The Uncommon Lauson Engines

Looking Beyond Frost Kings at Unusual Lauson Engines

WG Crankcase

Figure 11

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Catalog A also shows a new W Series model, the WG (Figure 11). The WG is an enclosed crankcase, hopper-cooled engine rated 2 HP at 500 rpm to 3 HP at 800 rpm. The bore, stroke and flywheel diameter are the same as on the open crankcase Model W. The WG engine uses Timken tapered roller-bearing main bearings and features splash lubrication of the crankcase components. Ignition is by Wico EK magneto and spark plug. This model features a water-cooled cylinder head (with atmospheric-operated intake valve) along with a throttling-governor carburetor for gas, gasoline or kerosene fuels. A gear-driven flyball governor is located inside the crankcase. These engines were available in semi-portable (mounted on wooden skids) and stationary (mounted on a sub-base) versions. The WG does not appear in Catalog F, dated 1937.

Catalog B introduces the Model LW vertical-cylinder water-cooled engine. The standard model LW engines were equipped with a pump/splash lubrication system, but a bottle-oiler equipped variation was produced that was, apparently, sold only as an Alpha-name plated engine by DeLaval under the designation of 'Alpha Junior.'2 This engine is described in detail in the DeLaval publication Alpha Dairy Power Plants, dated May 1931.

The Alpha Junior was equipped with the same bottle oiling system and suction-feed carburetor as used on the RA and RAU air-cooled engines. It had a published rating of 3/4 HP at 900 rpm and 1-1/4 HP at 1,600 rpm. The Alpha Junior was sold as a packaged unit featuring a vacuum-milker pump and electric lighting generator that would provide dairy farmers with vacuum for the milker system, lighting for the work area and hot water (from the engine cooling tank) for washing up after milking. See Figure 12 for an illustration of the Alpha Junior unit and Figure 13 for a cut-away of the engine showing the bottle oiling system.

The carburetor shown in Figure 12 appears to have a rack-and-pin-ion throttle linkage, which may not be representative of actual production carburetors. On two engines in the authors' collection (one RAU and one Alpha Junior), the throttle valve is a spool-valve located in-line with the governor weights. As an aside, it is interesting to note that Alpha Dairy Power Plants also shows the Lauson Model VW engine, designated as the 'Alpha Senior,' and the Lauson Model RAU engine, designated as the 'Alpha Midget.'

By the late 1930s, Lauson was building several models of inboard marine engines that were variations of standard industrial models. Catalog O-97A, dated Dec. 15, 1939, describes the following marine models:

Air-cooled: RLM 3/4 HP, RSM 1-1/2 HP, TLM 2-1/4 HP (Figure 14), LBM 3 HP.

Water-cooled: RCM 1-1/2 HP, LF 3-3/4 HP (Figure 15), ZW 5-1/2 HP (Figure 16).

All of these, with exception of the ZW, were supplied sans governor, with a hand throttle control connected directly to the carburetor. A water pump was included as standard equipment on the water-cooled models. Other standard features included a marine-style engine base, flame arrester air cleaner, magneto ignition and, except for the RLM, a float-feed carburetor. The RLM was equipped with a suction-feed carburetor.

Various combinations of reversing gear drives and gear reduction drives were options for all of these engines. A reverse gear was included as standard equipment on the TLM and a reduction-type forward/reverse v-belt drive was standard equipment on the RLM. The RLM, RSM, RCM and TLM engines could be furnished with a lighting coil in the magneto, while the LF could be ordered with a ring-gear type electric starter and v-belt driven generator. Production of the Model ZW ceased during 1941, but other marine models continued to be produced until, approximately 1951.

By 1940 Lauson was building, in addition to the Model LW, a smaller water-cooled engine designated as the Model RCR (Figure 17). The RCR developed 1.1 HP at 3,000 rpm and, like the LWR, it was furnished with a radiator, thermosyphon cooling system. Cooling air for the radiator was ducted from a shroud surrounding the flywheel fan. Aside from the cooling system, the design of the RCR is similar to the air-cooled Model RSC.

Outboard Motors

In 1940 Lauson entered the outboard boat motor market with the Sport King Model A-410, a single-cylinder, four-stroke, air-cooled engine. The complete motor (engine and lower unit) was produced by Lauson and the Sport King engine was designed specifically for the application. Around 1941 Lauson also produced some lower cost outboard motors using vertical crankshaft variations of the Model RSC and TLC industrial engines. The Model RSO carried a rating of 2-1/4 HP at 3,000 rpm. The Model TLO (Figure 18) carried a rating of 4 HP at 3,000 rpm.

Between the mid-1940s and 1957, Lauson produced the Model H-2 oil-test engine (Figurel9). The H-2 was built specifically for use by oil companies in the testing of lubricating oils. This engine is a water-cooled model rated 4.3 HP at 2,400 rpm. It was supplied with a rope starter, mechanical governor, flywheel magneto, float-feed carburetor, pump/splash lubrication and ball bearing main bearings. Standard special features of the Model H-2 included:

Electric heater built into the engine base.

Removable dry-type cylinder sleeve.

Evaporative cooling system with a condensing tank on the cylinder head.

Hinge between the cylinder block and engine base to facilitate inspection or overhaul.

Covered hand hole in the side of the crankcase to facilitate inspection of the connecting rod and bearing shell.

Stellite overlay on the exhaust valve and seat.

Adjustable spark timing.

Optional equipment consisted of an oil-bath air cleaner and a standardized loading fan with guard. Apparently, the H-2 was also available without a governor; the authors have two examples of the model that do not have any external governor linkage. One of the engines has the governor weights and sleeve on the crankshaft; the other does not.

The last inboard marine model to be added to the series, the PMM (Figure 20), was produced between 1948 and approximately 1951. The PMM was rated 5-1/2 HP at 3,000 rpm. This engine was furnished without a governor. Two versions were available; one with a plain rope starter and the other featuring a ring-gear type electric starter and a belt-driven generator.

The authors would like to thank Tecumseh Products Company for permission to reproduce the Lauson catalog images used in this article. The authors are unaware of any surviving examples of the two-cylinder opposed model, the two- and four-cylinder vertical models, the 40 HP and 50 HP single-cylinder models and the RSO/TLO models. Any information regarding survivors will be greatly appreciated.

Additionally, any date-specific Lauson information will be appreciated, as the authors are still working toward a long-term goal of producing an illustrated Lauson engine and tractor reference book.

Contact engine enthusiasts Betty and Mac Sine at: 13 Main St., Lawrenceville, PA 16929.


1. Gasoline Engines, Volume 6, by Alan C. King, 1980, page 48.

2.This engine was erroneously described in the 1996 article as being a variation of the Model RAG.