The initial thought was to use the Kato coreless motor. I picked one up. The version I received is very small & only has a shaft on one side, rather than the desired dual shaft configuration. Also it does not have a fly wheel. This unit is may be more appropriate for a steam engine application. The on going study involves diesel engines. I will hold this motor for some activities involving steam engines in a few weeks.
a second option was identified. A Namiki motor. They have been in business since 1924 & making coreless electric motors since the mid 90’s. It is a better size, 1634 (w,l) compared with the typical can which is 1824 or 1833. It was advertised to be rated at 9000 rpm at 12 volts, which is in the acceptable range over 8500-11000 rpm. Unfortunately, the bench test only yielded 5700 rpm at 12 volts. To low to be of much use here.
A number of other possibilities have been identified. For most, the manufacturer wants a minimum order of several hundred, which is impracticable particularly since it is not clear that they are a good choice.
a couple by Tramfabriek in the UK have been identified as possibilities. The first is a double shaft 0816 motor, a bit small. It is rated at 13,300 rpm at 12 volts. A bit on the high side, but may be acceptable.
the second of these is a 1020 rated at 14000 rpm at 12 volts. A bit larger & the rpm is moving yet higher. This one comes with a fly wheel. And shaft adapters. This is important because the shafts are 1 mm. The usual HO motor shafts are 2-2.4 mm.
If these later two actually run slower than their rated rpm, they may be nearly perfect.
The two motors arrived a few days ago. The shaft size makes the second one the best candidate.
Here is a comparison with the Athearn High Performance motor:
The no load test rpm measured at 13400 at 12 volts. The measured current draw was 0.o3 Amps. This is low and a power concern. We will see how it pulls a train.
Today the coreless motor was installed in the SP SD9 series engine. The full test series is not complete, but a quick run at 12 volts on the test track with no grade demonstrated a speed of 95 smph. This is right in the expected range. The current draw was roughly o.1o Amps.
11/23: the full test has been completed with mixed results. When lightly loaded, the motor powers the engine to a high competitive speed. It does not have very good low speed capabilities. It would not sustain speed below 4.1 volts. In addition, it only would pull 11 cars up a 2.5% grade. The engine is a six axle diesel and should pull 12 cars at least. This implies that the motor is under sized for the job.
11/25/20- still examining options. Today it was decided to run the Namiki motor. The speeds maybe low. But the size & torque may be a better choice. The motor may run faster under load. The next issue will be the flywheel & couplings. I will see what I can come up with.
the search for an appropriate motor has hit a brick wall. The new lead on a 1630 version that looks like it may be better is still out there, but the people at Rics want to much for the sample that may not be good for this application. Have not found a better option than possibly the Nakimi mentioned above.
These small motors likely would work in pairs, one per truck, like the Kato P42. The problem with that is the modification to the trucks may not be reversible. Which means more variability in the overall series.
If anyone has a source of a better coreless motor please let me know at ggnlars@verizon.net.
more later!
