This machine was originally patented by G.W. Pressey in the USA in 1880, but his invention did not succeed and it was later re-designed by W.S. Kelly and made more practical. The design of the pedals allowed both to be depressed together to get off the mark quickly, or in a close finish in races.
The driving mechanism has two ratchet and pawl clutches, one each side of the driving wheel. When the pedal is pressed the leather connecting strap causes the drum to revolve, a pawl on the wheel spindle engages with one of the ratchet teeth inside the drum and the road wheel rotates. On the upward stroke of the pedal the clutch goes out of action.
From “Bartleet’s Bicycle Book”, H.W. Bartleet, No. 10, page 42