Initially the Armstrong-Saurer lineup consisted of licensed built Saurer 5BL trucks, developed in Switzerland in 1928. All components were supplied by French division of Saurer. British standards allowed operating motor vehicles with higher load.
Thus, the basic 2-axle models received in England names Active, Durable and Effective, and had a capacity from 4 to 7 tonnes. All were equipped with a 6-cylinder diesel engine rated at 110 hp. For a while, there were also gasoline powered versions available, but they were quickly replaced by diesel trucks.
In addition to the 6-cylinder diesel engine, these trucks were offered with a 4-cylinder diesel power unit. Such trucks received designation Defiant and Diligent. There was also another model the 7-8-ton Dauntless with a 6-cylinder engine.