| 摘要 |
Automatic braking apparatus for controlling the speed of a vehicle travelling downwardly on an inclined slope. The apparatus comprises a wheel housing, a pair of specially designed wheels mounted in the housing for combined rotary and axial motion, and a rail engageable between the wheels and moveable longitudinally relative thereto. The wheels have tapered camming surfaces which confront one another and annular braking surfaces facing outwardly in juxtaposition with respect to pads of friction material carried by the housing. A load applied between the rail and the wheels forces the wheels axially outward into engagement with the friction pads to retard rotation of the wheels and thereby to limit the relative velocity between the rail and the wheel housing. In one embodiment, the wheel housing is carried by a pallet and the rail is mounted stationary. Wedge means is provided at the lower end of the rail for engaging between the wheels relatively close to their rotational axis to arrest motion of the pallet. In another embodiment, the wheel housing mounts a plurality of the special wheels, and the rail depends from the pallet and engages between the wheels. In this embodiment, motion of the pallet is arrested by causing the rail to enter a zone where the wheels are spaced further apart. Other embodiments are also disclosed. |
