Copyright Goodheart-Willcox Co., Inc. Heavy Equipment Power Trains and Systems 580 Dozer Single-Reduction Drop Axle Bull-and-Pinion Final Drives Single-reduction bull-and-pinion drives are found in low-track dozers and track load- ers, such as late model Caterpillar low-track dozers (D6K and a D7E), John Deere dozers, Leibherr dozers, and Komatsu dozers. When bull-and-pinion gears are used in dozers and track loaders, the gear set is a drop axle design. The final drive drops the power coming from the differential to a lower axis on the machine, in addition to multiplying torque. See Figure 17-11. Elevated Sprocket Track-Type Tractor Single-Reduction Final Drives Midsized Caterpillar elevated sprocket track-type tractors (D4H D5-D6 series H, M, N, R and D6T) use single-reduction final drives. Like the inboard single-reduction planetary final drives in agricultural tractors, the axle shaft delivers power to the sun gear. The ring gear is held. The reduction planetary carrier propels the drive sprocket. A simplified image of a Caterpillar D6R single-reduction final drive is shown in Figure 17-12. Elevated Sprocket Track-Type Tractor Double-Reduction Final Drives As explained in Chapter 9, Planetary Gear Set Theory, large Caterpillar elevated sprocket track-type tractors (D7H, D7R D8-D9 series H, L, N, R, T D10-D11 series N, R, and T) use double-reduction final drives. Like the outboard double-reduction planetary final drives in mining loaders and trucks, the axle shaft delivers power into the first reduction sun gear. Both ring gears are held. The first reduction planetary carrier drives the second reduction sun gear. The second reduction planetary carrier propels the drive sprocket. See Figure 17-13. Case New Holland Figure 17-11. The Case 1150B track loader used bull-and-pinion final drives. The left side final drive is shown here. Final drive Forward clutch Low speed track clutch Track brake Input from converter High speed track clutch High range clutch Ring gear Pinions Sun gear Forward and reverse drive gear Low range clutch Planetary carrier assembly Reverse clutch