Why Do Suspension Hanger Kits Have Different Height Hangers

Updated 12/16/2015 | Published 12/15/2015

Question:

Sirs, I need to know why you offer manufacturers spring hanger kits with differing height spring hangers, better stated, I would like to know the science behind offering differing height spring hanger kits. For example, your APT3HD kit has 2 1/2inch high front and rear spring hangers and a 5 7/16inch center hanger, the kits equalizer TREQE34 adds another 2inch of height for a total of over 7inch center spring hanger height as compared to the 2 1/2inch height of front and rear hangers. There must be a science reason to offer differing height hangers that would have the ends of the springs not being level or equal in distance from the frame. I am in the process of engineering an upgrade for my dual axle trailer to a triple axle and I need to know what the science reasoning is. Kits you sell that offer different height spring hangers are, APT1 APT3 APT3HD APTT3 APT7 APT8 Kits you sell that offer equal height spring hangers are, APT 4 APT5 APTT5 APT9

asked by: Lloyd

Helpful Expert Reply:

The varying heights of the hangers is all designed so that you end up with the leaf springs as level as possible and still end up a desired distance away from the trailer frame.

It may seem odd, but the center hanger will stick down further because the shackle straps that attach to the equalizers make up for the height difference. The equalizer is there so there is movement between the axles going over bumps to help smooth things out.

The # APT1 uses a very flat equalizer so to make up for the distance of the shackle straps the center hanger has to stick down further.

You'll notice on the hanger kits that use the same height hangers the equalizers have a larger height difference from the top bolt to the lower bolts on each side.

expert reply by: Jameson C