Mackwell Locomotives combine Mackwell boiler technology with a highly successful articulated locomotive concept and state of the art mechanical design.
- The long articulated wheelbase ensures an extremely stable ride allowing the Mackwell Locomotive to glide around the tightest curves and climb steep grades. The high power-to-weight ratio gives maximum drawbar power with the minimum of steel. Mackwell Locomotives are designed for bi-directional operation, no turning facilities are necessary.
- Large water capacity is provided beyond typical service requirements, allowing the locomotive’s weight to be actively adjusted to accommodate sections of lightly laid track.
- Fuel bunker capacity is large to enable the use of the lowest-cost grades of solid biofuel without compromising the useful range of the locomotive.
- An enclosed, climate controlled cab is provided, eliminating the hot working conditions experienced on traditional steam locomotives. Air suspended seats are fitted to minimise operator fatigue. Facilities are provided for using the heat of the boiler to prepare hot beverages and cook food.
Tightly sealed lightweight pistons convert superheated steam into kinetic energy to haul trains. Piston thrust is transferred through rolling element bearings and alloy steel rods to crankpins on each axle. A simple mechanism named Southern valve gear controls the direction and power output of the locomotive. Being external, the moving parts of the transmission are simple and time effective to maintain. The Mackwell Locomotive can be quickly reversed without stopping and dynamic counter-pressure braking is provided to minimise brake wear.
The Mackwell Locomotive is articulated on a highly successful pattern invented in 1908 by Herbert William Garratt. On curves, Garratt’s invention results in the locomotive’s centre of gravity moving inwards, aiding stability, especially on narrow gauge lines. Supplies of solid biofuel and water are carried by the driving wheels, improving adhesion. The length of the Mackwell Locomotive distributes its weight over a large distance, reducing bridge stress.