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Researching the Douglas Patents

by Doug Kephart

On the last trip over to the UK, I spent some time researching the published patents of the Douglas factory and its principal designers. This turned out to quite an enlightening task, much of which could be done via the Internet before I even left my home. Others may want to have a try, it is quite easy, and the steps outlined below apply equally to researching any other company or applicant. So if you wanted to look up patents taken out by the Velocette factory or by your grandfather, have a go!

The first published Douglas patent, first page (though actually for "Light Motors" the immediate predecessor to Douglas.

It is also handy for looking up the number cast on that old hand tool no one can fathom the purpose of. These are often the patent application number or "Patent Pending", but they can be searched for as well.

Searching for a particular patent currently can be broken into two groups, those pre and post 1920. Finding a post 1920 patent is the easier of the two with the use of a computer and the Internet. All British patents from 1920 onwards have been scanned in to electronic format, and can be viewed, printed, and saved to your computer for free.

The format of these files is Adobe Acrobat™ PDF (Portable Document File) a now fairly common format for on-line manuals, instructions, technical documentation and such in the computer world. To view, print, or save the patent to your computer you will need a copy of (Adobe) Acrobat Reader™ installed. This viewer program is free, widely available, and distributed. The computer you are using may already have it installed. If not, it can be had from Adobe's own website,, and I repeat, it is free. It is the program that creates PDF files and documents that costs money.

To access the patent files, go to the European Patent Search website or (note: no 'www'). There is an option to search patent applications for Great Britain only, ignore this! It only searches patents back to about 1960. Use the quick search on the home page or the option to search worldwide, both are for the same database. If you know the patent number, like from the list of patents in the back of Jeff Clew's book "The Best Twin", you enter it on the appropriate line in the search form. The only twist is you need to prefix it with "GB".

All British patents in the database were given the prefix "GB"; even when only searching the Great Britain list you still must use it or your search will come up empty! There is a question mark in a circle next to each field of entry on the search form. This is a button that will show more information as to properly entering the search criteria and correct format for entering dates; useful info.

If the number you enter is a good one, the search form will be replaced by a results form showing the patent number and a brief synopsis. The patent number is in a contrasting color, selecting this is a link to a sub-window showing a bibliography giving a little extra detail (not very much!) Pick the patent number, do not use the check box next to the number. The check box is for if you wish to purchase copies of the patent through the mail. If applicable, above the bibliography is a button to toggle to a view of the drawings associated with the patent, and back to the bibliography. A date and patent class code are given, but this bibliography is mainly a stepping stone to the full patent.

Once at the bibliography, you will again see the patent number in a contrasting color (it is blue). Selecting this takes you to yet another sub-window (it gets a bit cluttered) displaying the complete patent. Look at the opening lines of the patent, it lists the applicants and their address. Make sure you got the folks you intended! From there you can view the individual pages, print them out, or save a copy. My only complaint is each page is an individual file, the patent is not contiguous in one single document. So as you go from page to page, each new page has to be downloaded from the website for you to view. Even though it is automated, it takes time. Likewise if you wish to save a patent, you must open each page individually and save it. Tiresome, as some of Cyrill George Pullin's later patents in the field of helicopters ran nearly thirty pages!

If you are searching for a company name (you can use the applicant's name instead on the same line) enter only "GB" on the line for the patent number to limit your search to just British patents. Rather than a single patent the results form will give a list of patents, that may run over to several pages. Be as explicit as possible, patents use the individuals full name (when they supplied it!) So if you enter Stephen Leslie Bailey, a three page list will appear showing thirty-five patents with synopsis. Cyril George Pullin will produce one hundred forty matches; the last two may be another Cyril George Pullin (I'm not sure at this time.) If you forget to use "GB" to limit you search to Britain you will discover a patent our George took out in Czechoslovakia. If you just enter Douglas, you are going to get every individual and company that has 'Douglas' anywhere in their name! Some companies go through several name changes, or in the case of the Douglas factory, a lot! You have to try them all.

