S/H Gremlins - Hornby Rebuilt BoB issue.

[Guest]

Hello,

Today, while at a local 'Model Toy and Train Fair', I parted with some money in exchange for a Hornby Rebuilt Light pacific (R2586, 34053 "Sir Keith Park"). In the hands of its previous owner (Prioir to being sold to the retailer I bought the model off), it had spent it's life on a shelf on display. Detail pack unopened, flanged cartazzi wheel fitted.
 

 

While being visually perfect, an issue has cropped up when running the model in.

The model is a little jittery when running, due to a sticking point on rotation of the driving wheels. I checked the valve gear positioning and it remains constant in relation to the sticking position (i.e. It always sticks in the same place). Please could someone tell me how I could rectify this? I was wondering if, given it's time of a shelf, the lubricant is running low so the bearings aren't doing their job properly, or could it be a problem with the valve gear itself? Or worse, the chassis...

I suspect that the remidy will involve Light Machine Oil of some kind, so I'd be greatly appreciative if I could be recommended any particular companies to look at for this.

Thanks in advance.

Regards,
Matt

 

EDIT: Add clarity

Edited September 13, 2015 by TheSoutherner

[KalKat]

Sounds like a split drive gear

[johnb]

Maybe quartering slightlyamiss somewhere??

[darren01]

Hi 

I had one of the R2586, 34053 "Sir Keith Park" that my father had got from a split pack and it did exactly the same thing,stuck running backwards and always at the same point.

I had a good look at the rods, oiled them, looked at the quartering, ran it for two hours on the layout and nada!, I could not work out what was causing this problem.

In the end i sent it back to Hornby and got the chassis replaced, now run's fine.

Darren

Edited September 13, 2015 by darren01

[34theletterbetweenB&D]

Top suspect is a connecting rod fouling the leading crankpin. All too easy for someone handling the model to just put a slight bend into the connecting rod or slide bar so it can catch. Look at the model from underneath to see if there is any risk. Gently putting a slight curve in the connecting rod so it always clear the crankpin, or resetting the slide bar position as appropriate to the cause, is the cure. If not the rods catching ,then it is on to other causes, as already mentioned split or damaged axle gear and quartering are possibles, a slightly off length coupling rod, or even a piston rod with travel limited at the end of the forward stroke, a loose or out of position wheel bearing, a pick up wiper or other fixed chassis component catching on a wheelset.

 

There's no definite 'it will be this cause' answer: however, the important diagnostic you have made of same position every wheel revolution means it must be among the components attached to, or close enough to touch, the driven wheels or axles.

 

 

 

Incidentally, no Cartazzi truck on a Bulleid pacific; these had regular trailing pony trucks on a pivot. The Cartazzi truck has inclined slides for the axleboxes in rigid frames, exclusive to Doncaster designs in UK practise to the best of my knowledge.

[steviesparx]

Sounds like a split drive gear

 

I would suspect this also, having experienced such on a couple of models including an unrebuilt BoB...

 

 

The split in the nylon { ? } gear was barely visible to the eye, but opened up under load...

 

 

You could try dropping the valve gear from one side at a time and confirming the fault exists elsewhere...

Edited September 13, 2015 by steviesparx

[Mallard60022]

I had exactly the same problem with this particular model. (Hope it is not the same item still doing the rounds?) It was a beauty on first sight but would just not run. I sent it back to the dealer (EBay purchase I think). I wonder if there was a batch build problem at time of construction or just a fluke that so many No 53s have shown this fault?

There are a few Hornby repair places as well as HQ. You may have to bite the bullet and get the chassis replaced.....sorry that's not very helpful.

Phil

[Guest]

Cheers for the responses.
When I have time, I'll check into it more. However, a brief turonver of the model showed up a couple of issues with the valvegear, most notably the Slidebars. On both sides, these are angled inwards towards the front, rather than being parallel with the cylinder. It appears that a couple of other rods are also bent slightly.

 

Regards,

Matt

[Theduke71000]

Note: 

Edited May 12, 2018 by Theduke71000

[Guest]

I commandeered the breakfast bar.

 

An advantage of the Split Polystyrene packaging, is the ability to turn an engine upside down, for use as an 'engineering cradle'.
This showed up some obvious problems with the valvegear. Primarily, the coupling rod between the Centre, and leading driver on the R/H side was noticably bent outwards. While the Connecting Rod is also bent inward, albeit only slightly:

 

The Slidebar on the R/H side is bent inwards toward the cylinder:

 

While the L/H side appears to be in better shape.

 

Connected the model direct to a 12V DC Power Supply:

 

Stopping the model at the tight spot revealled no obvious issue with the quartering;

L/H Side:

 

R/H Side:

 

Also tested for any tension in the Valvegear while positioned in the tight spot. All rods were loose, with no excess tension between any of them.
However, something did crop up. Usually, when stationary, you can turn a driving axle just a little, forward and back, until the con-rods stop the rotation. This is also possible on the Main Driven Axle, which the motor and gears are connected to. But, in the tight spot, there was a lot of resistence on the main driven axle including lateral movement. From visual inspection, there was nothing catching on the axle or wheels.
 

