Rail end straightener
The rail end straigthener (RES) is a device for taking vertical bends out of rails which usually occur where rail joints have sunk as a result of the vibrations of wheels passing over them. The vibration causes the joint sleepers to sink into the ballast - and sometimes adjacent ones.
The RES is a special trolley which runs on the rails and has claws which can be closed under the rail ends. These are then raised by hydraulic jacks until the desired force is applied to bend the rails back up to straight. The "top" can then be checked with Sighting Boards to check the joint has been put right.