Locomotive pulling power

Overview

Locomotive pulling power has always been of interest to large scale railroaders, I believe because we have grades and curves more severe than the real thing.

There are many debates about pulling power, and things that seem to affect it. This page will attempt to look into some of this and present some helpful data.

I may add sections on techniques to increase pulling power, and point to specific mods on specific locomotives.

Actual measurements

Chuck Naeser has over the years kept track of a consistent method of measuring pulling power and documenting what he has found, so most of the following information is courtesy of him.

He uses a fish scale, (pictured below), but I also need to mention he uses a consistent method of preparing the conditions to get repeatable results. He uses brass track, not oxidized aluminum (more traction) or stainless steel (more slippery in my experience).

Recently, Chuck noticed that the basic relationship between loco weight and pulling power did not make sense for all locos, in particular a USAT Hudson.

Chuck reasoned that the weight on the leading and/or trailing trucks could have a significant effect. Therefore, he designed a setup to isolate the weight on these wheels:

Notice by keeping the loco level there should be minimal effect on the weight distribution as measured.

Chuck has been keeping track of his measurements and I twisted his arm a bit to present his information here, where it can help a number of people, and also present some interesting observations.

In the table below, Chuck has added columns to address the weight distribution, and see if there is a more consistent relationship between the weight on the driving wheels and pulling power.

Note that there are still some measurements to be made, those will be marked with ??. This table will be updated as time goes on.

 Adding weight to a loco

There are lots of ways to add weight to a loco, which almost always increases pulling power.

Before we "take off", there is some thought to be had first, before you destroy a loco.

• gears, drivetrain
• axle bearings
• ability to keep center of gravity low

Weights

Lead still the best for cost vs weight

Rock cod sinkers