Poor pulling 1946 #726

Oops, forgot to add it is a restored engine and tender

The 726 Berkshires have the Baldwin driver wheels with nickel-silver rims ("tires")   Because of this, they could not be Magnetraction-equipped, and the material shortages during the Korean War didn't help things either during it's later re-releases, so pulling power would not be as strong as its sister locomotive, the 736 that has Magnetraction.

You said it was already serviced, and assuming it was serviced properly there's not much you can do about the situation with the 726 since the lack of Magnetraction and traction tires will always be the limiting factor.  You can try pulling lighter cars or cars with more free-rolling wheels, and you can also try to add more weight to the engine (lead weights like those used for automotive wheels inside the boiler shell if there's enough room.  You will also want to make sure the driver wheels as well as the track are clean of oil & grease buildup.  Otherwise you can buy a 736 so you have better pulling power, or you can get the Williams/Williams by Bachmann Berkshire clone, which has the same Baldwin driver wheels & nickel-silver rims as the 726, but also include traction tires for much better pulling power.

Another thing to consider if you buy the 736 or any other Magnetraction-equipped postwar locomotive that the magnetism can degrade over time although they can be re-magnetized, and due to other other variables some Magnetraction-equipped locomotives will inherently have stronger magnetic attraction than others.

Hi

You call poor power because the wheels are moving but slip on rails or the motor is not enough to move the whole train?

they are two different things.

AG.

Without seeing the engine, all I can offer is some generic advice:

1)Are the drive wheels slipping? If so, then something like bullfrog snot or traction tire may help.

2)You also could play around with putting weight on the engine, and seeing if it pulls any better, it could be it is too light.

3)If the engine is restored, then it likely isn't dirty commutator or worn brushes, which could sap the power IME.

4)It could be the gearing, either the original or the ones used in restoring it, are geared for revving, not pulling (just a thought), or maybe the worm drive to the drivers is worn (though if restored, I would be skeptical) and thus can't pull

5)I don't know if that engine has side rods and valve gear,but if they are binding it could possibly cause this I would hazard a guess...

Could also be it was a weak engine.

motor shims too.

AG.

As others have posted, the first question is whether the wheels are slipping, or is it just running very slow?

As I recall, the 1946 version of the 726 Berkshire is geared to run rather slowly.

Another thing that hasn't been brought up is that the 1946 versions of the 726 Berkshire had no weights in it (since the light bulb smoke unit took up the most space in the boiler), so the center of gravity wasn't over the drive wheels, giving them poor tractive effort.

This was fixed on the 1947 model where the motor was attached diagonally, a smaller smoke unit was used, and weights were placed above the drive wheels.

A lot of info, thanks a lot.  The engine runs very smoothly by itself, full throttle on the transformer (MRC  with sound) but not fast, you can run it full throttle and not fear going off the track.  The wheels also slip pulling the 5 cars, so I guess it's getting enough power to pull.  ( four cars are fine) Will try all your suggestions, but at least I have some relief I wasn't taken with buying this engine, it wasn't cheap hahaha.  Thank again.

I think you better check that the loco is properly lubed.  Sluggish operation like this is usually a symptom of poor lube.  To lube this loco, you must remove the shell.  Then oil the motor bearings, oil the worm and spur gear, oil all the axle bearings, oil the side rods, oil the pony truck and the trailing truck.  You should be able to easily turn the wheels by hand.

I have 3 736 locos which I think come apart like your 726.  Two screws under neath at the rear and one screw in a deep hole in the middle of the pony truck.  Do not take off any of the rods or linkages.

The loco should start and run at about 10 volts.

The 1946 Berkshire had double worm gear drive and it was never a good puller. I recall reading in one the the Lionel history books that the 1946 726 would bareley pull the set it headed up.

Richard

I have 3 736s, and they pull like crazy.  Of course, they have Magnetraction.

I have a 2025 that has the nickel tires, and the nickel tires tend to be a little slippery.  No magnetraction in the loco.

If it were mine, I would take it apart and check the clearance of the worm gears and make sure there is no binding with them and the side rods.  And I would lube it with motor oil:  5W-20 or 10W-30.  Motor oil is all I use on my locos.  It lasts forever and never gets gummy or hard.

The 1946 edition of the 726 is constructed in a similar fashion to the 1946 editions of the turbine. The motor has a spur gear on the end, which turns a spur gear that is mounted to a shaft that runs the length of the wheel base. This shaft has a worm cut at both ends. These worms turn gears mounted on the end axles. There are bearings at the ends of the shafts.

There are specific service manual pages for this engine.

It does not compare to later models, the mechanism was redesigned for the 1947 (and later) model.

From his post a few posts above this, he said his only problem is wheel slippage.  It sounds like he has only two alternatives.

First, he can increase the tractive effort through cleaning his wheels and track to remove any oil or increase the engine weight.

Second, he can reduce the rolling friction of the cars by oiling the axle points on postwar cars or use modern cars which have lower rolling friction.

Earl

With double worm drive you won't get the high speed of a 736. 

While I've never used Bullfrog Snot this might be a case where it helps.  I'd try it on the rear drivers.

As much as the 1946 version is praised for it's over the top quality, the over all sad truth is that the engine is overbuilt. By the time the power transmits through the intricate drive train much of the energy is lost just due to the fact that the power is needed mostly to move itself. I am not saying there aren't a few that run like rockets but theose engines are the exception. The same drive train is in my 1946 671 turbine and it can fly off the track with 7 or 8 early post war cars behind it.

I have noted that when the 1946 726 is completely disassembled, each time I reassemble one it behaves differently. Each time more or less sluggish than the last. You might try taking the wheel / axle assemblies out and reinstalling while paying close attention to the position and freeness of the bearings. It is possible that the position of some axle bearings in the frame is keeping a few of the wheels from having good contact with the rails. This could be the cause of your slippage.

I have been told by a fellow who was an expert postwar Lionel repairman, as well as a machinist, that in order to get the best performance from a 1946 726 Berkshire, the wheel bearing have to be carefully shimmed to get them in proper alignment.

Since I don't run mine, I never bothered to try shimming them.

As a last resort you can do what I did, add weight and glue a pair of rubber tires to the rear drive wheels, now she's a good puller, smokes great and looks great pulling my 12 car passenger train. I have more than one of these so I did,'t care to try this trick, everyone told me it would burn up the motor, but I did this in the '50's, and she 's still puffing.

Rod

Another trick is to put tiny rubber bands on the drivers.  Use thin round bands that will sit against the flange, and not cover the entire wheel.  They sort of lock between the flange/tread corner and the track.  I did this years ago with my pre-war locos.  Downside is that the rubber bands don't last long.  I suspect that neoprene O-rings could be found which would last longer.

Guys, I don't think his problem is with wheel slip.

The motor stalls.

I did not see a post indicating that the motor stalls.

However, the comment raises a question in my mind.  The original poster stated that he gets wheel slip with five cars, but not with four cars.

I am now wondering whether his transformer is large enough to run his engine. It was described as an MRC transformer with sound. What is the output voltage range for that transformer, and how many watts does it put out?