Walschaerts valve gear in 4mm

[SWTDriver]

Please can somebody clarify which bit I need to solder to what? (See attached)

 

 

[JeremyC]

Yes the return crank needs to be soldered to the crankpin. Usual practice is to put a tight fitting paper washer behind the return crank to stop you soldering the connecting rod as well (this is removed after soldering).

Generally providing the crank pin is tight enough it won't unscrew. If you want you can secure the pin with a thread locking compound (proper thread lock is weak enough to let you remove the pin if you ever need to). Also note that on most locos, with the crankpin at the bottom the return crank leans forward on both sides, (most rtr gets this wrong.)

Edited August 29, 2018 by JeremyC

[Dave Holt]

I think Jeremy C has answered your question.

One other point to note. Your valve gear is modelled in mid-gear (that is, the radius rod (with the slotted end) is in line with the expansion link pivot/mounting) so the reversser lifting link should be in line with, and partially cover, the slotted portion rather than drooping down, as shown in your photo.

Dave.

[N15class]

Also note that on most locos, with the crankpin at the bottom the return crank leans forward on both sides, (most rtr gets this wrong.)

This depends on whether internal or external emission valves.

 

With the valve gear all the joints need to be mobile, except the return crank on the crankpin. And the part that holds the union link to the crosshead.

[Dave Holt]

This depends on whether internal or external emission valves.

 

 

Inside admission valves with outside Walschaerts valve gear is not so common in British practice, rebuilt Bulleids excepted. Would also require the connections to the valve spindle and radius rod to be swapped at the top of the combination lever.

It would help to know what loco is being modelled.