The Primary(?) gear, on the driven axle, under close inspection appears to be in good shape, and remains true to orientation at all speeds with no wayward movement. However, the second gear which interlinks with the primary gear, has some lateral movement which is only noticeable when the model is running at high speed. The application of a torch, shows there is a white substance stuck to the gear, in the position where the model sticks.

I have not been able to remove the body, to inspect this, as I can't remove the Speedo fitted to the model. I know how to do it, but it is secured very tightly and I don't have the tools to do it. Nor can I remove the second plastic plate from beneatth the chassis, for some reason.

Regards,
Matt

Edited September 14, 2015 by TheSoutherner

[Colin]

That intermediate gear on Hornby mechs seems to be a real Achilles Heel - to date I have replaced a total of 5 on a Britannia and various Bulleids and have resorted to keeping a few in the spares box " just in case".

[Mallard60022]

I commandeered the breakfast bar.

 

S2110009 - 1.jpg

 

An advantage of the Split Polystyrene packaging, is the ability to turn an engine upside down, for use as an 'engineering cradle'.

This showed up some obvious problems with the valvegear. Primarily, the coupling rod between the Centre, and leading driver on the R/H side was noticably bent outwards. While the Connecting Rod is also bent inward, albeit only slightly:

S2110001 - 1.jpg

 

The Slidebar on the R/H side is bent inwards toward the cylinder:

S2110002 - 1.jpg

 

While the L/H side appears to be in better shape.

S2110004 - 1.jpg

 

Connected the model direct to a 12V DC Power Supply:

S2110006 - 1.jpg

 

Stopping the model at the tight spot revealled no obvious issue with the quartering;

L/H Side:

S2110007 - 1.jpg

 

R/H Side:

S2110008 - 1.jpg

 

Also tested for any tension in the Valvegear while positioned in the tight spot. All rods were loose, with no excess tension between any of them.

However, something did crop up. Usually, when stationary, you can turn a driving axle just a little, forward and back, until the con-rods stop the rotation. This is also possible on the Main Driven Axle, which the motor and gears are connected to. But, in the tight spot, there was a lot of resistence on the main driven axle including lateral movement. From visual inspection, there was nothing catching on the axle or wheels.

 

The Primary(?) gear, on the driven axle, under close inspection appears to be in good shape, and remains true to orientation at all speeds with no wayward movement. However, the second gear which interlinks with the primary gear, has some lateral movement which is only noticeable when the model is running at high speed. The application of a torch, shows there is a white substance stuck to the gear, in the position where the model sticks.

 

I have not been able to remove the body, to inspect this, as I can't remove the Speedo fitted to the model. I know how to do it, but it is secured very tightly and I don't have the tools to do it. Nor can I remove the second plastic plate from beneatth the chassis, for some reason.

 

Regards,

Matt

That first motion pic shows quartering inaccuary, unless it is lens distortion.

Phil

[geoffers]

Had this issue develop after a little while on 34053 and 34045. Split drive gear as mentioned above. Returned to Hornby and returned very quickly - and despite offering to pay for repairs the two locos were returned FOC. Had to pay for initial postage of course (Royal Mail Next Day Special Delivery). Excellent after-sales from Hornby if I may say. Bachy have always charged me for repairs. So I would suggest sending it back to Hornby with a covering letter and await return.

 

Edit - Beware also of coupling rod nuts snagging on valve gear. If this happens at speed (as it has done so here) it results in a spectacular derailment and "exploding" valve gear.

Edited September 15, 2015 by geoffers

[Guest]

That first motion pic shows quartering inaccuary, unless it is lens distortion.

Phil

If you are talking about this picture (in particular the trailing driver), then that's my fault:

 

I rolled the trailing drivers forward and back to test how free they were within the tight spot, and left it as far as it would go.

 

Regards,

Matt

[Mallard60022]

OK sorry Matt.  Shame this happens as they are great looking loco's. I've got quite a few sitting upstairs awaiting the layout build and I do hope I don't discover that half of those need to go to Hornby.

Hope you get it sorted and if so I/we will be interested in the cause.

Phil

[Guest]

OK sorry Matt.  Shame this happens as they are great looking loco's. I've got quite a few sitting upstairs awaiting the layout build and I do hope I don't discover that half of those need to go to Hornby.

Hope you get it sorted and if so I/we will be interested in the cause.

Phil

That's fine, don't worry about it.

It's a bit disappointing, although I do find these troubleshooting evenings reasonably entertaining. I hope your fleet don't succumb to the same issues that appear to be reasonably common.

 

Regards,

Matt

[Guest]

Still unable to remove the body, I had another crack at removing the secondary plastic protector plate underneath the model.

Once again, the engine was placed upside down, using the packaging as a makeshift cradle.

 

Primary protector plate and Cartazzi truck removed, the trouble begins again. The Secondary plate is jamed on at the cab end on the L/H side:

 

Applying a little inginuity where possible to allow me to keep both hands free:

 

After a little persuasion, the secondary plate popped off allowing a clearer view of the primary and second gears:

 

Lifting the centre driver off of the second gear, and turning the wheels by hand revealled there to be nothing amiss with the Valvegear, nor quartering. Wheels turned freely without any trouble.

