Rigid Chassis Locos?

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jon price
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Rigid Chassis Locos?

Postby jon price » Wed Mar 18, 2020 9:53 am

i realise this may lead to me being marched out at the next ScaleFour exhibition, my card torn in two and a length of ready made track broken across the knee of the Chairman in front of me, but are there any members prepared to admity to simply running rigid chassis locos with success? (I'm thinking about small 0-4-0 and 0-6-0 locos, not Pacifics or 9Fs here)
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steamraiser
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Re: Rigid Chassis Locos?

Postby steamraiser » Wed Mar 18, 2020 10:06 am

A lot depends on the quality of your track building and laying.

I was fortunate to visit Robin Whittles Barrow Road shed, where he was running Bachman Jubilees with only axle and wheel changes.
These engines were running very smoothly.

Gordon A

Philip Hall
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Re: Rigid Chassis Locos?

Postby Philip Hall » Wed Mar 18, 2020 11:01 am

As Gordon says, track quality must be high. Given that, I have had no problems. I have converted lots of Hornby and Bachmann engines (steam, and not little ones either) over the years and the running has been very good indeed. I don’t think I’ve ever heard of anything falling off for lack of suspension - a few bumps maybe owing to a track defect.

I would not contemplate actually building a rigid chassis in P4, only converting one. The amount of slop in a commercial chassis does give a sort of compensation or whatever, even if I try to (slightly) tighten up clearances around the crankpins. My number one criteria is that wheels (at least driving wheels) are concentric and true. With our flanges that resemble turning burrs that’s important!

There are various guides on the Alan Gibson website, written (I think) by Pete Hill, and whilst these refer to EM, the principles are the same, only clearances around valve gear and splashers are different. They are a good place to start for information.

Philip

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Tim V
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Re: Rigid Chassis Locos?

Postby Tim V » Wed Mar 18, 2020 11:07 am

Several engines on Clutton had converted Bachman type chassis, ran without problems. I wouldn't have said the trackwork on that was 'high quality'. Plus those same engines were expected to run round 3' radius curves at line speed.

So go for it - there are other heretics in the society who haven't been 'drummed out' yet ...
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Proton
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Re: Rigid Chassis Locos?

Postby Proton » Wed Mar 18, 2020 11:08 am

Do diesels and electrics count? I have a Class 20 , several 24s and 25s, a class 35, and a variety of AC electrics, all with drop in Ultrascale wheels, and all run well and never derail. For the three-axle bogies, Heljan are the best. I have the Falcon, Lion, and a brush type 4, and all perfect runners. A couple of Hornby class 50s needed surgery to the phosphor bronze bearings to introduce a bit of slop, and are now 99% good runners, derailing only rarely. Bachmann three-axle trucks are hopeless. I have a Penbits kit for the NRM Deltic to build this summer. I also have a Bachmann class 08 with U/S wheels, and no springs. Perfect runner.

PBM

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Tim V
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Re: Rigid Chassis Locos?

Postby Tim V » Wed Mar 18, 2020 11:13 am

Oh well, as for diesels, I had a Bachman warship that ran beautifully with new wheels, a Helkan Hymek that, after a change of motor runs superbly.
Tim V
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jon price
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Re: Rigid Chassis Locos?

Postby jon price » Wed Mar 18, 2020 12:05 pm

So converting RTR seems OK, probably because the small amnount of slop mimics compensation. However I am building my own chassis, so how about building in the same limited amount of (vertical I assume) slop?
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Tim V
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Re: Rigid Chassis Locos?

Postby Tim V » Wed Mar 18, 2020 12:43 pm

Actually, there is quite a lot of slop in RTR mechanisms. And that slop isn't just for road-holding, but for pickup.

I can't recommend building rigid chassis with 'slop'. If you are going to that extent, putting in a simple beam system (remember that?) isn't much more work and will result in a far better running loco.
Tim V
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Philip Hall
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Re: Rigid Chassis Locos?

Postby Philip Hall » Wed Mar 18, 2020 3:23 pm

I wouldn’t build a chassis rigid, getting it absolutely plumb is very difficult and if it rocks in any way you could be in trouble. The RTR boys put these things together on a production line and quality machinery. It’s OK in 00 and to a lesser extent in EM but our minuscule flanges give much less room for error.

