Old tender drive A4

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Buelligan
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Old tender drive A4

Postby Buelligan » Thu Oct 10, 2019 8:04 pm

Hi all, I've finally got around to having a look at a model I bought a while back but which wouldn't run properly.

It's an old Hornby A4, from around 1997 I think. A special release for Beatties, (that shows how old it is), it's a BR experimental blue Woodcock. When I first got it, I put it on the track and it was jerky/jumpy, wouldn't run smoothly. I put it back in it's box awaiting a day where I had time to look at it. That day was yesterday, I oiled the motion on the loco, and popped the cover off the tender and (following the instructions in the box) oiled the relevant parts of the motor mechanism. I then put it on the rolling road and it ran lovely and smoothly.

I tried it on the track today, thinking that it was sorted and had only needed a service, but once again, going around the track it was jerky, stop/starting.
So I put it back on the rolling road, and again, it was lovely and smooth.

The coupling between the loco and tender is sprung, according to the instructions, to allow it to drop back on tighter corners. So I thought maybe there was a problem with the connection, and powering forward, extending the spring, breaking power connection and stopping, spring closing up the coupling, connection re-made, powering forward, and repeat. However, on the rolling road I simulated this by pulling the loco away from the tender and it made no difference to the motor running. The loco wheels are also all free moving so it's not them binding up and stopping it.

I'm at a loss now, limited knowledge and nothing obvious out of place, has anyone else got any ideas?

Heres a few videos I did today, first it the jerky track running, then (hard to show in a video) is the tender running fine on the rolling road and last is the wheels being free moving. Let me know if the videos don't work, they work for me but don't know if they'll work for others.

Image

Image

Image
Last edited by Buelligan on Thu Oct 10, 2019 8:06 pm, edited 1 time in total.

Buelligan
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Re: Old tender drive A4

Postby Buelligan » Thu Oct 10, 2019 8:05 pm

*please delete, accidental duplicate*

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footplat47
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Re: Old tender drive A4

Postby footplat47 » Thu Oct 10, 2019 9:19 pm

Firstly the R number would help to identifie the chassis. But here goes anyway Take off body and remove the pony truck to check if the spring is in place. I have had in th past bought an A4 from ebay or somewhere and found the springs missing. The result will be intermitent connection or no connection at all. make sure the spring is clean and clean out the hole the spring drops into with IPA or white spirit and a cotton bud and refit and oil. The spring should apply a good tention on the bogie. I have had in the past the small contact which connects with the tender pin being loos giving the same intermitent connection. If that is loose then tighten it with pliars or by tapping the rivet with centre punch on top of vice. Make sure it is tight. There is not much else that can go wrong with these other than the axles being dirty with dried oil so give the whole chassis a good clean and put together with fresh oil on the axles. If the plastice bottom is very distorted which holds the axles in place it may need replacing. The wheels will be flopping about badly if that is the case, this can cause shorting out on the chassis. But I doubt that will be the case. These chassis are normally very reliable. Good luck..........John
Never enough time is there.........John

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footplat47
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Re: Old tender drive A4

Postby footplat47 » Thu Oct 10, 2019 9:39 pm

Cant see vids sorry.......John
Never enough time is there.........John

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Ironduke
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Re: Old tender drive A4

Postby Ironduke » Thu Oct 10, 2019 10:08 pm

You can't use the [img] tags for videos. Just paste the address or use [url] tags.

first video

second video

third video
Regards
Rob

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Bufferstop
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Re: Old tender drive A4

Postby Bufferstop » Thu Oct 10, 2019 11:33 pm

It looks to me as though the motor is struggling to produce enough power to push the loco around. It turns the wheels continuously on the rollers but struggles to move the loco. you say it came from Beatties that makes it very old, if it has had long periods of no usage it's likely the magnet is shot. Even worse it comes from the period when Hornby were doing some real cost cutting. One of their more deplorable cuts was to swap the ferrite ring magnet for a sausage of ferrite shot in a ring shaped sausage skin packed into the body of the ringfield bogie. I'd track down a replacement magnet and a set of brushes and springs. Whichever magnet it has a replacement one won't go amiss.
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footplat47
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Re: Old tender drive A4

Postby footplat47 » Thu Oct 10, 2019 11:36 pm

Having looked at vid it looks to me the first thing I would do is have the pont truck off and check the spring and clean everything. Make sure spring is in place and it is clean and oiled when replaced. Test again
If that has not fixed it have look at the tow bar. If the tow bar looks iffy I would get new one one, they are cheap as chips and easy to get. I always keep couple in my box. Get tow bar complete with spring if you can some sellers sell them second hand I would try and get new one. Of course have fiddle and clean first to see if you can impproove it.
Try testing with a meter with a continuity buzzer. They make life easy. You can buy one from china for about £3 upwards and they are OK there is no need to spend loads of money on a meter.
It could be of course a case of traction tyres loose and slipping on the wheels. See if they are tight on the wheels first before taking off the Pony.
Never enough time is there.........John

