TURNING THE WHEELS
As we know it today, the basic mechanism of the drive axle differential is attributed to Onésiphore Pecqueur. A French watchmaker, he took out a patent for his invention in 1827. It was first used on steam-powered vehicles. Without a diff, to compensate for the speed differential between the wheels when a vehicle is travelling round a curve, some early vehicle builders used chain-drive to one wheel only. Correct – potentially awkward when the driven wheel is on the inside of the turn.
In 1884 – a year before Karl Benz introduced the first internal combustion engined car – inventive Shropshire electrical engineer Thomas Parker put the world’s first practical battery-electric car into limited production.
By the First World War, motor trucks had well and truly arrived. Engineers had three basic choices. A prop shaft driving an axle with a differential, a similar arrangement but with final drive by chains – or, lest we forget, the electric-transmission option, which Tilling Stevens first fitted to production chassis in 1911 (and built the last in the late 1930s).
In their respective markets, Scammell and Mack were two of the most prominent exponents of chain-drive. Mack continued to use it for some models until the late 1940s.
But why chain-drive, especially as power is taken from what in principle is an axle with a
