User:Conorbebe/Draft:Travel lift

A travel lift is a mobile crane used for transporting boats and small ships.

Construction
The travel lift is a form of gantry crane on four pneumatic wheels. It consists of a square box made of steel beams, which is open at the bottom and the front so that sailing ships and ships with higher bodies can be accommodated. By two or more hoists on each side of the crane attached to slings, ships can be lifted out of the water, transported, and re-launched. Depending on the size of the travel lift, ships weighing up to 1,000 metric tons can be raised. Thanks to the addition of steerable wheels, the travel lift can be moved freely about shipyards. The lifting device and wheels are typically hydraulically driven by a diesel engine. The world's most famous and largest manufacturer is Marine Travelift, Inc., Sturgeon Bay, in the US state of Wisconsin.

Operation
The travel lift is used to transport ships on the premises of a shipyard or marina. This allows a ship to be lifted out of the water and driven to its destination (dry berth, shipyard, low loader). For this purpose, the lift goes via a "lift box", which consists of two lanes (right and left) and the harbour basin in between. There, the slings are lowered into the water. The ship is then pulled over the slings and carefully positioned so that it will hang in perfect balance and no parts (drive shaft, propeller, rudder, keel) will be damaged by the straps. The correct position of the straps is marked on most vessels by a small triangle on the hull. Now the ship is raised at four points (six on larger travel lifts) at the same time. Then it is driven to its destination, with the travel lift being controlled either by radio remote control, or by an operator from a cabin on the side of the lift. The ship is lowered and re-launched in reverse order.

Secturity
The ship is safely protected from damage by the surrounding steel girders. Damage can be caused by incorrect positioning of the lifting slings, particularly paint damage as a result of dirty or scratching straps. The width of the lift may endanger other ships or buildings when manoeuvring.

Distribution
Thanks to its easy handling, the travel lift has replaced the previously customary fixed column-mounted jib crane.