Axle sink
An axle sink or wheelset sink is a device that is used in railway depots and by manufacturers of railway vehicles .
With the help of the axle sink, individual wheel sets or bogies of a vehicle can be lowered in order to overtake or replace them without lifting the vehicle. The axle sink is usually installed in a pit located transversely to the direction of travel between the tracks and consists of a mobile frame which is equipped with a lowering and lifting device. The vertical movement is carried out electrically or hydraulically by means of threaded spindles , scissor lift tables or hydraulic cylinders .