Second Generation Engines

RLA


The RLA was brought to market in around 1935 and was produced throughout the war. Every RLA I have ever seen has been tagged with a “Department of the Navy” identification. For this reason, I don't believe these engines were built as consumer products; though many were surplused after the war ended.

These were ½ HP cast iron engines and it appears that most of these engines were set up to power generators, I assume for field communications. I’ve seen many mounted in a frame and set up to drive a generator with dual 500 volt and 12 volt outputs, which would be typical of a vacuum tube radio of the era. These engines are setup to run in the reverse direction from most other small engines. Like most other second generation Lauson engines, the RLA is equipped with an oil pump and dipper trough. It has a high tension magneto, driven by magnets on the flywheel and a flyweight governor, built onto the crankshaft.

There are a surprising number of these engines available for collection, and they are quite popular with collectors

The engine pictured is from my personal collection. You may view other pictures of this engine by clicking Here

RLC


The civilian version of the RLA was the RLC, brought to market also around 1937. These engines were produced with either a suction or float carburetor. Many different configurations of RLC were built; some with petal start, lever start, or rope start. These engines are built with "nearly" the same block as the RLA and they run clockwise (from the blower side of the engine). This engine produced 1/2 HP and was built until the late 1940's. The engine has four cylinder head bolts, as do all other RL type engines.

I've seen these engines used on water pumps, tillers, and generators.

For Lausons, these engines are very popular with collectors and they are often merely identified as a "4-bolt head Lauson".

All these 4-bolt head models have ball bearing main bearings and most use a pump/splash oil system, where an oil pump delivers oil from the sump into a dipper trough, where the connecting rod dipper splashes the oil about the crankcase to lubricate the engine. All these 4-bolt head models but the RLM inboard marine engine are equipped with a flyweight governor.

You may view pictures of the RLCs in my collection by clicking Here or Here

RLB


The Model Type RLB was a modified RLC built for washing machine use with a vertical power-take-off attachment. Lauson must not have built many of these engines because I have never seen one.

These engines came out probably around the same time as the RLA and were probably built to replace the RU.

RLE


I have seen a few Model Type RLE Lausons. These engines appear very similar to the RLA and all the ones I have seen were used to drive generators. I've never seen any Lauson literature regarding a RLE and it's a mystery to me what distinguishes them from the RLC.

RLM


The RLM is an air cooled marine version of the RLC. The literature states it had a reduction-type forward/reverse V-belt drive as standard equipment. This engine could be furnished with a lighting coil in the magneto.

This engine would have powered the smallest of boats, probably not more than a small rowboat.

LMC


Around 1948, Lauson introduced the LMC Model Type. These were small cast iron engines of 3/4 HP and it is my belief that they were built to replace the RLC Model Type. They are small-displacement engines, with a bore of 1 5/8 inches and they were used primarily on small reel type lawn mowers. The LMC were built in two basic configurations; the earlier models were equipped with a Tillotson YA2A carburetor and the later models were equipped with a Tillotson MT7A carburetor. The LMC features ball bearing main bearings and employs simple splash lubrication. They were replaced by the slightly more powerful LMH in the early 1950's.

These engines are very popular with engine collectors.

The engine pictured is from my personal collection. You may view other pictures of the LMCs in my collection by clicking Here or Here

LMH


The LMH was an upgraded version of the LMC, offered from the early 1950's through until 1958. All these engines came equipped with a Tillotson MT7A float carburetor.

The LMH has a slightly larger bore than the LMC, giving it 1 HP. Most parts are interchangeable between the LMC and the LMH. It is difficult to tell the LMC and LMH apart; the telltale difference being the shape of the PTO side of the block, where the LMH is built so that equipment can be attached, where the LMC is not built in that manner.

These engines are probably as collectable as the LMC, but there are many more LMC available than the LMH so you rarely see an LMH

The engine pictured is from my personal collection. You may view other pictures of this engine by clicking Here

LMV


The LMV was the vertical shaft version of the LMH. The LMV were built during the same period as the LMH, both these engines share the same block design. The LMV has an extended oil sump bolted to the base of the engine which stores the crankcase oil. A wire extension to the connecting rod agitates the oil in this sump, thus providing lubrication.

It has been suggested that these engines were used to power small rotary mowers as used to mow around tombstones on cemetery applications and I have seen a LMV installed on a small rotary mower

This LMV and the above LMH are both fairly uncommon engines today.

The engine pictured is from my personal collection. You may view other pictures of this engine by clicking Here

RSC


The RSC Lauson was probably the most popular engine Lauson built. It is a "scaled-up" version of the RLC, producing 1 HP, and later in it's production cycle, 1 1/2 HP. The engine incorporates a 6-bolt cylinder head and is very difficult to distinguish from the RLC when looking at a picture.

The RSC first appeared around 1937 and were built through into the late 1940's and possibly into the early 1950's. These engines replaced the RAY and were eventually replaced by the RSH models.

They were built with ball bearing main bearings and replaceable sleeve bearings on the connecting rod. Most all were equipped with oil pumps, driven off a lobe on the camshaft.

The engines were built with rope start, kick start, level start, and crank start. This engine model was built in a wide profusion of models; the sub model number (as in model type RSC-591) generally indicates the customer for whom the specific model was built and the features incorporated in that specific model type.

These engines found a wide variety of uses including water pumps, reel mowers, sickle bar mowers, blowers, aircraft heaters, scooters; their application was nearly endless. Specific models of this engine were built for special purposes, such as the RSC701 was built specifically to power Jari sicker bar mower.

Being the most prevalent Lauson built, these engines are very popular with engine collectors.

The engines pictured are from my personal collection. You may view pictures of the RSCs in my collection by clicking Here or Here or Here or Here or Here or Here or Here or Here

RSM


The was an air cooled marine version of the RSC. The RSM was not equipped with a governor and had a hand throttle control connected directly to the carburetor. Other standard features of this marine engine were a marine style engine base, a flame arrester air cleaner, magneto ignition and a float feed carburetor. This engine could be furnished with a lighting coil in the magneto.

Various combinations of reversing gear drives and gear reduction drives were options.

The engine pictured is from the collection of Peter Bezanson.

RC


The RC was a water cooled engine, based upon the RSC engine.

The engine pictured is from the collection of Bart Price.

RSH


The RSH was the upgraded version of the RSC and for this reason, the RSH was a very popular engine for Lauson. The RSH was built in many versions, with many options, as requested by the customers for whom the different models were built.

The RSH has the same bore and stroke, and thus the same displacement as the RSC. Lauson states the power output of the RSH to be 2 HP. These engines were built with ball bearing mains and replaceable bearing inserts on the connecting rod. Most models were equipped with an oil pump and dipper trough.

Visually, it is difficult to tell the RSH from it's predecessor- the RSC. The easiest identification difference is to look for the absence of the crankcase breather which, with the RSH was moved from the front of the engine block to the valve cover beneath the blower housing. also, the Tillotson ML type carburetors that were widely used with the RSC engines were replaced by MT type carburetors; with the MT2B carburetor being the most prevalent.

Like the RSC, these engines are very popular with engine collectors.

The engine pictured is from my personal collection. You may view pictures of the RSHs in my collection by clicking Here or Here

RSV


The RSV was the vertical shaft version of the RSH. This engine differs from the Goodall/Lauson engine in that a sleeve bearing is incorporated on the PTO side of the block and a plunger driven oil pump is incorporated within the oil sump. A ball bearing main bearing is used at the bottom of the oil sump where the crankshaft exits the housing.

These engines can be differentiated from the Goodall/Lauson vertical shaft engines by the shape of the engine mounting plate/oil sump cover. The RSV utilizes a constantly sloping base while the Goodall/Lauson engine has a stepped base.

This engine matches the bore, stroke, and displacement of the RSC. The model RSV was stated to be a 2 HP engine.

The engine pictured is from my personal collection. You may view other pictures of this engine by clicking Here

55S


The 55 series of engines appear to be Lausons attempt to create "economy" versions of their RSH model. The 55S block has a cast protrusion on the PTO side that facilitates mounting a rectangular gas tank below the suction carburetor. This protrusion also appears to be built to support a lever and idler pulley, probably used to facilitate the employment of a simple slip-belt clutch for certain applications.