The European Patent Search website can be very slow at times, it is not just used for searching old patents but by patent lawyers to search more recent ones too. Even using a commercial connection, my computer gave up a few times while waiting for the next page to download. Other times it was quite fast. As you can expect of a site of this global nature, the traffic volume can be enormous. I have found you can actually search for patent numbers back to GB136000, which will include some patents that were first applied for in 1918 but published later.

If you want to see a patent prior to 1920, quite a bit more work is involved, depending on where you live. These patents (all British patents and many foreign ones) are held at the British Library, near St. Pancras Station, London. The British Library is a research library, not a lending library. Consequently you can not just walk in and browse the shelves. A pass is required to get into the reading rooms and access the collections. Fortunately the ground work for this too can be done over the Internet and I was able to apply in advance before arriving in the UK. Full details, rules, regulations, and application forms can be had at the British Library's website The British Library is in a newly constructed purpose built site that is quite swank. I must say I was quite impressed and glad it is not my tax dollars paying for it! Once at the library and obtaining your photo ID card at registration, one can then proceed upstairs to the Science 1 South reading room where the patent reference indexes are.

Lacking a convenient list of patent numbers, the first step would be to look in the annual alphabetical indexes of companies. Individual applicants are not always listed if employees. All this will give you is a name and a patent number. By the way, I found some forgotten placeholders next to the W. Douglas entries. Noting down these numbers and the year of the patent, across the room are the volumes containing patent abstracts where in you will find the full name of the applicant(s), address(es), and a descriptive paragraph or two.

There may even be a small picture. This will tell you if you have the right applicant or patent, and not William Douglas and Sons, Putney, London! It will also tell you if it is worth retrieving the complete patent for review. It is important to note the year of the patent. Before 1915, British patents started at patent number ONE every January. So the year will be necessary to find it in the abstracts or retrieve one of the bound volumes of patents. Only after 1915, when they started a new series 100,001 that they have been adding to ever since, is a patent number unique to only one individual patent.

By now you have a list of patents you would like to see. If you have just a few you put in a request at the desk and in about an hour (or more) they will be brought up to collect. If you have a lot, as I did, then you can apply for yet another pass to go down into the basement and search through the patent volumes yourself. This is the far more interesting route of the two. It is not any faster, as you can only be escorted to and from the basement at certain times. And you have to stay down there till the next return time, be warned there are no restrooms! I really do not know how far down the sub-basement is where the patent volumes are kept. You do have to be fit enough to ascend six flights of stairs to get to the nearest exit in case of a fire. All I can say is it is pretty deep. During the two days I spent there I never once had the slightest indication the Underground ran in front of the building.

You will be taken to one of the many large rooms per level, that contain the patent volumes, within which boundaries you are restricted. There is a self-use copier, but you must purchase your copier credits before you leave the reading rooms far above! The patent volumes are located on huge sliding shelf units with the hand capstans to propel them apart along their tracks, twelve feet high and about twenty-five feet long. Portable step ladders are provided; in the crypt like silence their castor wheels squealed enthusiastically. The shelf units line both sides of a ten foot aisle eighty feet long. The number of volumes is mind boggling. As one would expect the volumes are arranged by year and numerically by patent number, and this information appears on the spine so once you winch open the correct wall of books it will probably take you less than a minute or so to lay you hands on it. Other than a staff member occasionally retrieving more modern volumes from a remote part of the room, I had the place pretty much to myself the two days. Time seemed to run at a different, slower pace. Far removed from the real world above ground.

The patent volumes run the full gauntlet of condition. Some are as they were first bound, others have had new bindings in recent years, and others desperately require the same. BL have about 48 million patents in their various collections. There are other reserve sets scattered about England I suppose, as the ones available over the Internet were not taken from the St. Pancras site. For this the patents would have to be taken out of their bindings and fed through an automatic sheet feeder to be scanned. The sheer number of pages to process would demand such automation. Many from the Internet carry the rubber stamp Reserve Copy, Poor Quality (though perfectly legible) or even the price (4s 6d), none of the ones I photocopied at the British Library did. In the case of patent 249,989 Improvements to Silencers, the drawing was missing from esp@cenet but I was able to get it directly from the patent volumes.