As Tim says, there’s really no point as simple compensation is straightforward and will give more of a ‘guaranteed’ result.

Philip

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Re: Rigid Chassis Locos?

Postby Tony Wilkins » Wed Mar 18, 2020 4:18 pm

Hi Jon.
My thoughts are similar to Tim and Philip.
If building a kit or scratch-built chassis I always include some form of compensation. For the extra work involved, the results are worth it.
If converting an RTR item, the option of swapping wheel sets is worth trying for quickness. I have been known to add extra slop in the right places if I thought it necessary, but that needs to be done with care. Results can be mixed, but total failures rare with some notable exceptions already mentioned.
Regards
Tony.

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barrowroad
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Re: Rigid Chassis Locos?

Postby barrowroad » Wed Mar 18, 2020 9:30 pm

Jon , I have a Hornby Black 5, Bachmann Crab and WD, whilst more recently I have added three Bachmann Jubilees and one Patriot to my allocation for Barrow Road. Have a look at my postings and videos on this forum. I have just converted a Bachmann 4MT tank for a member of our group. They all run well. If you want any advice please ask.
Robin

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Re: Rigid Chassis Locos?

Postby triumph3 » Wed Mar 18, 2020 10:21 pm

I agree with Robin, I have a Bachmann Jubilee, Bachmann Pannier tank, Bachmann Hall and a Hornby B5 all converted by changing the wheels. The Standard Bachmann bogie seems to work well, but following Robins example the standard bogie on the Hornby B5 does not work and a replacement with a Masokits one is required.
I think the precision of the latest RTR helps matters and then the issue is whether to re use the original coupling and connecting rods or upgrade them with etched replacements such as provided by Comet, Lanarkshire Models or Brassmasters.
So I would say, give it a go!

David

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Re: Rigid Chassis Locos?

Postby triumph3 » Thu Mar 19, 2020 11:04 am

I forgot to say that whilst the loco chassis are cabable of a straight conversion this does not apply to tenders. None of my loco conversions which had tenders would run, so the tenders all have either Lanarkshire Models or High Level tender chassis, the High Level one is for a GW tender. I know Robin on Barrow Rd has converted his Bachmann tender locos with Dave Franks excellent Lanarkshire Models tender chassis.

David

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Re: Rigid Chassis Locos?

Postby Philip Hall » Thu Mar 19, 2020 11:38 am

This is interesting, as I have never replaced a tender chassis in any of the conversions I have done, either in P4 or EM. I do, however, always add more weight (tenders are always far too light) and ensure that there is some up and down movement on the centre axles. Also I make sure that the tender sits nicely on a surface plate. Until the current fashion for tender pickups, I always added them as well.

Philip

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Re: Rigid Chassis Locos?

Postby Enigma » Thu Mar 19, 2020 3:03 pm

Tony Wilkins wrote:Hi Jon.
My thoughts are similar to Tim and Philip.
If building a kit or scratch-built chassis I always include some form of compensation. For the extra work involved, the results are worth it.
If converting an RTR item, the option of swapping wheel sets is worth trying for quickness. I have been known to add extra slop in the right places if I thought it necessary, but that needs to be done with care. Results can be mixed, but total failures rare with some notable exceptions already mentioned.
Regards
Tony.

I found many years ago that building a compensated chassis, even in OO as my first couple were (and still runing converted to P4), a lot easier than trying to build a good rigid one. This is especially true these days with etched hornguides soldered into frame cutouts allowing a degree of adjustment etc. rather than trying to make a pair of thick brass frames and associated rods all match up.

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Will L
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Re: Rigid Chassis Locos?

Postby Will L » Thu Mar 19, 2020 4:34 pm

For me this is not really to do with a propensity, or otherwise to fall off, the real problem is electrical pickup. So a rigid 0-6-0 chassis is likely to have no more than 3 wheels in contact with the rails, so that's just one on one side or the other. Your loco then becomes very sensitive to dirty rails/wheels and you have little hope of exhibition quality steady running and reliable starting. For this reason, I had gone compensated on tank loco long before giving up on OO, let alone working in P4. Tender locos obviously have an an advantage so pickups on the tender will help a lot, as will pickups on bogies and pony trucks for tanks that had such things but they are adding to the complexity of the thing. As Phil has said it is actually quite hard to build a really flat rigid chassis. So, iIn the end I found it easier to build them compensated or, these days sprung.

