Allan Brothers Oil Engine on a Return to Glory

Scottish-built Allan Brothers oil engine settles in Arizona for complete restoration.

Allan Brothers Oil Engine

This Scottish-built Allan Brothers Oil Engine was completely restored by Wayne and his son, Brennen.

Photo By Wayne Peters

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Manufacturer: Allan Brothers, Aberdeen, Scotland
Year: Circa 1903
Serial number: 991
HP: 19
RPM: 230
Bore: 9-1/2-inch
Stroke: 17-inch
Flywheel dia.: 54 inches
Flywheel width: 6-1/2 inches
Weight: 6,000 pounds
Ignition: Hot tube
Governing: Hit-and-miss, vertical flyball 

Circa 1903 Allan Brothers Oil Engine

I am the proud owner of an Allan Brothers oil engine, serial no. 991. It's a product of Aberdeen, Scotland, manufacturing, and was built around 1903. It is rated at 19 HP at 230 RPM. It has a 9-1/2-inch bore and a 17-inch stroke. The flywheels are 54 inches in diameter with a 6-1/2-inch face and curved spokes. The engine alone weighs 6,000 pounds. This engine, unlike most oil engines, is a 4-cycle design and is hit-and-miss governed. It has a hot tube ignition and is headless. It is a sideshaft design with a vertical flyball governor and turns counterclockwise.

The history of this particular engine dates back to World War I. The engine was used in an English shipyard to power machinery. During the World War II scrap drives, it was somehow missed for the scrap heap. A club member from California informed me it may have been too large to deal with at the time or just located inside a building and long forgotten. At some point in time it was moved to the Hunday Museum in Corbridge, in northern England.

Jerry Towers purchased the engine on May 4, 1985, at an auction held at the museum and shipped it to Kansas. Mr. Towers sold it to Sam Curry, who now resides in Arizona. In March of 2009 I purchased the engine from Mr. Curry at the Arizona Flywheelers Engine Show. Mr. Curry also gave me an article written about the history of the Allan Brothers engines. It appeared in the June 1986 issue of The Old Machinery Mart Magazine, which is published in Australia.

Allan Brothers engines were manufactured in Aberdeen, Scotland, from the late 1800s to 1925. A series of three engine types were built during that time period: continuous lamp engines with serial numbers 0-500. None are known to exist today; the more common continuous lamp engines with serial numbers 501-2200 were produced during 1901-1912; lamp-less type engines, requiring only a lamp to start, were produced during 1911-1925 with serial numbers 2100-4315. The few Allan Brothers engines that we have seen are all smaller and most have been converted to magneto ignition. We were fortunate to purchase the Allan Brothers oil engine with the original hot tube and chimney setup.

I contacted Jerry Towers to see if he had any additional historical information about the engine. He, in turn, gave me the name of Geoff Challinor in England to contact. My letter to Mr. Challinor was returned unopened.

The engine did run when it was purchased, but after we returned home and gave it the once-over we decided it was best to do a complete restoration. My son, Brennen, and I spent 15 months restoring the engine to its present day condition.

Initially, we needed to take the engine off the trailer. I am retired from Southwest Industrial Rigging. They offered us use of a large forklift to lift the flywheels and the engine off the trailer and to reset the engine when completed. We built a rack to support the crankshaft and flywheels so it could be turned for cleaning and painting. All other parts of the engine were removed and boxed until needed. The cylinder was left on the base.

We inspected the trailer and noted that the cross members were bent and not positioned for proper weight distribution of the engine, which was mounted solid at only one end of the trailer. We figured the proper locations for additional cross members that would support the engine, air tanks, water tank, propane boxes, a toolbox and an air compressor. Our plan was made and work began.

My son is a technician for Sav-Trac of Arizona, a repair facility for equipment, which uses overhead cranes. We towed the trailer to their shop and used a crane to position the trailer for straightening and welding. The cross members were reinforced with 2-inch receiver tube under the engine and two additional cross members were affixed. We checked the axles, brakes and bearings and did repairs as needed. The trailer was painted and then rewired. Working in the Sav-Trac shop certainly made our job more efficient.

Mechanically, the engine was in pretty good shape. It had a lot of blowby and loose bearings. The cylinder bore was good; it was honed, cleaned and measured. The piston ring grooves were severely worn, so we had the ring grooves trued up to equal widths at a machine shop used by Sav-Trac. Custom rings were ordered from Niagara Piston Ring Works in Clymer, N.Y. The wrist pin was out of round; it was trued, hard-chromed and ground. The bearings were refit, and the valves cleaned and lapped. All parts were cleaned and bead blasted, and all broken bolts replaced.

The engine was painted and set on the trailer. We set the flywheels on the engine, adjusted all bearings, installed piston rings, connected and reinstalled the rod and piston in the cylinder, installed sideshaft gears and shaft bearings along with governor linkage, flyballs, etc. Next we installed the vaporizer, chimney and hot tube assembly along with brackets and mounts for the cooling tank. Air tanks and an air compressor were fabricated and installed. Both systems were then plumbed to the engine.

