSTING MECHANISM. The
adjusting mechanism must be extended enough to
remove slack between the front idler and spring. The
adjustment is made either manually (fig. 11-10) or
hydraulically (fig. 11-11). Older model dozers have
mnaually adjustments; whereas, newer dozers are