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The toy is operated manually by turning a handle (see below). This turns the cam profile, lifting the arm and food towards the ‘models’ mouth. Installing different cam profiles, gives a slightly different movement of the arm.

The pear shaped cam profile allows for a smoother action as the arm rises and falls. However, for half the rotation of the cam, the arm stays in the same place. The snail profile allows for a smooth rise and a quick / sudden drop of the arm.

The advantage of a pear shaped cam, is that the handle can be rotated in both directions, because the arm lifts and falls smoothly. However, if a snail drop cam is fitted to the mechanism, the handle must be rotated in an anti-clockwise direction only. Otherwise it will ‘jam’.

The pear cam below slowly rotates in an clockwise direction.

As it rotates the follower drops down.

For half the rotation, the height of the follower does not change, called the ‘dwell’ (a characteristic of pear shaped cam profiles). The dwell is when the cam continues to rotate, but its shape means that there is no change in the position / height of the follower.

The follower then begins to rise again.