| 摘要 |
A traction drive elevator system preferably comprises a pair of vertical tracks, a car, and at least one counterweight for supporting at least a portion of the weight of the car. A traction drive, which preferably includes a frame which is separate from the car, comprises two sets of drives, each including a large traction roller and a pair of smaller diameter counter rollers which are disposed on opposite sides of one of the tracks. The axis of the traction roller is horizontal preferably at a height midway between the axes of the counter rollers, and the counter rollers are moveable in a direction toward the track. Means, preferably an eccentric mounting in combination with a gas spring, urge the counter rollers towards the track, thereby creating friction between the rollers and the track. A motor and gear box, which preferably includes a worm and spur gear combination, selectively rotate the traction rollers for moving the car between landings. Finally, a safety bar maintains traction between the wheels and the track in the event the gas spring fails. Preferably, the tracks constitute one of two inwardly projecting tracks of a rail which is U-shape in cross-section. The counter rollers are located in the U-shaped trough, and the traction roller is located to the outside of the rail and therefore can be made of substantially larger diameter. The other track is used to guide the counterweight.
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