6-5-21 Hobbytown of Boston initiated on it 5-10-21

A named from the past. Or is it?

• Actually the entity still exists today.
  They make a number of HO engine kits.
• These include metal shells & the appropriate chassis for a number of diesels.
• These are first & second generation models.
  How do I know this?
• I have been asked to run some motors that are being promoted on a online site.
• To compare with the motors run in the 2020 series.
  These motors promoted are single shaft, usually focused on steam applications.
• However, in the distant past, the motors were all single shaft.
• Even on diesels.
• It took a special design to power both trucks.
• This configuration was common to Varney diesels.
• After Varney left the business, Life Like continued making cheaper versions of the design.
• Apparently Hobbytown of Boston did as well, and they still do today.
  Theirs are higher quality with more robust gearing.
• I ordered a powered chassis for a PA engine.
• the challenge will be to run a DOE test series using this new chassis and a selection of motors including the two promoted motors.
  

The HOB kit arrived. It is shown below:

The chassis consists of a kit that has to be assembled. I will be documenting that as the assembly progresses. The chassis will be the test bed for the 2021 motor series that is described in here: https://www.llxlocomotives.com/?p=2847

the test fit was made between the chassis frame & the Athearn shell shows that this will easily make for a great engine for the test bed for the 2021 motor tests.

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HoB chassis issues found so far:

1. The square dog bone shafts are a soft metal that bend under load.
2. The main plastic gear on the primary   truck moves on the shaft forward & disengages from gears
3. The wheel axle bearings are round fitting into rectangular slots.  Initially had lots of pinch bind.  Taken off material from the rectangle, much better, but still seems to have some non periodic bind.

Here is what my potential “solutions” for these:

1. Replace with a NWSL metal shaft and plastic coupling.  These are much stiffer, never had any bend just cutting.  Will super glue the plastic couplings.
2. Super glue the gear over the scribed area on the drive shaft.  It was not there as received. The instructions talk about raising the transfer gear housing.  I did not because it did not appear tight.  Will try a few mills to see if that helps.  
3. Here I guess I will take some more material off the rectangle verticals.  These bearings should be rectangular on the outside, but this is what I have.

The ideas seemed to work. However a large enough ball coupling to go with the NWSL shaft was not in hand.  An old blue box type spline shafts was substituted to create a flexible shaft.  As shown above. It seems to work OK.  

To test the impact, the engine was run ten times on the test track.  At 12 volts supply power.  The velocity & current draw were the same on all ten.  

There still seems to be a lot of internal load.  The measured current is 0.32 amps when the motor by it self measured 0.09 amps. 

Experience would say this should be less than 0.2 amps.  The measured speed is 73 SMPH compared to an expected level of 89 SMPH. The stall current measured previously was 0.8 amps.  (Note- the current draw & speed without the rear truck gears & shaft were the same as above, so the flexible shaft is not the reason.)

This implies the motor is using 31% of its available power for an engine only on a level surface.  There is still room to get data, but in the previous experience, this condition was at or less than 10% of the maximum power (stall current). With those engines the maximum usable power(defined by zero speed wheel slip) was around 35% of the maximum power(about where this engine is with the engine only).  Thus if this combination has the same power throttling. The maximum usable will be around 66% of the maximum.  The tests may still be relevant.  The speeds will be lower for a nominal train than the motor in a cleaner drive. 

The plan is to proceed with the final test preparation for this motor chassis combination (the motor is the HoB supplied dual shaft option). 

The first activity will be to run the engine on rollers for about 45 minutes.  Often that will reduce the power requirements, but not to these magnitudes (may be a surprise here).  

Then the engine motor combination will complete all of the testing in the plan. At that point the data can be examined & decision can be made on what else needs to be done to have confidence in the testing.

6/5/21-

The result of running 45 minutes was a good reduction in the 12 volt running current draw. The current dropped from 0.32 to 9.24 amps. This is still higher than the expected level, but definitely better. The velocity edged up only slightly.
The static torque load is still higher than desired.  The low power min speed is between 8 & 9 SMPH at a supply voltage of 3.6 volts.  The expected values are 3-4 SMPH at around 2.5 volts.  Additionally, the 12 volt engine only speed is 75 SMPH as opposed the no load projection of 89 SMPH.  
Both of these are implying more internal torque loss than the usual amounts.  All the bearings have been lightly oiled & gears greased. 

in reviewing the data that was taken during the initial run, additional running of the first motor with added engine weight is appropriate.

With success of this run, the study will go on to install the second motor in the test series (Mabuchi SF-266SA-1G160). Because the idler wheels do not do much for this series the engine will run without them .

The results of any subsequent testing will be discussed in the link above.