Copyright Goodheart-Willcox Co., Inc. Heavy Equipment Power Trains and Systems 578 planetary carrier sends power to the second stage sun gear. The second stage planetary carrier is attached to the spindle and is held stationary, which forces the sec- ond stage ring gear to rotate in the opposite direction of the differential’s side gear. See Figure 17-10. Pro Tip The axle manufacturer can control the direction of dif- ferential rotation by the placement of the ring gear in relation to the pinion gear—for example, placing the ring gear on the right or left side of the pinion gear. The direction of differential rotation is controlled so the second stage planetary can force the power to rotate back in the correct direction. Nonintegrated Final Drives Unlike traditional inboard or outboard final drives, nonintegrated final drives are not part of the front or rear axle housing. Examples are: • Dozers. • Single-reduction drop axle bull-and-pinion final drives. • Single-reduction planetary final drives. • Double-reduction planetary final drives. • Cotton pickers and combines. • Single-reduction bull-and-pinion final drives. A B C Fixed spindle Sun gear Planetary carrier Stationary ring gear Drive hub Axle shaft Goodheart-Willcox Publisher Figure 17-7. This front axle was removed from a Caterpillar 988F wheel loader. The left side outboard final drive is still attached to the axle. The left-side final drive housing has a barrel-shaped design. Figure 17-8. Articulated dump trucks and mining wheel loaders can use outboard single-reduction planetary final drives. A—A diagram of an outboard single-reduction planetary final drive with a trumpet-shaped design. B—The final drives are attached to the axle housing. C—Outboard single-reduction final drives that were removed from the front axle of a Caterpillar 992G mining wheel loader to be salvaged for use in another loader. Goodheart-Willcox Publisher Goodheart-Willcox Publisher Goodheart-Willcox Publisher