Valve Gear

[No.7]

I wonder if anybody can help with a question from England. I am a member of the Trust that owns and operates A4 Class Pacific Sir Nigel Gresley in the Uk. The designer of our locomotive, after which it was named, patented the Gresley Conjugated Valve Gear for 3 cylinder locomotives. The patent was licensed to ALCO in the 1920's.

We know the Gresley design was used on UP 9000 class 4-10-2. We also believe Alton and Southern 0-8-0 used the design and possible New Haven R3 & R3a. Can anybody help with information about these and other ALCO locomotives that may have used the Gresley arrangement?

Thanks!

[Allen Hazen]

I think the Greseley combination gear was used on the 4-12-2 locomotives Alco built for the Union Pacific. (U.P. replaced it, on at least one, with a third set of Walschaerts valve gear.) These locomotives were the topic of one of the old "Locomotive Profiles" pamphlets from the ??? 1970s ???, which might be a starting place for looking for more information.
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The very large 0-8-0 switchers for the IHB (Indiana Harbor Belt -- Chicago area terminal company) had three cylinders. I think they may also have had Greseley gear. Alco built 3-cylinder locomotives for a variety of U.S. railroads in the 1920s, with only a few companies buying more than an experimental sample. I don't know whether Gresley gear was a standard part of the package or an option.

[mp15ac]

Alco used the Gresley three cylinder valve gear system on all of the three cylinder locomotives that they built. The beauty of the Gresley system is that with the exception of the mainrod for the center cylinder all other parts were outside of the frames. This made servicing easier than the double Walcherats system used by Baldwin.

Stuart

[No.7]

Thank for the info, very useful.

In the UK the Gresley gear sometimes gets a bad press because of maintenance required on the pivot for the 3:1 leavers that drive the middle cylinder, however I think you’ve hit the nail on the head when you point out the rest of the parts are on the outside, I’ve read in a number of places that Gresley was very mindful of this when developing the design as he had been involved with some very complex mutli-cylinder designs while an apprentice.

[mp15ac]

The Union Pacific 9000 class 4-12-2's also originally had problems with the center pivot until ALCO beefed up the parts and added a roller bearing to the pivot.

Stuart

[No.7]

Intersting, thanks.