Unfortunately a few of the earliest patents applied for by John Joseph Barter or Douglas were abandoned. The numbers are listed in the annual indexes, but when you get to the abstracts you read the dreaded word ABANDONED or VOID after the tantalizing synopsis. Do not even waste you time looking through the patent volumes downstairs for those numbers, I did. You will not find them; they skip right over the number. When a patent was abandoned the Patent Office discarded the patent and all related correspondence, therefore the Library received nothing. But I copied everything I could from 1906 to 1920; £40 spent at the photocopier! Be aware some patents had duplicate first pages, often a correction to the applicants or their addresses had to be made, and tipped in.

I had a look back to about 1885 in the annual indexes, but it does not appear the Douglas foundry started to patent anything till after their association with Barter. There were a pair of Douglas boot last patents that I passed over but it was the Edward Douglas side of the family and was not motorcycle related anyway. If anyone wants to go for them they are 14168 of 1902 and 17820 of 1907. I also passed over a few W. W. Moore's patents of 1908 to 1910. While they were petrol engine related, and he did work for Barter, I believe the history says he declined follow Barter and work for Douglas at that time when he found Douglas were £8000 in the red. One of his patents was a rotary engine, and two were for sleeve valve gear. Probably best for Douglas' formative years that he moved away to Coventry for a while. They were probably not ready for him yet!

Also available at the British Library are the trademark registrations. The indexing and searching of these is too convoluted to describe here. Best to ask the staff to explain it. Suffice to say all the expected ones are there. Unexpected was the registered trademark "Mastiff" number 533,159 in index 2851, Nov. 16, 1932 (but none of the other dog-model names) and "Diamond Star" 534,918 in the index 2852, Nov. 23, 1932. There was no "Golden Star" registered for the proposed 250cc transverse twin. I found in the index of March 13, 1907 "Fairy", number 287,829 registered to "Light Motors Ltd. 180 Gray Inn Road, London W.C. (late of Orchard Street Bristol); Manufacturers- 12 November 1906". The older trademark volumes are brittle and literally disintegrating from high acid content. Every night a little more falls in a gentle shower to the floor and disappears forever into the vacuum cleaner.

So between the various incarnations of the Douglas company, its principle designers, and trade marks I find myself with a stack of 1810 sheets of paper. However the whole lot is now available on computer compact disk at a pittance (see advert in For Sale section) for your convenience.

But what of the individual patents and what conclusions can be drawn from them. One interesting aspect is the address of the applicants is given, though often this is the company address. Sometimes both, as in the case of the Light Motors Ltd. of Orchard St. Bristol, while J.J. Barter resided at "Breamere", Luckwell Lane, Bedminster, Bristol. In 1907 Light Motors Ltd. removed to 180 Grays Inn Rd, London; while Barter still resided at "Breamere". Later he moved to 505 Fishponds Rd, Bristol; given in all his subsequent patents. Likewise William Douglas' address is given as Woodlands, Kingswood, when not using the address of the Works.

One thing I found most interesting was S. L. Bailey held a number of patents of signature Douglas features in his name only. Items like the exhaust valve tappet lifter above the cam shaft of the o.h.v. engines, wick oil reservoirs for the o.h.v. rockers, the RA style brake, the flywheel clutch, mica insulated valve guides, the duplex frame for the OB/OC, the cross-over counter shaft gearbox, the RA crankcase and forked connecting rod, and many others. British law only recognizes those applicants clearly given at the opening statement of the patent as owners of the patent. Yet Bailey must have had some sort agreement with the factory. I could not imagine any company now or then tolerating an employee developing ideas on the clock and then patenting those ideas as personal property. One hoped he waived the royalties!


