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Location: Salop
Car type: '28 GE Cup. '28 AD Chummy '30 RL Saloon. '34 RP Saloon. Too Many toys!
Graham
I suspect the bloody great flanges on the Austin pulleys somehow manage to keep the belt on.
Father had a 3 bearing engine in the RP for a whill. That had a crowned cam pulley in cast iron, no flanges. But the fan pulley retained its flanges. It worked fine
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Of course the pulley should be crowned.
The one in the photo is completely worn out.
Like Hugh I do wonder why on earth you'd want to fit ball bearings.
Austin would not approve of the extra expense.
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Location: Deepest Frogland 30960
Car type: 1933 RP Standard Saloon
There's not really much point in over-complicating the fan pulley design by adding ball or needle rollers, the original design works fine, but if it floats your boat why not. What is important though is that the fan belt is not over-tensioned - that just puts strain on the pulley, its shaft and the bearing. The only thing driven by the belt is the fan, so it doesn't have to be bowstring tight. In fact quite loose (or even not there at all) seems to work fine in most circumstances.
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Location: Auckland, NZ
15-02-2022, 03:48 PM
(This post was last modified: 15-02-2022, 08:29 PM by Bob Culver.)
I have read explanations of how the crowning works but whilst I am happy to explain roll centres, effect on handling etc, secondary unbalance and so on, I am not confident to attempt!
My father's lathe had a soft flat canvas belt and fast and loose pulleys and the way the belt sorted itself on each pulley intrigued me from a very small boy.
(for those less than 70 years old, machinery was commonly driven from constant rotating shafting. Larger machines had clutches but for smaller the driven pulley had a loose or free pulley alongside . The belt was pushed by a slider (or hand!) sideways and quickly centred itself on the other pulley
(editted to correct. Driven not driving pulleys are fixed and loose so the belt is always running. As not convenient to have the paired pulleys on the actual machine, usaully an intermediate countershaft involved.)
Joined: Feb 2021 Posts: 292 Threads: 31
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Location: New Zealand
Car type: Austin 7 Ruby 1938
Hi Bob,
Yes, I also worked my father's lathe driven by flat belts on crowned pulleys with no flanges. As a young engineer I spent a lot of time working with conveyor belts on crowned unflanged pulleys.
RR,
Thanks for the explanation of how crowning works. I now finally understand what is happening.
Regards
Graham Barker
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Location: Llandrindod Wells
Car type: 29 Special, 30 RK, 28 C Cab
Hi Steve
While on the subject of fan pulleys remember to fit the felt washer behind the pulley. I couldn’t see the reason for this felt until I heard the dreadful chatter and then grease thrown around the engine.
The felts sold by the Cherished suppliers are Austin spec but I found them too thick so cut them in half with a Stanley knife.
Cheers
Howard
Joined: Aug 2017 Posts: 2,418 Threads: 33
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Location: Deepest Frogland 30960
Car type: 1933 RP Standard Saloon
At the top of the page click on "Website Home" and then on that page click on "Cherished Suppliers" and take your pick...
but where do I purchase them from. Thank you Dom