Section 137 (Drive Shafts -- Excursion & F250-F550 Super Duty): Description
The source of the drivetrain's power is generated by the engine and delivered to the transmission. The driveline transfers the engine torque through the drive shaft to the axle. On 2WD vehicles, power is transmitted through the transmission to the drive shaft and then to the rear axle. On 4WD vehicles, power is transmitted through the transmission and the transfer case. The transfer case directs the power to the rear drive shaft and then to the rear axle. When engaged, it also transmits power through the front drive shaft to the front axle pinion flange.
The following types of drive shafts are available on Excursion and F250-F550 models:
- One-piece rear drive shaft with 2 "U" joints and a front slip yoke.
- Two-piece rear drive shaft with 3 "U" joints, a front coupling shaft, a center bearing and a rear slip yoke.
- Three-piece rear drive shaft with 4 "U" Joints, 2 center bearings and a rear slip yoke.
- One-piece front drive shaft with 2 "U"joints and a slip yoke.
For exploded view of drive shafts, see Fig 1-Fig 9 . The rear drive shaft is connected to the output shaft of the transmission or transfer case pinion flange and to the rear axle pinion flange. The front drive shaft is connected to the transfer case pinion flange and to the front axle pinion flange. Universal joints are used at both ends of the drive shaft to allow for angular motions. Slip yokes are used to allow for any changes to the length of the drive shaft. The engine torque enters the axle through the drive pinion, which rotates the ring gear.
Universal joints are a lubed-for-life design, equipped with nylon thrust washers, located at the base of each "U" joint bearing cup, which control end play and positions the needle bearings and improves grease movement. Two types of universal joints are used, a Dana design and a Ford design.