TMC CleanBench 68-500 High Capacity Vibration Lab Table

Low-Amplitude Input Response:

The greatest challenge in designing an effective isolator is maintaining good performance at the low vibration amplitude inputs typical of ambient building floor vibration. Isolator specifications are often based on measurements done with the isolator placed on a “shaker table” with very high amplitude input levels. Such testing, with input amplitudes on the order of millimeters, yields unrealistic performance expectations and is misleading as results will not reflect the actual performance.

The Gimbal Piston Isolator design uniquely maintains its stated resonant frequency and high attenuation level in even quiet, natural floor environments. The performance is linear to such low amplitudes because the design is virtually free of friction and, therefore, can avoid rolling friction to static friction transitions.

Every other system we have tested at levels typical for floor vibration exhibits a higher resonant frequency than claimed or a substantial increase in transmission through the isolator mount. We stress the importance of performance specifications at low levels because we have repeatedly observed, in our testing and many as-used installations, that better performance is much easier to achieve at greater amplitudes and higher frequencies.

Horizontal vs. Vertical Inputs:

Our innovative Isolator allows a thin-wall, rolling diaphragm seal to accommodate horizontal displacement by acting as a gimbal. Instead of using a cable-type pendulum suspension, the Gimbal Piston Isolator carries the load on a separate top plate with a rigid rod extending into a well in the main piston. The bottom of the rod has a ball-end that bears on a hard, flat seat. An inherently flexible coupling allows horizontal flexure in the isolator as the ball simply rocks (without sliding or rolling) very slightly on the seat. The approach works exceptionally well, even with sub-microinch levels of input displacement, because the static friction is virtually the same as the rolling friction. Horizontal motion is converted to the usual vertical diaphragm flexure but out of phase: one side of the piston up, the other down, in a gimbal-like motion.