Should every gear case be pressure tested?

Answer: Yes. Inflating to 4 kPa and holding 60 seconds is non-destructive and takes under 90 seconds per unit.

Is drop height set by weight or by size?

Answer: By loaded weight: a 32 kg load uses 1.2 m; above 45 kg it falls to 0.9 m with more edge drops.

Where does the 450 N latch figure come from?

Answer: From a lateral impact estimate with a factor of two. It covers a 32 kg gear case dropped from 1.2 m, so a 600 N latch class is enough.

How long is 30 000 hinge cycles in service?

Answer: About ten years at eight openings a day, or four at twenty.

What happens when one unit fails the batch verdict?

Answer: Check the class first. Class A rejects the unit, Class B doubles the sample, Class C passes by concession.

Gear Case Acceptance Standards: Test Items and Pass Criteria

Quick answer: A gear case acceptance standard is a list of test items, each with its own condition and pass value. Lay them out by class, then run stacking, drop, vibration, seal, latch, hinge and cold impact before releasing a batch.

How Gear Case Inspection Items Are Layered
Stacking and Drop Test Criteria
Vibration Sweep and Latch Retention
Seal Pressure, Hinge Life and Cold Impact
Marking Durability and Batch Verdict
FAQ

1. How Gear Case Inspection Items Are Layered

Start with the duty cycle, not the drawing: a gear case here is judged on daily turnover and transport, not on long-term storage.

Items fall into three classes: A covers sealing and load path, tested on every unit; B covers destructive work, sampled per batch and doubled after a failure; C covers appearance and marking.

Class	Items	Method	On failure
A	Seal, latch, handle load	Every unit	Unit rejected, sample doubled
B	Stack, drop, vibration, cold	Batch sample	Second failure rejects batch
C	Appearance, colour, marking	Every unit, visual	Concession allowed

A pass value without a condition is not a pass value; temperature, dwell time and support surface belong in the same cell.

2. Stacking and Drop Test Criteria

Stacking uses the load the bottom unit carries: four cases at 32 kg put 96 kg on the bottom lid. Hold 48 hours at 40 °C, unload, wait 30 minutes, then measure: lid set under 1.5 mm, no wall crack, no latch released.

Drop testing runs ten impacts on one loaded sample: one corner, three edges, six faces. Three questions decide: did the wall crack, did a latch open, does it still seal. The corner and three bottom edges drop at 1.2 m, the six faces at 1.0 m with 3 mm lid set, plus an 0.8 m drop handle-down, where the mount must not pull out.

Pressure re-testing after the drop is the step people skip: a case can look intact with its gasket pushed off the groove, and decay jumps from 0.12 kPa to over 0.5 kPa.

3. Vibration Sweep and Latch Retention

Vibration is a sine sweep from 10 Hz to 500 Hz and back at 1 octave per minute, 30 minutes per axis at 1.0 g peak, with the case ballasted to its loaded mass. No latch opens, no fixing shifts more than 2 mm, no hinge pin walks out.

Latch retention is measured alone: 450 N in the opening direction for 60 seconds, no release, no plastic set beyond 1 mm. After 200 cycles retention may fall 15% at most.

Opening force needs a window too. Between 25 N and 45 N works. Below that, road vibration pops the latch; above it, a gloved operator leaves the case unlatched.

4. Seal Pressure, Hinge Life and Cold Impact

Sealing is judged by pressure decay because decay gives a number. Inflate a closed gear case to 4 kPa, hold 60 seconds, allow 0.15 kPa of decay, and record ambient temperature so a spread above 5 °C can be corrected.

Hinges run 30 000 cycles between 0 and 105 degrees at 15 per minute, after which lid sag may reach 2 mm and axial play must stay under 0.4 mm.

Cold impact is the item warm-region buyers forget. Condition at -30 °C for four hours, then strike the thinnest wall with a 1 kg tup from 500 mm. No crack through, and an 0.8 m drop at that temperature must still hold pressure. Polypropylene loses about two thirds of its notched impact strength at -30 °C.

5. Marking Durability and Batch Verdict

Marking must outlast the turnover cycle: moulded characters 5 mm high and 0.4 mm deep, printed marks legible after 50 alcohol rubs, and a QR code that reads at 300 mm.

Item	Method	Pass	Fail
Moulded marking	Visual plus gauge	5 mm high, 0.4 mm deep	Missing characters
Print and label	50 alcohol rubs	Still legible	Lifting, fading
QR code	Scan at 300 mm	First-read success	Needs refocus
Colour	D65 light box	ΔE 2.0 or less	Visible shift

The batch verdict has three steps: three performance samples passing release the batch, one failure doubles the sample, a second failure sends it back. Appearance defects pass by concession once quantity and location are recorded.

Keep test date, ambient temperature, equipment number and raw curve for two years; disputes surface six months later, not on delivery day.

Conclusion

A standard earns its keep through repeatability, not length. Put duty cycle, sample size, condition and pass value on one line, and once stacking, drop, vibration, seal, latch, hinge and cold impact are recorded, a gear case has been accepted.

This article discusses only the container (case body) side of specifications and design intent, and does not cover any handling, loading or use of the contents.