Transit Systems Use Recycling to Reduce Maintenance Costs

Rail maintenance departments are discovering a new strategy to reduce operating costs. Transit systems have learned that shock absorbers, long considered throw-away items, can now be reused indefinitely. Twenty-five years ago rail car shock absorbers were primarily larger versions of those used on automobiles. They were simple, hydraulic devices and very inexpensive.  New rail car designs that began to appear in the 1980s and 1990s featured trucks with advanced suspension systems. Most of these trucks utilized European-designed shock absorbers that had more sophisticated damping technology and were often rebuildable. These shock absorbers were also much more expensive than the units U.S. rail systems had previously used. Many were priced at least four to five times higher than the older style shock absorbers. Unfortunately, many properties continued to discard their shock absorbers based on age or mileage, regardless of condition. About 10 years ago the Chicago Transit Authority Rail Car Engineering Department did an investigation into the various types of replacement shock absorbers that were available. The department had reason to believe that OEM shock absorbers were far superior in performance to some of the shock absorbers available on the aftermarket. After thorough research, the CTA decided to change its specification for replacement shock absorbers to reflect the new European design. Realizing that the new style shock absorbers had a useful life of 20 to 30 years, the CTA engineers then began to pursue a method to evaluate the condition of shock absorbers removed from trucks during planned overhauls. CTA found the answer in professional auto racing. Professional racers had discovered the advantages of the European shock absorbers years earlier and switched to them because they offered almost infinite damping adjustability. Racers needed a tool to measure the damping force for each configuration they built. They used dynamometer testing machines to set these parameters. The CTA staff researched manufacturers of racing shock absorber dynamometers to see if they could find a machine to accommodate their rail car shock absorbers. They ended up connecting with a small racing equipment manufacturer in Ventura, California called Maxwell Industries Inc. Maxwell  adapted one of its racing shock dynos to test the larger rail car shocks and then tested a half dozen used shock absorbers and compared damping rates to several new shock absorbers supplied by the CTA. The test data revealed that all six used shocks were still within the damping specs for the new shocks. The CTA marked the six shocks and placed them back into service. The re-certified shocks worked flawlessly during several years of service. Reusing those six shock absorbers saved the CTA almost $2,000. The CTA was normally replacing 500 to 600 shock absorbers a year at a cost of nearly $150,000. That was enough to convince the CTA to purchase their own shock dyno and begin to test and re-cycle their shock absorbers and the CTA has experienced a 90 percent reuse rate on shock absorbers since purchasing the shock dyno. Ralph Malec is a sales consultant with Maxwell Industries Inc.