Author Topic: Steam engine suffering from hydraulic lock  (Read 1437 times)

Offline Gas_mantle

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Steam engine suffering from hydraulic lock
« on: December 10, 2017, 02:57:46 PM »
Hi all,

I wonder whether someone can help with a problem I'm having getting my large horizontal engine to run on steam for the first time.

I bought the engine last summer and its a great runner on air so now that I have a boiler I thought I'd give it a spin on steam, after about 5 hrs of trying it's a big disappointment as the cylinder fills with water before the engine can run  :(

Admittedly is doesn't have drain cocks (and that maybe a design flaw) but I thought with care I ought to be able to warm the cylinder by turning the engine by hand for a while - The cylinder gets adequately hot but still it fills with water to the point where the engine locks.

The steam is being supplied via a superheater on the boiler and I can comfortably raise 90psi so I'm convinced I have enough steam at a realistic pressure.

I've waited 6mths to run this engine on steam and gutted that it wont run  :(

This is the engine running on air a few months ago :-


Many thanks
Peter

Offline b.lindsey

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Re: Steam engine suffering from hydraulic lock
« Reply #1 on: December 10, 2017, 03:01:17 PM »
Peter,

I think it will need those drain cocks. Without a way for the condensate to get out the problem will remain and at that running pressure could even damage something.

Bill

Online crueby

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Re: Steam engine suffering from hydraulic lock
« Reply #2 on: December 10, 2017, 03:52:00 PM »
On smaller engines you can usually hand turn it to push out the water, but with the exhaust tube coming up like that, that would be hard. Any way you can reroute the exhaust out the bottom of the steam chest base? Can't tell if that is cast in or not. Even running one drain valve out the bottom of the exhaust passage would be a big help though one at each end of the cylinder at the bottom is best.

Offline Jasonb

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Re: Steam engine suffering from hydraulic lock
« Reply #3 on: December 10, 2017, 04:17:23 PM »
being a bloody cold weekend won't help matters as the castings will be cold and the steam will quickly condense on them. Run it on a bench so any condensate in the feed will run back to the boiler which will help.

Also how much can the valve lift off the port face, if it can't lift then the water will not have an escape route.

Adding drain cocks will be the best option, you may be able to get them at the bottom of the cylinder covers or have to drill up from the bottom ends of the cylinder, a third drain to the bottom of tee valve chest won't hurt nor will altering the exhaust position as previously mentioned.

Failing all that get a hair dryer out to warm the cylinder.

Offline Gas_mantle

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Re: Steam engine suffering from hydraulic lock
« Reply #4 on: December 10, 2017, 06:10:51 PM »
Thanks guys,

It kinda looks like to do a proper job of things I'll have to fit drain cocks  :(

I'll have a proper good look at it tomorrow after a night to think it through but initially moving the exhaust outlet to the underside looks out of the question, there is very little space and whilst there is an attractive cast boss on the top that the exhaust pipe screws into there isn't one underneath.

Until I strip it down I can't say how much lift there is on the slide valve.

The cylinder covers are about 1/4" thick so I'd prefer to drill into the cylinder - Owing to space limitations I'd rather mount draincocks on the side rather than underneath, is that likely to be an issue ?

This engine looks to be about the same size and copes without draincocks although he does say the valve can lift to allow water to escape



Online crueby

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Re: Steam engine suffering from hydraulic lock
« Reply #5 on: December 10, 2017, 06:36:03 PM »
The lower you can get the drains in a chamber, the more you can drain - water flowing downhill and all that.

Offline Pete49

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Re: Steam engine suffering from hydraulic lock
« Reply #6 on: December 11, 2017, 03:09:25 AM »
dumb comment I know but as you bought it do you think the steam chest is upside down. It seems logical to place a drain underneath, wellto me anyhow.
I used to have a friend.....but the rope broke and he ran away :(

Offline Jasonb

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Re: Steam engine suffering from hydraulic lock
« Reply #7 on: December 11, 2017, 07:28:03 AM »
There is no drain on the chest so it would make no difference, exhaust is coming out of the cylinder which could not be turned upside down.

Offline Zephyrin

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Re: Steam engine suffering from hydraulic lock
« Reply #8 on: December 11, 2017, 09:24:46 AM »
Without drain cocks, it would be very difficult to make this engine running on steam...

I would first heat the engine up to about 100c before opening the steam valve, or to the point where this large mass of metal will not imediately condense incoming steam, and give a chance to the steam to push pistons, and you can see steam from the exhaust...

Even with cylinder drain plugs, it takes about 15 min of efforts to get my largest engine (40mm bore x 70mm stroke) running freely, and to have escaping steam trough the exhaust and not water !
Of course, a blow with an hot air gun on the steam chest and cylinder shorten this delay.
As soon as my engine slows down, condensing occurs, and water is gurgling in exhaust tube, because the boiler is poorly efficient and cannot reach pressure above 2 bar to provide higher temp steam...
[/youtube1]
« Last Edit: December 12, 2017, 08:26:14 AM by Zephyrin »

Offline Gas_mantle

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Re: Steam engine suffering from hydraulic lock
« Reply #9 on: December 11, 2017, 05:39:15 PM »
Thanks everyone, I'll have to bite the bullet and fit drain cocks. To be honest it's a nice engine as it is and I didn't really want to start modifying it but I bought it a few months ago with the intention of running it on steam.

Zephyrin, I love that engine in your video - mine is a similar cylinder capacity so if you struggle I guess its to be expected mine will be the same.

It would kind of help if I could get a decent steady constant turn on the flywheels and introduce steam steadily but as they are a small diameter it's not easy getting a decent turn on them without risking losing a finger or two
« Last Edit: December 11, 2017, 08:19:03 PM by Gas_mantle »

Offline Bertie_Bassett

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Re: Steam engine suffering from hydraulic lock
« Reply #10 on: December 11, 2017, 08:07:30 PM »
can you not rig up a small motor to turn it over? or maybe a cordless drill a simple rubber wheel could be a friction drive?


might need three hands for that idea though :headscratch:
one day ill finish a project before starting another!
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Offline Gas_mantle

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Re: Steam engine suffering from hydraulic lock
« Reply #11 on: December 11, 2017, 08:18:17 PM »
can you not rig up a small motor to turn it over? or maybe a cordless drill a simple rubber wheel could be a friction drive?


might need three hands for that idea though :headscratch:

Thanks Bertie, I have actually considered doing that  :)

It would be a temporary arrangement just so I could see it run once, but maybe worth a try. I think as others have said it needs drain cocks so I'm going to have to do that ultimately.