Rear Axle Description Single-Speed Axles
The single speed rear axles are composed of the following two main components:
| • | The rear axle housing |
| • | The differential carrier assembly |
The banjo-type rear axle housing carries the weight of the vehicle. The rear axle housing provides a machined spindle surface for the rear wheel bearings. The rear wheel hubs rotate on the rear wheel bearings, allowing the rear axle shafts to float within the rear axle housing.
The differential carrier assembly performs the following two functions:
| • | Changes the driving force 90 degrees from the propeller shaft |
| • | Allows the rear wheels to turn at different speeds |
The differential carrier assembly consists of the following components:
| • | The differential drive pinion gear |
| • | The input yoke (drive pinion) |
| • | The ring gear |
| • | The differential carrier |
| • | The differential case |
| • | The side gears |
| • | The differential gears |
| • | All related bearings |
The complete carrier assembly may be removed from the vehicle without removing the rear axle assembly.
Rear Axle Description Two-Speed Axles
The two speed rear axle contains two different gear ratios or ranges. The two speed rear axles operate in the same way as the single speed rear axles. The driver selects the range using a control switch on the instrument panel.
A two speed rear axle shift actuator mounted on the rear carrier engages a shift fork. The shift fork selects the range chosen by the driver.
The two speed rear axle shift actuator is electric powered.
The shift fork will perform one of the following functions:
| • | Slide a collar onto the sun gear of a planetary gear set. |
| • | Slide the entire sun gear assembly in or out of the gear set |
Two possible gear ratios may originate from the same gear axle.
Rear Axle Description Tandem Axles
A tandem rear axle increases the amount of payload a vehicle may carry. The tandem rear axle increases the traction factor when both rear axles are locked together. A tandem rear axle consists of the following components:
| • | A rear axle front unit |
| • | A rear axle rear unit |
The rear axle front unit has a power divider with an inter-axle differential. The power divider sends power to the individual axle differentials. The power divider allows inter-axle differential action between the two rear axles.
The tandem rear axles have the ability to be locked together, providing power to both the rear axles without the inter-axle differential action.
The inter rear axle differential air shift chamber has the following characteristics:
| • | Is part of the power divider |
| • | Is mounted to the rear axle front unit differential carrier |
The inter rear axle differential air shift chamber controls the tandem rear axles.
The driver controls the electric or air operated inter-axle differential lock system using one of the following items:
| • | An inter-axle differential lock switch |
| • | An inter-axle differential lock control valve |
All the rear axles have a removable differential carrier. The tandem rear axles operate in the same way as the single speed rear axles.
Rear Axle Description Overhaul - Dana/Spicer
For complete rear axle identification information, refer to Rear Axle Identification in General Information.
For unit repair information of the Dana/Spicer® differential carrier assembly, contact the Spicer® Support Line at 1-800-666-8688.
Rear Axle Description Overhaul - Eaton
For complete rear axle identification information, refer to Rear Axle Identification in General Information.
For unit repair information of the Eaton® differential carrier assembly or the power divider, contact Eaton® Roadranger® Service at 1-800-826-HELP (1-800-826-4357).
