Case Study: Counterbalanced Hinges for Tanning Bed Industry

ETS Tan asked Weber Knapp to develop an adjustable counterbalance hinge system to support a series of lids ranging in size and weight from 250lbs to 309 lbs for their new tanning bed line.

Weber Knapp was able to develop a single unique counterbalance hinge that could manage the varying center of gravity locations and weights for the entire tanning bed line. With this type of flexibility in a single counterbalance design, ETS was able to minimize the inventory needed to support its tanning bed line.

This hinge was made to be adjusted to allow minimal operating force no matter which lid was assembled onto it and allowed for a greater range of manufacturing tolerances on the lid itself. Along with providing a full counterbalance of the various lids, it also functioned as the main end support for the tanning bed. It was able to provide over 3,100 in-lbs of torque and hold 3,400 lbs of spring force in a space no wider than 3.375 inches. These tanning beds are meant for commercial use and the hinge was designed to meet a rigorous 300,000 cycle life.