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footplat47
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Re: Old tender drive A4

Postby footplat47 » Thu Oct 10, 2019 11:38 pm

Ironduke wrote:You can't use the [img] tags for videos. Just paste the address or use [url] tags.

first video

second video

third video

Thanks ironduke. Magic that works..........John
Never enough time is there.........John

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footplat47
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Location: Norham on banks of the river Tweed

Re: Old tender drive A4

Postby footplat47 » Thu Oct 10, 2019 11:55 pm

Have found out it is an R2037 and indeed it was a beaties special but I cannot find out the year of release. So have not yet found the service sheet but dont think you need iut as these did not change much untill they went to china made locos.
Never enough time is there.........John

Bigmet
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Re: Old tender drive A4

Postby Bigmet » Fri Oct 11, 2019 10:21 am

footplat47 wrote:... It could be of course a case of traction tyres loose and slipping on the wheels. See if they are tight on the wheels first before taking off the Pony.

Traction tyres are the most likely cause. These are cheap rubber bands over twenty years old. They perish and go hard and slippy, even if they still appear to be on the drive wheels tightly enough. Try fitting a new set. The tender drive is dependent on traction tyres to properly put the power down on the rails. It may actually do better with the old tyres taken off if they have gone hard...

The motor has plenty of oomph to move the free running loco section as shown in vid 1, so don't worry about the motor magnet: if the magnet is weak it's usually very slow movement, and then runs down smoothly to a halt as heating occurs in the motor.

Buelligan
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Re: Old tender drive A4

Postby Buelligan » Fri Oct 11, 2019 1:51 pm

Thanks all, gives me a few things to have a look at, will have to search for some traction tyres and get them ordered. Hopefully I can get it all working as it's in lovely condition. I'll update once I have a change to try out these things and figure out what the problem is.

Interesting about the videos not working in the post, must work for me because I'm logged into my imgur account.

Buelligan
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Joined: Sun Aug 12, 2018 5:18 pm

Re: Old tender drive A4

Postby Buelligan » Fri Oct 11, 2019 6:46 pm

Just a little update. I suddenly realised earlier that I actually have 3 tender drive A4's (possibly more), so I got a known working one out (Seagull, also originally from Beatties), and swapped the tenders over. This proved that the tender from Woodcock was in fact in fine working order, and though the traction tyres may well be 20+ years old, it still pushed the loco fine, while pulling 6 coaches.

Using the tender from Seagull with the loco of Woodcock, it was still jerky, maybe not quite as bad as with it's own tender, but still definitely not right.

So to me that rules out any issues of magnets, tyres, or any motor related issues. So I'll be looking at the tender-loco coupling next, can't understand why the I can't replicate the issue on the rolling road, but we'll see.

Footplat47, is it this spring that you refer to? Image

Bigmet
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Re: Old tender drive A4

Postby Bigmet » Fri Oct 11, 2019 11:23 pm

Buelligan wrote:...So I'll be looking at the tender-loco coupling next...

At least you now know it is failure of electrical supply continuity, and the problem location is on the loco. The problem isn't necessarily anything to do with the loco to tender linkage, see below. (The good news is that it works reliably, provided that the electrical supply is maintained.)

Buelligan wrote:... can't understand why the I can't replicate the issue on the rolling road, but we'll see...

It bears repeating, roiling roads don't get close to replicating what the mechanism does on the rails. Consider for a start in this case that the 'loco' is static, unlike when being shoved along the rails by the tender drive; so wherever the loss of continuity or momentary short circuit is occurring, it probably has something to do with the movement of the loco. You may have a dry soldered joint, making and breaking, a strand of wire that has come loose from a joint and momentarily causing a short, wires cores broken inside insulation and losing and remaking contact, poor contact between a pick up strip and a contact pin on the underside of the chassis block; all the sort of things generated by the movement of the loco on track, jiggling components around.

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Peterm
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Re: Old tender drive A4

Postby Peterm » Sat Oct 12, 2019 2:19 am

If all else fails you could wire the loco to tender using micro connectors.
Pete.

Buelligan
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Re: Old tender drive A4

Postby Buelligan » Sat Oct 12, 2019 1:25 pm

I've had another play, swapped the pony truck for the one off of Seagull and the issue remained. So I've now stripped it as far as I can see how to. All wheels have been removed, and I'm in the process of cleaning the underside of the chassis and the axles. But I can't see any sign of wires or pickups, so does this mean it picks up the power through 1 side of the wheels, passes through the axle and chassis and then through to the tender? If so, I'm guessing the wheels need to go back in a certain way? My helpful and inquisitive son came in and kept picking things up so I now have no idea which way the wheels were fitted! Anyone able to help?

It looks like this at the moment:

Image


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