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Useful Chassis for British H0 Loco and Railcar Projects


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On 08/10/2020 at 02:15, johnhutnick said:

I am in the US.  If, for example the Mantua articulated cylinder block is too wide, then what US chassis are a proper width?  What width in mm do we want?  I can measure a lot of different engines if anyone needs the numbers.

 

John,

 

It would be interesting to know the dimensions you found.

 

If the width across the cylinders turns out to be much too much for the British outline, there is often still an option to remove them to make a chassis for an engine with inside cylinders.

 

I can add potentially useful chassis to the table in the first post.

 

- Richard.

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I measured outside cylinder block width for a PFM HO brass Santa Fe 2-8-0 and a brass UP 2-8-0.  These are relatively small engines.  They are 36-37mm wide.  Also, I measured width over crossheads at about 32mm.  The 8'10" cylinder quoted earlier at 3.5mm = 31mm.  So if you want a scale width, US engines would be generally too large.  I tried an 0-6-0 CP switcher - 34mm.   I then got a GEM GWR King, which is 33mm, with tiny cylinders set well ahead of the drivers.  So what chassis are suitable?  And how to build anywhere close to scale cylinder width using HO drivers, which are overscale?

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28-30mm is absolute maximum, and for most 28mm . 33m on the King which I presume is 4mm scale is 8ft 3in. Remember the cylinders on the Halls were out of gauge for some lines(eg ex GCR) and one on a tour in the 1960s had to be taken off train because it wa out of gauge.

I suspect for r2r chassis only really suitable for insde cylinder locos(possibly similar reason to why Jack Nelson modelled LNWR which had mainly inside cylinder locos).

Some continental HO locos might be OK. An obvious one would be the USATC loco. The Electrotren/Hornby low cost steam loco is too wide, mainly because it is a model of 5ft 6in (ish) gauge.

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First, the King class that I measured is HO.  It is one of the few British HO locos ever made.  It is much smaller than a Hornby King.  It is 1964, 1 of 30.  If you search for Gem brass HO GWR King Olympia, or some combination, you will find it on Worthpoint.  Now you may then say - oh, it is overscale - but that is what has been made.

Next, I took out of the box(first time) a Roco USATC 2-8-0.  The cylinders measure 34mm, and they are small.  I also went through my collection of HO brass parts, and the tiniest cylinder block was also 34mm.

Then I measured a number of various HO drivers, and they are typically 22.5 - 23 mm width at the crankpin holes.  So assume that we try to somehow achieve 31mm overall.  Set the piston rod centers 3mm in from each side of the cylinders.  31 - 6 =25mm.  Now the drivers are 23 mm wide.   So we have 1mm to spare on each side.  There simply does not seem to be room for side rods, main rods and outside valve gear.

I am in the US, so I am no expert on British.  Does someone here know of steam loco models that are actually British HO scale width?(not inside cylinder)

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As my main interest has been smaller locos I had not checked the big ones. Certainly nothing over 9ft wide, which is 31.5mm in HO.

On checking some of my HO locos which are continental, but could be used on a British layout(eg Liliput fireless loco) they are slightly wider over the cylinders, but it is not that obvious.

I would suspect many r2r manufaturers would increase width across cylinders if that was only way to get a working model. It is a pity the old Rivarossi LMS Royal Sot was done to slightly bgger scale, maybe because that was only way to get it to work.

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On 20/10/2020 at 20:37, johnhutnick said:

I am in the US, so I am no expert on British.  Does someone here know of steam loco models that are actually British HO scale width?(not inside cylinder)

 

I have a Rapido J70 tram. This model was designed specifically for 00 gauge (1:76 scale) and there is little or no provision for conversion to EM or P4. However, the designers managed to include outside cylinders about 29 mm across. They are of course quite slender, in the form of the cylinders on a steam tram.

 

- Richard.

