These were in two parts, the body and the chassis. The chassis was either 0-6-0, 2-6-2 or 4-6-2, with the driving wheels always the same size and spacing, the middle pair of wheels with no flange.
Couplings for tank engines and the diesel shunter were usually a loop but sometimes a down turned pin. Early models had the loop made up of a riveted tin plate eye but this gave way to a more robust moulded loop.
Couplings for the tender engines had the locomotive were made of a riveted tin plate eye and its matching tender would be a down pin. This gave way to a more robust moulded loop and an up pin. The coupling at the back of the tender was always a moulded loop.