Gearbox/Motor for Comet chassis for Hornby Terrier

[hespertalbahn]

Hello there !

 

With the intention to upgrade my Hornby Terrier optically and technically (performance) I have purchased a Comet chassis kit together with the gearbox (38:1) and mashima motor.

I would like to use the modified loco for a small layout for shunting, so performance at a slow speed is more important for me.

So I would like to ask if someone of you has already used successfully an alternative (perhaps with flywheel) which will allow slower performance then.

 

I am looking forward for suggestions.

 

Thank you in advance for your efforts.

 

Best wishes

Dirk

[brossard]

Dirk, the GB ratio is very important for the type of loco.  38:1 is typically used for a mainline passenger loco so slow speed running may not be as good as you would want.  A flywheel will help but can you get one in?

I will point you to High Level ( http://www.highlevelkits.co.uk/ ) whose gearboxes have a wide range of ratios, up to 108:1.  For myself, I would go for at least 60:1 or even 80:1 for shunting/unfitted freight.  The idea is for the motor to be running at close to its design speed to avoid stalling.

 

 

80:1 box, the final drive hasn't been installed.

John

[alfsboy]

I agree .High Level /Mashima are the best/easiest  out there .Very sweet running and easy to install .

[artisan100]

Ensuring a reliable pickup from all six wheels is very important to prevent stuttering over pointwork etc. And with driving wheels that are just 4' 0" diameter this loco is not capable of a very high top speed anyway. The Terrier was capable of quite quick acceleration around the yard, etc., and my recollection is that drivers would get on with the job in hand as quickly as possible so that when it was done they could get back to their billy can. Moving at a barely discernible speed is more common on layouts than it was in the real world.

 

Geoff 

Comet Models

[alfsboy]

i was thinking about very slow running  while running up my SE Buckjumper ,with a Mashima/High Level  set up.  Geoff is right about the pickups.Essential to get them  working on every wheel possible  . ."Slow" running looks good with a bit of speed behind it .it looks just like a proper steam loco  running ,smooth and a fair pace   .All the steam locos I ever saw  were fair chugging along  what ever they were doing .I think maybe this slow running malarky may well come from the USA where slow running with a huge freight train at walking pace up a mountain was often needed.Even switching in the street is often done at a fair lick over there  though .

[Thane of Fife]

I have used a Mashima 1020 with a High level humpshunter 80:1 geabox in my Mainline J72 and it works well with a load of lead added.

I find 80:1 a good ratio to use with a dedicated shunter. With a dockshunter (Y8 in my case), I use 108:1 as dockshunters rarely went above walking pace.

[34theletterbetweenB&D]

..."Slow" running looks good with a bit of speed behind it .it looks just like a proper steam loco  running ,smooth...

 If I am reading this correctly, then I agree. The whole point of a mechanism being able to run well at dead slow is that it can then replicate the smooth acceleration and deceleration of an object of high inertia.

 

As others above, the drivers on shunting machines used to 'press on' with some vigour. If it were my Terrier then being able to reach something approaching maximum speed (at least 50mph/80kph) would matter to me; that typically needs around 40:1 ratio on this wheel size. Good smooth running already available at this ratio, and it may help with drive compactness over a higher reduction gear train.

[brossard]

I don't disagree that shunting was done with some vigor.  My point about low gearing is that the ability to run dead slow and reliably is a good performance tick mark.  It is certainly possible to get a high gear ratio loco to run slowly, but in my experience, not reliably because the motor isn't turning fast enough and the slightest track irregularity will stall it.  With 80:1, I daresay that scale 50mph is possible - perhaps Thane can confirm.  You definitely don't need express train speeds.

 

John

[t-b-g]

I can only agree strongly with the comments about a High Level gearbox and a Mashima can motor.

 

This is a set of Branchline frames for a Terrier (scratchbuilt body). The wheels are compensated, to aid pick up as the layout is a terminus and there won't be much fast running, so good pick up is essential.

 

If I could remember which gearbox it was I would give the name but I do know it was an 80:1 reduction. You can get a good brisk start by turning the controller up fairly quickly and as you are using the full sweep of the controller knob, the response to the controller is good.

 

The gearbox protrudes ever so slightly into the cab but is invisible between the side tanks unless you can see round corners.

 

 

I hope that helps you make up your mind.

 

Tony 

[brossard]

I do like that Tony, luvly looking loco.  The gearbox looks like the Loadhauler Compact.  I have one that I built up recently (but of course I can't find it at the moment).  I was puzzled by one thing - the final drive gear seems to be brass with no way to secure to the axle other than loctite or cyano (my engineering instincts tell me that for something as critical as this, mechanical fastening is best).  The taller Loadhauler has a brass final drive gear with grub screw.  I've been meaning to drop a line to Chris about it.

 

John

[Thane of Fife]

If you download the High Level Gearbox planner, it shows which gears are fixed with Loctite and which with a grubscrew.

From memory: Roadrunner plus, Highflier, and Loadhauler plus have grub screws.The rest use Loctite.

