Model 37: stepping belt mechanism

Kinematic scheme:

Explanation:

The sun gear of the planetary gear pair (centre A0, radius R0) is fixed to the frame. The point B lies on the rolling circle of the planet gear (centre A, radius R0/2) and moves along a straight horizontal line through A0. A belt pulley (centre B, radius R0) is rigidly attached to the planet wheel. The contact point between the pulley and the belt, guided by pulleys at C0 and D0, moves by superposition of the sliding motion of point B and the rotation of its pulley. In the vertical position of the crank A0A the velocity of the belt is zero: The belt makes a continuous, but intermittent, motion (stepping motion).

The usual application is to drive a transportation belt with intermittent motion, as sometimes required in production machinery. The (infinitesimal) dwell is short, but the motion is very smooth, see the graph below.

Dimensions:

For a given value of the sun gear radius R0 the other dimensions

are determined as follows:

Planet gear radius AB = R0/ 2

Crank length A0A = R0/ 2

The size of the step of the belt is 2pR0

The pulleys at C0 and D0 may have any radius. In the simulation R0/ 2 has been

taken, yielding two revolutions for one crank revolution.

Literature: Rankers, H.: