Two-Leg Gantry System
25 March 2008
Orlando-based Crane Rental Corp. is often called on to transport, lift and place heavy awkward equipment. Such is the case at a large-scale power plant under construction in South Florida. Much of the large equipment required in the construction of the plant is imported into a local port and then hauled to a rail yard closer to the job site. Since the railroad does not run all the way to the job site, the owners of a local processing plant agreed to allow the equipment to be offioaded at its rail siding. However, the off-loading operation could not interfere with the plant's operation.
Equipment being delivered ranged in size from 20 to 80 feet long and from 143,000 to 547,000 pounds, making the rail siding area very tight. The large-capacity crane needed to handle the weights would not fit. Crane Rental Corp.'s 500 ton gantry system was the equipment chosen for the job.
Two gantry legs were set up on each side of the railway track with the header beam going across the tracks. Twenty-foot by 5 foot by 1 foot dragline mats, and 4 by 4 inch timbers, were used to support the gantry legs. Four sections of 12 foot gantry tracks were placed on top of the dragline mats and timbers.
Twenty-seven foot header beams with lifting links for shackle attachment were placed on top of the gantry legs. Each rail car carrying the power plant equipment was pushed to the gantries.
The equipment was then attached to the gantries by basketing a lifting trunion wiThendless nylon slings or by attaching a shackle to a lifting lug. The gantries then lifted the load, the rail car was pushed out of the way, and the load was lowered onto a 15-line Goldhofer hydraulic platform trailer pulled by a Kenworth C500B prime mover with 20,000 pounds of counterweight. After detaching the equipment and securing it to the trailer, each load was carefully transported to the job site to be set in its final place by a mobile crane.