Motorised extending scissors arm for movement of tools - has guide plates at base end with tracks guiding middle link pins of first scissor pair always and pins of last scissors pair when arm is withdrawn

摘要

The free end (16) of the arm is supported on two parallel series of scissors (2,3). At the base end (8) of the arm are guide plates (17,18) with tracks (28,29) in line with the middle link pins (4,5) of the scissors pairs. Guided always in the tracks are rollers (20,21) on the middle link pins of at least the first scissors pairs (19). Guided in the tracks when the free end (16) is withdrawn are rollers (26,27) on the middle link pins of the last scissors pairs (15). Joining the middle link pins (24) of the last scissors pairs is a bracket (23) sliding on a guide rod (22) fastened to the free end. The rear end of the guide rod enters a bore at the base end (8) when the arm is fully withdrawn. ADVANTAGE - Greater accuracy of arm movement and reduced play. Loaded arm can be accelerated sideways without stressing scissors linkage.