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Methods for Removable Loco Wheelsets.

Posted: Wed Jul 03, 2019 11:47 am
by polybear
Hi All,
(With apologies for anyone previously seeing this question on RMWeb....)
When constructing a loco chassis with fixed axles (i.e. no compensation or springing) are there any methods for making the wheelsets (i.e. wheels still fitted to axles) removable from the frames? Whilst Markits wheels are easy to remove, it would at times be useful to be able to remove the likes of Alan Gibson wheels from the frames without removing them from the axles, as I feel they're best left alone once fitted and quartered to the axle.

So, any ideas or methods please?

Thanks,

Brian

Re: Methods for Removable Loco Wheelsets.

Posted: Wed Jul 03, 2019 12:02 pm
by Tim V
You have to build this into the chassis when you construct it.

I think it is poor practice from frame designers that this feature is not included in their kits. It does result in a lot of extra work for the constructor.

Re: Methods for Removable Loco Wheelsets.

Posted: Wed Jul 03, 2019 12:08 pm
by polybear
Thanks Tim; do you have any suggested methods during construction?
Cheers,
Brian.

Re: Methods for Removable Loco Wheelsets.

Posted: Wed Jul 03, 2019 12:29 pm
by Tim V
Have a look on my workbench thread, some pictures lower down this page:
viewtopic.php?f=105&t=913&start=25

Re: Methods for Removable Loco Wheelsets.

Posted: Wed Jul 03, 2019 6:20 pm
by steamraiser
You will need cut outs in the chassis so that the wheel bearings axles and gearbox can drop out.
If you are using scraper pick ups, the base for them will also need to be demountable - screwed to frame spacers possible?
Also you will need to build your brake hangars and linkage so that it can unclip from the chassis in one piece.

Gordon A

Re: Methods for Removable Loco Wheelsets.

Posted: Wed Jul 03, 2019 8:42 pm
by polybear
Hi Tim & Gordon,
Many thanks for the replies :)
Tim: Many thanks for the link; I'm reading thru' your Workbench thread at the moment, and it's one of the most useful I've read in a long time :thumb
Gordon: Good point about the brakes needing to be removable also, though I fancy a crack at split axles so at least this will mean no problems with pickups.

Cheers,
Brian

Re: Methods for Removable Loco Wheelsets.

Posted: Wed Jul 03, 2019 9:14 pm
by Julian Roberts
Brian, I fully concur with your desire to have removable wheelsets. With all respect to you that you may have a secret motive for having no suspension, I can't think of a reason, in P4 at least, for not having it, after all the work described above involved in making the wheelsets removable. It's hardly any more work to put in simple yet provenly effective compensation. With no fixed bearings a 6 coupled chassis works beautifully with twin beams for two axles and one rocking axle. And it is no additional further work to make that compensation unequalized as I described in Snooze 199 to further improve the likelihood of it staying on the rails whatever track faults there may be.

Or....

Springs as you can see in Tim's link are easily bought and little slots for them can be quite simply cut or filed above the top of each hornblock cutout if they don't already exist. Very easy but getting the ride height correct involves playing around with lead weight and/or deepening those slots.

Maybe you've thought about and rejected these possibilities - but if you're new to P4 I would suggest a good kit (I would recommend a High Level chassis kit) where these things are already thought out, would give a more satisfying result than a perhaps basic kit with no suspension.

Re: Methods for Removable Loco Wheelsets.

Posted: Thu Jul 04, 2019 6:13 am
by Paul Townsend
I reckon Julian is an agent provocateur :D
Having over 700 posts here over 9 years he is hardly a beginner!
Not just an armchair modeller either if you delve back.

While I agree Tim’s workbench has had its good bits, the structured course from Allan Goodwillie is even more useful, as JR well knows.

I wonder, Julian, if Will Lichfield’s series on csb passed you by?

The combination of csb, removeable wheelsets and split frames is the holy grail for me, oh dcc and auto couplings at rake ends with 3 link or screws within the rake too.

Re: Methods for Removable Loco Wheelsets.

Posted: Thu Jul 04, 2019 7:49 am
by Jol Wilkinson
Tim V wrote:You have to build this into the chassis when you construct it.

I think it is poor practice from frame designers that this feature is not included in their kits. It does result in a lot of extra work for the constructor.


Tim,

if designer/manufacturers didn't have the commercial need to take into account the different wants/preferences of 00, EM and P4 modellers, then it would make life a lot easier. As those modelling in 00 and EM still account for a considerable number of those modellers who buy kits, we are stuck with a number of unsatisfactory compromises when it comes to designing 4mm kits.

Jol

Re: Methods for Removable Loco Wheelsets.

Posted: Thu Jul 04, 2019 8:14 am
by Julian Roberts
:lol: Paul. Absolutely agree re your suggestions. Many High Level kits have the csb option. However I was trying to imagine what Brian's starting point is and what the simplest way of adding suspension is. I guess a milled frame from Alan Gibson with hornblock slots and brake rod holes. To add compensation one of the brake rodshafts can also be used as the beam for my assymetric approach and thereon it's simple.

