Holland Moving & Rigging Supplies was approached in 2009 about designing a custom piece of equipment to transport trees weighing up to 10 tons. The project was then tabled until fall of 2010 when the customer again called to find a solution to planting the Swamp White Oak trees on the elevated 9/11 Memorial plaza in New York City.
Holland designed the "Straddle Mover" to meet the special needs of planting trees. It was important that the specialized lifting machine be able to carry the tree in the center of all the axles, be capable of traversing sideways and able to negotiate openings on the surface of the plaza. There are also up to eight stories underneath the plaza for access, equipment and a museum requiring low ground pressure and a wider tire base.
The Straddle Mover's knuckle suspension allows for up to 135 degrees of steering, and it is able to lift and lower the frame and load 20 inches. There is a gate located on one side to allow the trunk of the tree to pass through. The load is then carried via a block and cable mechanism with a hook that raises and lowers as hydraulic cylinders are extended or retracted. The block and cable system is capable of lowering the load below ground level. The hydraulic cylinders supporting the frame are connected to form a three point system to provide stability and suspension as it travels over uneven surfaces. A single operator and a remote control operate the straddle mover.
Although the Straddle Mover was originally designed for moving trees, it can also be used for bridge deck replacement, according to Holland. Upgrading bridges has been high priority in the past couple years, and contractors have asked for an easier method of upgrading bridge decking to reduce the downtime for bridge repair.
Holland Moving and Rigging Supplies has been a manufacturer of the Holland Dollie for 30 years. The company performs complete design and build solutions of custom heavy transport equipment, including equipment for the oil, gas, wind, marine, heavy transport, structural moving and large product industries such as those that build large vessels and bridge structures.