Santa Fe 5353 ABA Question

[Anonymous]

I just had my fathers old Santa Fe 5353 ABA set refurbished at my local hobby shop.  I have one powered A unit, one non-powered B unit, and one non-powered A unit.  They work great but I have a stupid question.  When you run an ABA combo does the powered locomotive go up fron to pull the whole consist including the non-powered A and B units, or does the powered A unit push the non-powered A and B units while pulling the rest of the consist?  I know this question is probably very dumb, and the answer is straightforward, but I jusy want to make sure before I start running the locomotive too much.

Here are some pictures of the set.

 

Thanks,

SK 

[Buckeye Riveter]

The only thing I have ever seen over the years, is sometimes I seem to have better traction if the powered unit is in the third position.  I have never heard of any definitive reason to run in the first or third position other than how the headlights might function or which one includes figures of a crew.

[Frank53]

I recently read somewhere that the powered unit in the third position is a better solution for a number of reasons, not the least of which is strain on the couplers in the first position. It makes sense to me.

[lionelsoni]

Having the power farther back is like having a shorter train, as far as pulling the cars off the track on curves is concerned.

[lionel2]

I have the solution..many trains in the 50's were run powered unit first...after 50 years of running them that way...you should run them in the 3 unit position to put some wear on the other brush inside the motor..it will go faster and pull more....i personally rotate it every year...up front 1 year in back another...thanks

[lionelsoni]

But which brush gets the more wear?  Is it the brush with the current flowing alternately in and out, with the commutator rotating against it in the, say, clockwise direction, or the one on the exact opposite side of the shaft, with the current flowing alternately out and in, respectively, with the commutator rotating against it in the clockwise direction?

I think that the motor is pretty much symmetrical with respect to the brushes.  I can see that there could be differential wear on the thrust bearings and on gear teeth with respect to direction.  And there could be differential wear between the brushes with respect to brush-spring force.  But not with respect to direction.