Dentists chair with drive at centre of swing arm - has equal length jacks above and below arm

摘要

The dentists chair has an adjustable top part in one or more sections and which can be raised and lowered on a floor-mounted base. The base comprises a baseplate (1), a support (13-16) for the top part (5) and a swing arm (3) the latter attached between the baseplate and the top part. To keep the baseplate and top part parallel when adjusting the latter for height, a drive (12) is mounted roughly at the mid-point of the arm, with jacks of equal length on either side, acting against baseplate and top part. The length of these jacks is kept equal while the drive is working and the arm is swung up and down.