Another look at the tricycle
The tricycle, usually a forgotten part of childhood, has given rise to a transporter which is ideal for moving large, heavy and delicate loads around congested spaces such as a drydock.
“We can move large sections around with very small clearances,” Trikelifter inventor Mel Terry of Wheelift Systems tells MJ. The unit is different to the larger, more common models in that it has a very low profile and is extremely compact. It is made for lighter loads in the 2 tonne to 9 tonne carrying range while keeping to around a third of the size of other units.
Mr Terry explains a submarine’s propeller and shaft systems, for example, are very hard to get at. Maintenance teams usually rely on welding bat-eyes to help crane-lift the hull – but these lifting eyes then have to be taken off again and the hull recertified, a long and costly process.
Not only can one of these transporters slip underneath and lift up the hull, the accuracy of the Trikelifter means that a second unit, fitted with a tower, can be used to ease the shaft and propeller system apart. “You can imagine this can be a tricky business,” says Mr Terry, “but all the moves can be calculated to within 1/32 of an inch – less than 0.8mm – and its truly omnidirectional.”
The new Trikelifter uses a power driven steerable front axle and two power driven wheels on a fixed rear axle and are mostly based on the company’s 6” mini module axle assemblies. All three points have vertical lifting cylinders attached to a platform so the unit can be driven under any stand supported load and then lift and carry it off.
The design also has a fluid lifting suspension at each of the three points, and it is configured so that all cylinders will raise and lower in unison, while the base of the load will remain parallel to the operating surface.
An embedded controller (EC) inputs to the independent wheel drive motors. The EC includes logic to linearly and rotationally control the tricycle lifting suspension, an algorithmic steering calculator moves the steerable front axle assembly and controls the speed and direction of each of the fixed rear axle driven wheels. The controller also provides command signals to the rear wheel to match the angularity of the steering axle, along with controlling the lift and carry functionality. Additionally, it is possible to have two transporters drive under a load and operate in tandem as a single unit via a single operator.
However, perhaps one of its most features is that the small Trikelifter can easily itself be moved, carrying on other duties around the yard when needed.