 

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9 hours ago, rue_d_etropal said:

I had wondered about the J70 chassis, but how many locos are there with wheelbase  3ft 9in and 3ft 9in, and with 3ft 6in diameter wheels which is what it works out in HO,

 

 

Surely, the J70 chassis is useful as an example of how to build a slender mechanism.

 

- Richard.

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The subject of chassis for the Mainline J72 has been discussed on the "main British H0 forum thread"  (starting about here) so I have added the kits by Comet Models and High Level Kits to the original post above.

 

I am afraid I have had to split the table into two parts. This is not ideal, but it lets me take screen grabs from the spreadsheet at 100% to post here. So there is now a table of RTR chassis, and a separate table of kit chassis.

 

See:

https://www.rmweb.co.uk/community/index.php?/topic/150691-useful-chassis-for-british-h0-loco-and-railcar-projects/

 

Corrections, missing details and fresh examples are always welcome of course.

 

- Richard.

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I just managed to get a Jouef internal cylindered 0-6-0 on eBay for less than £30 and there's an even cheaper one whose auction finishes in a couple of hours.  I'll measure it when it comes but hopefully some suitable HO body will fit it.

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On 22/10/2020 at 21:34, rue_d_etropal said:

I had wondered about the J70 chassis, but how many locos are there with wheelbase  3ft 9in and 3ft 9in, and with 3ft 6in diameter wheels which is what it works out in HO,

 

some standard gauge double fairlies were very close - though not built for British railways

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  • 2 months later...
On 01/02/2020 at 14:21, rue_d_etropal said:

Neded a break from designing coaches and locos so knocked up a simple loco chasis with 26 +28mm wheelbase. I would recommend using one of those gearbox/motor combinations which DJH use on their locos. Was not sure of exact distance motor sits above axle,but I can either modify design or packing could be added. It takes 1/8in axles with 3.7mm bearings(eg Romfords).

chassis-block-060-26-28-1a.jpg

I decided to have a break, so had another look at this. I have come up with a modular version, so any wheelbase can be created. Simple slot the axle holders onto the beam(cut to suitable length), then just ad bearings and loco wheels. The longer axle support is for gears to be fitted. It might be possible to creat some sort of cradle to hold motor, and this cradle could then slot into the top of the chassis beam.

Just waiting to get a test sample. The package will have one long beam, 3 supports for wheels with gears, and 10 axle supports for non geared wheels. Should be enough for 2-3 locos.

modular-chassis.jpg

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This looks rather good.

 

I wonder if the larger axle support could be usefully integrated into the beam, offset a little from the middle? And above this, a bracket to hold one of the miniature coreless motors which seem all the rage in RTR at the moment?

 

Doing this would allow for an 0-4-0 or 0-6-0. If the beam were to be long enough, the driven axle of an 0-6-0 could be the centre axle or one of the outer axles.

 

Do remember, the wheels of H0 locos are smaller than those of 00 ones. So the gear on the driven axle may be quite small. We might need an idler between this gear and the worm.

 

You must let us know how the test sample works out.

 

- Richard.

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for this, the aim was to try and keep it to one design for all 16.5mm gauge locos, any scale. I actually want one for my Irish 3.14mm scale model.

For tender locos I would probably use tender drive, which is something Mark at Locos n Stuff might be able to do as already has some units which are close.

I am now also working on similar units to hold wheels under non bogie coaches and wagons, based on a 2mm thick axle,which I tink is pretty common in 16.5mm gauge wheels. I might then be possible to combine the idea to create something for non driving wheels on locos.

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I have added the Hornby Peckett W4 to the list because its chassis dimensions work well for the larger Peckett E class:

 

  • Wheel diameter 12.6 mm is spot-on for the prototype 3ft 7in.
  • Wheelbase 22 mm equates to 6ft 3in so only 0.8 mm too short for the prototype 6ft 6in.

I cannot help thinking, new boiler fittings and new buffer beams would make for quite a pleasing model.

 

Lengthen the footplate at both ends and modify the cab as well and the result will be a fair representation of an E class.

