Lauson Small Engines

My Collection - Second Generation Engines - later group




55A-400

Watch video of my 55A-400 in operation

click an image of a renovated engine on the left to get a larger photo


The Lauson 55 series contains three members: the 55S, the 55A, and the 55AB. I have always thought of these engines as the Lauson “economy” model types; mainly because they must have been cheaper for Lauson to build than the RSH Model they closely resemble. The major difference between the 55 models and the RSH model is that the 55 models incorporate one or more sleeve main bearings, where the RSH has ball bearing main bearings on both the PTO and magneto side of the crankshaft. Additional differences are that the 55 series is devoid of the oil pumps and connecting rod inserts found in most RSH models. All three of the 55 model engines have a bore and stroke of 2 in. x 1 7/8 in; the same bore and stroke as the Lauson RSH.

The 55A and 55S are built from the same block and both have sleeve main bearings on the PTO side as well as the magneto side of the crankshaft. Lauson began building the 55 series around 1951, at the same time they were bringing the RSH series to market and discontinuing the RSC series.

The Lauson 55A more closely resembles a RSH in that a cylindrical gas tank was mounted above the blower housing and a sediment bowl and Tillotson MT2B float carburetor was utilized. The carburetor and tank setup on the model type 55A is also shared by the 55AB model type. The 55A is rated at 2 HP like the RSH.

I acquired this engine through a contact I made through a Yahoo engine interest group. I provide a "before" picture of this engine as well as pictures of it after it's renovation.


55AB-600

Watch video of my 55AB-600 in operation

click an image of a renovated engine on the left to get a larger photo


The 55AB, externally, looks exactly like a Lauson RSH. Internally, it has a ball bearing on the PTO side of the crankshaft and a sleeve bearing on the magneto side.

I acquired this engine from an ebay auction.


55S-103

Watch video of my 55S-103 in operation

click an image of a renovated engine on the left to get a larger photo


The 55S and 55A can be distinguished from the RSH by the different shape of the block on the PTO side of the engine. The block for both the 55S and 55A is cast with a protrusion that was used to attach the gas tank on the 55S model type. This protrusion is not evident on the 55AB model type block.

The 55S model type came equipped with a suction carburetor and had a gas tank mounted to the rear of the engine. In casual appearance, the Lauson 55S looks much like a Briggs 5S or 6S.

The 55S is rated at 1 ½ HP. I believe this rating is a result of the 55S having a suction carburetor and therefore considered less capable of developing the same power as an equivalent engine equipped with a float carburetor.

I acquired this engine at the Lake Waccamaw engine show in North Carolina from a fellow collector. I provide a "before" picture of this engine as well as pictures of it after it's renovation.


LMH-225

Watch video of my LMH-225 in operation
Access an article discussing the renovation of this engine

click an image of a renovated engine on the left to get a larger photo


The LMH was an upgraded LMC, developing 1 HP due to it having a larger bore than the LMC.

This engine is another one that I built from two different engines. It is comprised of the “best” parts from both engines and the result is a very good engine in that it exhibits very little wear.

The first engine was acquired from an eBay auction. It was being parted out, but I contacted the seller and was able to purchase most of the engine. The second was purchased as the result of an Email inquiry.

I include a "before" picture of the first engine of this type I acquired as well as pictures of the renovated engine. One is lucky to find one of these LMH Lausons, let alone two so I am quite fortunate in that regard.


LMV-500

Watch video of my LMV-500 in operation

click an image of a renovated engine on the left to get a larger photo


The LMV is a vertical shaft engine, based upon the LMH design. These engines were uses on small rotary mowers.

I acquired this engine from an ebay auction. I provide a "before" picture of this engine as well as pictures of it after it's renovation.


P-25

Watch video of my P-25 in operation

click an image of a renovated engine on the left to get a larger photo


The Lauson P-25 is a member of the “P” series of engines; starting with the PAC, which was upgraded to the PAH and PAX, and finally culminating with the P-25 through P-44 series. The P-25 through P-44 continued to be built after the purchase of Lauson by Tecumseh into the 1960’s and it is my speculation that Tecumseh probably replaced the P-25 through P-44 with their HH series.

All engines in the Lauson “P” series have the same displacement (nearly 18 cubic inch) with the P-25 through P-44 developing 6 ¼ HP through engineering changes to the same basic PAC design.

The P-25 features ball bearing main bearings, an internal flyweight governor, replaceable connecting rod insert bearings, a forged steel crankshaft, and a plunger driven oil pump; all the hallmarks of other top-of-the-line Lauson engine designs.

I acquired this engine through a "wanted" add I placed on Harry's "Engine Ads" web site. The owner contacted me, saying he had this engine and a sale was arranged. I provide a "before" picture of this engine as well as pictures of it after it's renovation.


PAH-303

Watch video of my PAH-303 in operation
Access an article discussing the renovation of this engine

click an image of a renovated engine on the left to get a larger photo


This engine is an upgraded PAC, developing 5 1/2 HP. It came with the clutch that you see attached to the PTO side of the engine. It is a friction plate clutch that is engaged by pulling the hand lever out, thus sliding the clutch plates together and engaging the clutch. The clutch has a chain sprocket for power output.

The PAH was first introduced in the early 1950's and was replaced by the P-25 through P-44 series in the mid 1950's.

I acquired this engine via a contact I made through my youtube channel with a fellow collector. He had seen one of my videos stating I was looking for a PAH and responded.

A "before" picture of this engine as well as pictures of it after it's renovation are provided.


R-10

Watch video of my R-10 in operation

click an image of a renovated engine on the left to get a larger photo


The Model Type “R” is a unique vertical shaft engine (to Lauson at least) in that the main drive is the crankshaft output that is meant to drive the blade of a rotary mower, but the engine also is equipped with a secondary PTO in the horizontal plane, meant to be utilized to power a self propelled mower.

