Friction Wheel Drive System

The Friction Wheel Assembly, used on many of our self-propelled snow throwers and some of our other self-propelled devices, operates on the principle of two intersecting circles (or drive discs) positioned at right angles to each other.

In a practical example, the following is a lesson on how a friction drive system changes wheel drive speed and direction, while the augers and engine use the same drive mechanism that maintains a constant and fixed rotational direction and speed.

1. Imagine two discs (dinner plates, coins etc...) positioned with one horizontal and one vertical and having the vertical disc positioned standing with its bottom edge centered over the exact center of the horizontal disc.
2. If the horizontal disc is rotated the vertical disc in the exact center position should remain stationary.
3. Now begin to rotate the horizontal disc clockwise at a constant rotational speed, slowly move the vertical disc to the left. The horizontal disc should begin to rotate and as you move it slowly from center. The farther to the left of center the disc is moved, the faster it should rotate. This increase in vertical disc rotational speed will occur even if the horizontal disc remains at a constant rotational speed.
4. Now slowly move the vertical disc to the right of center. As the vertical disc passes the center position and moves to the right of center, the rotational direction of the vertical disc will reverse and rotate the opposite direction. This rotation will also increase in speed as the vertical disc is moved towards the right edge.
5. All of this while the horizontal disc remains at a constant clockwise speed and rotational direction.

To adjust the NEUTRAL position on your wheel drive system the rubber coated friction drive wheel must be positioned at the exact center of the friction drive plate when the shift lever is placed in the NEUTRAL position. NOTE: If your snow thrower does not have a designated Neutral, then the friction wheel should be slightly off-center in each of the lowest speeds for both forward and reverse. Please refer to your Operator's Manual or Professional Shop Manual on how to do this adjustment for your particular model.