What are handling forces?

Written by: Camloc Motion Control | Published: 10/18
Figure One: Idealised P1-P4 Force/Displacement Graph

What are handling forces and how are they categorised?

The primary function of a gas spring is to lift and support an object in a safe and controlled manner. For the designer and end-user of an application, the handling forces are the most important consideration; these are the human and mechanical interactions the spring has with an application.

Handling forces can be categorised as either a System or Ergonomic force, and can be related back to the P1-P4 chart (discussed in Technical Guide – Edition 1: Gas Spring Overview), seen in figure one:

System Forces

The P1 and P4 points of the chart are System Forces which can be calculated and must be taken into consideration by the designer of the application.

P1 – This is the force required to keep the application fully open, e.g. a car tailgate being held in open position.

P4 – This is the maximum load the system will experience. The spring is reaching full closure in the compression direction, the bracket and the hinge design must be capable of withstanding this force.

Ergonomic Forces

The P2 and P3 points are Ergonomic Forces. These are the subjective forces that the end user will assess the gas springs performance by.

P2 – This is the key handling force when lifting a lid, it dictates when you have reached an in-balance position. In the example of the car tailgate, the tailgate is shut and the end user is opening the tailgate; the target for this is to be less than 60N.

P3 – This is the key handling force when closing a lid, this is the force required to close when the spring is fully extended, the target for this is to be 60N or less.