9 inputs determine the right shock absorber.

A distributor-facing pre-quote checklist. If the customer answers most of these at the first call, the second call is the quote.

1. 01
   What's the load mass at end of stroke — the part, the tooling, the cylinder rod itself?

   Mass × impact velocity² × ½ = kinetic energy the shock has to absorb. Customers consistently underestimate this — they forget the rod weight, the end-of-arm tooling, and any product the cylinder is carrying. Get total moving mass at end-of-stroke, not just the part being moved.
2. 02
   What's the cylinder's velocity at the moment of impact?

   A 5 kg load at 0.5 m/s = 0.625 Nm; the same load at 1.5 m/s = 5.6 Nm — nearly an order of magnitude difference. Measure the cylinder's terminal velocity at end of stroke, not its average — air-driven cylinders accelerate continuously until impact unless metered.
3. 03
   Is the cylinder still pressurized and pushing when the rod hits the shock?

   If yes, add the drive force × stroke into the energy calc. A cylinder still delivering 200 lbf at impact over 25 mm of shock travel adds ~22 Nm of energy on top of the kinetic load. This is the single biggest under-sizing trap.
4. 04
   How many cycles per minute is the cylinder running?

   Cycle frequency determines whether you need a shock at all (>30 cyc/min is the rule of thumb) and whether you can survive on an under-sized self-compensating model. Above 60 cyc/min on a dedicated line, adjustable is the only spec that holds — the self-compensating compromise burns out too fast.
5. 05
   Is this a dedicated production line, or a job-shop / mixed-part cell?

   Dedicated → adjustable, tune once, longest life. Job-shop → self-compensating, no re-tune required. The operator-tuning assumption is the hidden cost; if no one is going to re-tune the shock when the part changes, don't quote adjustable.
6. 06
   Is the impact axial onto the shock, or at an angle?

   Side-loading the shock plunger destroys the seal fast and voids the warranty. Impact has to be ±2° of axial; anything more needs a guided pad on the shock face or an external alignment guide on the cylinder. Photograph the install plane on retrofit jobs.
7. 07
   What's the ambient temperature at the install location?

   The hydraulic fluid inside the shock thickens cold and thins hot. Standard shocks are rated -20 to +80 °C; outdoor, cold-room, or hot-process installs need temperature-rated variants. Cold-start a standard shock at -30 °C and it won't compress on the first hit; the cylinder slams.
8. 08
   How is the shock mounted — threaded into the machine, or in a separate bracket?

   Thread size + mounting nut style + jam nut clearance all have to match the machine bracket. Most installs are M12 to M27 threaded with a single jam nut; flange-mount variants exist for larger capacities. Measure the bracket before quoting; wrong thread is the #1 returns reason.
9. 09
   How will the customer know the shock is wearing out?

   Failure mode is degraded deceleration — the cylinder starts slamming again, gradually. No warning, no leak, no alarm in most installs. Quote a spare with every shock on a dedicated high-cycle line; replace at the first sign of harder end-of-stroke sound, not when the cylinder finally breaks.