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04-13-2011, 06:23 PM
A little piece of British motorcyle history.

Some of you may know that my father was one of the engineers who designed the Norton Commando. Here is a copy of an e-mail that he just sent in reply to a friend in Australia, who had sent him information on a proposal for an engine that is supposed to return 100mpg.

There are a few never-heard-before insights and anecdotes in here:

Hi John,

Might be an idea to go to the attached link and printing a copy of the front page of GB Patent # 1171767

The extract is from one of the patents that my colleague and I invented, is shown on the link. This is a two stroke engine with the induction process and the working chamber separated completely from the lubrication process. The lubrication to the piston is dependant upon piston ring technology as present four stroke engines thus preventing lubricating oil being part of the combustion process..

This is the single cylinder version which was derived from our original multi-cylinder version which foillowed the principle that with a two stroke engine it is essential to separate the working part from the lubrication system. The multi cylinder is more obvious in that one pumping chamber transfers into the adjacent working chamber.
This single cylinder version is less obvious but follow through with this description of the cycle.

As the piston moves down air or an air fuel mixture is pulled into the chamber with the larger diameter of the "stepped-piston" then on the up-stroke is transferred into the side reciever volume as the piston moves towards TDC. Then as the piston moves down again through side ports in the cylinder the charge contained in the receiver is transferreds to the cylinder volume above the smaller diameter of the piston. As the piston moves back towards TDC the charge is compressed to be followed by ignition.

The drawing on the patent indicate the working volume is identical to the pumping volume as is the receiver volume. So if one uses logical reasoning we have the following.

One volume is pumped into one volume and expected to be transferred into one volume. How can that work?

When we invented the engine we argued with ourselves that the engine could not possibly work yet our instinct said it would. Calculations could not prove one way or another but we submitted the patent application on the assumption that our instinct, as engine designers, was correct. The only way to prove it one way or another was to build a prototype. We did it on a shoestring as Bernard and I were self employed designing all kinds of things such as ice cream cone manufacturing machines ( I kid you not) other than engines to earn money, and in our spare time we designed engines in accordance with our thinking. I made all the necessary wood patterns, mainly from chipboard, at home. We had the castings made and the machining done and paid for. We "borrowed" certain parts from Villiers which had been taken over during our time self employed, and had become Norton-Villiers. When we finally had all the parts I assembled this prototype engine on the kitchen table at Bernard's house. This was a prototype single cylinder engine with a capacity of 150ccs and we had made twin reciever volumes from standard air cylinders with sealed movable by hand pistons , like large bicycle pumps, each 10 times the swept volume of the single cylinder engine. When ready we took this strange looking engine into the back garden, placed the engine on a concrete slab, wound a length of cord around the crankshaft pulley and then, making sure we had petrol getting to the carburettor, I pulled the cord and although the engine turned over, nothing happened. So I wound the cord around the pulley again then pulled again. The engine started and ran. We all danced around the garden as our instinct had proved to be correct, although we still had no idea why it worked.

We had been invited to cease being self employed and begin an Advanced Development department at Norton-Villiers by the new managing director of the new company based on a recommendation by the Managing Director of Cotton Motorcycles, Monty Denley, and the raft of patents we now had on new engine designs. The idea was that we would work on these new ideas of ours with the object of Norton-Villers producing the results of our research under royalty agreements. We duly returned to the Villiers factory where we had left some 12 months previously and began working on our single cylinder engine. Our work led us to discover the capability and the potential of our engine although we never managed to develop the theory of why it worked. We realized that in some way gas dynamics played a part, but we never did discover how they did. We found as we increased the reciever volume the power ouput of the engine increased. We gradually increased the reciever volume until we reached a volume of 5 imperial gallons, as we would utilize any suitable container in our experiments. So by using a 5 gallon container we were pumping a volume of 150ccs into a volume of 22730 ccs which then was transferred back into 150ccs of the working chamber of the engine.
Everything was going well until the 5 gallon container of gasoline/air mix exploded. Luckily although we were standing close to the engine controlling the Heenan and Froude dynamometer and parts flew everywhere bedding themselves in the noise reducing wall tiles, all the parts missed us. We had realized this was a possibility but the experiment was all important and finding the limit of the reciever volume was our aim. With air only and injecting the fuel into the combustion chamber was the solution and we knew that was the way to go. But events took over.