 

Thane

[brossard]

Many years ago, the Engineering Director where I worked threatened to fire any designer who specified "glue" to hold parts together.  These were aircraft engines so perhaps justified.

 

John

[Gruffalo]

When considering loco speed, a point that is often overlooked is that an express loco (be it steam or diesel) requires some distance to achieve its maximum speed. If a modeller has 25m of mainline track after the station exit, that would equate to 6,250 feet of real railway which represents less than 1.2 miles. In all probability, that distance would never amount to much more than 70% of the loco's maximum speed. If you then factor that into the HighLevel gearing calculator on Chris's website www.highlevelkits.co.uk you can get a more realistic arrangement that will allow good hauling power and traction, excellent torque and extremely realistic operation.

 

Using the excellent HighLevel speed calculator, the 6'9" driver with a 54:1 gearbox reduction and a Mashima 1220 motor running at 17,000 rpm will give a scale speed of 76 mph although the 1220 is not a very powerful device. Bigger motors run slower - a Mashima 1424 runs at 15,000 rpm and this would give a speed of 67 mph. If you can get a Mashima 1626 within the frame and body, the scale speed would be no more than 60 mph but the hauling power would be excellent. Using a smaller driver of 4'7 1/2", the Mashima 1626 and 54:1 gearbox would give 41 mph - a pretty fast heavy freight by steam standards.

 

As for Brossard's comments re fastening the final gear to the driven axle, I agree it isn't perfect but how are Gibson or Hornby and Bachmann wheels secured to their axles?

[brossard]

Loctite does provide a very good bond.  I use it for securing worm gears to the motor shaft.  I'm glad to see that there seems to be a consensus on the use of Loctite.

 

John

[Thane of Fife]

The first time I used Loctite for fitting the final drive to a High Level gearbox, I was nervous. I had to use it to fit a Humnpshunter gearbox into an old Kays Y8, which was hopelessly fast with the original Kays motor and gearbox. However, there were no problems, and the Y8 will now run smoothly at less than a scale 1mph. If the gear needs to be removed, it can be knocked out with care.

Thane of Fife

[34theletterbetweenB&D]

When considering loco speed, a point that is often overlooked is that an express loco (be it steam or diesel) requires some distance to achieve its maximum speed. If a modeller has 25m of mainline track after the station exit, that would equate to 6,250 feet of real railway which represents less than 1.2 miles...

I only have a quarter mile on view. But the traction can have had anything up to 50 odd miles of favourably aligned continuous run up to really get a move on, so can be through that quarter mile of express rated track 'briskly'. The stopping, shunting, reversing manouevres all happen at the appropriate rates. But even the small wheeled tankies sometimes found themselves on a 'run through' and were then flogged along at the fullest chat achievable.

 

Let's be clear, I want it all. Glacially smooth modelling of the high inertia movement of railway vehicles, with a smooth creep in and out of motion; and the loco able to run at a realistic maximum speed for the type when on a run through. This can be achieved, but not with really high gear ratios which apply a mechanical limit to maximum speed. The winner for me is moderate ratios, and a good decoder and motor combination for smooth going at relatively small rotational rates.

[DLT]

If you download the High Level Gearbox planner, it shows which gears are fixed with Loctite and which with a grubscrew.

From memory: Roadrunner plus, Highflier, and Loadhauler plus have grub screws.The rest use Loctite.

I too recomend Highlevel gearboxes, preferebly with grubscrew axle fitting.  The problem with the more compact boxes in the range is that there isnt the physical room to accomodate a final drive gear with a large boss on the side for the grubscrew.  Hence the need for Loctite fitting.

Another one with grubscrew fitting is the Slimliner-Plus, essentially a narrower versuion of the Roadrunner-plus, with a gearbox body only 7.2mm wide.  Very useful in locos with small diameter or high pitched boilers.

Cheers, Dave.

[hartleymartin]

It makes me wonder why flywheels are not yet a standard item in model locomotives...

 

I work mostly in 7mm scale, and after the Ixion Hudswell Clarke showed me the advantages of a flywheel drive with a low 40:1 ratio gearset, I decided to rebuilt my other locomotives with a similar drive set up.

 

From the reviews I have read, it seems that the Terrier has a fairly decent slow-running mechanism as it is, but if it were being used purely as a shunting locomotive, I suppose one would want a smoother drive train with a gear ratio better for slow running. I also note that the smaller mashima motors operate at higher speeds. The 1833 is rated at 8,500 rpm, whilst I think the 14xx series are about 10,000 to 12,000 rpm

[Thane of Fife]

G'day all

A little late with comment, but better late than never.

A Mashima 1620 can just about squeeze in a J72/Terrier size loco, and with 80:1 gears will give max power at scale 23mph and max speed (no load) at 46mph, with 16mm wheels. I don't think shunters ever ran at greater speeds. My Y8 with 12mm wheels and 108:1 gears gives max power at 10mph and potential max speed of 20mph.

When I first started modelling back in the 70's Alex Bowie, one time editor of MRC, said anyone can build a loco to go fast, but the skill comes when making a loco run smoothly at low speed.

Thane of fife