Figure 8-45 - "Broken back"- type driveshaft, angles A and B are equal.
4.1.1 joint Working Angles
Proper U-joint working angles are required for vibration-free and long-lasting driveline
operation. Most drivelines are angled on a vertical plane as shown in
Figure 8-46, View
A
, but on some trucks, the drivelines are also horizontally offset (angled) as shown in
Figure 8-46, View B
. When a driveshaft is angled on both the vertical and horizontal
planes, a compound angle exists.
Figure 8-46 - One-plane-angle and two-plane angle driveshafts.
All U-joints have a maximum working angle at which they can smoothly transmit torque.
This working angle depends in part on the U-joint size and design. Exceeding the
maximum recommended working angles of U-joints can destroy a U-joint rapidly and
also damage interconnected driveline components.
High working angles combined with high rpms tend to result in a reduced U-joint life.
Unequal U-joint working angles can cause vibrations and contribute to U-joint
transmission, and differential problems. Ideally, the operating angles on each end of a
driveshaft should be equal or within 1 degree of each other and have a 3-degree-
NAVEDTRA 14050A
8-51