| 摘要 |
921,485. Retractive switches. TELEMECANIQUE ELECTRIQUE. Jan. 7, 1960 [Jan. 7, 1959], No. 669/60. Class 38 (5). A limit switch comprises a snap-action switch 1 enclosed in a casing 3 and having a spring- loaded operating button 2 for engagement by a push member 11 mounted as shown in a notch 6b in a shaft 6 journalled in a casing 4 which is screwed on to casing 3. A lever 8 secured on shaft 6 carries a roller 9 which may be struck by a moving object to rock shaft 6 and lift the push member 11 against a spring 16 to allow button 2 to retract (as shown in Fig. 3). The spring 16 acts between the base of casing 4 and a guide cup 15 which has grooves seating on shoulders 11c of member 11. The cup 15 has a part-spherical periphery 18 and allows the member 11 to rock sideways such that a sharp edge A or B of notch 6b can lift the member 11 (Fig. 3) without relative sliding action and hence substantially no friction. A fluid-tight resilient diaphragm 13 having a rigid disc 14 in its centre is interposed between member 11 and button 2. |
