Working my way through the testing of my four upgraded Athearn blue box loco’s. These loco’s are as follows:
All have the later rectangular motor with brass fly wheels. They all have 42 inch wheels with inside frame trucks
1- a new from old stock undecorated GP38-2
2- a used Pennsylvania F7A with Ernst type gears to reduce the loco speed
3- a used Santa Fe freight GP38-2
4- a used Union Pacific GP50. This units wheels were badly rusted and they would not rotate in the bearing. They had to be replaced with some used wheels and gears.
This series of tests include the following variations:
1- As received (only the undecorated GP38 was tested in this manner)
2- After the modified five wire up grade. This includes the wires and screw mounts with the as received blue box wheels.
3- After polishing the wheels with a Kaydee wheel cleaning brush for 20 seconds per wheel.
4- After replacing the wheels and gears with Athearn Nickel Silver sets. (The F7A Ernst system had two special axle gears. These gear were used with new RTR wheels and new bearings.)
5- after a lubricant update with the proper grease and oil.
6- After upgrading the truck tower gears to the latest high performance design. (May only apply to undecorated GP38-2, depends on results)
This presented a good opportunity to examine several engine variations around the same fundamental motor model. The fundamental variables are:
1- the age of the unit
2- weight of the unit
3- truck gear ratio
4- Overall condition of the unit
As of this writing the test series is nearing the completion of step 4.
Some observations at this point:
1- Some insights about the axle gears.
This design wheel and axle gears has been known to have cracked gears, particularly as Life Like did them in P2K units.
In this case, none of the units sounded like the axle gears were cracked. However, in eleven of the sixteen sets the wheel shafts were loose in the gear. They easily would rotate holding the gear. This has to have impacted the performance up to the point of the wheel change. Normally I would have said these were cracked axles.
Because the F7A had two unique axle gears, these needed to be retained. In this case the blue box wheel and bearings were removed and replaced with the RTR wheel and new bearings.
Interestingly the loose BB wheels were easily removed and the new RTR wheels had to be pressed fit into the axle. They did not easily rotate in the axle. So these unique axles appear to be good after all.
To further examine this, the axle gear that was removed from the RTR new wheel set was assembled with two of the just removed BB wheels. To remove the RTR wheels took significant effort. The BB wheel slipped in easily and would rotate relative to the gear with little effort.
Finally, a RTR wheel was test fit in this RTR axle gear and in one of the loose BB axle gears. In both cases, the fit was tight and would not easily rotate relative to the axle gear.
Clearly this is still a performance problem. It is happening because of under sized diameter axle shafts on the wheels. Is this a contributing factor to the axles cracking? Because of the looseness, the axle will rotate faster than the wheel shaft. The result will be heat generation and a questionable result.
2- RTR wheel impact
Even with the above discussion in mind, the maximum draw bar force is significantly lower with the RTR wheels.
3- Ernst type gearing in trucks
Appear to reduce the maximum speed by a factor of four. Increases the minimum movement voltage and speed
4- motor health
current increase appears largest at maximum load even with the wheels slipping.
When the testing is finished, these and other results will be graphically defined.