W.A. Stevens was established in Maidstone, Kent in 1897 by William Arthur Stevens and had by 1906 built its first petrol-electric vehicle using designs patented by Percival (Percy) Frost-Smith. A petrol engine was connected to an electrical generator and the current produced passed to a traction motor which drove the rear wheels. According to the website of the Birmingham and Midland Motor Omnibus Trust the simpler to operate petrol-electric transmission was popular among bus drivers rather than the conventional crash gearbox (in the days before synchromesh) as few bus staff had previously driven motor vehicles.
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... The Tilling-Stevens petrol-electric bus is interesting as an early example of a hybrid vehicle, although without any direct engine propulsion or battery storage ...