Although not as well known as Hagerstown inventor, Ralph Teetor, Marion Davis was also successful with his V-Plex clutch, which was featured as the cover story of Popular Science magazine in June 1969.

This information is from the display located in the Nettle Creek Valley Museum in Hagerstown, Indiana.

• Hagerstown, Indiana

1: By connecting the cone drive's control linkage to a pivoted steering post, the steering wheel becomes the driver's control.  Push the wheel ahead and you go forward.  Pull the wheel back and you go backward. Push the right side of the wheel and you go one way, push the left side of the wheel and turn the other.
 

2: Both wheels turn with full power and the inside wheel can turn on an 18 inch radius.
 

3: The clutch mechanism (shown here in green) was an engineering revolution featured as the cover story of Popular Science magazine, June 1969.
 

4:  There is enough give in the drive, either in the frame's springy mounting, in control rod play, or elsewhere, to allow the twin independent action.
 

• Link

How the V-Plex Clutch Works:

For neutral, cones are unengaged.  In absence of control pressure, self-centering frames of outer cones keep them out of contact with inner cones.

Drive goes into low as control pressure, swinging frames, brings cones into contact.  Small sides of inner cones engage large sides of outer cones.

Contact point travels to high, where large sides of inner cones engage small sides of others, with more control pressure and movement of frame.

For reverse, moving control the other way engages opposite faces of cones.  Otherwise, neutral-low-high action is the same as going forward.

V-Plex Clutch Prototype (as described in the display above)

With a big idea and a little luck, Hagerstown inventor Marion Davis invented the V-Plex clutch in 1958.

The V-Plex clutch was a revolution in engine clutches, transmissions, and differentials.  Though they thought it would not work, they tried it anyway.  To the surprise of Davis and his staff, the mechanism, by a twist of fate, actually worked.  The mysterious clutch worked due to a change in a piece of steel that weakened it and allowed "give" in the material.

The revolutionary clutch went on to be used in the manufacturer of small tractors, golf carts, snow blowers, and garden implements.  The V-Plex system enables the driver to have one control which will start, shift from low to high, slip into neutral, and even into reverse without clutching.  It also allows the vehicle to run as fast in reverse as in forward with the same choice of ratios.

All text after photos is Copyright © Nettle Creek Valley Museum, Hagerstown, Indiana.