can motor for post war lionel...726/736 Pullmor replacement

Something in the neighborhood of 5500 motor RPM (with the STOCK 16:1 gearing) will get you your 70 mph.  That's a pretty low RPM; I personally wouldn't waste time with a Mabuchi RS-385.  You'll need a slow-turning motor like the Pittman 9434. OR you can run a higher-voltage winding at less than its rated voltage.  For example: a Pittman 8000-series motor has a no-load speed of ~9000 RPM.  If you run a 24V motor at 16V, it'll turn around 6000 RPM, with the added benefit of lower current draw.

The best bet would be to change the gear ratio, but unfortunately Lionel took (and continues to take) some engineering shortcuts. So that's very hard for us to do.  A gear ratio of about 25:1 to 30:1 would be ideal.  In order to achieve that with a 16:1 axle gear, you would need a planetary gearhead on the motor with a ratio of 1.5:1 or 2:1.  Personally I doubt you'll find one that low.  So this loco, like many others, will never deliver fully on the promise of realistic operation suggested by its original price or scale dimensions.

That being said, search for posts by HARMONYARDS.  He has done some excellent conversions of the Lionel Reading T-1 and NYC Mohawk by shoehorning in a Pittman 9434.  His technique isn't for the faint of heart ("don't try this at home!")

The next question would be how much torque is reasonable to make it pull?

A smaller motor with the gear reducer needs to have to have how much output torque at the output of the gearbox to equal, say, a stock Pittman in an older generation can motor engine?

What's wrong with the Mabuchi 385? Every William's Loco have is powered with that motor, it's a fine and excellent motor that can run at really slow speeds and will run for days at a time carefree!

The "pulling power" or drawbar pull is determined not by the motor, but by the weight on the driving wheels, and available traction.  Obviously rubber tires help a lot (maybe double the pulling power on some types of track) but I hate them.  Some wheelspin is prototypical.  Besides, how long is your layout?  With 30" of loco, how much room is left for the train?

I wouldn't use an RS-385 in the Lionel T-1 together with rubber tires.  Add speed control, and in slow-speed running you have a recipe for high current draw and motor burnout.  The motor is the heart of your model locomotive.  IMO the RS-385 is worth what the manufacturers pay for it-- about $1 each.  And I'm pretty sure that it doesn't make as much starting torque as the Pullmor motor that Lionel installed at the factory.  Think about this... from about 1991 until the advent of speed control circa 2001, another magazine conducted detailed test reviews of O gauge locomotives.  The best Pullmor-powered locos were able to run as slowly as 3-8 mph.  Scale-oriented models with Pittman motors also tested out at 3-5 scale mph.  But few RS-385 motored diesels ever managed to break the 9-mph barrier, despite enjoying 25% lower gearing than a Lionel diesel.  Its a physically small motor, and the low-speed torque just isn't there.

To get full points in an NMRA contest, a loco has to run smoothly at 3-4 mph.  No DC brush motor is really "happy" until it's turning about 800 RPM.  And to achieve that 800 RPM in a typical steam loco, the gear ratio has to be about 30:1.  All-day running at 10 mph is great, but IMO that's a boring way to run trains.  Pull-in torque from zero RPM is equally important.  One of the things I've tested, and few others look at, is: what are the starting characteristics with the slack stretched?  Here, a little wheelspin helps (not possible with rubber tires.)  The key to a realistic start is what happens below 1 mph.  Some of this comes down to the design of the drivetrain.  But the motor's torque characteristics are important too.

Ted S posted:

The "pulling power" or drawbar pull is determined not by the motor, but by the weight on the driving wheels, and available traction.  Obviously rubber tires help a lot (maybe double the pulling power on some types of track) but I hate them.  Some wheelspin is prototypical.  Besides, how long is your layout?  With 30" of loco, how much room is left for the train?

I wouldn't use an RS-385 in the Lionel T-1 together with rubber tires.  Add speed control, and in slow-speed running you have a recipe for high current draw and motor burnout.  The motor is the heart of your model locomotive.  IMO the RS-385 is worth what the manufacturers pay for it-- about $1 each.  And I'm pretty sure that it doesn't make as much starting torque as the Pullmor motor that Lionel installed at the factory.  Think about this... from about 1991 until the advent of speed control circa 2001, another magazine conducted detailed test reviews of O gauge locomotives.  The best Pullmor-powered locos were able to run as slowly as 3-8 mph.  Scale-oriented models with Pittman motors also tested out at 3-5 scale mph.  But few RS-385 motored diesels ever managed to break the 9-mph barrier, despite enjoying 25% lower gearing than a Lionel diesel.  Its a physically small motor, and the low-speed torque just isn't there.

To get full points in an NMRA contest, a loco has to run smoothly at 3-4 mph.  No DC brush motor is really "happy" until it's turning about 800 RPM.  And to achieve that 800 RPM in a typical steam loco, the gear ratio has to be about 30:1.  All-day running at 10 mph is great, but IMO that's a boring way to run trains.  Pull-in torque from zero RPM is equally important.  One of the things I've tested, and few others look at, is: what are the starting characteristics with the slack stretched?  Here, a little wheelspin helps (not possible with rubber tires.)  The key to a realistic start is what happens below 1 mph.  Some of this comes down to the design of the drivetrain.  But the motor's torque characteristics are important too.

.......Pat

I put a Dallee electronic reversing unit in my 736 4-8-4 conversion and it now runs slower at the same throttle setting than it did with the original E-unit. It 'seems' to have more slow speed control but...it may just be that I forget what it did before.