3.2 Life

What is the expected life of a Lift Support?

When estimating the life of a Lift Support, one must first determine how much force the support can lose before the application becomes unacceptable. The time it takes to lose this amount of force is considered to be the life of the support.

All Lift Supports lose output force over time. The rate at which force loss occurs varies greatly by application and manufacturer. Many factors affect the rate of force loss, such as: size of the support, orientation, amount of cycles, ambient temperature, vibration, and the geometry of the application. Considering all of the variables, it is very difficult to estimate life accurately without actual testing in the application.

As noted above, all Lift Supports will lose output force over time. It is recommended that the supports be periodically checked to ensure that they are functioning as intended. This inspection should be implemented as part of a planned maintenance activity, if possible.

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How can a designer ensure the longest life
for a Lift Support in an application?

Orient the support "shaft down". As explained above, this will continually lubricate the seal and shaft and reduce permeation through the seal.

Utilize the largest gas volume possible in the support. In general, use the minimum stroke required with the largest body possible. In a support with a large gas volume, small gas losses are imperceptible in the output force. The temperature of the Lift Support should remain well within the temperature limits. If temperature extremes will be encountered, it should be for a short duration and the support should not be cycled while at the extremes. Utilize the highest force Lift Support possible that still provides acceptable handle loads for the application. This will allow for some force loss without the loss of function of the application.

Provide multiple mounting locations so that the support can be moved to accommodate for force loss as the support ages.

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