Monon B unit. First introduced in 1955 with a four wheeled electric motor, and tab/slot coupler. A cheaper version was available, with a two wheeled non reversing electric motor, fitted with tab and slot coupler. Various versions include powered A units, non powered A units and non powered B units. Couplers include tab and slot, plastic knuckle and plastic tilt. B units were either four or eight wheeled. Powered A unit also available with mechanical (clockwork) motor.
