How were K2 rods jointed?

[John Palmer]

With my lever frame simmering nicely on back burner, I’m now hoping to turn my hand to making an actual model, and have dug out the bits and pieces I’d previously gathered for a Gresley K2. After poring over my collection of photographs of such engines, I was surprised to find that none showed clearly the knuckle arrangement for the coupling rods. I have noted at least one six-coupled model in which the fork is located abaft the trailing crankpin on the front rod section, but so far as memory serves it was more usual for it to form the front of the rear rod section. Consistent with this, I have Roger Farrant’s drawing of a K2 from the March 1975 edition of Model Railways, which shows the rear section as being the one that was forked. Can anyone can confirm that this is correct?

[Tim V]

Lever frame's coming on well John!

I see that the Farrant drawing shows the joint in plan, but not in elevation.

[45609]

Hi John,

I'll post this question to the LNER forum if you are happy with that? Having flicked through my copy of Yeadon's I agree that it is very difficult question to answer as the gib and cotter big end of the connecting rod hides the coupling rod joint in almost all the photos. Even the rear three quarter views.

Cheers....Morgan

[John Palmer]

Tim, I'm very pleased with the frame's progress: nice positive action as the lever pins snap into their detents. You're quite right about the Farrant drawing, and I think the absence of any representation of the knuckle in elevation is a drafting error. If the plan view is accurate, part of it ought to be visible, if only by showing the run-out of the fluting.

Morgan, many thanks for doing that. Stupid of me not to have posted the query on the LNER forum myself, as I'm an occasional contributor there too. I'm surprised by the extent to which that marine-style big end gets in the way in so many photographs. The best I have come up with is a three-quarters rear view of GNR 1671 at page 12 of Locomotives Illustrated issue 67. I think this bears out my provisional conclusion that it was the rear rod section that was forked, but the halftone makes it difficult to be sure and I may be deceiving myself as to what the photo shows.

[Horsetan]

.... I'm surprised by the extent to which that marine-style big end gets in the way in so many photographs. The best I have come up with is a three-quarters rear view of GNR 1671 at page 12 of Locomotives Illustrated issue 67. I think this bears out my provisional conclusion that it was the rear rod section that was forked, but the halftone makes it difficult to be sure and I may be deceiving myself as to what the photo shows.

As a general observation, the popular three-quarter view that photographers go for can sometimes really hinder you when you're looking for the detail.