MG Type Bridge Girder Erection Crane

Product Overview

The MG Type single-hook gantry crane for road & bridge construction — also known as the engineering gantry crane, beam lifter, or beam transporter — is the core equipment used for hoisting and placing precast girders in road and bridge projects. With a lifting capacity of 50t~200t, a span of 20~40m, and a work duty of M3, it features a truss-type main girder structure that offers low cost, reduced wind exposure, and easy assembly and relocation. Standard configuration supports twin-crane tandem lifting operations (for details on synchronized twin-crane lifting, refer to the shipyard twin-trolley tandem lifting case study). It is ideal for girder hoisting and transport in precast yards for highways and high-speed railway bridges.

Q: What's the difference between a girder launcher and a standard gantry crane?

A: A girder launcher is a specialized variant of the gantry crane used in bridge and road construction—it offers a higher lifting capacity (60–100t), a wider span (20–40m), and features a truss structure for easy assembly, disassembly, and relocation. Standard gantry cranes are typically used for cargo handling (10–50t), feature a box-type structure, and are not frequently relocated.

Q: Why is a truss structure preferred over a box girder structure on bridge and road construction sites?

A: The truss structure offers three key advantages—it costs about 30%–40% less, has a smaller wind-facing area (better wind resistance), and can be dismantled and transported to the next site for reuse. Box girder structures are better suited for fixed factory buildings and offer poor cost-effectiveness on bridge and road sites that require frequent relocation.

Q: Does a girder launcher require a special foundation?

A: Yes, temporary crane rails are required (typically P43/P50 rails), and the ground bearing capacity must be ≥150kPa. Precast yards typically use crushed stone ballast plus sleepers, and the rails can be removed and recycled after the project is completed. Operating directly on bare soil is not recommended.

Q: How do you ensure synchronization when two girder launchers lift in tandem?

A: The traditional approach involves two independently operated cranes coordinated via two-way radio (which demands highly skilled operators). An upgraded solution is electrical synchronization control—where a master-slave PLC system uses laser distance measurement to provide real-time feedback on the position deviation between the two cranes, achieving accuracy of ±10mm.