How long can four wheeled coaches be, in practice? Wheelbase and between the buffers?
On straight track as long as you like, both wheelbase and overall (I assume that's what you mean by 'between the buffers') until the thing sags in the middle and rubs on the railhead.
The problem is that narrow gauge railways often go around bends (just like narrow gauge modellers?), so in practice it is the radius of the curves that determines both the maximum wheelbase and also, due to needing to be couple up to a loco and the overhang from the wheel to the end, how much longer then the wheelbase the overall length can be.
My ruling radius is 9".
Within reason it will not be the wheelbase that is the issue it will be the coupling overhang that gives you the most problems.
I have a layout with 9-inch curves, and I have always found it is very restrictive on what I can run.
In general, all the rolling stock I use has small four-wheel bogies with the couplings on the bogies.
What sort of length wheelbase are you thinking about and what length of vehicle?
QuoteWhat sort of length wheelbase are you thinking about and what length of vehicle?
Er, Brian, now you're challenging me to think....
Something significantly longer than all the new little Peco four wheel coaches, which are about 5 cm long; and something far shorter than the Peco bogie coaches, which are about 14 cm long. So throwing out a number quickly ... 7 cm long, which I suppose would mean a wheelbase about 6 cm?
I'm steering away from long bogie wagons because I'm committed to maximum train lengths of 60 cm for reasons that will become apparent sometime in the next ten years .... I'm not very attracted to those 5 cm coaches and want more than three coaches in a train so something like about 8 cm when coupled could give me a train of six longish four wheelers if that's workable.
My idea is to design and 3D print them, by the way.
Do they have to be four wheel coaches? could they be short bogie coaches? There are plenty of examples of shorter coaches than the Peco ones.
Another possibility is 'two wheel bogies' as in Lilliput (I think, is it?) coaches.
I think an issue with a long wheelbase four wheel coach is the wheels will normally be set a long way from the buffer beams meaning that there will be quite a lot of overhang and hence 'end swing' that might affect coupling. That could mean having to pivot the couplings and it may be part of the reason for the use of two wheel bogies (if the couplings have to pivot then the wheels may as well do so too.)
Bemo do the longest 4 wheeler I know of in H0e/009 and use swivel couplings, had it down to 9" curves! The axles are well out towards the ends of the chassis, though!
https://www.schmalspur-bahn-werke-eu.info/data/upload/Shop/images/572-4.jpg
QuoteDo they have to be four wheel coaches? could they be short bogie coaches? There are plenty of examples shorter coaches than the Peco ones.
A couple of examples come to mind - the Dundas kits for the FR opens DM22 and the Society members kit No. 1 for the Hudson toast-rack - that are about 1/2 to 2/3rds the length of the Peco L&B stock.
Quote from: Tom Haythornthwaite on February 23, 2021, 16:40
QuoteWhat sort of length wheelbase are you thinking about and what length of vehicle?
Er, Brian, now you're challenging me to think....
Something significantly longer than all the new little Peco four wheel coaches, which are about 5 cm long; and something far shorter than the Peco bogie coaches, which are about 14 cm long. So throwing out a number quickly ... 7 cm long,
7cm sounds like a good idea - that's two coaches from one Peco one!
David.
I have a couple of Liliput coaches which are 4 wheelers I'll dig one out of its stock box and measure it. They have swinging couplings
About 42mm wheelbase overall length to buffing surfaces 97mm (depends on the couplings...
(https://i.imgur.com/XIdJZvL.jpg)
(https://i.imgur.com/lBrcYyI.jpg)
Thanks everybody!
Wow, that Bemo coach must be longer than some bogie coaches!
This all helps me to visualize a bit. Now I have to think about whether I want balconies.
Tom
I am not at all sure that the couplings on the Liliput coaches will be ok on 9 inch curves?
12 inch is ok with these coaches and 18 inch reverse curves, but I think even 12 inch reverse curves are too much??
Quote from: B.Meldon on February 24, 2021, 16:24I am not at all sure that the couplings on the Liliput coaches will be ok on 9 inch curves?
Yes they are, Brian, I've used them on that radius, as have many others I've seen at exhibitions who use 9" set track curves on their layouts.
Quote from: Hobby on February 24, 2021, 19:08
Quote from: B.Meldon on February 24, 2021, 16:24I am not at all sure that the couplings on the Liliput coaches will be ok on 9 inch curves?
Yes they are, Brian, I've used them on that radius, as have many others I've seen at exhibitions who use 9" set track curves on their layouts.
Do you retain the self centralising arm on the couplings when used on 9 inch curves?
Can the liliput four wheel coaches and vans be pushed around the 9 inch curves?
We found that they caused problem being pushed through 12 inch reverse curves, so we built the layout with only 18 inch reverse curves (ie. Y points) and that worked fine.
Obviously if the self centralising arm is removed they will go round much tighter curves, but that is useless when shuntting as the couplings will not self centralise to couple up and can also give problems when pushing them.
I have 9" curves on Angst-Lesspork and the coach as shown has no issues. (but I don't propel it)
They are standard out of the box coaches, Brian, no changes at all and there's still play on the couplers so they'd probably go round sharper than 9". I don't shunt so they are all pulled.
I now feel the need to buy one and see what happens on my 6" pizza ;D
Quote from: Hobby on February 25, 2021, 12:40
They are standard out of the box coaches, Brian, no changes at all and there's still play on the couplers so they'd probably go round sharper than 9". I don't shunt so they are all pulled.
Yes I have just tested the ones I have and I agree they can be pulled around 9 inch curves, pushing them is less reliable!!