| 摘要 |
<p>A tachometer for high and low speeds, has a lever that operates a microswitch. To ensure low speed functioning, the microswitch (11) operating arm (10) is located as close to the pivot point of the switching lever (9) as possible. The centre of gravity of the lever coincides with its pivot. The lever is made of plastics with a metal part where it touches the operating arm. The switch can be operated despite the small angular momentum of the cage at low speeds. By using a weak return spring, sufficient force can be exerted on the lever to make it operate the switch.</p> |
