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Mechanical End Stops and Energy Absorbers: A Design Review for Machine Builders

A practical design review for machine end stops where residual motion, structural force and repeatable stopping must be considered together.

Direct answer

An energy absorber can reduce the force transmitted when a moving member reaches an end position, but it must be selected as part of the complete end-stop system. Define the credible approach speed, moving mass, available stopping travel, continued drive force, structural load path and reset condition. A shock absorber does not replace a machine risk assessment, a positive stop or any required guarding and control measures.

Questions this page answers

When should a machine end stop use an energy absorber?
What should be checked when designing a mechanical end stop?
Can a shock absorber be used as a safety end stop?

Required inputs

movingMassKgcredibleApproachSpeedMpsavailableStoppingTravelMmcontinuedDriveForceNstructureForceLimitNendStopFunctionresetCondition

Formula logic

Average stopping force

A longer usable energy-absorbing stroke reduces average force for the same impact energy. Check the protected structure against actual peak-force behavior, not only this average value.

Favg = E / s

Unit: N

Review steps

1
Define the end-stop function
State whether the stop is part of normal cycle control, a commissioning limit, a maintenance limit or a credible abnormal-motion case. These cases can have different speeds and duties.
2
Map the energy and load path
Calculate motion and continued-drive energy, then confirm how the striker, absorber, bracket, fasteners and machine frame transmit the resulting force.
3
Separate energy absorption from safety control
Use the machine risk assessment to decide the required guarding, interlocks, controls and positive stops. The absorber should be specified for its mechanical duty rather than assumed to solve every safety function.

Common mistakes

Using the normal operating speed for a credible end-of-travel or control-fault case.
Selecting the absorber before checking the stiffness and force limit of the mounting structure.
Describing a product as a safety solution without defining the wider machine safety function.

Technical notes

For machinery placed on the EU market from 20 January 2027, Regulation (EU) 2023/1230 replaces the Machinery Directive. This engineering note is not legal or conformity-assessment advice.

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