Young's Spring, Inc. has repaired beam suspensions on Hendrickson equipped tandem trucks for many years. Our techniques for the removal of the beams and bushing replacement may be of value and interest.
The Emerson Company makes simple and safe air-powered jacks which, when used in pairs, are capable of lifting 24 Ton loads. We use these jacks to lift a truck frame and chassis to just clear the drive tires from the floor. The jacks are then pinned, depressurized, and remain until the job is completed.
After removing the tires from one side of the truck we employ a common 10 ton floor jack to lift and lower the walking beam, lifting near the beam's center. Heavy duty jack stands positioned at each axle hub hold the axles level while the spring saddle caps are removed. Jack up the beam and move the stands away from the hubs. Lower the beam slightly and remove the main spring pin and rebound pin. Now lower the beam to hang free. The saddle, with the leaf spring still bolted in place, can now be tipped outboard and lifted away from the beam and the truck. Now jack the beam back up to where the stands can be repositioned under the hubs and progress to the end adaptors.
Beam end adaptor caps are first unbolted, then removed. This can be the most difficult part of the repair. We drive out adaptor endcaps with a Mako air chisel in minutes. A carefully used torch can loosen frozen endcaps but cutting must not go into the beam hanger! Allow each disconnected end of the walking beam to drop to the floor for safety. Beams can weigh over 150 pounds and may fall easily.
When cleaning each axle's beam hangers the technician should use a flap sanding wheel so as not to enlarge precision bores, removing rust and damaged metal only. An enlarged beam hanger will collect moisture, and the resulting corrosion will make the next repair difficult. Graphite based grease should be liberally applied during assembly on all metal parts.
Remove, rebush and replace one
beam at a time, you will have an easier time of it when the axles and driveshafts stay in place. And take notice of the orientation of the beam so it goes back in the way it came out, a shot of spray paint does the trick.
Beam Bushing Replacement
When replacing beam bushings there is no substitute for a shop press of 100 tons minimum. We use a Beeline 150 ton press that never fails to move a bushing. Hendrickson cautions against using a torch, or heat from any source on their beams. We have found many beams that have scoring from a cutting torch in the bushing bores. Hendrickson says to replace a scored beam, we leave it to the owner's discretion.
The bottle brush type of cylinder hone used with a liberal amount of cutting oil leaves beam bores in a smoother condition than anything else we have tried. Clean bores and lots of grease on the new bushing jackets will keep the press from banging.
Always change the cross tube, saddle studs, spring pins and bushings during the repair, and the torque rod bushings too if the customer will ok it. Having the very least amount of mechanical play when finished is the ultimate objective of the whole procedure. This job should take less than a day for two technicians to complete.
Truck Owner Recommendations
If you, the truck owner, have beam rebushing done at a suspension specialist's shop then you can be assured of the proper treatment of the beam and, most likely, a professional job done in a timely manner. At the least, if you undertake the job of removing the beam, take it to a spring shop which has the type of equipment described above to have the bushings installed. Worn beam bushings are a primary cause for tire wear and in extreme cases can have an effect on steering and control of the truck. A noticeable amount of articulation in the tandem axles and driver complaints are a good indication that rebushing time has arrived.