Jan Posted November 2, 2009 Share Posted November 2, 2009 Which Motor/Gearbox in a 4mm Impetus 15" Hunslet? by Jan original page on Old RMweb __________________________________________ ??? posted on Tue Jan 20, 2009 11:19 am Greetings, I am just easing my way back into the hobby after a long absence, and I have a number of projects to finish off from the last time.... One of these is the P4'd beast in the title. I have all the upperworks complete and dandy, but trying to find a choice of motor/gearbox to sit in the firebox (and thereby powering the back axle) is proving difficult; sadly, the instruction sheet (that had a nice diagram of the loco to 4mm scale on it) has vanished... So I was wondering if anyone could advise me. Way back then, I decided a High Level Minimiser would do the job (I know that because it's in the same box!). Has anyone else used one in this loco? Views welcomed... Cheers Jan __________________________________________ Comment posted by industrial on Tue Jan 20, 2009 11:26 am There are drawings in MRC 9/86 of the 15" engin but I think your choice is the best also Highlevel do a lot more gear boxes than when you got yours including 2mm worms as well to get a good powerfull motor in there. __________________________________________ Comment posted by Adam on Tue Jan 20, 2009 12:14 pm Ah, something I actually have direct experience of! See below: The 'box you suggest is the one I used; my loco' was acquired secondhand with a great big Romford (I think) cog in it, and the little Tenshodo motor that was de rigeur when the kit was actually available. A Mashima 1020 should fit (with the shaft cut off on one end), but without a bit of butchery or wholesale re-design in the construction phase, that's probably the best you'll manage. With a boiler and tank full of lead however, that's not a bad prospect for a loco' of that size. HTH Adam __________________________________________ ??? posted on Tue Jan 20, 2009 12:42 pm industrial wrote: There are drawings in MRC 9/86 of the 15" engin but I think your choice is the best also Highlevel do a lot more gear boxes than when you got yours including 2mm worms as well to get a good powerfull moter in there. Hi industrial, Thanks for that: I'll try and track down a copy of MRC for reference. Cheers Jan __________________________________________ ??? posted on Tue Jan 20, 2009 12:48 pm Adam wrote: Ah, something I actually have direct experience of! The 'box you suggest is the one I used; my loco' was acquired secondhand with a great big Romford (I think) cog in it, and the little Tenshodo motor that was de rigeur when the kit was actually available. A Mashima 1020 should fit (with the shaft cut off on one end), but without a bit of butchery or wholesale re-design in the construction phase, that's probably the best you'll manage. With a boiler and tank full of lead however, that's not a bad prospect for a loco' of that size. HTH Adam Hi Adam, Excellent. I think I'm going to have to involve 'a bit of butchery' as (if I recall correctly) the output shaft of the High Level gearbox is 2mm, and the loco has 1/8" bearings in it. To make matters worse, I've never tried fitting a 2mm axle through a 2mm bearing, and then up to a 1/8" wheel before (I have the conversion bearings - just lacking the bravery!) .... all that AND the quartering to maintain.... Eek! Cheers Jan __________________________________________ Comment posted by Adam on Tue Jan 20, 2009 1:52 pm Sorry, I got that wrong - I knew I should have checked the website first... I actually used a Slimliner compact + (54:1) which with those small wheels gives an acceptable top speed and solves the issues with a 2mm axle. HTH Adam __________________________________________ Comment posted by industrial on Tue Jan 20, 2009 2:35 pm I think it will be better to download the gearbox plans from the Highlevel web site as there are many new gearboxes out there with 1/8 gears not like in the days when you got yours and get a new one. __________________________________________ Comment posted by Nigelcliffe on Tue Jan 20, 2009 3:01 pm Like others have said, I'd go for a new HighLevel gearbox; there are a lot of options. I'd watch the "tank full of lead" doesn't get too heavy for the motor, there is a compromise between sensible weight for reliable pickup and adhesion and over-loading the motor. I'd experiment by watching the motor load on an ammeter whilst adding temporary weight and stop when there is a distinct rise in current due to the weight, then I'd drop the weight down a bit from there. One thing I'd now do whilst building is put in a big enough slot for a DCC decoder. You might not be going DCC now, you might think DCC is the work of Stan, but the law of Sod will ensure that you regret not fitting the space in two years time. (*) The outer dimensions of a NEM651 compatible decoder should do (eg. Zimo MX620 or Lenz Silver Mini) - bit of plasticard of the correct size to ensure there is the space, with enough extra space for the wires off the end and at least fag-paper insulation around the chip. The "well prepared for the future" builder installs a NEM651 socket with a blanking plug (as per a DCC-Ready Ready-To-Run N gauge loco), available for a few quid from the better DCC suppliers. (* retro-fitting chips into relatively small kit built metal locos can be seriously time consuming if my experience is anything to go by. OK, I make it harder for myself by adding DCC controlled gizmos, but just carving out spaces in already built locos can be quite hard work - taking care not to damage parts or paint finishes, not upsetting the balance, etc... Designing in space as you build makes it so much easier ). - Nigel __________________________________________ Link to post Share on other sites More sharing options...
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