| 摘要 |
A lifting-type boat trailer which collapses to a substantially flat position to allow the trailer to be driven between the pontoons of a pontoon boat with its pontoons sitting on the ground. A winch fixed to the front of the trailer applies force via a cable both to the front end of the trailer through a pulley attachment and also to the rear end of the trailer through a bell crank mechanism whose effective working lever arm varies from a maximum at the collapsed position of the trailer to a minimum at the fully raised position, whereby lifting forces applied to the trailer are self-equalizing so that the maximum lifting forces are always applied to those points of the trailer which are subjected to the heaviest weight load. The maximum lifting force is automatically transferred from the rear to the front of the trailer as the trailer is raised. The cable is attached to the bell crank mechanism through a dual diameter drum and shaft assembly which provides further force-multiplication or mechanical advantage at the rear of the trailer.
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