The Heybridge Railway, 1889 to 1913

[Richard Gawler]

I have made a brief video and uploaded it to YouTube, this shows how the chassis runs at the moment:

The truck now has a 14 g weight on top of it. Adding this (in lieu of the dowel rod) his has let me increase the vertical free play above the driven wheels to about 1 mm above the datum, and maybe this will allow better running at the foot of a gradient.

Addendum - 6 July 2022:
1) There is a'kick' at about 48.5 seconds when the wheel touches the check rail, annoying.
2) The bearing part of the tubes is about 9/16 inch tall. This is still short enough to let the truck rock slightly when the loco is on straight track, and this should help the loco ride over normal minor undulations in one rail.
3) The pivot tightens when the loco runs around a tight curve and exerts a lateral force on the inner tube.

If Fraser @Overseer or Simon @simond return this way your thoughts would be welcome. At the moment I am happy enough to keep this arrangement and maybe refine it, but I am reluctant to rip it out to try something else.

This whole idea of a 0-4-2 conversion (and a crane tank) came about because I ordered an extra pair of Lomac wheels for my first brass wagon kit

 

[spikey faz]

Hi Richard

I'm wondering if the 5mm of movement between wheel and rail that you've mentioned is causing the alignment issue at 48.5 seconds.

One of the reasons I adopted S7 standards was to try to eliminate such issues.

But I think your experimental approach is exactly what I'd do, so please persevere.

For what it's worth I found by compensating/springing my locos and wagons I was pretty much able to eliminate any track/stock alignment problems (my track-laying is a bit rough in places!).

It'll be nice to see another crane locomotive when you've completed yours.

Mike

 

[Overseer]

Personally I would change it to one of the prototypical arrangements, either fixed bearings with side play, a radial axle (Webb or Adams geometry) or a Bissell truck, as used by the LNWR on their 0-4-2T Bissell Tanks. Probably a Bissell truck for this one.The floppy rotating axle will lead to derailments.

 

[Richard Gawler]

Personally I would change it to one of the prototypical arrangements, either fixed bearings with side play, a radial axle (Webb or Adams geometry) or a Bissell truck, as used by the LNWR on their 0-4-2T Bissell Tanks. Probably a Bissell truck for this one.The floppy rotating axle will lead to derailments.

Please, are there diagrams online of these various arrangements for trucks?

My searches are returning only details of pickup trucks in North America and some bogies of modern diesel locomotives. I have arranged my axle so that the wheelset rotates radially around a pivot, but lacking background information I am beginning to suspect this is not a radial truck.

Many thanks.

 

[PhilH]

Are these any help ?

Radial axle - Wikipedia

Bissel truck - Wikipedia

In effect a radial axle works like a pony truck, but the axle bearings are carried in curved housings in the locomotive frames.

 

[Richard Gawler]

Hi Phil and thanks ever so much. It's funny how Wikipedia comes out on top in search results I don't want, and not at all here! I have been confused by terminology; a Bissell truck is a pony truck. I told myself I wouldn't build a pony truck because of the instability problems I had with a K's kit in 4mm scale.

I think I have built a non-prototypical (but possibly model-valid) pony truck where the pivot is above the axle, and as such the truck might be able to guide the model chassis in curves or might of course give up in the process and derail. To be fair, at the moment it does actually stay on the track. The truck retains the axle laterally so it cannot slide, and so (I think!) it doesn't relate to an Adams radial truck.

It is sensible to change only one thing at a time and at the moment I am adding the side rods. When I test again but with a second driven axle, the behaviour on the track might change as the chassis goes from being a 2-2-2 to an 0-4-2. If all is ok, I might try a gentle spring (thin piano wire) to give the truck a self-centering ability.

I have an easy exit from all this, in that I can file down the axle bushes on the truck and lock the pivot solid to make for a sloppy axle. I could do this after I finish the model if my testing proves to have been inadequate.

 

[PhilH]

I don't think your arrangement with a central fixed pivot allowing the axle to twist really helps in going round curves and ideally the axle should be moving sideways, either by arranging clearance between the wheels and bearings (assuming the latter are fixed in the frames) or with a pony truck or radial axle.

If you look at the construction drawing in the top right hand corner of this:
Adams axle - Wikipedia

It shows an example of a radial axle, but I think some form of pony truck would probably be easier to construct.

 

[Richard Gawler]

My chassis now has its side rods and hopefully these will stay undisturbed until I strip the chassis for painting.

I have done a simple test to see whether the truck affects the alignment of the chassis on a curve, I hope this isn't too formal but I may want to repeat it:

• I have a short straight track connected to a Setrack curve (the straight is to the left of the curve, out of shot).
• I have placed two markers beside the curve so I can stop the chassis in a consistent location.
• The chassis is placed on the straight track and driven from left to right onto the curve and stopped at the markers.
• Power is removed from the track and an engineer's square placed on the track to check the alignment of the chassis.

