Oil-shear brakes, like the X-Class Posidyne motor and holding brakes from Force Control Industries Inc., Fairfield, Ohio (www.forcecontrol.com), offer several advantages over dry brakes. The X brakes, for example, can handle two to 10 times the cycle rates of dry brakes last 10 times as long. The units are life tested to 40 million cycles at 250 cycles/min. Oil-shear brakes also have four to five times the thermal ratings of dry brakes, letting them provide fade-free stopping with no burnt linings or discs.

The brakes shear automatic-transmission fluid between several friction discs. The fluid absorbs the heat of the engagement and dissipates it throughout the housing. Circulating fluid minimizes wear and lets the brake deliver controllable, cushioned stops that are smoother, quieter, and accurate than dry friction

The brakes come in 0.5 through 10-hp drives with 10-msec response times and low power demands. The brakes also feature a clamped-split quill to eliminate play between keyway, key, and input quill shaft for long life and reduced maintenance. For installation flexibility, the units come in horizontal, vertical-input down, and vertical-input up versions.