We purchased two new propane torches for their fine adjustment. We made an adjustable sled for the hot tube torch, as well as brackets for the vaporizer torch. Other items were addressed e.g., we re-routed and streamlined fuel and propane gas lines, made a bracket for the exhaust valve spring, made four wood blocks to support the trailer while running the engine and purchased two hydraulic jacks for setting up the engine. We also purchased tools and fittings that might be needed at an engine show. All items can be stored in the toolbox and/or trays, so the engine is ready to go at any time.

Intake valve and flyball governor

The Allan Brothers engine runs on no. 2 diesel fuel. The fuel is drawn up through a check valve to a needle valve to an orifice in the seat of the 3-inch atmospheric intake valve. The intake valve housing is mounted to a 90-degree ball chamber called a vaporizer. The hot tube is mounted in the bottom of the ball, and the other end of the vaporizer is mounted to the combustion chamber.

Engine speed is controlled by the flyball governor, which is attached to a catch block on the exhaust rocker through a pivoting linkage.

Most hot tube oil engines are volume-governed, firing every ignition cycle, and are a 2-stroke design firing every rotation. This maintains a higher temperature so lower grade fuels can be used. Since this is a hit-and-miss governed, 4-stroke engine, temperature control can be challenging because of the cooling effect of the miss cycle and when the engine runs while not under load at shows. This is most notable in windy conditions, which cool the vaporizer.

The engine is a continuous lamp engine i.e., an external heat source must be on the hot tube at all times. The vaporizer generally needs to maintain a temperature between 300-400 degrees internally. The vaporizer torch is used only to start the engine, and when it has run for a short time the torch can be turned off.

When the engine slows down, the exhaust valve closes and a charge of liquid fuel and air is drawn into the cylinder through the vaporizer where it is then heated to a vapor but not burnt. The mixture is then compressed down into the heated hot tube where it is ignited then discharged on the exhaust stroke. This concept is simple — once proper temperatures are reached and maintained. If the vaporizer becomes too cool, the engine will misfire. If it is too hot, the charge is burnt or the engine preignites or fires early. In most cases, the engine starts and runs continuously all day without any issues.

The torches we use are propane with fine adjustment on the flames. They are not original, but because of safety issues with old liquid blowtorches, we decided to go this route. The original hot tube burner was also missing.

An infrared thermometer helps maintain the proper temperature. A support pin cast into the vaporizer helps to support the chimney. The engine runs perfectly as long as the external temperature on this pin is maintained at 520-530 degrees.

Other issues we dealt with involved carbon build-up in the hot tube and vaporizer; the buildup was due to the cool running and the location of the hot tube on the bottom of the chamber versus the top as on most hot tube engines. After cleaning out the carbon, I contacted a few people for their suggestions to address these issues. One person suggested injecting water into the combustion chamber to help break up the carbon before it builds up. As luck would have it, this engine is equipped with a valve for injecting water. The original purpose of the valve was to prevent the engine from preignition when kerosene was used as fuel. We recently checked the hot tube and vaporizer and both seem to be working properly. There is a little white smoke in the exhaust, and it doesn’t fire quite as hard, but the engine runs great.

This engine is equipped with an air start, but also has a starting lobe on the sideshaft cam. We have never tried to start it by hand because of safety issues i.e., having to stand on the fenders of the trailer, and the number of people it would require in order to achieve a hand-start. The engine starts easily with 80-90 psi air pressure. When everything is oiled, primer cup filled, hot tube and vaporizer heated, and engine set just past top dead center, air is sent through a ball and check valve to the cylinder and, in most cases, the engine starts on the next revolution.

Most people assume that the casting has filler in it. We assure them it doesn’t. It is amazing considering the size of the casting and the era in which it was built. It is truly a great testament to the expertise of the mold and casting crews of that time. The engine is well-balanced. The crankshaft has large counterweights on the throw, and when blocked up the engine and trailer barely move while it is running. It is another testament to their engineering skill.

The restoration and the EDGE&TA

The restoration of this engine was an immense project. A lot of planning and effort was involved in restoring an engine of this size. There was a bit of a learning curve, but each issue was worked out separately to achieve the final result.

We enjoy sharing information and answering questions on the engine’s mechanism and history with people at the eight or nine shows we attend each year. We are members of the EDGE&TA Branch #206, where our engine was featured at the 2012 show in Wellton, Ariz. We are also members of the Arizona Flywheelers and attend various shows and festivals around the state.

I want to extend a special thanks to all of the following for their help in making this project a success: Southwest Industrial Rigging for providing us with a forklift; Sav-Trac of Arizona for the use of their shop; Tom Kelley, who offered his assistance on several occasions and for his expert brass polishing; club members who provided us with helpful information and advice; Sun City West Metal Club for items they machined and fabricated; Fred and Helen Zinn, Tom Kelley and Imogene Black for providing photographs of the engine for our use. Lastly, a special thank you to my son, Brennen, for the many hours he spent working on this project with me, for the use of his property and for his help writing this article.

I welcome all letters and emails regarding the history of Allan Brothers engines.

Contact Wayne and Brennen Peters at 17774 W. Camino Real Drive, Surprise, AZ 85374 • imo1212@aol.com