Hello All,

I have another question out there,

Has anyone heard of the Franklin tandem light main or side rods? These rods were made by the Franklin Railway Supply. I'm researching the CPR 3100 and it and its sister 3101 were equipped with this experimental running gear. However, almost immediately they were removed my the new Chief of Motive Power but no reason was given.

You can see the Franklin tandem rods here in this video which is now in the public domain. Between 11:40-12:30 you can see the light rods and where the main rod connectts to the eccentric crank pin.
https://www.youtube.com/watch?v=NcbTXlMSCwk

Many thanks,
Archbar

Yes, I've heard of them. Do you have access to Omer Lavalee's book "Canadian Pacific Steam Locomotives"? There is some information about the rods in there. Whether there were any deficiencies with this design of rod I have no idea, but suspect these were a patented design which had costs associated with their use. This could have been enough reason to abandon their use on the "Cheap. P. R." when they required replacement. The CPR was known to a reluctant user of patented items which could only be sourced from one supplier, this is the reason for the absence of Baker-Pilliod valve gear on the CP fleet. And their continued use of the in house developed Vaughan-Horsey superheater on smaller engines right up to the end of steam. When you compare similar engines on the CP and CN you will often find the CN engine much better equipped when it comes to castings, appliances and labour saving devices.

As and aside, I once met the late Jack Hewitson who had run the dynamometer car for CPR during the late steam era, he told an interesting story about CP and the Baker gear. Apparently they decided to try out the Baker gear, and so fitted it to a Pacific locomotive for trial, but only to one side of the engine!

Pat Hosford

SO one side had Baker, and the other side had the normal Walschaerts valve gear, kinda sounds like American Politics, one side fighting against the other and neither going anywhere fast.

How would you even rig that did the engineer have 2 Johnson bars to adjust the cut-off positions? I haven't studied the 2 valve gear types too much, but just a quick look would suggest that it would be nae to impossible to get the 2 systems to work correctly together without a lot of experimentation.

Imagine the project review after the Dyno test, `We spent 5,000 in parts and labor to Jerry-rig half a Baker Valve Gear System and the fuel efficiency and drawbar pull went down, glad we didn't waste 10,000 properly installing a complete system...' (number pulled out of you know where...)

Rich C.

You are actually conflating two rather different approaches into one question. The answer to both can be found on p.215 of Bruce's book on the Steam Locomotive in America.

The earlier version is a variant on 'fork and blade' where the end of the main rod is doubled to go around the forward end of the side rod to the rear of the main. A long bushing is driven through this, with the bushing surface providing the 'bearing surface' for the side rod eye, and the entire surface between the bushing and the main pin available for thrust.

The 'later' version is the original system used on some engines with the Timken light roller rods (most notably on the early N&W J 4-8-4s). Here the 2-3 side rod is doubled, one on either side of the single light main, and the 3-4 rod can be placed between ends so the drive is 'in line' with the piston rod (and load shared equally by the various roller bearings) for all three rearmost driver pairs.

The former system is what was applied to the two large Canadian 4-8-4s.