Monthly Archives: February 2015

2-28-2015 new projects rev 3-14-15

Thinking about new projects to examine, some things seem to just drop in my lap.

This week I got an E8A in a bunch of items I picked up. The interesting about this unit is that it seems to be a hybrid. The bottom of the drive is clearly Athearn a Blue box vintage. The four motor mount holes are there, but filled with some substance. The shell is either a Rivarossi or Con Cor. The chassis is held on with four screws that have been drilled in the chassis as part of this match. The shell has not been kit bashed. Removing the shell, reveals a Mashima motor has been installed, clearly as an upgrade. These motors have come from several sources over the years. I believe NWSL imported them until recently.

This engine will be added to the list of tested engines in a few days. It struck me that it would be nice to have some understanding of the benefit of adding a motor like this to an HO engine. At the same time, in the spare motor pile are a few Mashima HO units. These all seem to test well by themselves, so a one or two point result can be determined. The E8 unit will serve as an indicator of stall current and operating current draw levels.

The approach to achieve the increment for this style motor upgrade is to add one to an engine that has been used in a series of tests already. One of the units used in the Athearn blue box tune up activity was an undecorated GP38-2. This unit was used to define several increments in performance due to tune up features. It will be interesting to add a Mashima motor to this set of data. The required missing parts have been ordered from A-line. Thus upgrade and testing will start in a week or so.

A second activity that has been brought to the front is the performance of older brass locomotives. Three various model Pacific Fast mail units have become available. Two of these do not run at all and one only begins to run at 12 volts.
A series of tests on these units will be very enlightening. The initial thought will be a series that will measure the impact from the initial running to adding improved motors essentially making them “DCC ready”

(Edit 3-14-15) In the same group as the E8, I also received three engines with Cary metal shells. At the time I really did not think much about it. Then in various discussions, some people have claimed, you have a problem with pulling power, just add a little weight. While in general that is true, it really depends on where you are on the motor torque characteristic function. For every unit of weight that is
added, the motor has to produce between a quarter and a third of the unit in torque. A portion of this actually shows up as increased pulling power. Because the motor is limited in max torque, at some point, the extra weight will start reducing draw bar pull.

To further examine this the testing on the Mashima engines will be expanded to include a series of weight variations as well. A base chassis and plastic shell weighs 310 grams. An all metal shell increase that weight to 655 grams. The maximum engine weight seem so far is around 700 grams. The plan will be to run weight increments of 115 grams from the base engine. Running five variations including the base will describe the pulling power to weight characteristics. Doing this as part of the Mashima series will show how different motors handle the weight. Recent vintage engines tend to be at or near the maximum proposed weight.

The details of the test plans and subsequent testing will be summarized as progress is achieved. Should be a fun spring.