We wanted to made a prototype diesel engine version and experiment with increasing the ratio of working volume to pumping volume. And all manner of ideas, but the gods had different plans for us. Norton-Villiers had taken over the bancrupt AMC company that made Norton, Matchless and AJS motorcycles. AMC management had stated they had a new motorcycle engine all ready to be put into production and painted a rosy picture. The truth was totally different.
The engine was a terrible design so the new owners of Norton-Villiers needed a new motorcycle to replace the antiquated products. Bernard and I were approached by the Managing Director who had invited us to join the new company, and asked us if we would cease our work on our engines, form a design team that would have the task of designing a practical new motorcycle as otherwise there was no future for the company.

The end result was the Norton Commando, the prototype of which we did in three months.

When the dust has settled and the Commando was a success Norton-Villiers turned to thoughts of new future products. The company produced one of our engine designs in accordance with Hooper-Favill patents and production began. This engine was called the "Vertex". A verticle shaft lawnmower engine with a capacity of 150ccs, a two stroke but with differences defined by our patent. I have a brochure somewhere that state the engine is in accordance with Hooper-Favill Patents The company also approached the National Research Development Corporation ( NRDC) and an agreement for financial support was reached for a new motorcycle design using Hooper-Favill patents for the multi cylinder stepped piston engine. This came all too late to reach production as before development was finalized and the company ceased trading, which is long sad story in itself. The prototype motorcycle called the "WULF" is now in the British Motorcycle Museum in Birmingham.

My colleague and myself the re-formed our design and development company, rented test facilities and office space and continued our engine design consultancy. We continued development of our stepped piston engines and when the manufacturing machine tools and assembly line for the Vertex engine was purchased by a mower manufacturing company we became consultants to the company on the production and engineering side under conditions defined under a royalty agreement. The company was Mountfield Mowers of Maidenhead in Berks.

In 1978 I visited the US in an attempt to interest Briggs and Stratton and Harley-Davidson in our engine designs. This visit was done with the support of the NRDC and the end result was that Briggs were not interested in our engine ideas and neither was Harley-Davidson but Harley made an offer I couldn't refuse and because of numerous reasons I finally agreed to join Harley and my colleague and myself parted ways although we remained friends and through my efforts I was able to get three design contracts, two from Harley and one from another Wisconsin company for design work to be done by Bernard. Bernard continued with the design and development for many years and I always met with him during my visits to England. This ended suddenly when during a visit to England I had arranged to meet with him together with an ex Norton-Villiers colleague and we were to have lunch together. Our ex-colleague met me at our agreed meeting location with the sad news that Bernard had died suddenly.

So now to comments about the engine as part of the Deltic.

The need is to separate the power developing bit from the bit that need lubrication. The use of Stepped pistons would provide the answer. I have doubts about the use of the long con-rod for the second piston and I would guess it brings problems unique to it's use. Gear , chain or toothed belt might be worth looking at . Using stepped pistons, fuel injection and the uniflow two stroke design would produce a very light engine and using a single reciever for both pistons would be easy to do although work on gas dynamics would be necessary. The crank support bearings, big and small end etc. could be lubricated in the traditional manner as a four stroke engines and lubrication of the piston, both diameters would follow four stroke practice with compression, oil control and scraper ring technology. Any liquid fuel that could be injected into the combustion chamber could be made to work but the most efficient would be a using a diesel cycle.


This link will take you to a list of articles by Ed Youngblood but scroll down until you come to an article headed "The Wulf - 1975 to 1980" by Mick Duckworth. You will find a piece about The Wulf Motorcycle now in the National Motorcycle Museum in B-ham that has a twin cylinder 500cc SPX engine ( Stepped Piston Crosscharge) plus a diagram showing the basic principle of how the engine works. Bernard Hooper and John Favill are names mentioned.


04-13-2011, 07:37 PM
Great story. Thanks for sharing. You should post this to the Norton Commando Forum or may I?


04-20-2011, 05:59 PM

Be my guest.....