Backbalance testing shall be carried out only on accelerating machines.

In backbalance testing the maximum load shall first be placed on the load receptor and the machine balanced so that the beam or indicating element only just maintains its horizontal position on its stop or carrier. The beam or indicating element shall then be moved to its position of greatest displacement from the horizontal position, after which the load on the load receptor shall be reduced by the minimum amount which is required to restore the beam or indicating element to its horizontal position.

The minimum amount which is required to be removed from the load receptor must not exceed three times the verification scale interval of the machine.