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traction vs weight


hdrider

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Hello to all.

 

I'm a newcomer to this forum and to the hobby so please forgive my relative ignorance!

 

I used to love the old Hornby Dublo trains in an antique model store where I used to live some 10 years ago but I could never afford to buy them, then or now! However, by chance I managed to pick up a job lot of tired looking super detail BR Mk 1 coaches and I decided to try converting 4 of them to represent a 4CEP EMU.

 

After experimenting with pushing the coaches around with a Hornby class 110 DMU power car I decided that one power car was insufficient so I opted for a power car at each end with the leading bogie in each being replaced with a Hornby Ringfield 3 pole motor bogie with pick up from the second bogie for which I retained the Hornby dublo bogie with my own sprung brass pickup.

 

I found that in order to get decent pickup and sufficient traction on curves I had to substantially increase the weight of the power cars so they now weigh in at 325g a piece. This compares to 240g for the Hornby 110 power car. The Hornby Dublo trailer cars weigh in at 190g a piece compared with 160g and 130g repectively for the 110 driving trailer and centre coach.

 

The complete set seems to run adequately now but after test running for about 15 minutes around an oval the pickup becomes poor owing to black deposit on the wheels which looks as though it is probably deposited by the rubber tyres which are showing wear.

 

I am wondering if the power cars are simply too heavy causing the tyres to wear quickly.

The tyres appear to be an integral part of the wheel since there is a flange to hold them in place but I wonder if it is possible to get compatible geared wheels minus the tyre although I then might not have enough traction on curves again.

 

It has also occured to me that I could shift some of the weight into the pickup bogie itself to improve contact, as most of the weight currently consists of lead blocks on the chassis and the bogie is unweighted. I could perhaps then lighten the chassis.

 

I am also curious as to how Hornby overcame traction issues with other multiple unit sets. I am assuming, for instance, that HST sets would contain more than 3 trailer cars which could collectively weigh as much as if not more than 3 Hornby Dublo trailers and would be reliant on just one power bogie.

 

Any comments or advice would be appreciated. As you can tell I'm no expert. I'm just messing about with trains!

 

Alastair

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BTW 325g isn't hugely heavy, my 3mm/ft J72 weighs in at around 150g and that's a 0-6-0 tank engine in a smaller scale. So given the larger scale your certainly not overweight.

 

The other thing to consider is the trailers, if the wheels are not very free running then that'll create drag. Using pinpoint bearings it's surprising how much weight can be hauled.

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  • 6 years later...

I know this is a pretty old thread now but after a few years of working on it on and off I finally got the Hornby Dublo 4CEP more or less finished last year. There are still one or two details to address and it leaves a bit to be desired in terms of accuracy but I began this project before any of the Mk 1 based RTR EMU's were available and, having a soft spot for the Hornby Dublo super detail coach stock I just had to finish it.

 

I had it out today running round my loft and I've got it running quite nicely. I managed to sort out the traction and weight issues. Just like the real thing it's push and pull powered by the two endmost bogies which are Hornby Ringfields.

 

Like most of my projects, I'm not sure that it's worth the effort but it's a bit of fun all the same!post-14617-0-62077600-1525034415_thumb.jpgpost-14617-0-12663400-1525034428_thumb.jpgpost-14617-0-47196900-1525034441_thumb.jpg

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The black gunge is symptomatic of traction tyres, I really hate the things and have taken most of my traction tyred locos out of use with a dramatic reduction in amount of track cleaning required.

 

I have fitted Lima wheels to Hornby Dublo coach bogies using Romford pin point bearings with the points filed off. The wheels are insulated one side which allows pick up on one side through the bogie frame. Mine are fitted to plastic Triang coaches and allow lights to be powered without any pick up wipers.

 

I would have thought the Wrenn class 20 power bogie would have been the most logical readily available choice for a H/D EMU, I have Romford 12(?) mm wheels in mine so no traction tyres however it might struggle with 4 coaches so might need 2.

 

Arguably the worst RTR chassis ever was the H/D E3000 (or was it E3001) Electric with Ring Field Motor and only a one axle drive and traction tyres. Fortunately although they might be ideal I am fairly sure they have all been scrapped or fetch a fortune on Ebay. 

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Thanks for the replies. Nearly all my locos apart from the steamers have traction tyres so I guess I either have to clean the track regularly or invest in the Bullfrog Snot.

 

The 4CEP seems to run much better now. I think part of the problem was wheelslip owing to faltering pick up on one of the units but now I have sorted that out it seems to run smoothly at all speeds. The two ringfields seem to have enough oomph to shift 4 coaches easily even with no modification to the Hornby Dublo trailer bogies.

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