This is a 2 HP engine, first announced in the early 1950's and discontinued in 1958.

I acquired this engine from a contact I made at the "Old Fashoned Farmers Days" show in Silk Hope, North Carolina. The owner claimed he had a Lauson engine that I did not have included in my exhibit- and he was right! (I'd been looking for an "R" for years!). A subsiquent meeting and a little negociating resolved that issue.

I provide a "before" picture of this engine as well as pictures of it after it's renovation.


RSH-753-9-WT

Watch video of my RSH-753-9-WT in operation

click an image of a renovated engine on the left to get a larger photo


The RSH model is an upgrade to the RSC, producing 2 HP. The RSH were introduced in the early 1950's and several models continued in production after Tecumseh purchased the company and remained in production through into the early 1960's.

I acquired this engine at the "Old Fashoned Threshers Reunion" at the Denton Farm Park in North Carolina. I bought it off of a "junk engine" trailer. It appeared to be "all there", with the exception of a carburetor. I bought it with the intention of it being a "parts donor" but decided to get it running when winter set in and I ran out of other projects.

This specific engine comes equipped with a gear reduction drive.


Goodall-RSHRSH-775

Watch video of my RSH-775 in operation

click an image of a renovated engine on the left to get a larger photo


This is the same engine as the RSC-goodall, but built with the RSH block instead of the RSC block.

I acquired this engine from a contact I made through a Yahoo engine interest group. I provide a "before" picture of this engine as well as pictures of it after it's renovation.


RSH-899

Watch video of my RSH-899 in operation

click an image of a renovated engine on the left to get a larger photo


This RSH was built to power a Toro Roto-Hoe, and is one of the more popular RSH engines built.

I acquired this engine from an ebay auction. I provide a "before" picture of this engine as well as pictures of it after it's renovation.


RSV-800

Watch video of my RSV-800 in operation

click an image of a renovated engine on the left to get a larger photo


The RSV is Lausons vertical shaft version of the Goodall RSH. This engine is the vertical shaft version of the RSH model.

Once the five year contract Lauson had signed with Goodall expired, Lauson was free to build vertical shaft engines and sell them to Goodall competition. In the early 1950's, the RSV was Lauson's top-of-the-line rotary mower engine targeted for this market. The engine differs little from the Goodall RSH-775, other than having a different engine base, a slieve PTO bearing at the block, and a plunger driven oil pump in lieu of Goodall's centrifugal pump.

I acquired this engine from an eBay auction. I provide a "before" picture of this engine as well as pictures of it after it's renovation.


TLH-725

Watch video of my TLH-725 in operation

click an image of a renovated engine on the left to get a larger photo


The TLC was phased out in the early 1950's and was replaced with the TLH, rated at 3 HP. The TLH is a look-alike to the TLC. Externally, the only differences appear to be the different gas tanks and mounting brackets that were used. It appears that the carburetor for the TLH was upgraded to the tillotson MT series. A larger plastic air-cleaner, (larger than the one used on the RSH) was a popular air cleaner for the TLH. Like the TLC, many different sub-models of the TLH were produced.

I acquired this engine from Bob's Small Engines of Iowa. It was sitting in one of his "engines as is" pile. I watched it for over a year, and finally broke down and bought it. When it arrived, Bob had included an additional magneto, a part I discovered the engine needed to get it running; I can't say enough about Bob; he really seems to support his customers.

I provide a "before" picture of this engine as well as pictures of it after it's renovation.


TLV-900

Watch video of my TLV-900 in operation

click an image of a renovated engine on the left to get a larger photo


The TLV is the vertical shaft version of the TLH. This engine shares may internal parts with the RSV.

I acquired this engine from a a fellow collector from whom I'd purchased another engine in an ebay auction previously. I had posted a thread on Harry's SmokStak engine forum, and this collector posted a picture of this engine in response. Wow! this was the first (and to date only) TLV I've ever seen. A little negociating, and a lot of begging and pleading :) got him to sell it to me.

I've supplied a "before" picture of this engine as well as pictures of it after it's renovation.


V-2

Watch video of my V-2 in operation

click an image of a renovated engine on the left to get a larger photo


The cast iron V series stores the crankcase oil in a tank attached to the engine base. With this arrangement, mower manufactures were able to add a thin steel mounting plate to the PTO side of the engine block, thus providing a flush mount for the engine without the need for an oil sump as is found on the RSV, TLV, and Goodall engines. The oil pump, built onto the magneto plate and driven by the same gear on the crankshaft that drives the camshaft gear, could have proven to be a weak design point. With this engine model, an operator definitely wants to make a special effort to keep the engine oil clean and free of sludge and debris.

Oil is suctioned out of the above mentioned oil tank and up through a five-inch long tube before entering the pump on the magneto plate. Two gears that run at high speed and intermesh form the pump internals. The pump has two output ports; one to lubricate the magneto plate main bearing and the other, a small pinhole of approximately four hundredths inch diameter from which oil is injected as a stream into the crankcase. The motion of the connecting rod interrupts this stream of oil and distributes it to the other engines internal parts. The oil pump also has a spring loaded pressure release ball valve that vents into the crankcase to prevent excessive pressures from building up within the oil pump.

Were debris to clog the suction tube, or were the ball valve to unseat with debris, or were either of the pump output ports to clog; lubrication critical for the longevity of the engine would cease. It appears that this happened with this engine, because the camshaft had lost several teeth and the magneto plate crankshaft main bearing had been scored; fortunately, the camshaft gear failed before the bearing was ruined and the engine seized.

I acquired this engine from an ebay auction. I provide a "before" picture of this engine as well as pictures of it after it's renovation.


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