Jack stands – or axle stands – are adjustable supports that are used with vehicle jacks and are designed to take the weight of the vehicle after the vehicle has been raised by a jack. When they are positioned correctly the vehicle can be lowered onto the stands, and the jack can be moved out of the way.
Lifting devices are also lowering devices, so it is unsafe to work underneath a vehicle that is supported only by a jack, in case it gives way or is accidentally lowered. Jack stands provide a stable support for a raised vehicle that is safer because the vehicle cannot be accidentally lowered while the stands are in place. To lower a vehicle that is on stands, it has to be raised again first, so that the stands can be removed.
There are different types of stand, each designed for a particular application. Stands should never be used for a job for which they not recommended. They normally come in matched pairs and should always be used as a pair. Stands are load rated, and should only be used for loads less than the rating indicated on the stand.