Fireman's Friend

I have frequently heard reference to informal devices carried by loco crews known by various names - 'fireman's friend', 'jimmy', etc., but have never quite got to the bottom of what they do, how they do it, and where they go.

So:

1) Where is it fitted?

2) What does it do?

3) How does this help the fireman?

4) How does it do it?

5) I have heard that they were frowned upon by the bosses. Why?

 

But wouldn't that be counter-productive as it would slightly increase the back-pressure at the exhaust valves, making the operation of the cylinders fractionally less efficient, meaning the fireman would have to shovel fractionally more coal, cancelling out any savings made by better draughting? Presumably the original size and shape of the exit from the blastpipe was carefully designed to suit a particular loco design.

 

I think the British school of loco design was until the post-war period a case of trial and error and what worked before will work again. 'Careful design' is probably not the best description - compared to elsewhere, including France.

 

From my book of railway slang...."Piece of metal illicitly placed in blast pipe causing greater draught on fire and better steaming.Used in 1890-1930 period when drivers were paid bonus for saving coal and oil and Railways bought cheap coal"

 

It was used well beyond 1930 going by some of the "life on the footplate" books I've read.

 

A jimmy as I remenber was not unusual on Sentinels when they would not steam.
A piece of weling rod or something similar was tacked to the blast pipe dividing it in two and sometimes a second at 90 degrees to the first so you would either split or quarter the blast.
Apparently could make a big difference to steaming.
The two wire variant was effectively a multiple jet blastpipe.

Cheers Dave

 

On the S & D they were called Choppers.

 

Sentinel actually provided a range of nozzle sizes so you could tune the loco to the coal/coke that you were using. No need to modify them in this way although it may have been done. It would have been quicker to change the nozzle.

 

A jimmy would give an increase in steam generation (or make steam generation easier) but they were supposed to increase coal consumption and 'strain' the loco and/or force the boiler, hence officially frowned on.

Properly made ones had a chain and clamp fitting to stop them falling down the blastpipe. Usual price would have been a few packets of fags to the fitter.

As Gaurd_jamie says, there was a lot of superstition rather than intelligent design regarding blastpipe design in the UK, and while some light was gradually shed there was still a great deal of such superstition persisting right up until the end of steam.