Re: Remotoring WSM articulateds.



These large articulateds had one rigid frame engine directly attached to the boiler. and one articulated engine swinging under neath the boiler/smokebox.

Many low cost plastic/diecast models included the Broadway Limited and MTH SP Cab Forwards do not have a rigid frame engine, instead both sets of drivers

pivot under the boiler allowing these large articulateds to go around much tighter curves.

The WSM AC-4 had twin idler gearboxes with the motor shaft drivetrain up in the boiler.  The gearboxes were on the second axle of each engine.  The articulated

pivot point was at the end of the rigid frame engine.  Since the gearbox extended up into the shell, the swing of the articulated engine interferred with the shell.  By

moving the gearbox a scale 6 feet closer to the pivot point, a smaller turning radius was achieved (about 30" radius) on later WSM cab forwards.

ken clark

On 2019-09-19 11:09, George Galyon via Groups.Io wrote:

I absolutely would like to see this web page created.. your web page is one of my favorites.   One question re the 36" radius requirement...Our club regularly runs Big Boys (Trix ) through 30" curves with no running problems at all.  I don't know if any of the drivers are blind but I can easily find out.  And I can measure the lateral "play" also.  I also run an Westside 4-4-6-4 thru the same 30" curves (I removed the cab-to-tender short failure mode) without any running problems although I do worry about excessive wear on the gear train.  But the 4-4-6-4 is a uni-frame whereas the big boys and the 4-8-8-2s  are articulated (aren't they?).  


ken clark
HO and Sn42

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