| 摘要 |
1342352 Current collectors MORGANITE CARBON Ltd 20 April 1971 [20 April 1970] 18671/70 Heading B7L A pantograph comprises a boom 10 pivoted at one end on an insulated mounting 12, an arm 20 carrying a collector head 21 and pivoted to the other end of the boom, springs 13, 28 for maintaining the head 21 in contact with the cable 40, and a thrust arm 27 linking the arm 20 and the mounting 12 and including a lost motion connection 24, 26. This arrangement means that the arm can pivot on the boom without causing the boom to pivot, to accommodate a limited range of variation in operating height, but when the lost motion is taken up the arm and boom pivot together to accommodate larger variations. The arm has a small moment of inertia compared to that of the boom, and may be made from carbon fibres. The lost motion connection consists of a pin 24 and a slot 26 and is offset from the connection between the arm and the boom. Cams 14, 30 over which chains or cables, connected to the respective springs 13, 28, are trained, ensure that the head 21 exerts a constant force on the cable. The boom may carry an adjustable notched cam 16 having a spring- loaded follower 17 to keep the boom in its normal operating position. The spring loading of the arm may be made inoperative on lowering the boom, see Figs. 6 and 7 (not shown). |
