The D-400 series engine or the Iron Horse engine was a light-duty

two-stroke engine A two-stroke (or two-stroke cycle) engine is a type of internal combustion engine that completes a power cycle with two strokes (up and down movements) of the piston during one power cycle, this power cycle being completed in one revolution of ...

used for powering

lawnmowers A lawn mower (also known as a mower, grass cutter or lawnmower) is a device utilizing one or more revolving blades (or a reel) to cut a grass surface to an even height. The height of the cut grass may be fixed by the design of the mower, but g ...

produced from the 1950s to the late 1970s. D-400 engines were

single-cylinder engine A single-cylinder engine, sometimes called a thumper, is a piston engine with one cylinder. This engine is often used for motorcycles, motor scooters, go-karts, all-terrain vehicles, radio-controlled vehicles, portable tools and garden machinery ...

s designed and manufactured by the

Outboard Marine Corporation Outboard Marine Corporation (OMC) was a maker of Evinrude, Johnson and Gale Outboard Motors, and many different brands of boats. It was a multibillion-dollar Fortune 500 corporation. Evinrude began in Milwaukee, Wisconsin in 1907. OMC was based ...

(OMC; Johnson and Evinrude) for

Lawn-Boy Lawn-Boy is a brand of lawn mower, originally manufactured by the Evinrude Company in 1934 and owned since 1989 by Toro. It was the first one-handed reel power mower{{what, What is a "one-handed reel power mower"?, date=December 2021 introduce ...

and Masport. The D-400 engines displaced 109 cc, generated of power, and operated in the range of 2400-3300 RPM.

Description

The engines have a distinctive rectangular cowling that has created a nickname of brick-top mowers. Another distinctive feature is the two-finger vertical recoil starter. The kidney-shaped

muffler A muffler (North American and Australian English) or silencer (British English) is a device for reducing the noise emitted by the exhaust of an internal combustion engine—especially a noise-deadening device forming part of the exhaust sys ...

and exhaust unit is mounted beneath the mowers' deck and gives the engine a small, low profile design when compared to the newer and more powerful lawnmower engines. The ignition system employs a

magneto A magneto is an electrical generator that uses permanent magnets to produce periodic pulses of alternating current. Unlike a dynamo, a magneto does not contain a commutator to produce direct current. It is categorized as a form of alternator, ...

, points, and a condenser (capacitor) set-up with an unusual spark-advance system which utilised a weight on the crankshaft to adjust the spark-advance amount depending on engine speed. The sprung governor was also unusual with a throw-yoke which operated under the flywheel and was linked to the throttle. The carburetor was a float design and fed into a pair of reed valves. In

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

and Australia, Masport also known in New Zealand as "Charlie Gamble" offered the D-400 engine on their Premier, Premier II, Rancher, Rotacut, and Tornado models. In this Oceania market, the D-400 was called the Iron Horse engine.

References

{{Reflist Lawn mowers