Early 3rd rail gear boxes

All of my larger 3rd Rail engines have a belt drive which eliminates the need for idler gears in the gearbox. Never had a problem with the gearboxes. A few engines had problems with drivers out of quarter though. Fixable but time consuming to make right.

Pete

The Decapod, circa 1990 had a KTM-style gearbox.  Other than using very small screws to hold the gearbox together (which were prone to stripping), no problem with that one.  However... circa 1999 the C&O T-1 and PRR J-1 used a transverse gear tower which was undersized.  I heard at least one credible account of someone stripping the gears attempting to pull a heavy load.  Immediately after this they adopted the "Quiet Drive," a belt-and-pulley arrangement driving a layshaft set low in the frame.  

Pros and cons IMO: From the side it's invisible so the gearbox doesn't spoil the appearance.  However, the bull gear on the main driving axle can't be as large as it would be if it were directly driven (compare to Lionel's 700E for example.)  This translates into a shorter lever arm for the worm and less pull-in torque.  On my 2007 C&O Greenbrier, the screws anchoring the retainer for the layshaft's bearings were tiny and stripped out, allowing the layshaft to flop around; I had to replace them with larger screws.

Bottom line, I endorse their current production with the quiet drive (the ability to change pulley size is a plus.)  But the C&O T-1 / PRR J-1 might have the weakest mechanical pedigree of 3rd Rail's recent production.

My $.02, it would be interesting to hear BOB2 or RRFJJF's opinion on this.  -Ted

There was a time when Mort specified brass for the axle gears.  It was a very long time ago, before the name "3rd Rail" came about.  Most of the affected models came unpainted.

A brass axle gear will last approximately four hours under light load.  Sunset had some bronze gears for replacement, but doing so requires knowledge of driver quartering.  Joe Foehrkolb does this stuff in his sleep.

Bronze is good.  Celcon Acetyl is good.  Brass is lousy gear material.

Thanks for the responses.  Any one still using this engine today that can speak about long term use.  Is there a fix for the gear box through purchased parts (not machining your own), or destined to be a shelf queen?

Mike, I have two of the 3rd Rail PRR J1a's (same mechanism as the C&O T1).  One of them in particular has seen quite a bit of use on my layout.  It pulls 10-11 car freights up and down grades as steep as 3.5%.  I've had no problems with it.  The J1a's do run better since I converted them to TMCC (Electric RR Cruise Commander Lite, Railsounds and an electrocoupler on the tender).  I have quite a few 3rd Rail PRR locomotives and my experience has been that the Decapod is the best runner.  It has a gear ratio of 31:1.  The J1a is 16:1.  Like Ted says above, the 3rd Rail locos newer than the J1a/C&O T1 have the belt drive where pulleys can be changed.  For example, my PRR N1s 2-10-2's came with a 16:1 gear ratio but I was able to change pulleys and get 28:1.  I wrote an article for OGR magazine (Run 216, Aug/Sept 2006) about this stuff.

hello guys and gals.........

Back in 1997, I had Sunset 3rd rail PRR J1 engine and it had one of those weak gearbox which of course didn't last.  It was like putting a VW transmission in a 40 ton 18 wheeler semi.  It was a handsome engine of it time but a shelf queen.  I order it from Sunset in 1994 , had to wait 3 years for it.  I haven't bought any Sunset 3 rail engines until 2012 fearing of weak gearbox.  In 2012 I took a chance and purchased Sunset 3rd S.F. 5011 class 2-10-4 and this engine has a "quiet drive" heavy duty gearbox , bronze gear and cogged belt drive which is very pleasing to know ( engine was made in 2002).   I guess they improved the gearboxes to heavier grade.  I don't know what the gear ratio is but sure like to know.  Changing the pulleys changes the gear ratios, that is interesting !!  This engine has the Pittman motor # 9232 and 73 inch drivers, what would be the best gear ratio for this engine ?  I see that the white plastic pulleys are pinned to the shafts, looks easy to change pulleys.

Tiffany

Tiffany posted:

what would be the best gear ratio for this engine ?

Unless your layout has 50' straightaways, generally as low as possible.  I believe the gearbox itself is about 15.5 to 1.  So if you used a 10-tooth pulley on top and a 16-tooth pulley on the lower shaft, you would be at around 25:1.  I wouldn't recommend going smaller on top, and I'm not sure there's room for more than 16 teeth below.  Bob (B.) has done this swap, maybe he'll chime in.

One thing you should know... your motor will be running at higher RPMs.  If the flywheel is even slightly out of balance, the brass shell will amplify the vibration and things will get noisy.  (There's a reason they don't make trumpets out of die-cast metal!)  When I did the pulley swap on my Greenbrier, I let the motor run and burnished the flywheel with a finishing file to even it out.  I also added a material called Dynaxorb to the inside of the boiler shell above the flywheel.  This is an acoustic lining used in auto sound systems to reduce buzzing and unwanted reverbration; you can find it at shops that install custom sound systems for automobiles.)  3rd Rail brass is great, you won't regret the swap.  But you'll like it better if you take some time to quiet things down.