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Mantua Mikado Repower Kit

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  • Member since
    November 2005
  • From: St. Paul
  • 711 posts
Mantua Mikado Repower Kit
Posted by garya on Wednesday, June 3, 2020 12:10 PM

I have an old Mantua Mikado that I put a Cary Heavy USRA boiler on.  The motor is not doing well.  I have cleaned, lubed, and replaced the magnets, but it is noisy and current draw is higher than I would like.

I can replace the motor with another Mantua motor easily enough, but I was searching for a better solution, possibly with a can motor.  The problem with these old steamers is how narrow the frame is and the lack of a gearbox.  (At least this version does not have a gearbox--motor has a worm on the shaft)

The best solution appears to be the NWSL remotor kit, Part Number: 1174-4.  It consists of:

  • (1) 16x30 Motor (#1630D-9)
  • (1) Worm (#50400-6)
  • (1) Gear (#2276-6)
  • (1) Wire, 12" (#10010-9)
  • (4) Wire Tab, Bronze (#120-4)
  • (1pc) Quick-Mount (#199-6)
  • Instructions

I can't find any information about this kit.  Has anyone used it?  Pictures?  How hard was it?

Anyone used a dfferent approach?

If I were lucky, I would have a Helix Humper, but they're long gone and if one shows up on eBay it sells for $$$$.

 

Gary

  • Member since
    September 2003
  • 11,571 posts
Posted by Overmod on Wednesday, June 3, 2020 1:14 PM

It looks to me as if the greatest part of a Helix Humper is the large-diameter multiple-thread worm (it is verging on flywheel size) with a corresponding driven gear in a cast pedestal that engages the axle gear originally driven by an angled worm shaft.  It seems to me that different sorts of 'subframe' for different chassis should be easy to program for 3D printing and then provided either as files or on Shapeways; it might be interesting to see if suppliers could make either the worm or the intermediate gear the same way.  One person could probably adapt the resulting frame for many physically-suitable motors with only a couple of hours of coding...

 

  • Member since
    November 2013
  • 1,054 posts
Posted by snjroy on Wednesday, June 3, 2020 2:21 PM

I have not used this kit. But since you ask, I have repowered Mantuas with other 12V motors and it was not that difficult. I like using a flywheel but apparently, this is not essential if you are using DCC. The most difficult steps are removing the worm gear from the old motor (NWSL sells a gear puller, which works great), and installing the new motor on the frame. I built a plastic support and attached the motor using silicone caulk. A few tries might be necessary to get the right angle. But I'm confident that the NWSL product is a good one, if you are OK paying for it. 12V motors are dirt cheap now with online shopping resources..

Simon

  • Member since
    February 2002
  • From: Mpls/St.Paul
  • 11,557 posts
Posted by wjstix on Wednesday, June 3, 2020 2:32 PM

Mantua in the 1990's sold a replacement Sagami can motor. The Sagami can motor replaced the open-frame motor in most new Mantua engines around 1988. It's basically just a drop-in replacement for the existing open-frame motor, and connecting up the wiring to it. I've done a couple of engines and it worked quite well. I imagine you could still find one online.

Stix
  • Member since
    November 2005
  • From: St. Paul
  • 711 posts
Posted by garya on Wednesday, June 3, 2020 2:45 PM

snjroy

I have not used this kit. But since you ask, I have repowered Mantuas with other 12V motors and it was not that difficult. I like using a flywheel but apparently, this is not essential if you are using DCC. The most difficult steps are removing the worm gear from the old motor (NWSL sells a gear puller, which works great), and installing the new motor on the frame. I built a plastic support and attached the motor using silicone caulk. A few tries might be necessary to get the right angle. But I'm confident that the NWSL product is a good one, if you are OK paying for it. 12V motors are dirt cheap now with online shopping resources..

Simon

 

I assume you had a narrow motor.  Did it maintain gear lash correctly?  I guess I thought silicone would have too much give in it.

 

wjstix

Mantua in the 1990's sold a replacement Sagami can motor. The Sagami can motor replaced the open-frame motor in most new Mantua engines around 1988. It's basically just a drop-in replacement for the existing open-frame motor, and connecting up the wiring to it. I've done a couple of engines and it worked quite well. I imagine you could still find one online.

 

I've looked, but not had success.  I think that version had a can motor with a gearbox, which may or may not fit on my version.  

Gary

  • Member since
    December 2001
  • From: AU
  • 623 posts
Posted by xdford on Wednesday, June 3, 2020 5:13 PM

I have a Berkshire (same as the Mikado chassis wise) with a Mashima motor and an 0-6-0 with a CD Rom motor. I made  angle brackets for these in brass, placed a worm on the motors -  the hardest part was getting the angle of the bracket as such that it aligned with the worm gear but I have have very good operation since. 

PM me with your email and I will send a drawing and pic of what I have done! 

Cheers from Australia

Trevor

  • Member since
    September 2003
  • 11,571 posts
Posted by Overmod on Wednesday, June 3, 2020 5:29 PM

garya
I assume you had a narrow motor.  Did it maintain gear lash correctly?  I guess I thought silicone would have too much give in it.

I wouldn't think that any of the ad hoc 'elastic' methods of motor gluing would work right with a Helix-Humper style worm drive (which has no adjustable thrust link at the outer end of the worm shaft to keep the gears at correct depth under load).  Those methods are for universal shaft or 'tube' drive, which is inherently tolerant of both motion and misalignment under full forward and reverse torque.

That is not to say that you couldn't have elastomeric mounting of a worm-gear drive, but it would need elastic preload on that floating driven gear, the equivalent of spring pressure, to keep the worm from 'camming' out of proper depthing engagement, which over time and load will damage the mating teeth of something even like the floating gear in the Helix Humper (which I think uses spur-gear slop at the 'bottom' to push the gear up into mesh with the worm-- if the shaft then deflects up some of the effect may be lost)

I think if I were doing a 'conversion' drive with a large multiple-thread shallow-pitch worm like this I'd use skew gears for both the axle and intermediate gear, press the shaft enough through the worm to get a follower bearing on it, and put some kind of vernier adjustment both on the shaft end of the can and a link between the frame and that outer-end bearing.  That would let you adjust the depthing of the worm teeth relative to 'correct' spur-gear engagement down below, which is the critical thing for quiet long life.  
Someone here will have 'best practice' for what kind of plastic works best for the new skew gears ('self-lubricating' acetal?) and what lubricant (if any) is best for the worm and the pedestal contact -- probably a PTFE-loaded grease but it needs to be dust-tolerant.

I won't go into problems with unpowered operation: with a shallow pitch worm when it stops, you stop.  Think of it as an ultimate anti-coasting drive, which you could 'spring' to avoid damage but which would then have to return to dynamically-stable 'register'.

I wonder if the people making the Mantua General tender-drive can-motor conversion have designed something for this application too?

  • Member since
    November 2013
  • 1,054 posts
Posted by snjroy on Thursday, June 4, 2020 7:17 AM

The Sagami upgrade is now hard to find. The original open-frame motor is not bad, if you are in DC. But the silicone method works fine and it is quite stable. You might have to re-do it a few times, but this is a hobby...

Simon

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