Modular bridge expansion devices are divided into: GQF-C-type bridge expansion, GQF-MZL-type bridge expansion GQF-C-type bridge expansion characteristics: low building height, the overall shape of the domestic hot-rolled shaped steel height of only 50mm, simple structure , easy installation, with significant reliability, comfort and durability. Telescopic device is convenient to replace the old, and the choice available when the new bridge. Bridge expansion selection principles: deck pavement layer thickness ≥ 80mm telescopic volume ≤ 80mm GQF-MZL-type bridge expansion features: prominent MZL telescopic device structure is characterized by: the edge of the beam, the beam, beam, displacement control system, rubber seal with other members of the family consisting of telescopic device. Displacement load-bearing structure and the control system of the telescopic device separately, the two forces interfering, clear division of labor, both to guarantee the security forces, but also to achieve a uniform displacement, so that all the beams are supported by a displacement of the control box a vertical beam in the same traditional practices, so that the large displacement of the telescopic device is very beneficial, reducing the number of beams, so that the displacement control box volume is reduced to a minimum, saving steel. The structure also overcome the oblique supporting telescopic device requires very high precision machining and assembly of the harsh conditions, otherwise the four-link structure prone to self-locking phenomenon, affecting telescopic guarantee free and easy displacement uniform ills. The structure of each connection are used both to rotate and can slide structure. Therefore, the curved, sloping, oblique, wide adaptability bridge, bridge structures can meet a variety of requirements.