Test run as an 0-4-0 (truck removed)





Test run as an 0-4-2 (truck installed)





I did four runs (all with the chassis running 'in reverse') and the results were consistent.

So at the moment, I think the truck can and does influence the alignment of the chassis. I expect the truck to either do this or climb off the rails and derail, because its pivot is in line with its axle and not offset as with a pony truck.

What I do not know yet is whether the lateral forces from the pony truck will influence the alignment of the complete locomotive; this will weigh c.350 g more than the chassis in its test configuration here.

The cylindrical weight on the truck now fouls the floor of the crane base and I am waiting for a hand reamer to arrive so I can open up the existing hole in the base. Then I can put the body onto the chassis and try again.

 

[Richard Gawler]

I'm wondering if the 5mm of movement between wheel and rail that you've mentioned is causing the alignment issue at 48.5 seconds.

One of the reasons I adopted S7 standards was to try to eliminate such issues.

But I think your experimental approach is exactly what I'd do, so please persevere.

I have gone for the 'fine' standard over S7 because it gives me interoperability with four other layouts: the club test test track, a friend's garden railway, and two layouts at another club.

The experiments with Nellie's chassis are prompting me to want to find out about the "fine"(?) versions of the 'fine' standard. There is one where the gauge reduces to 31.5 mm and the check gauge stays the same, so the flangeways close up at the check rails and wing rails. If I am going to build my trackwork for the Heybridge Railway (this will be FB rail spiked onto 9 ft sleepers) this might be the one to go for.

 

[Richard Gawler]

Lacking the hand reamer to let me make a neat hole and combine the chassis, truck and body all together I have made a second video . . .

This one shows how the truck tightens the line of the chassis on a Setrack curve. At the same time, it probably shows how much slack there is in the wheel/rail relationship of the usual 0 gauge 'fine' standard. The B2Bs are 29.2 mm on the driving wheels and 29.3 mm on the truck wheels.

 

[Richard Gawler]

Thanks for the like John.

The YouTube analytics are showing me the average view duration for this second video was 65% which, taken at face value, means stopping at 46 seconds. This is immediately before the important sequence begins! But I know, statistics are usually meaningless. I will interpert this to mean, most people watched to the end or gave up very early on.

The tapered reamer is late.

 

[Renovater]

Hi Richard, i don't know what you've decided to do with the truck but having the pivot in the middle of the axle means the wheels will be fighting against themselves all the way down the track, whether it be forwards or backwards, there needs to be inside bearings on each end/side of the axle as close as possible to the backs of the wheels.

Colin.

 

[Richard Gawler]

Hi Colin @Renovater and everyone else who I have lost or confused, and of course those who have tried a similar approach and found it didn't work.

Here is a fresh photo of my truck, this is how it is at the moment and how it was in my video I posted yesterday.

(1) The truck started with a box-section brass tube. The axle of the wheel passes through this, with a top-hat bush for support at each end just behind the wheels. The wheelset spins freely in these bushes, but has no free movement in any other direction - no end play or ability to rock within its bushes.

(2) Soldered over the box section is a round brass tube which I am calling the inner or inside tube. This is, to be awkward, the larger of the two tubes in this photo. The even smaller tube is simply carrying some lead and we can ignore this tube for the rest of this post. The inner tube has a large notch to let it fit over the box section tube, so the axle goes all the way through.

(3) The inner tube is a light sliding fit inside a larger tube ("the outer tube"), which is fixed inside the chassis, perpendicular to the tracks and central between the frames. The inner tube slips inside the outer tube, where it is currently constrained by only its weight resting on the rails.

(4) So, if we think about the six possible degrees of freedom of the wheelset, we have these:

• free axial rotation, faciliated by the two bushes
• free radial rotation, by the action of the concentric round tubes (end stops provided by rectangular notches in the frames)
• extremely limited rotation along the third axis (the length of the loco), this is simply the free play between the tubes
• free vertical movement, by the inner tube sliding up and down inside the outer tube
• extremely limited lateral movement (both across or along the chassis), again this is down to the free play between the tubes

(5) When the loco moves forwards or backwards, it always propels the truck; the outer tube is pressing on the inner tube. This means, the radial stability of the truck is currently controlled by only the wheel/rail interface. The wheels are coned, and the wheels find a centre when the loco is moving in straight line.

(6) When the loco travels on curved track, a conflict of forces exists. The wheelset wants to be centred (because of the coning) but the chassis is trying to push the wheelset sideways. I want the centring force from the wheelset to be large enough to guide the chassis onto a tighter path. My second video (yesterday) shows this happening. My first video posted 5th July (at around the 46 second mark) shows instability I want to avoid. So far, increasing the weight of the truck about four-fold, from 4 g to 18 g, has removed this unwanted behaviour for the chassis running without the body. Clearly, a balance is needed so the wheels of the truck don't ride up off the rails.