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Noel
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Re: Rigid Chassis Locos?

Postby Noel » Thu Mar 19, 2020 5:32 pm

Will L wrote: So a rigid 0-6-0 chassis is likely to have no more than 3 wheels in contact with the rails, so that's just one on one side or the other.


Not disagreeing with your basic argument, Will, but I think this defies the laws of physics...
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Le Corbusier
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Re: Rigid Chassis Locos?

Postby Le Corbusier » Thu Mar 19, 2020 7:20 pm

Will L wrote:For me this is not really to do with a propensity, or otherwise to fall off, the real problem is electrical pickup. So a rigid 0-6-0 chassis is likely to have no more than 3 wheels in contact with the rails, so that's just one on one side or the other. Your loco then becomes very sensitive to dirty rails/wheels and you have little hope of exhibition quality steady running and reliable starting. For this reason, I had gone compensated on tank loco long before giving up on OO, let alone working in P4. Tender locos obviously have an an advantage so pickups on the tender will help a lot, as will pickups on bogies and pony trucks for tanks that had such things but they are adding to the complexity of the thing. As Phil has said it is actually quite hard to build a really flat rigid chassis. So, iIn the end I found it easier to build them compensated or, these days sprung.


Above my pay grade .... but this reasoning makes it very hard to explain the fatastically reliable running that Tony Wright gets with his rigid chassis ... and there may be many differing views about Mr Wright but I have never heard the reliability of his loco's questioned. :?
Tim Lee

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Will L
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Re: Rigid Chassis Locos?

Postby Will L » Fri Mar 20, 2020 3:04 pm

Le Corbusier wrote:
Will L wrote:For me this is not really to do with a propensity, or otherwise to fall off, the real problem is electrical pickup. So a rigid 0-6-0 chassis is likely to have no more than 3 wheels in contact with the rails, so that's just one on one side or the other. Your loco then becomes very sensitive to dirty rails/wheels and you have little hope of exhibition quality steady running and reliable starting. For this reason, I had gone compensated on tank loco long before giving up on OO, let alone working in P4. Tender locos obviously have an an advantage so pickups on the tender will help a lot, as will pickups on bogies and pony trucks for tanks that had such things but they are adding to the complexity of the thing. As Phil has said it is actually quite hard to build a really flat rigid chassis. So, iIn the end I found it easier to build them compensated or, these days sprung.


Above my pay grade .... but this reasoning makes it very hard to explain the fatastically reliable running that Tony Wright gets with his rigid chassis ... and there may be many differing views about Mr Wright but I have never heard the reliability of his loco's questioned. :?


Not sure anybody is questioning the reliability of Tony's Locos , but nobody who is reliant on electrical pickup from the rails can absolutely guarantee faultless starting and slow running with pickup from just the driving wheels in a rigid chassis. The merest smidgen of stray dirt in the wrong place is enough to stall things. Having very flat track and keeping thing scrupulously clean certainly helps, but being sure you have at least two wheels with pickups on both sides in contact with the rails at all times was for me the easiest way to make a really significant difference. They don't all have to be driving wheels. I've done my time (15 years) building and maintain the locos for an exhibition OO layout where reliable public starting stopping and shunting was the requirement and I promise you this is true. Interestingly your battery powered jobs are totally immune from this problem.

What exactly Mr Wight does to gain his reputation for reliable running I cant say but I promise you if he routinely allows locos run slowly and stop in public, he will be fully aware of this and have his own strategies for dealing with it.

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Le Corbusier
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Re: Rigid Chassis Locos?

