US Patent 7309115 Pull out guide assembly for drawers

A pull-out guide assembly for drawers, having on both sides of the drawer a support rail on the carcass and a pull-out rail on the drawer. The load of the drawer is transmitted between the rails by rollers that are borne in running carriages. The running carriages may be moved between a front end position and a rear end position in a differential manner. Locking means are provided for the running carriages and, in the event of a deviation from the differential running between the rails, they lock the running carriage on one of the rails at predetermined points between the two end positions. This locking is releasable by the movement of the rails with respect to one another.