7mm David Andrews Princess - 6206 Princess Marie Louise

mickoo

mickoo

Western Thunderer
You need to shorten the bracket holding the reversing lever cross (weight) shaft so that the shaft is centred in the frame hole, then you need to redrill the expansion link pivot hole in the radius rod closer to the slot.

That will also move the valve slide block into the middle of the slides, where it is now runs the risk of the crosshead smacking into the combination lever at full forward stroke.

It also looks like the combination lever is much too long, the slope on the union link is excessive.
 
G

Genghis

Western Thunderer
I wonder if it is intended that the combination lever has a joggle in it? That would shorten it. At present it looks like it might hit the crosshead. I am sure that it doesn't, just looks that way. But then I just got back home and it may just be the jet lag.............
 
mickoo

mickoo

Western Thunderer
Genghis said:
I wonder if it is intended that the combination lever has a joggle in it? That would shorten it. At present it looks like it might hit the crosshead. I am sure that it doesn't, just looks that way. But then I just got back home and it may just be the jet lag.............
Click to expand...
Good point but unfortunately no joggle on the Princess Royals.

Image1.jpg

This side on shot at 'virtually' BDC shows how all the levers and links should look.

6201_09.jpg

Note valve block in centre of slide and combination lever near vertical (it would be vertical if the engine rolled forward a few inches to true BDC).

This engine (6201) has a different expansion link and motion bracket so ignore all that, but, the crosshead, radius rod, valve block, union link and combination lever are all same.

It's always a good check to set the engine at BDC and in general (give or take a few inches) these levers and rods are set pretty much the same.
 
Rob Pulham

Rob Pulham

Western Thunderer
Thanks Mick,

Your photos are of Princess Elizabeth, the outside motion on the production engines (6203 onwards) is quite a bit different.
 
mickoo

mickoo

Western Thunderer
No it's not, your not reading what I wrote.

You need to look past the visuals and check the mechanical measurements, D33-12819 and D35-13851 show everything you need to know.
 
Rob Pulham

Rob Pulham

Western Thunderer
mickoo said:
No it's not, your not reading what I wrote.

You need to look past the visuals and check the mechanical measurements, D33-12819 and D35-13851 show everything you need to know.
Click to expand...
My apologies, I missed what you wrote under the images.
 
mickoo

mickoo

Western Thunderer
Rob Pulham said:
My apologies, I missed what you wrote under the images.
Click to expand...
:))

That's the problem with modern techno lifestyles, people just skim read and miss bits.

Either way, you're problems are not only confined to the reversing lever shaft bracket, there are other issues up front that will more as likely bite you when it gets up and running.
 
Rob Pulham

Rob Pulham

Western Thunderer
mickoo said:
Either way, you're problems are not only confined to the reversing lever shaft bracket, there are other issues up front that will more as likely bite you when it gets up and running.
Click to expand...

I agree, and you were right, the combination lever is 2.75mm too long. Fixing that is going to be an interesting exercise.
 
mickoo

mickoo

Western Thunderer
Rob Pulham said:
I agree, and you were right, the combination lever is 2.75mm too long. Fixing that is going to be an interesting exercise.
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Thanks, but I take no satisfaction as it means you now have a lot of work and the kit parts are just :shit:

Okay, there are two bearing holes at the top, are they about 3 mm apart?

If so, chop the top one off and retain the larger area of the lower bearing as it'll be visible above the valve slide block, then drill a new hole the correct distance below, it'll be in a fluted part of the rod but you won't see this as it's encased in the slide block.

That'll solve the combination lever length but you will have to also make sure the valve slide block is in the middle of the slide casting (it'll help hide the hole in the fluted section of the combination lever) and that means moving the radius rod forward as well. You may well find the pin for the expansion link falls inside the slot already to the rear, not a lot you can do about that but as you're stuck in mid gear it won't matter as it'll hold the radius rod at the right height.

Once you've done all that, worry about the reversing lever and shaft bearing bracket, that's the tail of the dog, not the other way around.
 
Brian McKenzie

Brian McKenzie

Western Thunderer
> . . . . the kit parts are just :shit:

Yes, quite disappointing, from a designer who I thought would do better.

I shouldn't bother trying to modify the combination lever and radius rod etc.
They bear no resemblance to the prototype. It would be easier to prepare new non fluted rods, preferably with a near-to-scale narrower width.

-Brian McK.

Caution: The prototype pic at Message #355 was flipped horizontally to align with Rob's model photo. Not sure if this affects return crank position and/etc.
 
mickoo

mickoo

Western Thunderer
Brian McKenzie said:
> . . . . the kit parts are just :shit:

Yes, quite disappointing, from a designer who I thought would do better.

I shouldn't bother trying to modify the combination lever and radius rod etc.
They bear no resemblance to the prototype. It would be easier to prepare new non fluted rods, preferably with a near-to-scale narrower width.

-Brian McK.

Caution: The prototype pic at Message #355 was flipped horizontally to align with Rob's model photo. Not sure if this affects return crank position and/etc.
Click to expand...
Good point about the combination lever not being fluted, you could of course just flip it around, it'd be near impossible to see the flutes on the inside and flooding with low melt and dressing back would make sure the flutes were not seen.
 
C

Clarence3815

Western Thunderer
Hello Rob,

I`m puzzled. When Nick Dunhill made three Princesses years ago did he have the same sort of problems with the motion?

Bernard
 
Rob Pulham

Rob Pulham

Western Thunderer
mickoo said:
Good point about the combination lever not being fluted, you could of course just flip it around, it'd be near impossible to see the flutes on the inside and flooding with low melt and dressing back would make sure the flutes were not seen.
Click to expand...
In the 1930's 6206 had fluted combination levers. A quick look at the WS Princess Supplement shows that all the production series had them fluted.
By good fortune I have a spare set of combination levers which have a much longer bottom section to I should be able to redrill them without having to modify the top part.
 
Nick Dunhill

Nick Dunhill

Western Thunderer
I heavily modified the kit. I made the inside motion which involved fabricating cylinder blocks and motion brackets, remember the locos are split drive so the inside cylinders and brackets are much further forward than the outside stuff. This meant that I didn't mount the outside cylinders and motion brackets as intended in the kit. I ended up fabricating new motion brackets, as the kit ones are wrong, as you have found out. Also Dave etched me some parts to improve the outside motion. New combination levers, union links and eccentric rods. The expansion links on mine were properly pivoted so that the valve rod could pass through it and not jointed in neutral gear.

The coupling rods in the kit are also jointed on the wrong way and I have some etches to correct that too.

I just followed the GA and in this way the rods are all in a straight line and the ends land in the correct place. The simplification of motion by kit manufacturers often takes builders down a dark rabbit hole. You're going to have to rebuild it and put everything where it should be. Modifying the rods will bring more pain.
 
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