Gordon Cheape Compound

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DetroiTug
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Re: Gordon Cheape Compound

Post by DetroiTug » Tue Oct 09, 2018 10:35 pm

On the steam cars with simple engines, we have no cylinder drains at all, they came from the factory like that originally. Starting procedure is rock it back and forth forward and reverse, and start on low pressure. On the tug, I just leave it in forward and open the throttle while firing up, around 10 psi she starts clicking over. These are both slide valve engines, can't do that with a piston valve, need cylinder drains.

Yes, that will destroy a pressure gauge with lower pressure ranges. I use pressure gauges on ram piston pumps as indicators, 10,000 psi hydraulic gauges, the needle barely moves, but it's enough to indicate the pump is working.

-Ron
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Re: Gordon Cheape Compound

Post by marinesteam » Wed Oct 10, 2018 3:21 am

Use a pressure snubber and gauge with a proper rating and you should have no problem.

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Re: Gordon Cheape Compound

Post by Martyn39 » Wed Oct 10, 2018 4:53 pm

Thank you all for the feedback. I have taken the thing apart and done some testing. First problem is that the cranks are not set at exactly 90 degrees but 88. At this point I am not going to do anything about it but if I can get it to run and the beats are too uneven I will cut the centre main in half and bore out the webs and then fit a new main in ground silver steel. Next problem is that the piston valves are 5 thou smaller in diameter than the bores so they will have to be remade, but before that the next job is to work out the dimensions of the piston valves as the ports are cast into the cylinder block and are different top to bottom and low pressure to high pressure but before I can do that I have to find mid gear and the valve travel.
There was no packing in the rod glands so all in all the lack of performance is explainable. The engine is the work of two people as the machining generally is excellent but the second person (who finished it) was clearly not as accomplished.
Joy valve gear still remains a mystery though.
I have fitted 60 psi gauges to the drain cock tappings as I hope to be able to test the engine on a much lower pressure than that.
Incidentally, where can I buy 1/8 bsp drain cocks?
Thanks to all for the help,
Martyn
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Re: Gordon Cheape Compound

Post by steamboatjack » Thu Oct 11, 2018 7:52 am

Martyn,

First of all, the angles between the crank throws is not important so long as the valve gear is timed to the relative piston, some Savery engines were made at about 118 degrees as they considered it better balanced. Forget about even beats when you have different sizes of cylinder! Leave the crank well alone if it is well made.
Piston valves:- Savery engines have no rings, the Cheape is the same, this is no problem if they fit well. NOT 5 thou!!! If the materials are the same then a maximum of 1 thou per inch of diameter. The problem is usually that the bores are not parallel if machined on a lathe face plate.
There is absolutely no point in fitting gauges to the drain cocks, carefully measure the dimensions of the ports taking the cylinder top as a datum. Please note these engines are “outside admission” Joy gear does not work well with “inside”.
Below is a copy of the data sheet for valve setting.
Martin Evans book, Manual of loco construction covers basic Joy gear. As I said before the difference is that the “slide shaft” is replaced by swing links similar to the difference between Hackworth and Marshall gear.
CCF11102018_00000.jpg
CCF11102018_00000.jpg (126.77 KiB) Viewed 7361 times
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Re: Gordon Cheape Compound

Post by dampfspieler » Thu Oct 11, 2018 12:43 pm

Jack,

thank you for explanation and sheet. What dimensions have A, B,C and D? At my steam engines i have a lead of 1 mm so they run smoother, why you haven't in the sheet.

Best Dietrich
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Re: Gordon Cheape Compound

Post by Martyn39 » Thu Oct 11, 2018 3:12 pm

Jack, Thank you for the information and diagram. Where can I find a copy of these diagrams as I only have a few of the original sheets, the rest are hand drawn?
The piston valves are made of cast iron as of course are the cylinders. I have ordered some more cast iron to make the new ones and this drawing is a great help. On this engine the steam is only admitted to the top of the HP piston valve which is hollow to allow the steam to pass to the other end of the valve with the transfer port cast in.
Do you know if these figures for lead and lap are the preferred sizes as they are very specific?
You guys are a great help as I don't feel lost now.
Thanks again,
Martyn
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Re: Gordon Cheape Compound

Post by steamboatjack » Fri Oct 12, 2018 7:28 am

The Cheape engine rights were sold to Hugh Mothersole who marketed them for a while and made a good set of drawings, the sheet above is a copy of one and is specific to this engine.
Hugh sold the rights to A.J. Reeves 2000 who market various bits/drawings for really silly money! I see this particular engine is not on their website but used to be??
The lead is not specified on this sheet, it is a function of the eccentric's angle of advance, I would suggest a small lead of 0.010 to 0.020" if it is possible to move the eccentrics, Either way you need to VERY ACCURATELY mark TDC & BDC to get this right.
Regards Jack
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Re: Gordon Cheape Compound

Post by Martyn39 » Fri Oct 12, 2018 10:30 am

Jack, thanks again for the info. Unfortunately Reeves no longer sell any bits for the engine but most importantly have no drawings either. That's why I asked you where you got yours from.
Marking tdc and bdc should be ok as I am used to doing that on steam locomotives.
It's strange that the lap is different on the low pressure cylinder from the HP.
That may be normal on a compound but I have only worked on simple engines up till now so this is all new.
The engine is now turning over freely. the gland packing on the cylinders was rock hard graphite which I have now removed and have ordered some PTFE square packing material from the net. I have shimmed the slide bars so that they are now in alignment so the remaining issues relate to the piston valves. I shall make up dummies to check the events before making then in cast iron.
Your support is brilliant.
Thank you, Martyn
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Re: Gordon Cheape Compound

Post by Martyn39 » Mon Oct 15, 2018 4:16 pm

Whilst waiting for the cast iron for the new piston valves I rang Reeves, having heard about Hugh Mothersole, to find out exactly what they have in the way of drawings. Basically the answer is that apart from a general arrangement drawing they have lost them which is why they no longer offer parts or drawings.
I am still at a loss as to what might have been fitted to the 2 bosses at the side of the engine. The air pump is driven by a timing belt from the crankshaft and I have a double acting feed water pump that I have to mount and find a way of driving. Maybe they are for mounting these auxiliaries.
Again showing my ignorance, where does the steam go after it leaves the low pressure cylinder? From what I understand it must go into a vessel that collects the condensate from which the air pump is connected? And also the feed pump?
Is the feed pump double acting so that one side pumps from the condenser and the other from a water tank?
Can anyone point me to a schematic diagram that shows the arrangement of these pumps and tanks with all of the check valves and control valves?
Steam locomotives are so much simpler!
There is so much to learn in this life, but with your help I will get there.
Martyn
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Re: Gordon Cheape Compound

Post by dampfspieler » Mon Oct 15, 2018 4:58 pm

The asked points are the assembly points for the pumps. How you can and should fit them you can see here (as an example).
S-SQuad1Pumps_000.jpg
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S-SQuad1_000.jpg
S-SQuad1_000.jpg (35.6 KiB) Viewed 7274 times
Hope it helps
Dietrich
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