This machine is used for pulling together or pushing apart 2 flat bottom rails in longitudinal direction.It is suitable for various types of rails of 43~75kg/m. It can not only push the rail outward to make the rail gap larger, but also pull the rail inward to make the rail gap smaller. An emergency unloading valve is installed on the main clamp body. When the wedge iron and the steel rail are" seized", the emergency unloading valve can be interrupted to make the machine safely down the road.