| 摘要 |
<p>SWITCH MECHANISM FOR DOOR OPERATOR An operator for an upwardly acting door. A reversible electric motor is drivingly connected to the door by an intermediate drive linkage. A switch assembly is associated with the operator for controlling the upward and downward movement of the door, which switch assembly includes first and second limit switches for deactivating the motor when the door reaches its lowermost and uppermost positions, respectively. A third switch functions as a safety switch for causing reversal in the motor rotation when the driving force exceeds a preselected maximum. Fourth and fifth cut-off switches are respectively positioned adjacent the first and second switches for overriding the third switch when the door is within a preselected distance from its closed or open position. The limit and cut-off switches are controlled by a rotatable screw member having a pair of traveling nuts thereon which coact with a pair of individually movable control slides. One of the control slides activates the first and fourth switches, and the other control slide activates the second and fifth switches.</p> |
