| 摘要 |
A switch and speed control assembly for use in a wet/dry utility vacuum or b lower is disclosed. The switch and speed control assembly provides a single rotary co ntrol actuator for turning the vacuum or blower on and off, for infinitely varying the speed of the motor, and for providing a momentary boost control. The switch and speed control assembly i ncludes a thumb wheel fitted to the shaft of a voltage varying potentiometer, a snap action switch in operable relation to the exterior edge of the thumb wheel, and a compression spring c ontained beneath the thumb wheel. As the thumb wheel is rotated in an increasing "on" direction, the contacts of the snap action switch are closed, allowing electric current to flow to the moto r of the wet/dry utility vacuum or blower. The voltage levels in the motor, and correspondingly the s peed of the motor, are controlled by varying the potentiometer voltage through rotation applied to the thumb wheel. During boost operating conditions, the thumb wheel engages the compression s pring such that when the force engaging the momentary boost condition abates, the thumb whee l returns to a normal operating condition. Additional features incorporated in the switch a nd speed control assembly include: mechanical stops for both the "Off" and "High On" modes; a static guard to protect the electrical components and the user from static discharges; faste ner free mounting within wet/dry utility vacuum or blower housings; a configuration designed t o prevent mechanical loads present on the thumb wheel from being transferred to the po tentiometer shaft and other electrical components, such as the switch; and internal wire routi ng designed to minimize inductive influences between the wires.
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