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Balancing rear brakes on uncoupled cars
#1
Has anyone looked how Rolls Royce solved this balancing problem between left and right rear bakes?
The principle is described below (https://www.rrec20hpregister.com/media/3579/small-hp-brake-systemsv2.pdf):
The function of the brake equalisers is to apply the same tension to the pull ropes on each side of the car, and this is done by a bevel differential, identical in principle to that of a rear axle. Th mechanisms consist of two shafts, one long and one short, each with an output lever at its outer end and a bevel wheel at its inner end. Between these bevels is a planet carrier trunnion to which is bolted the input lever.
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#2
"I could have thought of a much more complicated way of doing it said The Red Queen, immensely proud".
Jim
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#3
Wow! To paraphrase Conan Doyle, that looks like a two pipe read!
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#4
Good to know that one task is to "...the axle can be set up on a turret mill and a skim taken out of the bore to clean up." Joking aside, what a well-written article and such an amazing braking system.
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#5
How else would you design a braking system?
Alan Fairless
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#6
Like the "Small Horsepower" in the title!
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#7
Hi

I recently had cause to help out a friend troubleshoot the weakener system on his 1970's Rolls Royce. For those unfamiliar, this setup slightly leans off the mixture supplied by the two large SU carbs when cruising, by applying a small negative pressure to the top of the float chambers. It lowers emissions and improves the fuel economy, probably from 10 MPG to 10.5 MPG.

The total setup devised by RR for this one small function comprises a dedicated air filter, an air bleed needle valve, a cutoff solenoid with thermostatic switch, a "fuel receiver" device, a one way drain valve and no less than 11 rubber hoses.

I got the feeling that the RR designers got into a bit of a hole with this design, but kept on digging....

We did find the fault in the end, someone had inadverently swapped over two same-size hoses under the car. All good fun, and satisfying once you have worked out how it's supposed to function. Unlike the earlier cars, the RR workshop manuals assume you already know how the various bits work so it was quite a head scratcher.
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#8
If you think the SU set up is complicated, try the Solex 4A1
Alan Fairless
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#9
This equaliser set up was applied to an early 30's Talbot front brakes and worked very well even when the front brakes were intentionally set up incorrectly and gave perfectly balanced braking both straight ahead and on lock! It would be relatively easy to apply to the rear brakes on uncoupled brakes - after eliminating flexing brake cross shaft mountings. is it known for certain whether torsional strength of the cross shaft is inadequate?
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#10
Sounds like you are trying to fix a problem (with a complicated solution) that dosen't really exist in a properly set up and well maintained car. I have owned and worked on many Austin 7 for over 40 years now and never really found it necessary, even when racing, to move much beyond the std set up. It's an Austin 7 for heavens sake!
Black Art Enthusiast
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