Large “Rolling Road” type dynamometers, like the one shown below are used throughout the auto industry to measure engine and complete automobile performance. The rear wheels are centered on the roller or rollers and the car locked in place. The engine output and other data can be collected and analyzed based on the resistance and RPM of the rollers.
These dynamometers often generate vibration that negatively affects surrounding test and manufacturing areas.
We were called in by one of our consultant friends to confer on how best to isolate a new 64,000 lb. dynamometer on a 432,000 lb. concrete inertia block at the General Motors Proving Grounds in Milford, MI. The inertia block sits in a large pit which keeps the dyno at the same elevation as the surrounding floor.
The engineer wanted to achieve a natural frequency of about 3.5 Hz for the supports, but did not want to use steel or air springs, which would be our normal recommendation. We were able to meet his requirements with 9 layers of our Super W pad using our Low Dynamic Stiffness Bridge Bearing quality natural rubber separated by stainless steel shims.
Since the dyno can produce a substantial horizontal force when stopping and starting, we suggested and designed pre-compressed lateral restraints as shown below that keep the inertia base from shifting and hitting the pit walls.
The pre-compression bolts were removed after the construction of the inertia block to provide a completely free floating system. As with most of these special projects, we rarely get to see the final installation, so unfortunately, we have no photos of the dynamometer in place, but the client told us the system was excellent.
Please keep us in mind when you have an unusual vibration or acoustical problem. We can often apply a standard product a little differently, as we have done here, or develop a completely new system to suit your requirements. We look forward to working with you on industrial problems along with our HVAC, Seismic, Floating Floor, Piping, Acoustical, and countless other systems.