3.1. The mechanical device: design and construction
A bespoke rotary system for use in circular tanks was constructed.
The device (Fig. 1) which comprised of a novel bearing unit rotating
around a 350 mm high×40 mm diameter standpipe in an anti-clockwise
movement powered by an Air pax 12 V stepmotor with a 7.5° step angle
geared down through a McLennan G11L82 25:1 gearbox and finally
geared down again through a 5.5:1 internal gear housed within the device