Postby Le Corbusier » Fri Mar 20, 2020 3:30 pm

Will L wrote:
Le Corbusier wrote:
Will L wrote:For me this is not really to do with a propensity, or otherwise to fall off, the real problem is electrical pickup. So a rigid 0-6-0 chassis is likely to have no more than 3 wheels in contact with the rails, so that's just one on one side or the other. Your loco then becomes very sensitive to dirty rails/wheels and you have little hope of exhibition quality steady running and reliable starting. For this reason, I had gone compensated on tank loco long before giving up on OO, let alone working in P4. Tender locos obviously have an an advantage so pickups on the tender will help a lot, as will pickups on bogies and pony trucks for tanks that had such things but they are adding to the complexity of the thing. As Phil has said it is actually quite hard to build a really flat rigid chassis. So, iIn the end I found it easier to build them compensated or, these days sprung.


Above my pay grade .... but this reasoning makes it very hard to explain the fatastically reliable running that Tony Wright gets with his rigid chassis ... and there may be many differing views about Mr Wright but I have never heard the reliability of his loco's questioned. :?


Not sure anybody is questioning the reliability of Tony's Locos , but nobody who is reliant on electrical pickup from the rails can absolutely guarantee faultless starting and slow running with pickup from just the driving wheels in a rigid chassis. The merest smidgen of stray dirt in the wrong place is enough to stall things. Having very flat track and keeping thing scrupulously clean certainly helps, but being sure you have at least two wheels with pickups on both sides in contact with the rails at all times was for me the easiest way to make a really significant difference. They don't all have to be driving wheels. I've done my time (15 years) building and maintain the locos for an exhibition OO layout where reliable public starting stopping and shunting was the requirement and I promise you this is true. Interestingly your battery powered jobs are totally immune from this problem.

What exactly Mr Wight does to gain his reputation for reliable running I cant say but I promise you if he routinely allows locos run slowly and stop in public, he will be fully aware of this and have his own strategies for dealing with it.


As i say ... above my pay grade and will reamin so if the battery experiment works :thumb All seems eminently logical ... I would just like to know what is actually going on with Mr Wrights rigid chassis builds - as we all know he is obsessed with reliability and as a professional builder he must have a solution. Myself I like CSBs, but that is for track holding in P4 not electrical pick up ... plus I just like the engineering which I find an elegant solution. ;)
Tim Lee

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Re: Rigid Chassis Locos?

Postby triumph3 » Fri Mar 20, 2020 3:33 pm

A couple of photos of my RTR conversions.
Attachments
IMG_3251.JPG
4693 weathered..JPG

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Re: Rigid Chassis Locos?

Postby Philip Hall » Fri Mar 20, 2020 5:30 pm

I don’t know how Tony does it either. I don’t think he uses tender pickups but I wouldn't build a tender engine without them, rigid, compensated or sprung. I find I get steadier running and reliable starts as a result. For the same reason I have installed pickups on the leading and trailing trucks of my BR 82xxx, a real fiddle but I think will be worth it.

Philip

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Re: Rigid Chassis Locos?

Postby triumph3 » Fri Mar 20, 2020 6:05 pm

I think the key point here is that the majority of recent RTR are not “rigid” as there is a degree of movement in the axles. Bachman’s recent Coal Tank even has seperate axleboxes.
All the RTR conversions I have done have some degree of movement in the axles, some would say “ slop” but it works.

David

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Re: Rigid Chassis Locos?

Postby Enigma » Fri Mar 20, 2020 11:31 pm

The late Roy Jackson wasn't a believer in 'flexible' chassis either and his locos ran on 'Retford' faultlessly. I remember him saying that he did try compensation at least once, possibly more, but he wasn't convinced by it.

But then both Roy and Tony model in EM and OO which could make a difference if only for the deeper flanges which might offer a greater area for the electrics to make their way into the wheels.

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Le Corbusier
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Re: Rigid Chassis Locos?

Postby Le Corbusier » Sat Mar 21, 2020 8:28 am

Enigma wrote:The late Roy Jackson wasn't a believer in 'flexible' chassis either and his locos ran on 'Retford' faultlessly. I remember him saying that he did try compensation at least once, possibly more, but he wasn't convinced by it.

But then both Roy and Tony model in EM and OO which could make a difference if only for the deeper flanges which might offer a greater area for the electrics to make their way into the wheels.


That is an interesting observation. I also wonder if weight has anything to do with it? Tony always makes a point of the haulage power of his locos ... perhaps there is a degree of flex coming in to play?

Anyway ... nothing to do with conversion of RTR to P4 using the original chassis.
Tim Lee


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