So, I resorted to a direct power application approach as before, and lifting the centre driver off of the second gear. The gears demonstrated the sticking as before, however it appeared to be resonating from well within the chassis, rather than just the second gear. Nevertheless, a felt a small application of Oil was necessary, to see if that would cure it. Luckily, due to my heavy use of glue in the household, there's always a cottonbud nearby...somewhere...

 

I sprayed some WD40 on to the flat end of the bud, and rubbed the second gear with it. I had to do this, since I lack any other kind of low-ish viscosity oil, and no way of applying small amounts. Proceeding to run the model at a high speed, to spread the oil throughout the gears quickly, it has shown signs of improvement, with the stick becoming less prominant. However, it is still there, so will be taking another look soon.

Regards,

Matt

Edited February 14, 2016 by TheSoutherner

[Guest]

I believe I've 'cracked' it...you'll get that by the end of this post.

I had an hour or so free this afternoon, and decided to have another go at removing the body. In theory, this is the simplist of tasks. However, the fiddelity of the Valve gear screws can prove infuriating. Applying some serious pressure onto the screw with some tweezers, I finally managed to release the valve gear screw and subsequently the speedometre.

After removing the body, I was faced with the poor running chassis.

 

I test ran the chassis minus the body, as a precaution. This proved to be a useless exercise, given nothing was revealed. Therefore, delving a bit deeper, I removed the motor mounting and the worm cover, to subsequently remove the motor.

Testing the motor - Smooth running in both directions.
Testing the rolling chassis - Smooth rolling, no tugging or binding.

 

After which, I removed the primary gear in contact with the motor. This was reasonably covered in lubricant and required a clean up, which revealed the following:


A nasty crack in the gear. Unnoticeable in the rolling chassis, since it's a double gear, so this half with the crack in it is not in conact with anything when the motor is removed.

Closer inspection shows the consequence. The crack has forced apart two of the teeth on the gear.


When I held this up to the worm of the motor, the teeth wouldn't sit properly within the worm, forcing the gear out of the grove.
Time for some eBay searching for a replacement.

Regards,
Matt

Edited December 30, 2015 by TheSoutherner

[Ian Abel]

Had exactly the same problem with a couple of my BB/WC including "Sir Keith Park" - as described by several other posters.

 

What you need is Hornby part #X8849

Got mine from Peters Spares - order a couple to be safe/have spares available...

 

http://www.ebay.co.uk/itm/Hornby-X8849-Idler-Gear-Set-China-Built-Locos-/331680864976?hash=item4d39b85ad0

Edited October 27, 2015 by Ian Abel

[Guest]

Got a bit carried away with running the model after the fix, to remember to post an update here...

While I awaited the arrival of the replacement gear, to save me having to take the model apart again, I didn't bother putting it back together to begin with.

 

The new gear (beneath), with the old cracked one (top) for comparison

 

After fitting the new gear, I found the old insulating tape to be a bit beyond salvation with it covered in lubricant. I dug around a bit and found some spare white insulating tape and have replaced the absent pieces.

 

Reassembled, it runs as new with no sign of there ever being a problem to begin with.

Regards,

Matt

[John M Upton]

Reviving an old topic a bit, I have a rebuilt WC/BoB (unknown name/number as I renumbered it a long time ago, it's 34004 now) where the motor runs freely but the wheels do not turn although it can be pushed freely along the track.  Is this the same part that has failed by any chance?

[steviesparx]

Reviving an old topic a bit, I have a rebuilt WC/BoB (unknown name/number as I renumbered it a long time ago, it's 34004 now) where the motor runs freely but the wheels do not turn although it can be pushed freely along the track.  Is this the same part that has failed by any chance?

 

I'd check first that the motor hasn't come away from mating with the initial drive gear - it sits at the top of the chassis and is held in place by the collar around the main shaft ( actually easier to see than explain) - Otherwise its a case of following the drive train down through the chassis...

 

The original fault as reported here was a split gear which caused jerky running or jamming - your symptoms appear different.

[DCB]

Could be final drive gear loose on the axle.   If it was teeth off it would bind when the loco was pushed along.   Could be the motor mount, not sure if BBs suffered the mazak rot the T9s and our 9F tender frame suffered but they crumble to small flakes of dust.

 

The old thread is interesting, the photos show a bent leading coupling rod which may have been fouling the leading sand box and a damaged small end of the connecting rod bent about 20 degrees, which may well have caused resistance as it forced the crosshead sideways against the slidebars as well as dodgy quartering.  A display model which has been maulered around by numerous grubby's is probably not a great buy.

[John M Upton]

Makzak rot was my first suspicion as I had a T9 that went spectacularly the same way (disintegrated motor retainer and bracket) but lifting the lid reveals all is well in the metal work department.  I shall get a set of replacement cogs anyway as I will probably need them, brew up a cup of really strong tea and then investigate deeper...

[John M Upton]

Just got around to taking it apart and yes, both the cogs are cracked so an order into Peter's Spares is now in.