Bottle jacks are categorised according to the maximum working load they are able to lift. This is measured in tonne. Bottle jacks range between 1 tonne (1000 kg) and 50 tonnes (50000 kg).
Bottle jacks can only lift the maximum weight for which they are recommended. If you try to lift more weight than the bottle jack is able to, the overload protection system will not allow this to happen. The check valves open and permit oil to draw away from the main piston when pressure exceeds a set limit, not allowing the jack to lift any more weight.