The 55S employs simple splash lubrication, has sleeve main bearings, and does not employ replaceable bearings on the connecting rod. In other areas this engine resembles the RSH. This engine matches the bore, stroke, and displacement of the RSC. The model 55S, because it employs a suction carburetor, was downgraded to a 1 1/2 HP engine.

The 55S appeared in the early 1950's and was built through into 1958.

The engine pictured is from my personal collection. You may view other pictures of this engine by clicking Here

55A


The 55A was a model 55S but equipped with a MT-2B Tillotson float carburetor. This also necessitated the employment of a cylindrical gas tank as used by the RSH models. Lauson supplied a Parts Kit #26207, which included all the necessary parts to convert a 55S to a 55A.

The 55A appeared in the early 1950's and was built through into 1958. This engine matches the bore, stroke, and displacement of the RSC. The model 55A was stated to be a 2 HP engine.

The engine pictured is from my personal collection. You may view other pictures of this engine by clicking Here

55AB


The 55AB employed a RSH style block. The engine has a ball bearing on the PTO side of the crankshaft but a sleeve bearing on the magneto side. In all other respects, the engine is built like a model 55A. This engine matches the bore, stroke, and displacement of the RSC. The model 55AB was stated to be a 2 HP engine. These engines made their first appearance in the early 1950's and were built through into 1958.

The engine pictured is from my personal collection. You may view other pictures of this engine by clicking Here

V


The The cast iron model V was another attempt by Lauson to build an economy engine. Do not confuse this engine with the alloy block engines that Tecumseh built in the late 1950's. This engine has sleeve bearings on the crankshaft and it does not have replaceable bearing inserts on the connecting rod as the RSH engines do.

This engine is a vertical shaft engine that has a flush mount, there is no extended oil sump as with the RSV. The engine sports a rectangular oil reservoir to contain the crankcase oil, and an oil pump on the magneto plate suctions oil out of this reservoir and distributes it to the top main bearing and crankcase. This engine matches the bore, stroke, and displacement of the RSC. The model V was stated to be a 2 HP engine. These engines appeared in the early 1950's and were built through into the mid 1950's.

These engines appear to have been susceptible to lubrication system failures and for that reason, there are not that many extant.

The engine pictured is from my personal collection. You may view other pictures of this engine by clicking Here

R


The model R was a vertical shaft engine that provides an auxiliary output in the horizontal plane. These engines were built to power rotary mowers and the horizontal output was used to create a self propelled mower. The Model R has a ball bearing on the magneto plate and a sleeve bearing on the PTO side of the crankshaft. The engine has a wet sump and an oil pump integrated into the horizontal drive. This engine matches the bore, stroke, and displacement of the RSC. The model R was stated to be a 2 HP engine. The engine appeared in the early 1950's and was discontinued in 1958.

The Model R is a very uncommon engine.

The engine pictured is from my personal collection. You may view other pictures of this engine by clicking Here

CH17


I have very little information on the Lauson CH17 and CH20, though the information I have leads me to believe they were built very late in the sequence of Lauson production. Their model number matches the naming convention of the early Tecumseh engines, and for this reason, and several others, I am lead to believe they were built after the Lauson purchase by Tecumseh in 1956. Both appear to have been discontinued in 1958 when Tecumseh discontinued nearly all the Lauson cast iron models. Both the CH17 and CH20 appear to be built much like the 55 series, with sleeve bearings, simple splash lubrication, and no connecting rod inserts. Both engines appear to utilize a Tillotson MT type float carburetor. The engines appear identical with the exception of the gas tank.

The CH17 is a 1 ¾ HP engine and uses a rectangular tank, attached to the cylinder head.

CH20


(See specification for CH17 above for details)

The CH20 matches the CH17 in ever detail with the exception that it is stated to be a 2 HP engine and it uses a cylindrical gas tank, mounted to the cylinder head as in the RSH models.

