Got Questions? Hendrickson Ride Solutions

Q. What are the benefits of using a lift axle and what considerations should be made when spec’ing a trailer to determine if a lift axle is a beneficial addition?

A. Lifting an axle can help improve operational flexibility, maneuverability and fuel efficiency, extend tire and component life and reduce road tolls.

Variations in vehicle design can affect the operation of a liftable suspension by impacting the suspension’s operating ride height. Some valuable information to consider when spec’ing a lift axle include:

1. Frame-to-Ground Distance: The height of the vehicle from the ground to the bottom of the frame is used to determine the desired suspension ride height.
2. Fifth Wheel Height: Variations in the fifth wheel height can change the frame-to-ground height of the trailer frame and impact the suspension ride height.
3. Frame Deflection: Many vehicle frames are designed to deflect under load. As the frame deflects, the frame-to-ground distance is affected, which can change the suspension's ride height.
4. Tire Clearance: The amount of lift available is controlled by the suspension, which means that the liftable suspension will always raise the axle to the same distance below the frame. As a result, the lifted tire clearance could be increased by a reduction in tire radius. When making this spec’ing decision, be sure to consider the implications to the suspension ride height. Reducing the tire size will also increase the suspension ride height when the axle is lowered. The maximum allow ride height should never be exceeded as it could result in a loss of suspension capacity and damage to suspension components.