Figure 11-8.-Carrier rollers.The carrier rollers are mounted on brackets thatextend above the track frame (fig. 11-8). Two of theserollers are on each side of the dozer. The single flangeon the rollers extends upward between the links of thetrack chain and keeps the chain in alignment betweenthe drive sprocket and the front idler.The track rollers support the weight of the dozer andensure the track chain is in alignment with the truckframe, as it passes under the rollers (fig. 11-9). Trackrollers, both single and double flanged, are installedFigure 11-9.—Track rollers in position in track frame.alternately. In the normal arrangement, a double-flangedroller is positioned directly in front of the rear drivesprocket, followed by a single-flanged roller. The rollersalternate forward to the front idler.FRONT IDLER.— The front idler, as shown infigure 11-9, serves as a guiding support for the trackchain. The idler is spring-loaded and mounted on slides,or guides, that allow it to move back and forth inside thetrack frame, as the dozer passes over uneven ground.The spring-loading effect causes the idler to maintainthe desired tension regardless of operating conditions.RECOIL SPRING.— The recoil spring is a largecoil spring placed in the track frame in a way thatenables the spring to absorb shock from the front idler.The spring is compressed before installation and held inplace by stops or spacers. The track adjustingmechanism, by pressing against the spring stop,maintains the desired tension on the track assembly byholding the idler and yoke in the forward position. Theoperation of the coil spring depends on the amount oftension on the truck.TRACK ADJUSTING MECHANISM.— Theadjusting mechanism must be extended enough toremove slack between the front idler and spring. Theadjustment is made either manually (fig. 11-10) orhydraulically (fig. 11-11). Older model dozers havemnaually adjustments; whereas, newer dozers are11-4
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