Anyone want cheap motor gearbox units?

[Doddy]

Tim,

LMS 10000 (also applies to BR 10001) : Wheel diameter 3ft 6 ins;  motors were capable of 935rpm but were governed to 750 rpm giving a max. speed of 93mph.

John.

Hmn... @ 935 rpm that is a pair of 115 mph LMS twins! 

Nice idea John!

Almost as bad as these Class 37 LMS twins on ebay 

[Doddy]

With Tim's help on the formulas, I built an excel spreadsheet for calculating the axle RPM needed for a motor gearbox.

The results were quite pleasing in establishing the motor axle rpm for a Class 47 and making a comparison with the LMS Twins 10000 and 10001, and also their brethren Classes 44, 45 and 46 'Peaks'.

The HS4000 'Kestrel' design also used Class 47 bogies, so I added more detail to calculate the Kestrels 110mph maximum speed. I also played with the Twins figures by adding the unrestricted traction motor rpm of 935 to see what 10000 and 10001 would do for maximum speed.

The Class 47 uses MGR slow speed control of HAA hoppers on the merry go round circuits into power stations and I wanted to see the spped range to accomodate the 1.5mph of the MGR's through to the maximum prototypical speed of the locomotive.

For my own purposes, it is likely that I will confine the maximum axle rpm to 45mph for the Class 47 and Adtranz 127X to suit MGR and slow freight services.


Here are the charts for the Class 47 (and Kestrel), LMS Twins ans Peak locomotives.

Bob

[Peaky 556]

Good evening folks,
I have been progressing the fully enclosed motor-gearbox designs over the last two or three months, and have acquired all of the gears, ballraces, shafts and laser cut parts for a first batch of 11 LP units (being the lower powered, lower speed unit typically used singly for DMUs and railcars, or can be used in multiple for mainline locos), but also six of the HP design (of about double the power and more suitable for fast or powerful locos in multiple). 

I am just awaiting delivery of plastic casings, but with a prototype casing I have today built up the first LP unit, pictured thus:



The intention is to supply the unit ready-built complete with motor, with the user supplying his own axle and specifying whether to suit either a 1/4" axle or an 8 mm axle.  Time to fettle and build one is not yet bottomed out, early days(!), so pricing is not clear yet.  What is clear is that they will be very good value for money.  I shall keep you posted and try and add more detail for the Newsletter.

Regards, Tim

[Andy B]

That's a a very neat looking unit, Tim.
Did the laser cutting tolerances all work out as hoped?

Andy

[Peaky 556]

Thanks Andy, it's looks are all down to modern technology.  If I'd hewn it out of solid with chain drilling and files it would have had the Fred Flintstone look!

The question you are alluding to is whether or not the holes come out to the same diameter as drawn, when laser cut by MEL in 2mm steel plate?  This was cause for some unease and, not wanting sloppy holes for the ballraces, I did err slightly on the cautious side and made the holes about a 'thou' or 'thou and a half' undersize on diameter. 

I have just measured a typical piece and the holes are actually about one or two 'thou' smaller than drawn!  The smaller holes have the greatest delta.  This is useful information for the future, but treat with caution as it may not be true for all laser cutting companies.

Hope that helps 😎

[MikeWilliams]

Tim,

The laser cutting company I have used for many years say that the machine can be instructed in two ways - cut on the line or tell it which is wanted and which is scrap and it automatically offsets the laser the correct amount.

But when it comes to very fine detail like "one or two thou" I suspect other factors come in like wear.

Superb looking unit and I really hope you sells lots.

Mike

[Andy B]

Mike,
Tim and I had the discussion about offsetting (after all, it is only the same as setting offsets on a CNC milling machine, but smaller!), and even asked his supplier - but did not manage to get a sensible answer.

Andy

[cabbage]

I know from personal experience that the small SME motor is a good one! I only used that and the Johnson motor to power my G3 models.

Two SME  motors will pull four bogie coaches.

Regards

Ralph

[Peaky 556]

Thank you Ralph for that encouraging comment on the SME motor, which reinforces my belief that one of these units will be perfect for the likes of a railcar/rail bus, or that they can be used in multiple for larger trains.
Testing will happen in a few days when some longer case screws arrive to hold this prototype together properly.
Regards, Tim

[Andy B]

Testing will happen in a few days when some longer case screws arrive to hold this prototype together properly.

What size do you need?
Might have some if you only need a few.....

[Peaky 556]

Andy, it's ok as Boltbase have some correct length screws in the post to me.
They had supplied M2.5 x 16 instead of 18 long. 🤔

[keith Bristol]

My dmus are waiting expectedly...

[Peaky 556]

My dmus are waiting expectedly...

Let's hope they don't go over-term!
I'll get them available ASAP!
Cheers, Tim

[keith Bristol]

They will shudder on....

[Peaky 556]

Well tonight after fitting the correct length screws and fastening to a Slaters wheelset, the bench testing began!

This first LP unit, using the SME 12 V motor, has run for an hour without any sign of mishap, overheating or wear on gear teeth.  At 12V the axle is turned at 675 rpm, which equates to about 72 mph scale speed on 3' wheels.

I think this design is on target for powering DMUs and railcars, London tube stock, etc, giving a realistic limit on top speed (downhill with the wind behind).  As a reminder this is the smaller of the two intended units, and will sit between wheels as small as 33" diameter.  It does require the full width between the back to back, all bar about 4mm, so it cannot be used with inside bearing bogies, such as on some Westerns.

The photo shows it with 3'7" wheels, and the small hole on the underside, shown, is for tightening the gear to the axle with an Allen key.

I'll try and drop a bit more info into the Newsletter.

Regards,
Tim