Racing jacks are categorised according to the maximum working load they are able to lift. This is measured in tonne. They range from 1 tonne (1000 kg) to 2.5 tonnes (2500 kg).
Racing jacks should only be used to lift the maximum load capacity they are capable of. Lifting any more weight will trigger the overload protection system which will open the check valves and permit oil to draw away from the main piston when pressure exceeds a set limit.