Using the four bar chain model, rotary motion is converted into oscillatory motion. An anodised aluminium disc is mounted on ball bearings as a crank. The disc has a scale so that the input angle can be exactly measured. The crank pin can be set at different radii on the disc. The connecting rod and the oscillating lever, made of black anodised aluminium, can be connected together in different lengths using easy to fit knurled bolts. The oscillating crank is attached to a disc with an angle measuring scale.
All components are fitted to a white plate fitted with plastic feet. The unit is placed on the laboratory table for the experiment. Two metal handles make the unit easier to carry.