It was not always so. His first appearance as an applicant is: "Douglas Motors Limited, William Wilson Douglas, and Stephen Leslie Bailey, Engineer, all of Hanham Road …" in a patent granted May 8, 1919. And so it went, sometimes without William Wilson Douglas, till a patent granted March 24, 1921. Here, Bailey is still given as an engineer of Douglas Motors, Hanham Road, but Douglas Motors is not listed as an applicant. Coincidentally, it was about this time Bailey became General Manager. Least one think that listing your employer and the works address makes them a co-applicant as well (though I am advised it does not), many variations then followed. For a while it was just "Stephen Leslie Bailey, Hanham Rd". Then "Engineer, Hanham Rd"; "Engineer of Douglas Motors Ltd". (again); before moving address to "Park View", Staple Hill and giving employment as a "subject of the King…" During this time he used the same patent agent as the factory, Eric W. Walford in Coventry. Then there was a short stint using Boult, Wade & Tennant of London.

Douglas Motors apparently cracked the whip in 1924 on independent patent applications whilst an employee of the factory! Or once his close friend Willie Douglas had died, Bailey's activities came under more oversight. However it is more likely this simply coincides with Bailey departure and return to Australia. I surmise with Bailey gone, Douglas Motors Limited by prior arrangement became primary co-applicant on those patent submitted but not yet granted, the applications again being handled by Douglas Motors' agent, Eric W. Walford. Some of these last patents included the compensating transmission sprocket and the OB/OC timing chest kick start design.

Then in the patents of 1925 Bailey is out and Cyril George Pullin is in, also residing at "Park View", Staple Hill. (Bailey was married to Pullin's sister.) But unlike Bailey, Pullin already had quite a number of patents to his name prior to working for Douglas. As far back as 1920, Pullin and Stanley Lawrence Groom were developing and patenting a two-stoke engine motorcycle with pressed sheet metal frame and forks. After leaving Douglas the first time, Pullin would team up with Groom again to refine these ideas and develop and patent the Ascot Pullin motorcycle (though he discarded the two-cycle engine.)

Like Bailey, during his first stint with Douglas many recognizable features are to be seen in joint patents between the factory and Pullin. Features for the EW like the built up crankshaft, pressed steel wheel hubs and brake drums, the oiling system, timing gears broached for the cam lobes, exhaust valve lifter, and the servo brand brake. The slim oil sump, and the TG, UG, YG prefix cross-over series of gearbox for the o.h.v. models. The F28's head stock and integral steering damper, and the mounting and slip clutch drive of the BTH pancake dynamo. And so on up to 1928 when Pullin left to pursue his dream machine. Pullin scrupulously did not take out any patents of his own during the times he was employed by Douglas.

In 1926, Douglas and Barter took out their last joint patent, 262337(control lever) and 259861 (carburetors.) Just to show how tricky patent searching can be, on one of the patents Barter is listed as Joseph John, and not John Joseph. I almost missed it except for accidentally typing in his name backwards!

Though chief designer from 1913 till he left for ABC in 1922, W.W. Moore was not to have his name included on any Douglas patent, though he licensed his three speed countershaft gearbox to the factory when he joined in 1913. Not even during his second stint of employment with Douglas, when he held even more important positions, was he so favored. At Norton during the mid twenties, he received due recognition on four joint patents.

After Pullin left Frederick William Dixion's name starts to appear on company patents. However Dixion's first patent dates earlier, a joint one held with Bailey for the famous banking sidecar. Applied for June 5, 1923, it was finally accepted in June 26, 1924 (the one year was probably the minimum waiting period for challenges). But in 1928 the factory and he were patenting his chain driven twin cam engine design. Then there is the DT/SW frame, except curiously the lower frame tubes have been replaced by structural angle for the engine to mount on. It includes other claims, like the platform under the seat for mounting the transmission.

The substitution of the lower frame tubes by structural angle seems at first odd, but it appears Douglas wanted to patent the concept of horizontal, parallel frame members to which an engine could be clamped to easily, and allowing it to be slid fore and aft for chain adjustment. Yet they could not include the concept of clamping to a (frame) tube, as no doubt prior usage could cause their entire claim to be thrown out. This very feature of using the frame tube was already claimed in an earlier patent held by Bailey. Then there are some items for the S5/6 models: the oil pump, sump, center stand use on subsequent prewar models, refinements to the flywheel clutch, and the front hub speedometer gearbox drive.

