Common Causes of Shock Absorber Bottoming Out
How to diagnose a hard stop at the end of stroke before simply moving to a larger absorber.
Direct answer
Bottoming out usually means the absorber is reaching the end of its stroke before the energy has been controlled. The cause can be insufficient stroke, underestimated impact energy, excessive drive force, high cycle heating, wrong adjustment setting, side load or a mechanical stop interfering with absorber travel.
Questions this page answers
- Why is my shock absorber bottoming out?
- What causes a hard stop at the end of absorber stroke?
- Should I choose a larger absorber if bottoming out happens?
Required inputs
Review steps
- 1
Recognize the problem and its limits
After a speed or throughput increase, the absorber becomes hot, loses damping or bottoms out. Check energy per impact AND energy per hour, return time, alignment and cooling. Temperature alone does not establish the cause; compare measured conditions with model limits.
- 2
Collect the operating data
Weigh the complete moving assembly. Obtain speed at first contact from a trace or a safely recorded movement, rather than using the machine’s nominal speed. Count impacts at this individual stop during peak production. Measure usable travel and record whether a belt, queued pallets or an actuator keep pushing. Mark estimates and unknowns; send photos or a drawing when measurements are unavailable.
- 3
Worked engineering example — not a customer case
Assume one absorber stops a horizontal 50 kg load at 1 m/s, with no drive force during compression and 30 impacts/minute. Energy per impact = 0.5 × 50 × 1² = 25 J. Cycle rate = 30 × 60 = 1,800/h. Hourly energy = 25 × 1,800 = 45,000 J/h. These are assumed demonstration inputs, not your machine’s results.
- 4
Why one model is excluded
EK20x12 is listed at 31 J/cycle and 35,200 J/h. The 25 J impact is below its single-impact rating, but 45,000 J/h exceeds its hourly rating, so exclude it for this assumed continuous duty. A passing single-impact check cannot cancel a failed thermal-duty check.
- 5
What may enter the shortlist
EK25x25 is listed at 81 J/cycle, 77,000 J/h and 25 mm stroke. It passes only the two energy checks in this example and can enter further review if the mechanism accommodates its working stroke and mounting dimensions. This is not approval for installation.
- 6
Validate before ordering
Confirm effective mass and velocity range, peak transmitted force, allowable structural load, adjustment, full return before the next impact, alignment and thermal conditions. Record initial and stabilized temperature, cycle rate, stroke use and observed rebound during a controlled trial. Define acceptance limits with the machine designer; missing model limits require engineering confirmation.
Common mistakes
- Replacing the absorber with the same model without checking whether the application changed.
- Assuming bottoming out always means the product is defective.
- Increasing damping adjustment without checking whether the machine frame can accept the higher force.
Technical notes
- Illustrative calculation; EK20x12 and EK25x25 ratings checked against published EKD model records on 4 October 2026. J and Nm are equivalent energy units. Catalog ratings do not establish service life or application suitability.
Move from answer to model shortlist.
Use the sizing tool when you have the inputs, or send the application data for engineering review.