Kean Maygib 3'7" coach wheels

[craig_whilding]

Don't forget that these wheels are too big for mk1 coaches and similar, I wish they went for an accurate smaller size as they have a better shape than Branchlines wheels.

[Tim V]

But they haven't quite got that "edge" in being accurately round and concentric that the Branchlines ones do.

[craig_whilding]

But they haven't quite got that "edge" in being accurately round and concentric that the Branchlines ones do.

Only one in 100 of the axles I have had a moulding error, the rest were perfectly turned and fitted to their axles.

I don't use plastic centred wheels apart from Exactoscale as the other types i've found do wobble..

[Russ Elliott]

Don't forget that these wheels are too big for mk1 coaches and similar, I wish they went for an accurate smaller size as they have a better shape than Branchlines wheels.

MkIs don't have 3'7" wheels????

[grovenor-2685]

Tim, are you thinking of the older plastic centered ones or the recent all steel version?
The trial set of all steel ones I have are faultless and I would happily buy more, saves the need for painting that you have with Branchlines.
See the illustration for KM05 at http://www.scalefour.org/forum/stores/shops.php#rollingstockref
Regards

[Tim V]

No I was thinking of the turned steel ones, and I've had a far higher failure rate than Craig.

I've had a Zero failure rate on the Branchlines wheels, which is why I recommend them. However, they are not steel, and they are only insulated on one side, so having said that I've used the Maygib wheels (when available), but caveat emptor!

[craig_whilding]

Don't forget that these wheels are too big for mk1 coaches and similar, I wish they went for an accurate smaller size as they have a better shape than Branchlines wheels.

MkIs don't have 3'7" wheels????

No, they have 3' 6 (14mm) whereas Maygib steel wheels are all about ~14.50mm which makes them a bit big unless you leave brakes out of the way..

Branchlines are normally about 14.2mm as well mind but closer, I can't remember what the Exactoscale ones I measured were.

The bulk packs I had all came from the EMGS as they also had the bulk packs of 3-hole I wanted, Scalefour Stores and MSE had supply issues getting some. Maybe I was lucky with the batch they were from?

Branchlines black beetle wheels can be bought insulated on both sides as most of mine are. I've kept the live axle variety for my Bill Bedford DMU underframe to allow pickups through the bearings. DC kits also sells these wheels now.

[Parthia27]

Craig,

Are you sure that Mk1 wheels are 3'6". I measured a sample of 10 Mk1 wheels at work the other week which were very close to their lower wear tollerance and they were all over 3'6" in diameter. I'm not saying you are wrong, I just want to be sure as I have at least two rakes of Mk1s with KMs and want to sure they are correct. Do you have a source for your data?

Cheers

Chris

[grovenor-2685]

I think the problem here is that a lot of documentation gives 'nominal' values which often means 3ft for wagons and 3ft6in for coaches. When you get actual detail information for wheelsets that give new diameters, minimum diameters after turning etc then there will be differences. If you have access to the real thing then your measurements will mean more than any modellers drawing.
For what its worth I have undersood, for the last 40 years or so that nominal 3ft wagon wheels usually started out at 37.5 inches diameter when new and 3ft6in coach wheels at 43.5 inches. As these were generally to standard specs to be interchangeable exceptions were rare and only started to change for coaches with the DMUs then the Mark2.

Sources?? But someone, somewhere must have access to a Mark1 maintenance manual.
Regards

[ClikC]

Thanks for the replies gents, a simple wanted ad has turn into a fairly interesting topic in it's own right.

I purchased some sample wheels from Branchlines which included some of there Nickel Silver 'Black Beetle wheels, and the very last of their Kean Maygib 3ft DMU Disc wheels, for use under a selection of Mk2's for my planned 1974' Thames-Clyde rake. The Kean Maygibs were absolutely flawless, but a couple of the 12mm Black Beetle wheels had a distinct wobble on the insulated wheel. Coupled with my new found love of steel on steel, has all lead me to wanting to follow suit with the pile'o Mk1's.

