Copyright Goodheart-Willcox Co., Inc. Heavy Equipment Power Trains and Systems 588 Note Compact rubber track loaders are sometimes incor- rectly called skid steers. Compact rubber track loaders have a hydraulic motor and a single-reduction final drive, but they do not use chain drives and have only one drive sprocket on each side of the loader. Elevated Drives in Articulated Rubber Track Tractors Some articulated rubber track tractors have a unique drive mechanism consisting of two spur gears that ele- vate power up to the drive sprocket instead of lowering it like a drop axle. A Case IH STX Steiger® Quadtrac under- carriage is shown in Figure 17-26. The axle’s differen- tial delivers power to the bottom spur gear. The top spur gear drives a sun gear inside a planetary gear set that multiplies torque and delivers power to the track drive sprocket. Checking Final Drive Oil Level Many final drives in heavy equipment have a stand-alone fluid housing. The final drive reservoir must be checked separately from other components, such as the transmis- sion and differential. Examples of machines with stand- alone final drives are dozers with elevated sprocket undercarriages, and harvesters. On machines with inte- grated outboard final drives, such as large wheel loaders and haul trucks, each final drive fluid level should be Goodheart-Willcox Publisher Figure 17-26. This Case IH STX Steiger Quadtrac undercarriage uses two external-toothed spur gears to elevate the power to the track’s drive sprocket. A B Spur gears used to elevate track drive sprocket Input from differential side gear Figure 17-25. A single-reduction planetary final drive is used in a Case rubber track loader. A—The sun gear is driven by the hydraulic motor’s output shaft. The planetary carrier is held and the ring gear propels the sprocket housing. B—The backside of the final drive housing. The parking brake and hydraulic cam lobe motor are missing. Goodheart-Willcox Publisher Figure 17-24. These two final drive assemblies were rebuilt to be reinstalled in a Caterpillar 259B rubber track loader. Goodheart-Willcox Publisher Goodheart-Willcox Publisher