What are the composition of bridge girder launcher?

Launching Gantry

Walking bridge girder launcher is made up of main girder, lifting trolley, front legs, middle legs, rear legs, rear bracket ,electrical system and hydraulic system etc.

1)Main girder
The main girder and guiding girder is made up of bearing girder , front and rear connecting frames.
Front and rear connecting frames are made up of transverse girder, pull rod, reaming base and pin. Forming a closed stable structure with right and left main girder is their main function.
(2)Lifting trolley
It is made up of longitudinal moving gear box, transverse moving beam and rail, winch, pulley block, hanging beam . Trolley is the lifting mechanism. lower longitudinal moving mechanism makes trolley moves along the rails on main girder; upper transverse moving mechanism makes trolley move along the transverse moving beam and rails; winch can lift the precast girder; above three parts and trolley steel structure united as a whole machine, moving, dropping precast girder and installing boundary girder as well as lifting small articles to front abutment.
(3) Front legs
The front legs are consist of bracket, inner and outer casing, connecting transverse rails ,transverse wheel –box assembly, transverse rails , diagonal brace, fixing device, rail clamping device ,fixed setting, connecting base, universal coupling, hydraulic cylinder and pin etc.
The front legs is the important front support of the bridge girder launcher.
4、Middle legs
Middle legs are made up of active suspended mechanism, driving idler roller, driven idler roller, core plate, connecting beam, driving wheel-box assembly , driven wheel-box assembly, fixed setting, transverse rails, and pin etc.
The middle legs is the important rear support. The suspended mechanism can make the middle legs move forward by themselves.
5. Rear bracket
Rear bracket is made up by the suspended mechanism, idler roller and inner and outer casing ,hydraulic cylinder and pin etc. It is the rear support which make the bridge girder launcher move from one pier to next pier.
6.Rear legs
The rear legs is made up of coupling base, inner and outer casing and pin.
7、Accessories

Accessories are made up of main girder accessories, front legs accessories, lifting trolley accessories, middle legs accessories and rear accessories etc.