Paul Hammerstrom Design, Llc

Phone: 603 801 4411
Address: 14 Columbia DriveAmherst NH, 03031USA

Fox Spring Compressor

Paul Hammerstrom Design > Fox Spring Compressor

FOX Racing Spring Compressor Project

The team for this project consisted of Dennis Wootten (PHD), Josh Yablon (PHD), John Bullock (FOX), Dan Watkins (FOX) and Kerrick King (Areias Systems).

We have had a long term relationship with FOX. We cut our teeth doing R&D projects for them. A couple years ago we were approached to help out on the Manufacturing side. Since then we have been doing a lot of manufacturing tooling and fixture design for them. One of the more challenging projects was to design a spring compressor to install springs on their powersports shocks. The challenge centered around the number of different size shocks, and safety.

Fox designs and manufactures many different size shock absorbers for off-road vehicles. With so many different length shocks and spring diameters, the machine had to be very versatile. In addition, compressing springs of this size generates a lot of force, so this had to be extremely safe for the line workers. Fox had an idea to use rubber pads to grab the springs so that there would be no marks on the shock whatsoever due to installation.

In the end the team was able to develop a machine that met or exceeded all of the requirements. It uses a long travel lower vertical actuator with a variety of cups to handle different size shocks. We developed a unique self centering Grabber mechanism that can accommodate a wide range of spring diameters. The mechanism can align off center springs in two directions due to the linkage design and the v-shape of the pads. We added in a polycarbonate door that is closed during actuation and an automatic latching door to make the machine safe to use.

Since our forte is designing structures and mechanical/kinematic systems, we needed to bring in an expert on the software and control side. We worked with our partner Areias Systems to provide this expertise.

More information about Fox Racing Shox and the products they make can be found at

Check the FOX Spring Compressor in action in the video below