trevor shortland 51xx regulator

[nipperParticipant @nipper]

I have built the Trevor shortland 51XX regulator but omitted the pilot valve. The reason was that it presented an additional leakage path through the regulator and I was worried that it could tip up during operation and jam the system. My regulator works fine but is very heavy to operate at 100 PSI and consequently is difficult to set into position particularly on the move. Has anyone built the regulator as designed with a long slot or possibly a series of small holes as the pilot valve. Are there any problems with tipping. I would appreciate any comment. Thanks Dave.

[nipperParticipant @nipper]

[nipperParticipant @nipper]

Although there were no replies to my thread I elected to do the modification anyway. This was prompted by the fact that the regulator decided to stop working and when I opened it up the silver solder had broken at the end of the rod, inside the reglator housing, such was the amount of torque required to open it at 100 psi. I did the mod by drilling 3 1/16th holes as the pilot . Most of my worsed fears have come about, it leaks more than it did before and will not close properly without shutting the regulator and then opening slightly. A bit disconcerting as it is unnatural to do this. This is because at the end of the stroke the pilot valve tips up and lets steam into the pilot holes. It easy to use though as the effort is now quite light.

[Laurence BParticipant @laurenceb]

Hi Nipper,

I haven’t got this far with my 51xx (nowhere near!) but your postings were still very interesting.

I’ve just been looking at drawing T11 and (assuming l’m interpreting the drawing correctly)

it looks to me like the ports are a bit too “square-edged”.Some regulator ports have a triangular or ‘vee’ edge which should give more progressive opening.

I’m just wondering what sort of regulator the late Neville Evans specified for his ‘Penrose Grange’ loco. I think I still have the set of articles somewhere.

[nipperParticipant @nipper]

hi laurence. You are right about the V in the regulator opening, this would give a softer start. In my case I just made it to drawing and at a later date started thinking about the slider, in other words it was too late. In practice it needed a very small opening of the regulator to get started and if the regulator was closed on the move it was almost impossible to reset a small opening due to the small amount of movement required. The forces were very high. Its good now ,as far as ease of movement is concerned, but closing it is a fiddle. As you can see from the drawings there is a degree of leverage on the little slider and little to counteract it. I have considered putting a couple of small bars on the top of the main slider to stop the small one lifting up, that would lock the whole assembly together, while allowing the small one to move but not lift, but this would make it difficult or impossible to fit into the housing. We shall see, perhaps it just needs running in. Best of luck.

[Laurence BParticipant @laurenceb]

Hi Nipper,

Yes,I see what you mean about the leverage on the slider.There isn’t much surface area for the steam pressure to act upon and keep it in place.Your idea for retaining bars on the main valve bars sounds a good idea,but as you say,there isn’t a lot of room in the regulator housing!

Good to hear that you have your loco up and running.Would be nice to see a photo or two of your engine if possible.

[nipperParticipant @nipper]

Hi laurence. You have seen the problem now, its a pity that none of the existing builders replied as they may or may not have had a problem and may have a solution. I would consider a rotary valve as they can be bought really cheaply and I know others have used them. Not on a 51XX I might add. I would send pictures but have not figured out how to do it. I built a 56XX not a 51 but it uses the same boiler, smokebox, cab fittings etc. If I had an E Mail address I could do pictures without a problem. Dave

[Laurence BParticipant @laurenceb]

Hi Nipper,

Have sent you a private message regarding the photos.

There was a photo of a working model 51xx in M.E. a while ago built by someone referred to as ‘Ivor the Engine’ (presumably from one of the Welsh clubs! ) Would be interesting to know if he modified the regulator.

Have sent you a private message regarding the photos.

Laurence.

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