I considered I could lIve with the slightly too large wheels, but it's interesting about these nominal values Keith. It may go some way to throwing it out the idea of using undersized wheels based on the wear tolerances. If say, 3'6" is the nominal value, then is this wear tolerance subtracted from that figure, or the (and i think the more plausible) manufactured size. Obviously if anyone has chapter and verse on the subject i'd be interested to hear. But it does it does take some of the sting out of the idea of using what would be considered as oversized wheels.

I have contacted Colin Craig, who in turn pointed me toward the EMGS stores. So looks like I may be signing up to take advantage of the stores.

Regards

Matt

[Russ Elliott]

Well, blow me down with a feather, Craig is right. Looking at Keith Parkin's MkI coach book, it states, in the context of saving weight compared with pre-nationalistion designs: "Some of the weight penalty was recouped by reducing the wheelbase by 6" to 8'6" and the wheel diameter by 1.5" to 3'6"." Figure 3 (a 10mm drawing of the BR1 bogie by the Institution of Locomotive Engineers) also states 3'6" dia wheels.

[Parthia27]

Craig,

Are you sure that Mk1 wheels are 3'6". I measured a sample of 10 Mk1 wheels at work the other week which were very close to their lower wear tollerance and they were all over 3'6" in diameter. I'm not saying you are wrong, I just want to be sure as I have at least two rakes of Mk1s with KMs and want to sure they are correct. Do you have a source for your data?

Cheers

Chris

Craig,

I too have just had 3'6" confirmed by a friend of mine who is an encyclopedia on coach wheels (he used to work as shop foreman in our wheels business in Crewe) as an average which I was suprised at. I need to look at an alternative source of steel wheels for my Mk1's

Cheers

Chris

[grovenor-2685]

Chris,
Does that mean that the ones you measured have worn bigger? Or preservationists have been fitting the wrong wheels? Or your measuring stick has shrunk?

Regards

[Parthia27]

Chris,
Does that mean that the ones you measured have worn bigger? Or preservationists have been fitting the wrong wheels? Or your measuring stick has shrunk?

Regards

I'm confused TBH

Magic measuring stick is definately correct as it was only just calibrated last week

My only conclusion is that they were not Mk1 wheels, or the wheels were fitted with an odd sized tyre for a trial (not unheard of) they were all in one line so I'm thinking they were segregated for a reason. They were in the 'dead' wheel store (awaiting repair should a demand arise) in the area where we normally keep Mk1 wheels, as you can imagine they do not move very often nowadays because there is little demand. I'm going back sometime this week so I'll look around the site to see if anyone has a clue as to what they are.

Cheers

ChrisM

[craig_whilding]

Well, blow me down with a feather, Craig is right. Looking at Keith Parkin's MkI coach book, it states, in the context of saving weight compared with pre-nationalistion designs: "Some of the weight penalty was recouped by reducing the wheelbase by 6" to 8'6" and the wheel diameter by 1.5" to 3'6"." Figure 3 (a 10mm drawing of the BR1 bogie by the Institution of Locomotive Engineers) also states 3'6" dia wheels.

Such faith , that was indeed my source as I checked again after posting.

The checking was kicked off when I initially tried fitting KM coach wheels and they overlap the brakes on the original Bachmann bogies and also the Bill Bedford replacements needed tweaking to get them to avoid the brakes.

Is it possible diameters are now rounded up to a 'nice' metric number on newer wheelsets? Incidentally i've always seen wagon wheels quoted as 3' 1 1/2" on all of the drawings I have.

[allanferguson]

This is not a field in which I can profess any expertise, but it ran through my mind that there must be nearly a half inch difference between the diameter measured at the flange root, and the diameter at the front face of the wheel. I think the quoted diameter is the former(?), so which can you measure in practice? Sorry if I'm being naive!

