Scorpio Class 5 kit

[Richard Coleman]

Has anyone here built a Scorpio BR Class 5 kit?

I am currently building one and having trouble with the coupling rods, they seem to be too short and Jeff Ellis said to just lengthen the piston rod.

Interested to hear any comments.

Richard Coleman

 

[Kev T]

Richard
I can't get my head around your problem. The coupling rods connect the driving wheels together, so I assume you mean the con rods. If the con rods are too short I would have thought that they wouldn't reach the crossheads correctly. The crossheads position is largely dictated by the position of the motion brackets and the length of the piston rod. If you lengthen the piston rod the crosshead would stick out the back o the motion bracket.
Does this make sense?
Kev

 

[Rob R]

There was a thread a while ago aboit the same issue. I can't remember the details but is was something along the lines of a prototype variation where the piston rod was longer, pushing the crosshead back and shortening the connecting rod.
Black 5's.
A standard class of 845 individual locomotives

 

[spikey faz]

Class 5 thread

Is this any use to you?

Regards
Mike

 

[3 LINK]

Class 5 thread

Is this any use to you?

Regards
Mike

Hi Mike, the above thread is regarding the Stanier Black 5’s. The original post is about the BR STD Class 5.

Martyn.

 

[spikey faz]

Hi Mike, the above thread is regarding the Stanier Black 5’s. The original post is about the BR STD Class 5.

Martyn.

Oops!
Mike

 

[Richard Coleman]

Thank you gents for all your comments.

Here is a picture of the connecting and coupling rods. Hope you can see the problem.

Note that the slide bar isn't fixed. It should be fixed to rear of the cylinder but the crosshead is too far to the rear.

Richard

 

[Bill Campbell]

Hi Richard

The connecting rod appears to be the correct length. The slide bar, however, seems to be too far away from the cylinder and the piston rod too short.

There is a fairly good drawing in the BR Standard Steam Locomotives diagram book - this can be downloaded from the Barrowmore MRC website here:

Barrowmore Model Railway Group (BMRG)

The BR standards are in the last of the locomotive books - just scroll down the page a bit. The diagrams also show the various types of tender.

Regards.

 

[Kev T]

I've just had a quick look at a Standard 5 side on with the piston all the way back. It shows the crosshead just touching the back of the slidebars and the front of the slidebars just shy of the cylinder. The back of the slide bars look to just about inline with the rim of the driving wheel.
This supports what Bill has suggested the problem is.
Kev

 

[Richard Coleman]

Many thanks for your advice. It confirms what I thought was the problem. It looks like I will have to put in a longer piston rods and maybe make up a longer slide bars as the ones in the kit looks to be far too short. One wonders if Scorpio has ever made up a kit?
Thank you Bill for the link to the drawing, Very helpful.

Richard

 

[mickoo]

Connecting rod between centres is 10'-8" long

 

[Eastsidepilot]