Results- Engines As I received them

The first set of data to set the stage is a summary of the engines tested to date.  A total of 186.  The maximum force is measured at 12 volts.  The force is equal to the weight the engine can just lift off the floor, through a string and pully system.  Essentially zero velocity.  All but two had wheels slipping.  (I have checked these with a gage with good results)

Early on I tried to find the point where wheels start to slip.  It was very subjective, took a lot of time and the difference was small.  This point is easier to find and more consistently measured.

The maximum draw bar force to engine weight is shown below:

The key to this chart is grey symbols are pre 2000 manufactured engines and the blue are post 2000.  These dates are a little fuzzy.  Atlas Kato and Life Like P1K and P2K are considered pre and Atlas China and Walthers P2K are post.

These data imply an average force loss of more than an once pre to post.

Because I deal with mostly used engines, the pre significantly out number the post.

Results of the weight increments testing on seven engine in the next replay

Results- seven engines tested with weight increments

The activity to examine the various weight increments has included seven different engines thus far.  Three are used Athearn BB engines, a GP38-2, and SD9, and a Train Master.  These have two different types on BB motors, one round and two rectangular.  These have all be used and likely abused.

The other four engines are recent vintage engines.  Two are Athearn Genesis, an F9B and GP9.  The other two are a Bowser C-636 and a Kato P42.

Additional testing is planed on non Athearn engines, but the the results so far are are interesting:

The corresponding current draw is shown here:

I have not been able to identify a force-to-car relationship myself.  Using relationships implied by others, the number of 4 once cars that would stall the engine on a 2.5% grade are shown below:

The data implies a number of things, but for now I will leave it here.

Very Interesting

Awaiting your analysis and or inferences. Especially interested in your take on the relative performance of the Kato P-42 design with the two

P-42

Ken thank you for the comments.

The Power-42 test series does warrant a discussion of its own.  I am putting together a detailed assessment that will be put on the web site.  When that Is finished, I will post a summary here.  As indicated in the these data, it is very competitive.

Drawbar pull

Some observations about drawbar pull:

Older modelers may remember when Jim Fitzgerald's N Scale Cotton Brute was winning Bob Higgins' engine rating contests at NMRA events.  Jim's U-50(?) was weighted with depleted uranium to give the most weight in the least volume.  In that era, at least, he proved that weight matters.

As a counterpoint, one of the now-deceased members of the La Mesa Club took a 2-8-0 or 2-8-2 and rebuilt the mechanism with equalized drivers.  That increased its drawbar pull to 4 or 5 times that of a comparable B-B diesel.  So weight may not be the only thing that matters.

We've seen the commercial manufactures adding weight to their engines in the last couple of decades, but I don't know of any equalized diesel trucks as yet.  Somebody else will have to comment about modern day steam equalization, but a few of those previously mentioned older modelers may recall that some Varney steamers built after WWII had equalized drivers.  Time for full circle?

Look to the UK

Dear Don,i

Look to the UK, the UK modellers are past-masters of fully-compensated and simple "equalised" chassis. Gven the relatively small size of UK OO locos vs US HO literally anything which eeks out more tractive effort is a worthy mission, so these guys have refined it down to a fine art...

http://www.brassmasters.co.uk/easichas.htm

http://www.mjwsjw.co.uk/Loco%20Diagrams%203S.pdf

http://www.amazon.com/Flexichas-Compensated-Locomotive-Chassis-Edition/dp/0853615012

http://www.clag.org.uk/41-0rev.html

http://www.abcgears.co.uk/abc_gears_-_loco_suspension.pdf

Happy Modelling,
Aim to Improve,
Prof Klyzlr

Thanks Prof

I particularly liked the link to Elliot's work.  How common is this in HO?  I think it would have an impact on a number of running issues.  A quick look indicated that Proto:87 might have something as a kit or replacement.  I could not find a catalog to know what they have available.  Have you or anyone else done this?  

Thanks for sharing.