The 20.5″ Supertower is a system manufactured with the purpose of providing a lifting medium for a variety of Thomas trusses ranging from 12″ x 12″ to 30” x 30” Super-Mega.
The towers will provide the necessary equipment to support a truss rig in venues where the flying points are either not strong enough, or in the right place. Each tower is capable of lifting over 6 tons to a maximum height of 65 feet. The 6 ton weight must include the self weight of the truss rig and the motors. The truss rig is raised and lowered by means of electric chain hoists. The motor is rigged in the truss and works in double fall due to the chain being passed over the roller beam at the top of the tower. The motor is then connected onto the other side of the sleeve block. Below, we list a brief description of the parts which make up a ST20.5″ ground support tower.
The base of the tower has 4 screw jack assemblies with 6″ diameter foot pads which are adjustable to enable leveling of the tower. The base also incorporates 4 ball castors which allows the whole rig to be accurately positioned before the tower is raised. Once the tower system is ready to be raised, all the screw jacks must be adjusted evenly and must take the load off the ball castors.
The hinge section is designed to allow the towers to be assembled horizontally at truss top level before being swung and locked in the vertical operating position. The tower sections are manufactured from aluminum 6082-T6 2″ x .157″ thick wall tube with 1″ x .125″ wall diagonals. The tower sections are connected together by double ended spigoted connectors. The tower sections are in modular form to allow 30″ adjustments in height. Once the tower height has been determined, then the roller beam is fitted at the top of the tower.
The roller beam accepts the chain from the chain hoist which is run over the top of the roller beam and back down to the other side of the sleeve block. The sleeve block is the interface between the truss rig and the towers. It is designed to create a semi-rigid joint between the truss grid and the towers by using 16 heavy duty 4″ wheels to guide the rig up each tower. Outrigger arms are required when not used in a 4-post grid configuration.
A tower erecting system is available for the 20.5″ x 20.5″ tower as well as the B4209 Ballast Base that attaches directly to the tower base for up to 6,000 lb of weight.