It is mainly fixed in the running track of the pantograph slide plate to ensure that the contact line will not leave the Pantograph, thus reducing the wear of the contact line and transferring the horizontal load of the contact line to the support cylinder. The positioning device comprises a positioning device, a supporting device, a positioning device and related components thereof. The contact suspension device of overhead contact system transfers the energy from traction and transformation to the electric power of locomotive through the power supply device which supplies power to the equipment installed on the struts. When an electric locomotive is started, friction between the top of the pantograph and the contact wire causes the pantograph to fall. Therefore, not only the linear elastic uniformity, and the degree of relaxation to be small, but also to ensure that the locomotive in any case can not be required to cut off the power supply. The contact suspension device also comprises a contact wire, a hanger, a load-bearing cable and a fall compensator