This is where I am at the moment. The truck is, in mechanical terms, half of a small wagon installed inside a loco and relying on the wheel coning (and at the limits, the wheel flanges) for directional stability.

I can see good things here. Fundamentally, the truck is doing something useful, by helping the chassis to follow a tighter line on track where the 32 mm gauge is quite generous compared to the distance between the faces of the flanges on the driven wheels. The chassis wants to run in a straight line and not waddle along as some of my RTR 00 models do. The truck has vertical free play which will help the centre axle to retain traction at the foot of a gradient.

I like the idea of a centring spring and I have a few different thickneses of piano wire to try. However, there is no need for a spring at the moment; I can visit this when I get the body back onto the model.

I am describing how my design is evolving, not making claims for outright success. It may be, a wagon coupled behind the completed loco pulls it crooked or off the track. I will be giving the chassis a pivot for a more conventional pony truck, so my options stay open.

HTH.

 

[Richard Gawler]

The tapered reamer arrived yesterday afternoon and this has let me enlarge the hole in the floor of the crane base (see later) and continue the design development of the truck . . .


The truck now has a sleeve over the top of it. This gave me a diameter to accept a further weight, and enough metal (just)to tap M3. The M3 machine screw stops the truck falling out when I pick up the model. The all-up weight of the truck including its wheels and the further weight is now 45 g, nearly half of the weight of one of my wagons.


The chassis is now a self-contained unit.


The further weight came about because the truck often derailed on the Setrack point where the curved blade is straighter than I want and the gauge reduces to 31 mm. As hard as I try I cannot persuade this bit of rail to take on a tighter set.

The additional weight is a light sliding fit over the top of the truck. The screw passes through the hole in the floor to let me lift the body off. I had intended to use this space for the decoder and its socket, space is getting tight but doesn't look totally impossible. I don't actually want DCC but provision seems sensible because a friend with home and garden layouts uses it. And I just might give up on the model railway hobby as a holistic sort of thing with a layout and just build more locos

Anyway . . . the model with its body and the chassis now runs fine on my test track. I gave the model a couple of dozen runs in every permutation on both legs of the Setrack point and the reverse curve. I had one derailment, when the loco ran over its umbilical.

I doubt a spring will achieve anything useful on this particular 0-4-2 chassis. I would give it a go on something with more coupled wheels and the C of G further away from the truck. I fancy adding a damper but the only thing I can make is a probe in an open dashpot and I think this is taking experimentation too far.

I want to return to the build of the model; if I fancy a break I have the footage to make a third video.

 

[Ian@StEnochs]

Hi Richard,

I have been watching your experiment with interest. However I think you are over complicating what is quite a simple model.

I have a few 0-4-2s under my belt and all have the three axles in the frames without ponies or radial axles and running has been excellent. This photo shows my solution, a square bar, bored through for the axle, held in cutouts in the frames. You can just see the spring which acts as down force. Both ends of the spring fit into little pockets, a slice of tube soldered on, nothing protrudes above footplate level.



Your use of a piece of square tube with top hat bearings at each end is a neat solution if you don’t have access to a lathe and you already have the cutouts in the frames.

Ian.

 

[Richard Gawler]

Hi Ian and thank you so much for this . . . and thank you especially for waiting until I had finished my first attempt.

I used the 5/32" square tube (K&S) because I had some to hand and the top hat bushes just slipped in as though it was ready-made. I wanted to separate the rotating wheelset from the rest of the mechanism, and now I see the same idea but taken through in a more elegant way. I could have chosen a round tube but I had nothing the right size and it was easier to cut rectangular instead of semi-circular notches in the frames.

The notches in the frames are wide enough to let the tube and wheelset turn, but they stop the tube before the wheel flanges can touch the frames. I arrived at this by trial and error. I do have a bit of a personal aversion to springs in models but this stems from models in smaller scales where there is less weight to keep everything in check.

This is my first loco build for 7 mm. I want to get the chassis painted and the pickups installed for the four driving wheels. Then find out whether the loco will benefit from pickups on the truck. If the truck proves unreliable in service, or I fancy using this loco as a test bed, I would try your method next in preference to a conventional pony truck or an axle with extra sideplay. It looks really neat.

 

[AJC]

Hi Richard,

I have been watching your experiment with interest. However I think you are over complicating what is quite a simple model.

I have a few 0-4-2s under my belt and all have the three axles in the frames without ponies or radial axles and running has been excellent. This photo shows my solution, a square bar, bored through for the axle, held in cutouts in the frames. You can just see the spring which acts as down force. Both ends of the spring fit into little pockets, a slice of tube soldered on, nothing protrudes above footplate level.

