| 摘要 |
A mechanical lifting jack. The jack includes a single gear rack having a single row of spaced-apart teeth. A gear member having two pin members is held in meshing engagement with the gear rack by a gear housing circumscribing the gear rack. The teeth of the gear rack collectively define a teeth profile line. The gear member is rotatable about an axis of rotation, and is held by the gear housing such that the axis is maintained interiorly of the teeth profile line as the gear member operates and engageably advances along the gear rack. The pin members preferably reside on opposing sides of the axis of rotation and the teeth are sufficiently long to define gaps therebetween that are longer than diameters of the pin members, structural conditions which combine with the position of the axis to enable the pin members to impose forces against and normal to upper surfaces of the teeth.
|
