| 摘要 |
A brake and clutch assembly for electric motors is mounted to a drive shaft of such an electric motor. The drive shaft includes a pin extending diametrically therethrough. A brake pad provided around the motor shaft abuts on the motor side a fixed plate with the following components being provided also around the motor shaft in succession outwardly from the brake pad: a drive disk, a clutch plate, a pulley, a compression spring and an end cap. The drive disk includes a sleeve extending around the motor shaft. The clutch plate and the pulley are slidably mounted around the sleeve of the drive disk. The drive disk defines a diametrical V-shaped recess which faces towards the brake pad with the pin extending in this recess. The spring biases the pulley and thus the clutch plate and the disk drive towards the brake pad. Therefore, when the motor is not operating, the drive disk is frictionally retained into position against the brake pad. The force of the spring and the friction between the pulley, the clutch plate and the drive disk, in addition to the gearing-down mechanism between the pulley and the equipment end driven by the motor, prevent these components from rotating when the motor is not operating. When the motor is started, the pin will climb out of the bottom of the recess defined in the drive disk by pushing the drive disk against the compression spring, thereby axially also displacing slightly the clutch plate and the pulley, whereby the disk drive becomes spaced apart from the brake pad and can thus rotate with the motor shaft while frictionally rotatably driving the clutch plate and the pulley. During operation of the motor, the rotation of the pin drives the drive disk and of the components in frictional engagement therewith. If outside resistance forces are applied against the rotation of the pulley, the clutch plate will slip thereby allowing the pulley to slow down or even stop while the clutch plate, the disk drive and the motor shaft continue to rotate thereby preventing damage to the motor. The friction forces between the clutch plate and the pulley are sufficient in -order to operate the pulley under normal conditions but are insufficient to stop the clutch plate and thus the drive disk and the motor shaft if the pulley is forced to stop rotating. |
