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PD: Primary Drive Three-gear primary drive (Irving Vincent)


peter holmes

Well Known and Active Website User
VOC Member
I don't know the answer to your question, but I would be very interested to know how the ESA is constructed and works, and whether the ESA would be appropriate for a chain driven primary drive.
 

timetraveller

Well Known and Active Website User
VOC Member
If this is designed correctly then the shock absorber is built into the rear of the clutch where it interfaces to the large gear. This is the same idea which is used on some Japanese bikes where there are springs, the same idea as in a car clutch, where one set of springs takes up the forces in the drive direction and the other in the over run direction. This, in conjunction with a Bendix or pre-engaged starter motor in the original dynamo position, would be my direction of travel if I could get round to it.
 

greg brillus

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VOC Member
Several things to remember here......Ok all the engines the Horner's produce are for racing only.........they have a full CNC workshop at their disposal.........and all their parts are new, so not genuine cases and so on. There are very few of us that can approach this level of machining work, except for Vic that is........ For the rest of us, it is a challenge to come up with any of these ideas without destroying expensive parts in the process........They are great ideas non the less. The Horner's engines are visually a Vincent design, the rest is a different story. This is why they are not interested in producing a road bike as they are too different and no standard parts would be interchangeable. They have so many great features that most of us would love to have...........
 

vinhrd998

Website User
VOC Member
Greg, yes very non-standard. This picture showing how the shaft for the middle gear is fitted in the crank case.
Apparently Phil Vincent-Day, PCV’s grandson in the background.

Irving Vincent - Philip-and-the-winningest-modern-iteration-of-his-grandfathers-motorcycles.jpg
 
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timetraveller

Well Known and Active Website User
VOC Member
If anyone is unsure what one of the shock absorbers looks like here is a picture of one from a Suzuki clutch of the type ClevTrev was fitting several years ago. The plate on the right fits on top of the plate on the left. I have put one spring back in place to show how they fit. The plate on the right takes the clutch and the helical teeth on the left hand gear are driven directly from the engine main shaft.
P3280332.JPG
 
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Black Flash

Well Known and Active Website User
VOC Member
Well it is a race engine. I would not be surprised if this engine produces more transmission whine than a standard twin with all straight cut gears in there.
 

plasticbeer

Well Known and Active Website User
VOC Member
Years ago I visited the Horner workshop with Neal Videan. During the tour Ken showed us an HRD crankcase that came from an old speedway outfit. It had a gear driven primary drive with the middle gear mounted on an offset boss fitted into the hole originally used for the left-hand gear change conversion. I just hope my memory of this is correct and I haven’t imagined it.

Vince Farrell
 

Nigel Spaxman

Well Known and Active Website User
VOC Member
Greg, yes very non-standard. This picture showing how the shaft for the middle gear is fitted in the crank case.
Apparently Phil Vincent-Day, PVC's grandson in the background.

View attachment 33085
From this picture you can see how special the heads are. It looks as though the angle between the valves is a lot less than standard.. I knew they had 4 valve heads, I didn't know about these ones.
 

Glenliman

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VOC Member
I wonder which method of primary drive power transmission has the greatest efficiency, belt drive, triplex chain in oil bath or gears in oil bath?
Some claim the belt is best, others the chain. I've gone looking for hard data on this but found nothing substantial.
 
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vinhrd998

Website User
VOC Member
Vince, an offset shaft is on my list! Been thinking of doing that. Someting like this:
offset shaft.jpg
Glen, for me width is the issue. Belts need to be too wide with 1300+cc (as you know) while keeping standard appearance. Chain will always work, but some how I like the idea with gears.
Black Flash, sounds from the gears would probably not drown the roar of the twin anyway, would it?
 

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