Allan F

[craig_whilding]

This is not a field in which I can profess any expertise, but it ran through my mind that there must be nearly a half inch difference between the diameter measured at the flange root, and the diameter at the front face of the wheel. I think the quoted diameter is the former(?), so which can you measure in practice? Sorry if I'm being naive!
Allan F

To quote an LMS drawing for a 13T Medfit of 1935:
"Wheels 3 1 1/2 dia on tread, Rolled Steel Centre to Drg No 15/2650A" Possibly measured in the middle of the coning then perhaps as the nominal amount?

Sadly the LMS CCT drawing I have is only the body and not the chassis which would have been interesting to see as it would have given the larger wheel dimension the LMS used.

[grovenor-2685]

but it ran through my mind that there must be nearly a half inch difference between the diameter measured at the flange root, and the diameter at the front face of the wheel. I think the quoted diameter is the former(?), so which can you measure in practice?

Well at 1:20 for something well under 5 inches you are looking at less than a quarter of an inch difference.

The drawings usually specify where the diameter is to be measured, normally close to the centre of the tread.
In this post, the third drawing down the 70mm is indicating where to check the diameter.
http://www.scalefour.org/forum/viewtopic.php?f=64&t=532#p2533
Regards

PS. This discussion has gone well beyond 'sales and wants' I'll copy it into the rolling stock section later.
Keith

[allanferguson]

"Well at 1:20 for something well under 5 inches you are looking at less than a quarter of an inch difference."

With respect(!) 1 in 20 on each side of the wheel equals 1 in 10 on the diameter.

"The drawings usually specify where the diameter is to be measured, normally close to the centre of the tread.
In this post, the third drawing down the 70mm is indicating where to check the diameter."

I would be interested to know how you measure the diameter of a wheel in service. Is it some form of giant caliper gauge?

Apologies if this is flippant; but I'm interested.

Allan F

[Matthew]

To measure the thickness of a tread there is a device that looks like a trigger handle, with a sliding, marked scale with a end that is shaped such to fit in the centre of the wheel when the handle is against the tread (harder to describe than photo, I'll get a snap tomorrow at work).

EDIT - BR cat numbers
039/028032 without magnet
039/028033 with magnet according to PADS, but I can't find a photo this evening.

M

[grovenor-2685]

With respect(!) 1 in 20 on each side of the wheel equals 1 in 10 on the diameter.

Yes, Ok, guess I'm to used to working on the tyre profiles.
Regards
Keith

[Matthew]

In reply to the gent who asked about measuring wheels.

06072010837.jpg

06072010835.jpg

06072010838.jpg

06072010836.jpg

There is also a go/no go gauge, but it is rarely used since all the specs provided ask for dimensions to monitor tyre wear. Turn under, knifing, flats and damage to the wheel centre are given a visual examination.

[allanferguson]

Mathew said "In reply to the gent who asked about measuring wheels........."

Thank you very much for showing us these. It's fascinating to see how the real railway does it. Presumably the wheel disk is of a known diameter, so just add twice the rim thickness to get the overall diameter?

Allan F

[grovenor-2685]

Presumably the wheel disk is of a known diameter, so just add twice the rim thickness to get the overall diameter?

True but the interest is not in the diameter as such but in the tyre thickness, both to monitor wear rates and to ensure that the various wheels in a set don't differ by more than the specified tolerance.
Regards

[Matthew]

Mr Ferguson - bang on, the measurement being looked up on a chart which give the nominal resultant diameter. a new tyre being around 20mm thick, the minimum being something around 6-8mm

Mr Norgrove, you are right, the diameter is only important when setting the wheel wear compensator - this is wired into the speedo and wheel slip circuits, and allows for the wheels wearing, hopefully giving an accurate speedo reading.

However there are different tolarances for:
wheelsets on the same axle,
for a powered bogie,
for a non powered bogie.

I'll find an example tomorrow.

Matt.