Jack Newton's twin motor 9F ?

[simes]

Hello everyone, Jack Newton was a prolific and talented OO modeller in the 1950s & 60s.  One of his best known creations was a 9F powered by two X04 motors which he described in the September 1963 MRN.  He reported that it performed very well and he appears not to have had problems with the motors locking up despite both using worm gears.  Does anybody know what happened to this model?  It was a magnificent machine and I imagine it still exists in somebody's collection, but I have not found any references to it online.  I am interested in doing something similar.

[34theletterbetweenB&D]

19 hours ago, simes said:

I am interested in doing something similar...

Pourquoi?

 

Just in case it is relevant, when I wanted a 9F with real loco traction for outdoor use, I lobbed an Airfix GMR motor from an N2 (five pole job clearly based on the MW 005 motor design) into an early Hornby push along 9F chassis, that had a chassis block with the shaped section to allow an XO4 to drive on the unflanged wheelset. That combination would still slip the wheels when made up to 800g and held back on the track. And after some years very effective service - neither trainload, nor rain, nor adverse gradient, nor headwind, or any combination of same, ever stopped a train it was hauling - it hurled itself off the track. Two wheels had slipped on the axles and the coupling rods were very bent. There would appear to be a limit to how much torque RTR OO friction fit driven wheels will stand, if worked hard for long enough.

 

(The motor and driveline to the axle were all absolutely fine and the mechanism had all damaged parts replaced, it now lives indoors with a regular plastic body and has given no trouble since.)

[simes]

Why?  It's an interesting engineering challenge.  I have tried the original Hornby tender drive 9F (Fleischmann motor, 6 driven wheels, will pull the house down but looks ugly) and the Chinese-built Railroad version with loco drive (nicer to look at, quite effective, but I doubt its longevity).  I haven't tried the re-tooled Hornby version because I'm more interested in running quality than fragile detail.  If I could build my own chassis (I have built an 0-6-0, maybe I could do a 2-10-0! Or maybe not) I'd try to do the Jack Newton version.  Interesting to hear about your motorising the early push-along chassis; do you have any photos of that?  I have wondered whether the Jack Newton model developed any problems over time because of driving two axles with two motors through worm gears so I'd be fascinated to hear from its current owner, if the loco still exists - and I hope it does.

[34theletterbetweenB&D]

I would gently suggest that the engineering challenge of such a mechanism is making the inadvisable into a working proposition. It was very noticeable that diesels with a pair of worm drive bogies for improved traction, wore out far more rapidly than a pair of spur gear drives used in the same way. And those paired worm drives were not directly mechanically coupled...

 

The Bachmann 9F is a proven workhorse as your benchmark. My small fleet is coming up 18 years in service, carrying extra lead ballast, and totally trouble free, will exert 85g force, which was required for a reliable restart with a total 3kg train entirely on a 1 in 80 rising gradient. (I have now revised the gradient to 1 in 160, so nothing like this force is required, but have yet to remove the added ballast on these and other  locos, since they are all performing without complaint.)

[simes]

Thanks. I suspect you are right about the engineering difficulty with twin worm drives.  That's really why I was asking whether anybody knew the whereabouts or the eventual outcome of the Jack Newton model.  You're probably also right that I would do well to acquire a Bachmann 9F for comparison.  I'm still interested to see your converted push-along Hornby 9F if there's more you can share about that.

[34theletterbetweenB&D]

7 hours ago, simes said:

I'm still interested to see your converted push-along Hornby 9F if there's more you can share about that.

Not really, it was retired when the Bachmann 9F became available and is now with a friend, and outside the UK.