In the gaps between 'famous' chief designers John Douglas, residing at Woodstock, Kingswood, was co-applicant with the factory on patents. During the period between Dixon departure and that of Pullin's return, the factory enclosed the valve rockers on the F/G 31 models and placed the single carburetor in the air box for protection. Both warranted a patent. So too the shift gate cum knee grip of the A31 and more improvements to the flywheel clutch. An aluminum clutch disk with friction inserts first appears. Also many patents related to unexciting industrial lift and platform trucks were granted during this period. Yet John dabbled on the side too. There are a few sidecar related patents in his name only, as well as two for identifying livestock (cast number tags) and one for buttons. The iron 'sandwich' valve plate like used on the aluminum barrel Blue Chief and Endeavour models is in John's name only, as well.

Pullin is back in 1932, with the Douglas three wheel car. After getting that out of his system there are the cooling aspects of the S5/6 sump to claim, and the engine cradle of the Douglas Bantam model. The kick starter they had been using since about 1926 finally got legal protection in 1932. Then Pullin's name appears on a string of patents for the lift truck and stationary engine end of the business. No doubt this is so exciting it drives him away for good! Then it is back to John Douglas, now of the same address as the Works.

Submitted September 16, 1932, but not accepted until February 8, 1934, was the o.h.c. valve mechanism of the Dryad light aircraft engine. As I had a preview of Dave Rodgers' article before it was published (Nov/Dec 2001, New ConRod Magazine). I had a look in the trademarks for Dryad but Douglas did not register it. Personally I think a more appropriate name would have been Dyad. It would have made more sense than naming it after a wood-nymph. Perhaps they were returning to their Fairy origins.

Aero Engines' first patent was applied for in February 1938 for a duplex tube frame that does not appear to have been for any model produced. It shows the rear wheel bearings in the frame as first used on the Endeavour, but no claim is made for them. It also shows the side by side top frame tubes that went into production later on the post war Mk series. Reading the patent language, it is hard to figure out just what is innovative or novel about this "rigid and robust frame", but it does say the frame particularly lends itself to a transverse engine layout. With conversion to normal rigid rear spindle and telescopic seat post, I suppose it could have been the precursor to the DV60 prototypes, or an early genesis for the T35.

As befitted their aeronautical name, there are patents related to improvements of various aircraft engine sub-systems. It looks like Aero was trying to get into the fuel injection business, with patents for metering and pump devices. However like their plans of manufacturing aircraft engines under license, this new direction in patents never took off. The only way they were going to get off the ground was with a lift truck, now with a novelty of a hydraulic lift system powered by the engine, patented of course.

Then there is a string of electrical related patents, new territory for Douglas (sorry, Aero Engines Limited.) Philemon Sykes of Huddersfeild working for Aero, was an electrical engineer. In fact from 1925 to 1937 he had taken out patents under the firm of Sykes & Dyson Ltd, all of an electrical nature. But motorcycles were where Aero Engine's fate lay. It would be interesting to find out why Philemon left Huddersfeild to work for Douglas, with his background he must have seen something terminal in them.

The suspension system used on the post war range is, as expected, patented by (now) Douglas Kingswood Ltd. An interesting variation of rear torsion bar suspension has a fast helix at the back end; the swing arm is connected directly to a coaxial piston-nut threaded over this helix. They have the grace to admit it is not as good as the other system (that went into production), due to the greater friction. The torsion bar front suspension patent I found interesting as it showed how they planed to connect the torsion bar to the leading link.

These did not actually go into production, instead being replaced by the 'Radiadralic' front forks (I forgot to look that up in the trademark journals.) Besides the link and shuttle arrangement used, an alternate variation is given using a rack and quadrant gear connection. Interestingly enough the coil spring depicted is round wire section. Perhaps that is what the earliest machines used, though I only know the square section taper ground o.d. of variable rate as used on my Mk3.

The last Works patent was applied for in 1946, and granted in September 1948, for a bi-fuel carburetor. Oddly, thought they still had ten years left and one more motorcycle model to go, that was it for their patents.

The Last Douglas patent, top of first page.

© 2002 D. Kephart



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