| 摘要 |
A hoist mechanism is provided that includes a first and a second lifting arm connected at a first pivot point, a hydraulic cylinder connected to said lifting arms, and a stop located on one end of the second lifting arm. During the initial lifting of the hoist mechanism the first arm remains stationary as the second lifting arm rotates around the first pivot point. The hoist mechanism functions in this manner until the two lifting arms reach a predetermined angle with each other. When the lifting arms reach this angle, the stop acts to convert the action of the hoist mechanism into that resembling a scissors hoist, with both lifting arms rotating, as the hoist mechanism is further extended. The hoist mechanism is designed such that the effective length of the second lifting arm is constantly increasing as the second lifting arm rotates from the rest position to the predetermined angle. This is accomplished in certain embodiments including a shaft attached to the dump bed and a track which is a part of the second lifting arm. The shaft and the track function as a slidable connection which transmits the weight of the dump bed and its payload onto the hoist assembly. The shaft is confined within the track and moves back and forth therein as the dump bed is raised and lowered. |
