A load test is a literal testing of limits. Pushing a crane beyond it's rated capacity under controlled conditions to expose any flaws or breaking points so that any repairs can be done.
When a new overhead crane is installed or if any physical changes have occurred to the crane system itself, a series of weight assessment protocol is mandatory for the safety of all workers and employees. Occupational Health and Safety requires a Load Test Certificate before the crane can be put into regular use.
Overhead cranes are tested at 125% of it's rated safe working load capacity. (ex. if rated for 5 tons, a load of 6.25 tons will be applied).
While under the additional burden of weight, the bridge and runways will then be measured, using the proper equipment, to see if the amount of deflection in the steel falls within the safe parameters laid out by the original engineered design.
The crane will also be tested to see that all functions are working correctly. A complete check of hoisting, lowering, trolley travel, bridge travel, limit switches as well as locking and safety devices will be completed under the extra stress.
This also allows the technician to determine and verify any load limit switches to proper and safe settings.