Improving Hornby Dublo Bo-Bo 2 rail

[locomad]

I've a few of these in 2 rail, unlike the 3 rail versions there are to say at least poor runners, I've done various modifications over the years remove rubber tyres, add weight, change wheels around etc etc

 

I still like them so open to advice, I've a few, all have different modifications yet none are really up to job, recently I came across this article in an old magazine dated 1961, seems although new they had there problems then, here is the article, it's interesting as it seems to get to the source of the problem.

 

I'am in the process of using these modifications as described in 1961

[Il Grifone]

Dublo did indeed have problems with the 2 rail Bo-Bo and it was withdrawn from sale. Wrenn redesigned the whole thing. I don't have one, but I believe it uses a power bogie less armature as the unpowered bogie.

 

The usual method or powering twin bogie diesels is traction tyres on one wheel per axle on the power bogie and pick up from the other side. The other bogie then handles the other rail. I would be inclined to add pickups to all the wheels. A bit more weight on the unpowered bogie wouldn't hurt either. Removal of the traction tyres is not really an option, if the loco would be required to haul anything.

 

A problem with the two axle traction tyre method is that one of the wheels is not insulated. Spares should be available however,

[sagaguy]

The 3 rail model also had its problems in poorer haulage.Running bonnet forward,the torqu reaction would cause the motor bogie to pivot around the tyred wheel set & lift the front wheels off the track.

 

                             Ray.

[Il Grifone]

My solution follows the prototype - couple two together nose to nose. My D8017 has a reversed magnet to permit this as both are 3 rail

[roythebus]

I've had several of these over the years and never noticed any problems with running. I had a couple on the MRC's New Annington layout in the 1980s and they never needed any attention.

[Titan]

I've had several of these over the years and never noticed any problems with running. I had a couple on the MRC's New Annington layout in the 1980s and they never needed any attention.

 

I think it depends on which ones you have got, later ones did not have both traction tyres on one axle and were much better.

[melmerby]

The E3001 also had traction tyres on one axle and suffered a similar problem when running in one direction, less so in the other.

I wonder why they didn't go for 4 wheel drive?

Surely the vertical Ringfield motor could have been arranged to drive a shaft which drove both axles?

 

Keith

[Colin_McLeod]

I like the style of writing in the 1961 magazine article.

[Titan]

The E3001 also had traction tyres on one axle and suffered a similar problem when running in one direction, less so in the other.

I wonder why they didn't go for 4 wheel drive?

Surely the vertical Ringfield motor could have been arranged to drive a shaft which drove both axles?

 

Keith

 

They were four wheel drive. I suppose that the tyres ended up on one axle because on three rail pickup was not a problem. However on two rail it meant that it had only three wheels picking up, which was bound to cause trouble even if the traction problems didn't...

[melmerby]

They were four wheel drive. I suppose that the tyres ended up on one axle because on three rail pickup was not a problem. However on two rail it meant that it had only three wheels picking up, which was bound to cause trouble even if the traction problems didn't...

The E3001 definitely was not 4 wheel drive.

The vertical motor worm drove the pinion on one axle (the inner one) with rubber tyred wheels, the other was unpowered and picked up power from the track but lifted a certain amount as the loco started to move, losing contact giving the symptoms described in that article.

 

Keith

Edited June 3, 2017 by melmerby

[locomad]

My solution follows the prototype - couple two together nose to nose. My D8017 has a reversed magnet to permit this as both are 3 rail

Done exactly the same about 10 years ago, went step further wired using a very small 2 wire connector so both locos share the pick ups. Like the prototype very successful excellent haulage very much like a "Garrett", will pull quite easily 4 Hornby dublo breakdown cranes, only disadvantage is the length

[locomad]

They were four wheel drive. I suppose that the tyres ended up on one axle because on three rail pickup was not a problem. However on two rail it meant that it had only three wheels picking up, which was bound to cause trouble even if the traction problems didn't...

This seems to crux of the problem, the rocking of one of the bogies which means you get this jerking action, I'am experimenting making the two bogies more rigid, still keeping the top bar which holds the plastic body.

 

The compatible bogie at the time was the triang version, this does not use rubber tyres but have very rough ridges on the wheels, pick up on all four wheels, more noisy however more reliable, again I am going to try using wire pickups to get pick up on all four wheels per bogie, then wire up both bogies together.

 

Question of rubber tyres is interesting, I've removed all on one loco, it does slip but it's a better runner extra weight helps.

 

Finally twin powered loco, there's a lot one can do with this model

[bertiedog]

The worst problem was the armatures, they have too thin a wire and too many turns, but it is a task re-winding them, I cannot remember the SWG to use nor the length. The other thing is to get them remagnetised, and alter the support pivot with springs to keep the bogies level.

The thin wire reduced the current but also the power available. Purely as reference:-

 

If you do rewind, then simply strip the old wire and measure the dia, work out the SWG, (tables on net), pick  about one size larger and wind on as much as practical back on to the armature core. The steel can be covered in manilla envelope paper, glued on with epoxy, to protect the wire. Re solder the wires to the commutator segments in order around it.

Re winding use to be done much more than today, it is not difficult, but needs care to get it right, but if the first attempt fails, you can always have another go!

 

Stephen

[Golden Fleece 30]

To start with the Bo-Bo was a standard horizontal armature with a worm at both ends driving the two axles. It is completely different to the Ringfields so it is wrong to compare as such. The EMU and E3002 had the Ringfield driving one axle only but the Ringfield in the Deltic/Co-Co and Co-Bo DID drive four axles through a layshaft. All four of these driven axles had tyres.

 

It is no use swapping a Dublo tyred wheel for a non tyred one as the nickel plating causes wheel slip.

 

I made some plain steel wheels to try as I do not like tyres and fitted an EMU, Deltic and Co-Bo with these and you can see on some YouTube clips how these run, you will have to search under Garry Hall. None of these have any additional weight. Unfortunately on my phone I cannot put links on.

 

I did try plain steel wheels on a Bo-Bo and E3002 but without success, probably due to plastic bodies and I have not had time to continue my experiments.

 

Garry

Edited June 4, 2017 by Golden Fleece 30

[Pebbles]

For older XO4s its about 240 winds with 39swg although I have used both 38swg, with reduced winds, and 40swg, the wind arrangement being described as "Star Wind". Hornby Dublo used a different wind pattern. 

[Nimbus]

Hornby-Dublo used 'star wind', that is, one end of each coil was soldered to a commutator segment, and the other ends were soldered together (the 'star point'). Tri-ang used 'delta wind', where each coil had one end soldered to a commutator segment, and the other end soldered to the adjacent commutator segment.

 

I spent a lot of time trying to sort my first ringfield 8F, the motor used to start screeching, slowed down and released magic smoke. Rewound it several times without achieving satisfaction.

 

The Nim.

[Il Grifone]

Screeching is due to the gears binding and/or lack of lubrication. Both should be fairly easy to sort out, unless the binding is due to wear. This requires bushing or new armature bearings. The latter are in short supply.

 

Tri-ang motors are prone to the soldering to the commutator being dry jointed. Whether this is due to faulty manufacture or overheating* I don't know. Some have thick varnish on the windings which makes repair difficult.

 

* Crud in the commutator slots is endemic to Tri-ang motors and causes erratic running and/or overheating. It doesn't seem to affect Dublo motors for some reason.