Help please with building a set of Walschaerts valve gear

[hayfield]

I am building a DJH H15 loco and until now have kept away from complicated valve gear, for fear on messing it up. I have attached copies of both the written and diagrammatic instructions which for me are too simple. I am hoping for a bit of online tuition from my online piers 

 

 

Written instructions

 

 

Diagrams

 

 

This is the start of the build diagram Z1

 

I have attached the parts but the crosshead front (D) and other etched part* are able to rotate. I will glue the crosshead front to the crosshead which solves one issue, but should the other etched part be free or attached to either the crosshead front or 14ba nut & bolt please

 

*  other etched part has no letter or description 

 

Thanks

[Skinnylinny]

The other part should be attached to the crosshead front. There's a rather nice animation of Walschaerts valve gear which shows how all the bits rotate and swing, and which bits are fixed relative to the others here:

 

http://trumpetb.net/loco/locoimages/rodsmed.gif

The dangling part is very rigidly attached to the crosshead on the real locos - see this photo available as a stock photo:

https://www.alamy.com/stock-photo-the-front-end-of-a-steam-locomotive-showing-the-walschaerts-valve-125976643.html

[Skinnylinny]

The other part should be attached to the crosshead front. There's a rather nice animation of Walschaerts valve gear which shows how all the bits rotate and swing, and which bits are fixed relative to the others here:

 

http://trumpetb.net/loco/locoimages/rodsmed.gif

The dangling part is very rigidly attached to the crosshead on the real locos - see this photo available as a stock photo:

https://www.alamy.com/stock-photo-the-front-end-of-a-steam-locomotive-showing-the-walschaerts-valve-125976643.html

 

[Edit: Sorry, this seems to have posted twice!]

Edited August 30, 2018 by Skinnylinny

[N15class]

Walschaerts gear is quite simple really. Every joint is flexible apart from the one between the crank pin and and return crank, and the anchor link and the top of the attachment to the crosshead. If there are no tight spots or anything catching on another part nothing will unscrew.

[hayfield]

Skinneylinny

 

Perfect, thank you very much, a picture is worth a thousand words

 

Peter

 

Again indebted to you, will keep the thread going in case I get stuck again

 

Quick question

 

With the rivets, is it worth trying to burr the ends (if so how please). Or can I solder the end without the head?

 

Second quick question

 

On the crosshead regarding the 14 ba bolt, should I cut off the excess and secure the nut with a bit of glue?

 

Thanks

[N15class]

With 7mm I tend to solders 14BA nut to outside, if there's not one, drill and tap 12BA screw from inside with a fan of nut lock to hold in place.

As for rivets I would solder the back. I actually prefer to use forked ends and wire soldered front and back. If you use 14BA screw and nut to hold the gear to the crosshead and one to the return crank, and possibly the expansion link it can all be made removable.

[doilum]

Back to school. Google and watch the animations. Try to learn the correct terminology. I had successfully sorted out W valve gear on an A4 and V2 but confess I didnt really understand it until I built one of the Roundhouse live steam kits. There are some very well illustrated accounts of Finney / Hatchette A3/4 locos.

The tricky bits are the eccentric return crank and creating sufficient clearance between the front wheel and the crosshead. This is assuming the partsyou have to work with are fit for purpose without too much fettling