Today, both the CH17 and CH20 are very uncommon engines.

TLC


The TLC engines were available with a choice of hand crank or rope starter. Several models were equipped with a gear reduction drive. Other models had a magneto lighting coil and some were supplied sans an air cleaner.

The TLC was a 2.3 HP engine, a scaled up version of the RSC. These engines proved to be another popular engine model for Lauson, and many were built. These engines featured ball bearing mains, and replaceable sleeve bearings on the connecting rod. They were equipped with oil pumps, driven off a lobe on the camshaft. As with the RSC, one cam lobe drove a pair of cam followers which in turn, drove the valve lifters and valves.

The TLC were first built in the late 1930's and were replaced by the TLH model in the early 1950's.

These engines also found a wide variety of applications. They were used for grain elevators, scooters, mowers, concrete mixers, pumps, blowers, and many other applications. As with the RSC, specific models of the TLC were specifically adapted for a specific purpose; such as the TLC316 which was built specifically to power the Model 74 Salsbury motor scooter.

The TLC is another very popular engine with engine collectors.

The engine pictured is from my personal collection. You may view pictures of the TLCs in my collection by clicking Here or Here or Here

TLM


The TLM was an air cooled marine engine, built from the TLC design. This engine was delivered without a governor and a reverse gear could be included as optional equipment. These engines also could be furnished with a lighting coil in the magneto.

You may view a picture of the TLM in my collection by clicking Here

TLH


The TLH was the upgraded version of the TLC. The TLH was built in numerous versions and with many options, as requested by the customers for whom the different models were built.

The TLH has the same bore and stroke, and thus the same displacement as the TLC. Lauson states the power output of the TLH to be 3 HP. Most of these engines were built with a MT5B Tillotson float carburetor. They were built with ball bearing mains and replaceable bearing inserts on the connecting rod. All models were equipped with an oil pump and dipper trough.

Visually, it is difficult to tell the TLH from it's predecessor- the TLC. The easiest identification difference is to look for the carburetor type. The TLC was equipped mostly with a MS type carburetor while the TLH was equipped with a MT type carburetor.

The TLH first appeared in the early 1950's. The TLH was built by Tecumseh into the early 1960's and was eventually replaced by the Tecumseh H series.

The engine pictured is from my personal collection. You may view other pictures of this engine by clicking Here

TLV


The TLV was the vertical shaft version of the TLH. The engine is built in the style of the RSV and many of the parts that make this a vertical shaft engine are interchangeable with the RSV. The TLV is a very difficult engine to find now-a-days, I suspect very few were built. This engine appeared in the 1950's and was discontinued in 1958. It was replaced by the alloy block Tecumseh V30.

The engine pictured is from my personal collection. You may view other pictures of this engine by clicking Here

PAC


The PAC was a scaled up version of the TLC, providing 4.25 HP. This was a large, heavy engine having nearly an 18 cu. in. displacement with a bore and stroke of 2 7/8th in. x 2 ¾ in. These engines first appeared in the mid 1940's and were built into the early 1950's. They were replaced by the PAH model.

These engines also featured oil pumps with dipper troughs, ball bearings on the crankshaft, and replaceable insert bearings on the connecting rod. This engine used the same governor design as the RLC, RSC, and TLC.

The engine pictured is from my personal collection. You may view other pictures of this PAC in my collection by clicking Here

PAM


The PAM was an air cooled marine version of the PAC. Photo courtesy of Peter Bezanson

PAX


The PAX was brought to market around the same time as the PAC, in the mid to late 1940's. The engine differs from the PAC by having an external magneto; either the FMX1B93 Fairbanks Morse or the Wico XH-2256 magneto was used. This engine also produced 5 1/2 HP. The PAX is a difficult engine to find today; I suspect relatively few were built.

The engine pictured is from my personal collection. You may view other pictures of this PAX in my collection by clicking Here

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PAH


The PAH was an upgrade replacement to the PAC. The engine looks much like the PAC; however the engine produces 5 1/2 HP. The engine first appeared in the early 1950's and was replaced by the P25 through P44 series.

