| 摘要 |
1,230,215. Switch actuation; handles. WESTHEM CORP. Ltd. 18 Sept.,1968 [3 Nov., 1967], No. 44382/68. Heading H1N. An arm 12, Fig. 1, mounted on pivot pins 20 and which may actuate an electric switch, has an integral resilient arm 22 connected by an integral flexible web 26 to an arm 25 on fixed pivots 30, whereby the arm 12 is constrained due to the moment of the tensile force in the arm 22 about the pin 20. As seen in Fig. 1, the arm 22 tends to seek an unstressed position out of the plane of the arm 12. In the arrangement shown, the distance between the axes 18, 28 of the pivot pins 20, 30 is less than the length of the arm 25, whereby the line of action of the arm 25 goes over-centre of the pin 20 to reverse the bias on the arm 12. In a modification, the distance between the axes 20, 30 is greater than the length of the arm 25, whereby the actuator 12 is always biased towards its initial position. Projections 36 of the arm 12 engage the pins 30 to provide an end stop. The pins 30 may engage alternative holes in a fixed plate 32, whereby the arm 12 may have alternative operating positions. The ends of the pins 30 may also be rounded, whereby the arm 12 may be forcibly rotated to disengage the pins from the holes 34. The arm 12 may be of a thermoplastic material such as polypropylene. |
