Suspension Control ( Automatic - Electronic ): Service and Repair

Preventive Maintenance

The following procedure is required when servicing a vehicle with a Hendrickson Suspension model HAS air suspension:

Notice: If the tightening torques recommended are not achieved and maintained, metal surfaces can work and wear the spring seats, axle bottom caps and possibly other components related in the total assembly.

Important: Check for proper seating of components to eliminate gaps or misalignment.


1. Torque the U-bolt nuts at preparation for delivery.
2. Retorque the U-bolt locknuts at regular maintenance intervals. Refer to Maintenance Schedule Maintenance.





Notice: Refer to Fastener Notice .

3. Use the following procedure in order to replace the U-bolts or other components:

1. Torque the U-bolt nuts evenly.

Use 37 Nm (50 lb ft) increments in order to achieve uniform bolt tension and correct level/altitude of the main support beam, the spring seat, and the axle bottom cap at the final torque.

2. Drive the vehicle in order to seat the components.
3. After the road test, retorque the U-bolt nuts.

Tighten the nuts to 394 Nm (291 lb ft).

4. Retorque the U-bolt nuts at regular maintenance intervals. Refer to Maintenance Schedule Maintenance.