 

A useful topic:

https://www.rmweb.co.uk/community/index.php?/topic/166246-peckett-saddle-tank-classes-e-vs-w5-or-w6/

 

- Richard.

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  • 4 weeks later...

Has been a minute since ive made a forum post, but ive just heard about this and it had me thinking of what project I could work off of an existing RTR chassis.

 

What ive found is the Ivatt 2MT ( a class I know little of considering how deep into pregrouping I am). Hornby & Bachmann both offered these before, and Hornby has also reissued the model in a new tool.

  • Driver diameter is prototypically 5'
  • Wheelbase on drivers clock in at 6' 9" + 7' 0"

Now I would have to check the chassis height and many of the other dimensions on it beforehand, but I believe I could squeeze an Lbscr's K class body onto it with relative success, given a margin of 3" on the wheelbase and about 2" on the drivers. Where would this magical Ho body come from? Im a CAD wizard of course :P 

 

I would also want to check against a rtr pacific to make way for the Brighton L class/ southern N15x. Alternatively the Brighton J1/j2 could be done, but now im just regurgitating research that hasnt happened yet.

 

~Javier

 

re: looking at more diagrams from Jh russles "southern locomotives" I could possibly get away with an E5 or E5x using the Ivatt, but the boiler pitch might be something that needs work

Edited by Javier L
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Given how many BR Bo-Bos and DMU had 8'6" bogies, I've been considering the options for a 29.75mm wheelbase power bogie, ideally rtr and reasonably available. 

 

Not much close in the various US or continental ranges, but then I had a lightbulb moment and realised that the 1Co bogie under Classes 40/44/45/46 has a wheelbase of 8'+8' on the driving wheels, or 30mm+30mm on the 4mm:ft models. Close enough, I think. 

 

Better still, the various rtr models (old and new) have tended to power the lead/centre driving axles, with the pony and trailing axles being unpowered, so could be adapted to a Bo-bogie. 

 

I have at least 1 Mainline 45 squirreled away somewhere and having regauged one to EM many years ago, i know it can take 2mm axles, so rewheeling with 12mm disc wheels is doable. 

 

Likewise the newer Bachmann 40/44/45/46, I'll dig out my 'demic' 44 and have a play. Adding a 2nd motor means i should get 2 mechs out of 1 donor, given the short trains on my layout will only require 1 drive bogie per loco. 

 

I'll report back in due course. 

 

 

 

 

Edited by CloggyDog
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Following on from discussions in the commercial items topic I have put some minor updates into the tables in the first post:

  • For a LSWR G6, a J72 is a far better starting point then a Terrier
  • I've added the Lima GWR 45xx prairie as a way to build a 61xx large prairie

I have omitted the Ivatt 2MT and the classes 40/44/45/46 (above) for the time being simply because I hope they turn out to be a success but at the moment I am not quite sure whether they are suitable.

 

The most recent posts here do show how much the tables reflect my own preferences for small locomotives without leading or trailing wheels ... I am sure there are are other RTR donors for large steam locomotives especially the BR standard designs with a high running plate. I can put them into the tables if I find out what they are.

 

- Richard.

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My maths is being rubbish... 8ft in 4mm is 32mm, of course. :punish:

 

So ignore my thoughts on using the 4mm 1Co bogie. 

 

However... having recently acquired an H0 3D-printed Class 24/1 shell+bogie sideframes (courtesy of Lenny at Lincoln Locos rescaling his 3mm version), I am seriously looking at motorising options for that. 29.75mm bogie wheelbase at 98mm centres. 

 

Asking around various groups and forums, I was pointed at the German V90/BR290 type, RTR offerings from Roco, Trix and Brawa. The V90 bogie is 29. 88mm (2600mm / 87), though the bogie centres are short at 80mm, so the chassis would need stretching. An option may be to source the bogies as spares (Roco can certainly supply theirs) and fabricate a suitable chassis. 