The engine pictured is from my personal collection. You may view other pictures of this engine by clicking Here

P


The models P25, P26, P27, P30, P36, P39, P43, and P44 first appeared in the mid 1950's. These engines replaced the PAX and PAH and were the last evolution step of the PAC, PAX, PAH, P series. The P series were built by Tecumseh into the early 1960's and were eventually replaced by the Tecumseh HH engine.

The P25 also had an external magneto. The P25 through P44 uses the same two magnetos as the PAX models.

I have seen AD material where this engine was used on a garden tractor

The engine pictured is from the collection of Dave Kirk.

You may view pictures of the P-25 in my collection by clicking Here

H-2


The H-2 oil test engine was a specialized engine, developed by Lauson. It was a water cooled model rated at 4.3 HP at 2400 rpm. The H-2 was built specifically for use by oil companies in the testing of lubricating oils. The H-2 was supplied with a rope starter, a mechanical governor, a flywheel magneto, a float carburetor, an oil pump and dipper trough, and ball bearing mains. The H-2 included an electric heater built into the engine base, a removable dry-type cylinder sleeve, an evaporative cooling system with condensing tank on the cylinder head, a hinge between cylinder block and engine base to facilitate inspection or overhaul, a covered hand hole in side of engine to facilitate inspection of the connecting rod and bearing shell, a Stellite facing on exhaust valve and seat, and adjustable spark timing.

Optional equipment consisted of an oil bath air cleaner and a loading fan with guard. The H-2 was first available the mid-1940s and was produced through into 1957.

PMC


The PMC was a water cooled stationary marine engine offered from the late 1940's through into the early 1950's. This engine shares the same block as the PMM. Photo courtesy of Peter Bezanson

PMM


The PMM was a water cooled inboard marine engine offered from the late 1940's through into the early 1950's. Photo courtesy of Peter Bezanson

L50


I don't know much about this engine type; I suspect that they were built in the 1950’s. I've only seen two or three of these in my travels and the examples I’ve seen lead me to believe they were built for the military; I've never seen any literature regarding them. One of the examples I encountered was setup in a cage, as if it drove a generator or pump; another example appeared to have some type of pre-heater installed for low temperature operation (just a guess). The engine appears to share the same (or nearly the same) block as the P-25 and comes equipped with an external magneto as with the P-25 or PAX.

Goodall Lauson


Toward the end of the 2nd world war, Leonard Goodall began looking for a company who would produce vertical shaft engines for his new invention; the rotary mower. His negotiations with Lauson were successful, and Lauson was licensed to produce the vertical shaft engine for Goodall's push mower. The engine produced was a modified RSC with an attached oil sump positioned beneath the engine with the PTO passing through it. This oil sump contained a centrifugal pump, used to jet oil into the engine crankcase for the necessary lubrication. a flat plate with the crankcase breather attached was supplied at the engine base to close the crankcase. These engines were produced as early as 1947 and were supplied to Goodall without an engine identification tag.

These RSC horizontal to vertical conversions were the first engines to be applied to rotary mowers in sufficient quantity and with sufficient success to raise public awareness of the merits of rotary mowers. For this reason, the "Goodall Rotary cutter" should be considered the rotary mower that revolutionized power mower production and brought about the demise of the reel power mower.

Beginning with Goodall mower serial numbers 20K-12831 and 18K-7496 the RSC Lauson block was replaced with the RSH block. Lauson provided and engine identification for these engines which is RSH-775.

The Goodall mowers with the RSH blocks will use the RSV curved base with the crankcase breather located under the blower housing on the valve cover plate as with other RSH engines. The RSH-775 will also have the RSH type starter pulley and will use the MT-2B carburetor. In all other areas, the RSC Goodall and RSH Goodall engines are identical.

Here we see a Goodall-RSC on the left and a Goodall RSH-775 on the right.

Lauson built one additional engine for the Goodall mower. This was a modified RLC (modified in the same way the RSC was modified). This engine looks very much like the RSC Goodall engine, except it is based upon the 4-bolt head RLC.

The engines pictured are from my personal collection. You may view other pictures of these engines by clicking Here or Here

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