If Brian has a frame with just holes for wheels: if I wanted simplest possible removability and no suspension I would solder in bearings, ream out to fit the axle as necessary then file slots through frame and bearing to drop wheels out, retain with wire or whathaveyou.

Re: Methods for Removable Loco Wheelsets.

Posted: Thu Jul 04, 2019 9:22 am
by Tim V
Paul Townsend wrote:While I agree Tim’s workbench has had its good bits,

So I'm a 'has been'?

Turning to Jol's point, EM and OO modellers would also benefit from having removable wheelsets, it is I think, incumbent on kit designers to include this. It is just as important for OO/EM locos to have good wheels, correctly set on their axles. The one-shot approach adopted by kit designers means that if the modeller gets it wrong, recourse is difficult.

Interestingly K's with their key-hole chassis could do this in the 60s - crude but did the job.

Re: Methods for Removable Loco Wheelsets.

Posted: Thu Jul 04, 2019 9:52 am
by Paul Townsend
Tim V wrote:
Paul Townsend wrote:While I agree Tim’s workbench has had its good bits,

So I'm a 'has been'?


Not so much a "has been" as a traitor to the true path of onwards and upwards :-P as will be revealed at RailWells I suspect.

Re: Methods for Removable Loco Wheelsets.

Posted: Thu Jul 04, 2019 9:53 am
by David B
The easiest chassis I have made uses CSB where dropping (and replacing) the wheelset is a simple matter of removing (and replacing) the wire spring - no screws. With suspension as simple as this, like Julian, I can see no reason for not using it.

Re: Methods for Removable Loco Wheelsets.

Posted: Thu Jul 04, 2019 10:06 am
by Paul Townsend
Ooer, penalty for early morning posting pre-coffee is lack of precision.

Sorry Julian, the bits below, originally aimed at you was intended for Brian so edited and reposted for clarity, post coffee!

While I agree Tim’s workbench has had its good bits, all were state of the art when written a while back. IMHO the structured course from Allan Goodwillie is even more useful.

Meanwhile the hobby moves on, I wonder also Brian, if Will Lichfield’s series on csb passed you by?

The combination of csb, removeable wheelsets and split frames is the holy grail for me, oh dcc and auto couplings at rake ends with 3 link or screws within the rake too.

My chum, Tim ( not EditorTim) has just rebuilt a 4-6-0 loco chassis, that was compensated and underperforming, to CSB. Same wheels, motor & gearbox and transformed the hauling power.

Of course you can make a mess of CSB if you don't follow the guidelines but it is harder to mess up CSB than compensation design where some atrocious interpretations have appeared in kits.

Re: Methods for Removable Loco Wheelsets.

Posted: Thu Jul 04, 2019 10:31 am
by Enigma
I posted this on the RMWeb thread but it could also be of interest here. I always like to be able to drop axles out while chassis building and the fixed axle on a compensated chassis incorporating the gearbox is no exception. I ream out the axle hole to take a close fitting top hat bush then carefully open the hole downwards to the bottom of the frame to form a slot that the bush can slide out from with no undue 'slop'. With the bush at the 'bottom' of the slot a length of fine brass tube is soldered across the bush and to the inside edges of the frames. This is then cut through with a fine saw, the rough edges tidied up with fine files and an 'L' shape piece of wire of suitable close fitting gauge is used to hold it all together.

Barclay Frames with Compensation Pivot.2.A.jpg


This will show the concept but note that the tube has not been fully cut through and the 'L' wires are still to be fitted - as is the gearbox!

Re: Methods for Removable Loco Wheelsets.

Posted: Thu Jul 04, 2019 2:43 pm
by steamraiser
Brian,

If you are looking to build a loco like a pannier where the brake pull rods are on the outside of the wheel faces no problem.

But if your loco has the brake pull rods inbetween the wheels then you will need to make the brake rigging removeable.

Gordon

Re: Methods for Removable Loco Wheelsets.

Posted: Thu Jul 04, 2019 5:04 pm
by Tim V
Paul Townsend wrote:
Meanwhile the hobby moves on, I wonder also Brian, if Will Lichfield’s series on csb passed you by?

That kind of comment is a bit self defeating - it is merely a different way, not necessarily better. And for a beginner, the complications of a CSB chassis is certainly a step to far.

And does it reply to the OPs point?

Re: Methods for Removable Loco Wheelsets.

Posted: Thu Jul 04, 2019 6:01 pm
by Paul Townsend
Paul Townsend wrote:
Meanwhile the hobby moves on, I wonder also Brian, if Will Lichfield’s series on csb passed you by?


Tim V wrote:That kind of comment is a bit self defeating - it is merely a different way, not necessarily better. And for a beginner, the complications of a CSB chassis is certainly a step to far.


I might agree for a beginners scratch build, but definitely disagree for a kit or kit bash

Re: Methods for Removable Loco Wheelsets.

Posted: Thu Jul 04, 2019 10:16 pm
by Will L
Tim V wrote:
Paul Townsend wrote:
Meanwhile the hobby moves on, I wonder also Brian, if Will Lichfield’s series on csb passed you by?

