Speedy reversing gear

This topic has 6 replies, 4 voices, and was last updated 21 December 2025 at 10:20 by JA.

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19 December 2025 at 18:30 #829407
JA
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@ja
I know this is a popular subject (and has been for over 70 years).

As mentioned elsewhere I am slowly making an LBSC Speedy. I decided to use Don Ashton’s design of reversing gear. However I have just bought Paul Carpenter’s recent book “Miniature Passenger Hauling Railways” in which a post Ashton reversing gear designed by Professor Hall is discussed and recommended. It is dimensionally different to Don Ashton’s.

Before I sit down and do a comparison between the two, does anyone know anything about Professor Hall’s gear?

JA
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19 December 2025 at 20:15 #829415
Speedy Builder5
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@speedybuilder5
No! Speedy in France, I made mine to Ashton’s design. Club comments were impressed by SPEEDY’s adhesion and power.

Bob
19 December 2025 at 21:55 #829427
duncan webster 1
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@duncanwebster1
I know naught of Speedy valve gear, but I knew Prof Hall. He had built his Speedy to LBSC design, so his redesign would have been influenced by trying to use as much of original as possible.
20 December 2025 at 17:16 #829489
JA
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@ja
Duncan

Many thanks for the information. Prof Hall’s gear is very different to Don Ashton’s. He obviously had different constraints, probably the use of LBSC’s gear frame.

I now have to sit down to see if it is as good as Paul Carpenter makes it out to be before I cut metal. I may post my thoughts.

JA
20 December 2025 at 19:23 #829497
Clive Brown 1
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@clivebrown1
As I remember, Bill Hall devised a computerised valve gear simulator, with which he analysed the Speedy valve gear. I’d think you can take it as read that his resultant design is good.
21 December 2025 at 00:02 #829519
duncan webster 1
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@duncanwebster1
I’ve got a copy of Bill Hall’s simulator, but I’m not sure it will run on modern PC. It was written in a Borland C++ windows package.

I’ve also got ‘one wot I rote earlier’ which runs in Python. For a copy of either or both send me your email via pm
21 December 2025 at 10:20 #829530
JA
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@ja
Duncan

Thanks for the offer. I already have a spreadsheet and a FORTRAN program to do the analysis plus others in the club members offering their programs, some written for the old BBC computer. However I will send a PM since more of such things the merrier.

Such tools are an absolute must for anyone looking at or designing reversing gear. Before computers the design of gear must have been very very time and personnel consuming. Swindon originally made a mess of the Walschaerts gear on the 15xx (=Speedy). It was their first attempt at such a gear for about 30 years. I guess many design offices did not change the design once they had a working arrangement.

JA

[edit] C++ and FORTRAN 90 can be run on a PC using Microsoft Studio Visual. Surprisingly this, along with an Intel compiler for the FORTRAN, is free.
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