Disassembly of Merchant Navy loco and tender

[IslandBoy]

Hi, I think the worm gear on my Merchant Navy "United States Lines" 35012 is worn. It's from the VSOE boxed set 2004-7. Thanks to the guidance of Rob H (hi, Rob) I am plucking up the courage to take a look. I have the Maintenance Sheet and also the Service Sheets HSS 389 and 430. I note the screw under the bogie and also the speedometer cable on the left rear driving wheel.

Is the speedo cable just pull it out carefully or does it unscrew?

Is there a video walkthrough anywhere?

As well as fixing the gear, I'm also intrigued because the loco coupling to the tender has a couple of electrical pick-ups and the tender has a corresponding metal pickup and I wonder what that's for. I found the two chassis screws on the tender, took them out but couldn't see how to take the tender apart to see what's in there.

Thanks, Mike

[atom3624]

Speedo cable - BE VERY CAREFUL!!

You need a 2.5mm hex driver, carefully remove the screw, gently lift off the speedo drive, and I generally replace the (tiny) screw.

Tender - generally there's a couple of tabs one end, screws the other - carefully lift up the screw end, then push - see service sheet - always downloadable from somewhere - keep an eye on the vacuum pipe if fitted - normally 'pings' somewhere you cannot find for 3 months!

Why is 'the worm worn'?

This is a generally robust, brass part which normally doesn't wear out.

What can happen are:

1. Motor mounts are loosened - nip up the relevant screws - don't force.
2. PLASTIC drive gears are worn - from worm, or the final drive on the drive axle - this is a push-on fit onto splines on the driven axle. Too much rough treatment can mean the splines on the axle round off the inside of the plastic gear wheel - this is what will probably wear if not that the worm has worn the intermediate gears with a loose motor mount.

Al.

[Going Spare]

Service Sheet 267C is the one that covers your loco from set R1038. Other than a large weight, there is nothing inside the tender.

The transfer gears taking the drive from the motor worm to the centre driving axle are in pack X8849. Speak with the supplier before ordering to make sure you obtain the correct parts for your loco because there is now more than one X8849 pack, with differing contents.

The electrical contacts between the loco and tender are taking power from the tender pick-ups to the motor, the decoder socket being mounted on the loco chassis rather than in the tender.

[96RAF]

This diagram should help with the loco-tender pick up arrangement. These can be fickle and easily get bent out of shape then short out.

[ColinB]

Yes, I had this issue, I think when I looked there were 4 types. When I talked to that well know supplier of spare parts they weren't that helpful. I gather the best idea is to count the number of teeth, then contact the spares supplier. Also check it the intermediate spindle (just above the drive wheel) is locked into the frame or free moving. In most of all my cases of gear issues, it is the gear on the wheel axle that splits, so check that first. Unfortunately, you have to buy a new set of wheels to get that gear. The motor itself is shared with loads of other models, it seems to be pretty standard across the range. The tenders on my Merchant Navys/ Battle of Britain locos are held on by either two screws mid way towards back of tender or in one case a single screw in the centre. The tender top hinges at the loco end before you can pull it out of the slots. Watch out for the handrails on the tender and the water control post. The other thing to check is that your chassis hasen't got "metal rot" which is causing issues. I have just relocated the DCC socket to the tender on my Rebuilt Merchant Navys, so I know a lot about them. Watch the valve gear it is very fragile.

[IslandBoy]

Thanks for all the good info. I shall go through carefully. I have found the service sheet 267C, thanks. The number R1038 which is on the sheet is also stamped on my Maintenance sheet from the set.

I understand it's more likely to be the plastic gear than the brass gear but since I haven't got in it yet, didn't know which bit of the gear set might be worn.

Given the loco runs without the tender, what's the point of the electrical pickup in the tender?

I'll get the magnifying glass out and look at the speedo cable later.

Thanks, all.

[atom3624]

Extra electrical pickups are just to counter the possibilities of the drivers being over areas not supplied - cannot possibly be plastic the full length of the loco surely? ... is the theory.

Some 'frogs', particularly of the express points, are quite long relatively speaking.

Al.

[IslandBoy]

Is this the speedometer cable mentioned in the Maintenance sheet? Even through a magnifying glass I can't see a 2.5mm hex nut. Do I need to disconnect this to take the body off and if so, how? Thanks

[IslandBoy]

On closer inspection of Service Sheet 267C, it is titled Merchant Navy DCC. The sheet itself is dated Feb 2006 and the boxed set, from research, was produced 2004-2007. Do you think this means I could have the loco fitted with DCC?

Thanks.

[ColinB]

Yes IslandBoy that is the speedo, it isn't a 2.5mm nut it is the 2.5mm bolt/set screw that screws into the wheel, holding both the speedo and conrod to the wheel. I am always forgetting about these and breaking them when taking a body off. In my case not a good idea as is a devil of a job to put a new one on, if you can get one. This loco may well be DCC ready with a socket in the loco, which I assume houses a DC header/adapter. You will need a special nut runner for the nut, it is better than using long nosed pliers. I found it is better to buy a commercial 2.5mm nut runner rather than the Hornby tool, it is also harder to lose.

[96RAF]

Not fitted with DCC but ready for DCC. If the loco is from the later R1038 boxed set you will find there is a socket in the loco with a blanking plug in, as shown on the service sheet. This blanking plug is removed and an 8-pin decoder plugged in to make it fit for DCC use. The very early boxed set locos did not have the DCC socket.

This poor photo shows my MN with a TTS sound decoder poked into the smokebox and a speaker fitted on the forward chassis.

Speedo - you can either carefully pull the bracket from the body if it is not glued in, or you can remove that hex screw on the connecting rod. You will then see the arm attached to the speedo cable has a slot which mates with the end of the crank arm. It is essential to get this slot lined up when you reassemble it.

If you watch the speedo crank as the wheel revolves you will see the cable end of the crank is held at the wheel centre and the other cranks revolve around it. When you reassemble it all (note any spacers or washers) make sure it all slots into place so that you keep that clever mechanism function.

[IslandBoy]

Thanks ColinB and 96RAF, I see the nut now. Happily, I have been recommended someone here on the IoW by Max at TrainShop so I think I'll leave this to the expert. It's way too fiddly for my eyesight and (lack of) dexterity. And I'll get DCC fitted if it's possible. I was going to go down the bluetooth app route but I think DCC would be preferable.

[IslandBoy]

Because I got scared about the 2.5mm speedometer cable nut/spacer, I asked local expert (thanks, Max) who pointed me at Matt (who also 3d prints his own models!), Dropped round today and it was just a loose screw on the motor housing. Runs sweet, now. He also says it's a late model (of the 2004-7 production), has a sprung chassis and is DCC-ready. More reading and learning to get on with. Cheers.