That kind of comment is a bit self defeating - it is merely a different way, not necessarily better. And for a beginner, the complications of a CSB chassis is certainly a step to far.

While I accept that the way you've got things to work in the past always seems the easiest way to go, by definition that can't apply to beginners, so I don't agree. I always struggled to get rigid chassis flat and square, and I only really started to get chassis to worked well when I adopted compensation, the move to CSB just made things simpler.

There are lots of bits out there these days to help you make a chassis with real suspension and that make wheels that drop out simple and practicable. Support for drop out wheels on a rigid chassis seems to he exceedingly limited. The answer looks obvious to me,

Re: Methods for Removable Loco Wheelsets.

Posted: Fri Jul 05, 2019 6:14 am
by David B
Tim V wrote: And for a beginner, the complications of a CSB chassis is certainly a step to far.


I, too, disagree. Like Will, I have found CSB to be the simplest and most successful way to build a chassis. It does answer the original OP as removing the wheelset is also simple.

Re: Methods for Removable Loco Wheelsets.

Posted: Fri Jul 05, 2019 6:54 am
by Jol Wilkinson
Providing a solution that meets everyone's best interests isn't so easy. Having designed a number of 4mm loco kits and assisted a supplier of etched kits at shows for too many years, I have become aware of the modeller's needs, wants, foibles and concerns.

For those with experience of kit building and building in some sort of vertical wheel movement, then csb's and removable wheel sets may seem like a logical way to go. For a beginner to kit building anything which adds complication with little apparent benefit, e.g. compared to the Romford/Markits self quartering wheel "system", becomes a deterrent.

Many RTR locos have, as far as I know, some sort of removeable wheel set system with a keeper plate. However, the design concept is driven by production requirements and is part of a design unique to that particular model. If you can control every aspect of the design and assembly process, from motor size and mounting, through the gear drive gear, to wheel/axle design, pickup system, etc. you are in control of all the parameters. Not so with kits. What gauge will the model be built to, to, which wheels does the builder prefer, which gearbox/motor mount, etc. etc. So compromises in design have to be made, which in an ideal world wouldn't be necessary.

Re: Methods for Removable Loco Wheelsets.

Posted: Fri Jul 05, 2019 7:12 am
by billbedford
Tim V wrote:That kind of comment is a bit self defeating - it is merely a different way, not necessarily better. And for a beginner, the complications of a CSB chassis is certainly a step to far.


That does depend on whether the building is expected to bodge their CSBs onto an antiquated chassis design, or the chassis has been thoughtfully designed to incorporate CSBs.

Re: Methods for Removable Loco Wheelsets.

Posted: Fri Jul 05, 2019 7:25 am
by billbedford
[quote="Jol Wilkinson"Many RTR locos have, as far as I know, some sort of removeable wheel set system with a keeper plate. However, the design concept is driven by production requirements and is part of a design unique to that particular model. If you can control every aspect of the design and assembly process, from motor size and mounting, through the gear drive gear, to wheel/axle design, pickup system, etc. you are in control of all the parameters. Not so with kits. What gauge will the model be built to, to, which wheels does the builder prefer, which gearbox/motor mount, etc. etc. So compromises in design have to be made, which in an ideal world wouldn't be necessary.[/quote]

There is nothing to stop a kit designer taking a holistic approach to their work and provide the modeller with a kit that 'just goes together' The fact that they don't, seems to me, a lot to do with a 'this is the way we have always done it' attitude together with the economics of sourcing wheels etc.

Re: Methods for Removable Loco Wheelsets.

Posted: Fri Jul 05, 2019 8:43 am
by Guy Rixon
I often wonder about the economics of getting better components. Bearings for coupled axles are a good example: the cuboid kind that slide in hornguides. If the bearing blocks were accurately machined, then they could just slide in slots etched in the frames, without the hornguides, and it would be very easy. But they're not accurate (allegedly): the bores are significantly off-centre. We deal with this by adding hornguides that correct the errors, then we need jigs to set up the hornguides (and the best jigs cost hundreds of pounds). What would it cost to get the bearing blocks to an accuracy where no inspection or adjustment was necessary?

Re: Methods for Removable Loco Wheelsets.

Posted: Fri Jul 05, 2019 9:20 am
by billbedford
Guy Rixon wrote:I often wonder about the economics of getting better components. Bearings for coupled axles are a good example: the cuboid kind that slide in hornguides. If the bearing blocks were accurately machined, then they could just slide in slots etched in the frames, without the hornguides, and it would be very easy.


That is not a good idea, as the thin edge of the frames cuts into the bearing after a modicum of running

But they're not accurate (allegedly): the bores are significantly off-centre.


That is easily checked, just thread a number of bearings on an axle and feel the difference in the top faces. The asymmetry should be less of a problem if the bearings are made on a modern CNC machine rather than an old auto.

We deal with this by adding hornguides that correct the errors, then we need jigs to set up the hornguides (and the best jigs cost hundreds of pounds). What would it cost to get the bearing blocks to an accuracy where no inspection or adjustment was necessary?


Hornguides can be etched into the frames, though it takes some practice to bend them so that they are square to the frames.