View attachment 166449

Your use of a piece of square tube with top hat bearings at each end is a neat solution if you don’t have access to a lathe and you already have the cutouts in the frames.

Ian.

That’s a more elegant/better engineered version of what’s at the back end of my EM’d Bachmann 66xx. Once the lack of vertical travel was resolved it works very well.

Adam

 

[Ian@StEnochs]

Hi Ian and thank you so much for this . . . and thank you especially for waiting until I had finished my first attempt.

I used the 5/32" square tube (K&S) because I had some to hand and the top hat bushes just slipped in as though it was ready-made. I wanted to separate the rotating wheelset from the rest of the mechanism, and now I see the same idea but taken through in a more elegant way. I could have chosen a round tube but I had nothing the right size and it was easier to cut rectangular instead of semi-circular notches in the frames.

The notches in the frames are wide enough to let the tube and wheelset turn, but they stop the tube before the wheel flanges can touch the frames. I arrived at this by trial and error. I do have a bit of a personal aversion to springs in models but this stems from models in smaller scales where there is less weight to keep everything in check.

This is my first loco build for 7 mm. I want to get the chassis painted and the pickups installed for the four driving wheels. Then find out whether the loco will benefit from pickups on the truck. If the truck proves unreliable in service, or I fancy using this loco as a test bed, I would try your method next in preference to a conventional pony truck or an axle with extra sideplay. It looks really neat.

Hi Richard,

I understand where you are coming from. In the smaller scales weights are so much less and setting springs to carry the engines weight was/is very difficult. Suitable springs hard to come by and wire ‘leaf springs’ very tricky to adjust. In most cases when hornguides are used the loco runs on the stops with the spring only helping push the wheel into a dip.

The situation is different in the larger scales and it is much easier to get a range of coil springs which makes setting up springing relatively easy though it can be fiddly. The weight required is also much easier to fit into even small locos.

Since starting in S7 all my locos, except 0-4-0s, have fully sprung driving wheels with live springs, which let each axle rise above datum as well as push it down into dips. Running I find to be quiet and smooth with the loco just gliding over any bumps, also current pickup is better with all wheels firmly on the rail.

I no longer spring 0-4-0s because I find it impossible to eliminate the unrealistic nodding forward and back which results from the relatively short wheelbase. For these I use a 3 point suspension with a rocking axle.

Your approach to your build has been refreshing to watch and you have come up with something different. We will be watching you progress with interest.

Ian.

 

[Richard Gawler]

Your approach to your build has been refreshing to watch and you have come up with something different. We will be watching you progress with interest.

I am enjoying the build. I can see myself struggling to solder the smokebox and boiler together because of their bulk (I might just resort to Araldite!), but apart from this I know pretty much where and how the remaining parts need to fit. I have enjoyed stills photography for years but video work is completely new to me. WT is giving me an outlet for all three.

I want to catch up on some progress on the body.


The top of the crane base now has four small magnets and a fixed pivot. The idea was to put scraps of a baked beans tin into the base but the modern food tins are almost completely non-magnetic. So I had to use eight magnets instead of four. The pivot is fixed because the crane jib is going to be within the loading gauge and the loco can run on the main line with its crane in place.

The Connoisseur kit includes some simple cab fittings including a cast floor and a backhead. The backhead sits flush with the front spectacle plate and has a cut-out to go over the motor bracket, and this means the bracket appears in the cab. The footplate of my model is quite a bit more generous because the crane base uses only a part of the chassis extension and the original coal bunker has gone. So I can try for more modelling in the cab.


The size and pitch of the windows on the rear spectacle plate matches those on the front so I can model the inside of the windows. I have rebuilt the backhead so it moves backwards into the cab, and made a new cab floor.


All of the soldering on the backhead is 145 solder. I got away with it. The hole in the floor is to accept a cheese head screw, this is to let me use the original rear body mounting hole if I ever want to try a pony truck or fix something detachable inside the chassis here.



The inner spectacle plate has gone on with offcuts of fret to make a small gap to slip in the glazing. The backhead has a bit more 'presence' now. On the left is the back of the new coal bunker and on the right is space for the reversing lever and a representation of the back of the side tank. I have just noticed the gap above the top of the coal bunker, the driver's bag or a large oil can will have to stand here. The thin ring around the crane spindle holds the gear for rotation clear above the panel to make it look more realistic.

At the moment, the floor and the backhead are loose. After the floor is fixed I won't be soaking the model in hot soapy water, so they will need to be fixed near the end of the build.

 

[Longbow]

I do "wish" kit manufacturers could include a slack handful of half-etched rivet details on the fret for practice and setting-up. This would save puncture wounds like this one.

The Midland Rivet press that you and I use does seem prone to inflicting puncture wounds on thinner metal sheet, regardless of how much practice you put in.