2.1 Define & Show Simple Moment Balance

Once a basic understanding of how a gas spring works is obtained, the primary purpose of a gas spring existence can be pursued: lifting or holding an object. The first step is to understand the primary principle of moment balance or force times a distance. As shown in Figure 12 there is a simple pivot hinge (A) on the left, a weight (50 pounds) at the center of the beam at distance L from the pivot and a person holding up the other end of the beam at an additional length L. In order for the person to keep this system in balance a upward force at B (force F) of 25 pounds must be exerted.This force is determined by the following equations:

A: Pivot Location
B: Handle Location
W: Weight of liftgate
F: Force operator exerts
L: Length halfway between A & B

NOTE: CG usually will not be halfway betweew A & B, but shown here for clarity

The solution to the above problem is simple because all the forces are perpendicular to the beam and there is not a gas spring involved in the problem.

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