A crane load test at 125% is the last and most important check before a new EOT crane goes into daily work. The crane lifts a test weight equal to 125% of its safe working load (SWL), and every motion is run to show that the structure, hoist, brakes and controls can handle more than the plant will ever ask of them. For a 10 ton crane, that is a 12.5 ton test load. This guide explains what each test proves, how it is done at site, and which documents a plant head or purchase manager should insist on before signing the handover.
Why a crane is tested above its rated load
A crane is a safety item. If it fails, it can hurt people and stop a production line for days. If the crane lifts, holds and moves 125% of SWL with no slip, no crack, no abnormal sound and no permanent bend, the plant can trust it at 100% for many years. A signed test certificate is also the first paper a factory inspector, insurer or customer auditor asks for.
The three load tests on a new EOT crane
| Test | Test load | What is done | What it proves |
|---|---|---|---|
| 1. No-load test | Empty hook | All motions run both ways; limit switches, brakes, emergency stop and controls checked | Wiring, directions, limits and safety devices work |
| 2. Rated load test | 100% of SWL | Every motion run at rated speed; girder deflection measured at mid-span | The crane does its real job at contract speeds; girder bends only within the design limit |
| 3. Overload test | 125% of SWL | Load lifted a short height, held, and each motion run slowly | Structure, rope, hook, gearbox and brakes have the designed margin; brake holds with no slip |
How a 125% load test is done at site – step by step
- Pre-check: rail alignment, end stops, rope reeving, oil levels, brake settings and earthing. The area under the crane is cleared and barricaded.
- Test weights: certified weights or known steel blocks, checked against a weighbridge slip or calibrated load cell. Slings and shackles checked for the higher load.
- No-load run: all motions, limit switches and emergency stop with an empty hook.
- Rated load run: 100% load lifted; all motions at rated speed; speeds and motor currents recorded.
- Deflection reading: trolley at mid-span with 100% load; deflection measured from a fixed reference. After unloading, the girder must return to its original level.
- Overload run: 125% load lifted about 100-200 mm, held, and each motion run slowly. The brake must hold with no creep.
- After-test inspection: welds, wheels, gearbox, rope, hook and end carriages checked for cracks, leaks or damage.
- Sign-off: the certificate is signed by the crane maker’s engineer, the buyer’s engineer and, where the law asks, a competent person.
Deflection: the number most buyers forget to ask for
Deflection is how much the girder bends at mid-span under the rated load. Too much bend makes the trolley run uphill, wears wheels and rails, and can crack welds over time. Span/750 (L/750) is a common limit for general EOT cranes; some heavy-duty and precision specifications ask for L/1000.
| Span (L) | Limit at L/750 | Limit at L/1000 |
|---|---|---|
| 12 m | 16.0 mm | 12.0 mm |
| 16 m | 21.3 mm | 16.0 mm |
| 20 m | 26.7 mm | 20.0 mm |
| 25 m | 33.3 mm | 25.0 mm |
| 30 m | 40.0 mm | 30.0 mm |
Ask for the measured value in the test report, not only “OK”. A measured number is proof; a tick mark is a claim.
Test weights for common crane capacities
| Crane SWL | Rated load test (100%) | Overload test (125%) |
|---|---|---|
| 3 t | 3.0 t | 3.75 t |
| 5 t | 5.0 t | 6.25 t |
| 10 t | 10.0 t | 12.5 t |
| 15 t | 15.0 t | 18.75 t |
| 20 t | 20.0 t | 25.0 t |
| 30 t | 30.0 t | 37.5 t |
| 50 t | 50.0 t | 62.5 t |
For 30 t and above, arranging certified weights at site takes time and should be in the project schedule.
The documents your plant should receive
- GA drawing with SWL, span, lift, duty class and wheel loads.
- Design calculations for girder, end carriage, hoist and wheels, made to the agreed duty class.
- QAP showing factory and site checks.
- Material test certificates for main plates and steel sections.
- Test certificates for wire rope and hook from their makers.
- Site load test certificate: no-load, 100% and 125% results, deflection, date, test weights and signatures.
- Electrical test report: insulation resistance, earthing, limit switch and emergency stop checks.
- Operation and maintenance manual with spares list and lubrication chart.
What the law asks after handover
Section 29 of the Factories Act, 1948 required every crane in a factory to be thoroughly examined by a competent person at least once in every 12 months, and the OSH Code, 2020 with your state’s rules carries this duty forward. Rules may also ask for a fresh test after a major repair. Your plant safety officer will confirm the current rule for your state.
Five signs a load test was done properly
- Test weights are known and proven, not guessed.
- The certificate shows actual numbers: test load, deflection, speeds.
- Your own engineer was present and signed.
- The brake held 125% with no creep, and this is written down.
- A visual check after the test is recorded, with no cracks, leaks or permanent bend.
How RKEW approaches load testing
R K ENGINEERING WORKS has designed, built and installed EOT cranes, gantry cranes and hoists from VKI Area, Jaipur since 1998. Each crane is designed to the agreed duty class, checked at our works as per QAP, and load-tested at site before handover. ISO 9001, ISO 14001 and ISO 45001 certified. Planning a new crane, an upgrade or a re-test? Request an engineering consultation or book a site survey.
Frequently asked questions
Is the overload test done at full speed?
No. In the overload test, rated speeds need not be reached; the crane should handle the load smoothly. Full rated speed is checked in the 100% test.
Can a crane be used above its SWL after passing a 125% test?
No. The 125% test is a one-time proof of margin. In daily work, the crane must never lift more than its marked SWL.
Who should sign the crane load test certificate?
The crane maker’s engineer and the buyer’s engineer. Where the law or your insurer asks, a competent person also signs.