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Tenshodo have released a range of motor bogies using a coreless motor, including a version with a wheelbase of 31mm and 11.5 or 14mm diameter wheels. There are some on eBay at the moment but shipping is from Japan:

 

https://www.ebay.co.uk/itm/-/165237598612

 

I have had very mixed results with the running of older Tenshodo motor bogies, maybe these coreless ones are better.

 

- Richard.

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Returning to the list after a few years being busy elsewhere, and am only just now re-starting development work on my HO trucks.

 

Regarding both power trucks and trailing bogies, I have a few 29.5 mm (8-6), 32 mm (9-2)  and 34 (9-6) mm  inside frame, snap and glue together chassis kits that I can make available in short order. 

 

114690525_superglidewheeled665.jpg.cad6630f609f2d5418693635237460c7.jpg

 

TYPICAL TRAILING TRUCK

 

234533268_electroglidebodieswithunderfloorbolsterfitted.jpg.01f559b88f9c61e51e2fe3fa6c668e5c.jpg

 

BASIC POWER TRUCKS CHASSIS - long and short wheelbases - shown without wheels or gearbox.

 

360350953_E1singlemaxtruckclose-600.jpg.7d36860beec71a4d88044581aee0d945.jpg

 

SHORT WB MAX TRACTION VERSION OF POWER TRUCK showing wheels and gearbox fitted.

 

Lots of various shorter WB sizes are available for street cars and bogie wagons. Power trucks are designed for use mostly low/under floor with a central motor. So they can power HO DMUs/EMUs as well as HO  locos. The last picture shows the matching low profile gearbox that  powers 1 axle per truck using Ultrascale 15:1 gear sets. 

 

Andy

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1 hour ago, Andy Reichert said:

Returning to the list after a few years being busy elsewhere, and am only just now re-starting development work on my HO trucks.

 

Regarding both power trucks and trailing bogies, I have a few 29.5 mm (8-6), 32 mm (9-2)  and 34 (9-6) mm  inside frame, snap and glue together chassis kits that I can make available in short order. 

 

114690525_superglidewheeled665.jpg.cad6630f609f2d5418693635237460c7.jpg

 

TYPICAL TRAILING TRUCK

 

234533268_electroglidebodieswithunderfloorbolsterfitted.jpg.01f559b88f9c61e51e2fe3fa6c668e5c.jpg

 

BASIC POWER TRUCKS CHASSIS - long and short wheelbases - shown without wheels or gearbox.

 

360350953_E1singlemaxtruckclose-600.jpg.7d36860beec71a4d88044581aee0d945.jpg

 

SHORT WB MAX TRACTION VERSION OF POWER TRUCK showing wheels and gearbox fitted.

 

Lots of various shorter WB sizes are available for street cars and bogie wagons. Power trucks are designed for use mostly low/under floor with a central motor. So they can power HO DMUs/EMUs as well as HO  locos. The last picture shows the matching low profile gearbox that  powers 1 axle per truck using Ultrascale 15:1 gear sets. 

 

Andy

That looks really clever, Andy!

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  • 2 weeks later...

Taking a chunk of time to work on the K class Body for the Hornby 2MT. The chassis ive received is an R.852, and I had near immediately began work when it arrived. 
 

Ive discovered it is a much longer wheelbase than even what the OO 2MT should be, my guess is that it was a basic standard chassis anyway. Nonetheless it is not so severe in that I didn't think I could roll with it, and I now have a half completed Body to fit it.


Should be a few more days worth if work, I can report back once I think im ready with a printable file. More on that in March though.


I shall have to come back with the prototype dimensions for the R.852. The chassis ends up being a tad tall for the firebox area, and ive had to raise the firebox, boiler & cab slightly as a result. I believe that a Bachmann version of the 2MT would fit better, and I would be willing to work on a version of that should It ever come into my possession.

 

Javier

1AB80E98-64A0-4E34-B54F-AC4CF3BC5E6B.png

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