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Author Topic: "Run away" diesels  (Read 11014 times)

GuyFawkes

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"Run away" diesels
« on: February 09, 2006, 06:35:11 PM »
I've seen a few people mention this, and one or two mention it several times, this is frightening....

What happens when you get a run away is extra fuel is getting into the engine, this can be lube oil getting past the rings, lube oil getting past the valve guides, any fuel leaking into the intake (on other engines leaking lift pump diaphragms leak diesel into the sump, causing "dilution" and raising the oil level, which will eventually lead to a runaway) or just a broken injection system delivering far too much fuel.

Diesel engines, by their nature, will consume ever more fuel and rev ever higher until something breaks, and then that happens all hell breaks loose, I've seen 2 ton flywheels thrown 400 yards before touching the ground, con rods fired through block walls, and the entire bottom blown out of boats.

Listers use very little fuel by their nature, so very little extra fuel will cause them to run away.

Once the "other" fuel supply is sufficient by itself to run the engine, you can take a fire axe to the injector lines, it won't stop it.

Detroits had a "blast"" door on the blower for emergency shutdown, trouble was unless your blower oil seals were in tip top condition they would get sucked in and the engine got all the fuel it could ever use, and vacuum crushed the blast shutters out of the way.

The ONLY (non destrictive, such as a firehose down the intake the hydraulic the pistons and destroy them) shut off method that will work is this....

You need a ROBUST inlet manifold, "robust" = thick walled water pipe or seamless hydraulic steel pipe and it has to make a turn to vertical, on top of this you can mount a LARGE automotive type paper air filter can (ideally with a torque nossle) but most important is the top of the manifold must be inside this air filter can, flush with the bottom, and with a nice big welded on flange at least 1" wide and 1/2" thick, if you weld this flange then it needs to be skimmed flat, you also need to ensure the centre radius is a perfect circle, no protrusions from weld etc

On to this flange you have a sping loaded flap, at least 1/2 inch thick again, ground flat again, with a spring positioned so it will hold the flap shut with a few pounds force, this flap is hinged, in the centre of this flap you have a circle of steel again 1/2" thick (drill a 1/2" hole in the centre and weld to the upper flap) sized and positioned to JUST fit inside the top of the manifold, so you get a stepped door, similarish to the flaps at the top of tractor exhausts, but with the opposite purpose.

How you trigger it is up to you, a cheap and cheerful way would be a lawnmower type centrifugal clutch on the end of one crank.

NEVER try to stop it by putting your hand over the intake, a round peg of wood, a leather cricket ball, things like that "can" work if you have then to hand, the above design was knocked up to shut down engines that were deliberately over run to test various things, and it always worked a treat.

A fire hose will also work a treat, as will and handful of small ball bearings. Never use a small amount of water or a mist or spray, it will just aid combustion, drown that sucker.

YES these will destroy the motor, but trust me, far far far better to destroy the motor while it is still in one piece than letting it throw itself to pieces.

As someone else said, forget manually trying to close a rack held open by hydraulic pressure, you have zero chance.

Also, replace all your fuel shut off valves, especially if you have gate valves, with ball types, though this won't help much on a lister as it is so frugal on fuel

If you are quick enough, a small hand axe or heavy hammer to the injection pipe to fracture it, injection pipes are cheap. Only works if you have a stanley hatched permanently clamped near the motor and never ever removed for any reason.

ROTATING MACHINERY - those flywheels will literally tear you limb from limb, make sure none of your plans involve you going anywhere near them when you are in a state of panic.

Heat, potential runaways, even when caught as our deliberate ones were, generate one hell of a lot of heat, you start that engine again and everything is red hot and giving off fumes and just dying to run away again.

AFTER - YMMV, but if I have anything to do with it a through strip happens next and I discover why it happened then fix it, then check EVERYTHING for any damage done, bolts loosenes, or tolerances shifted.

Listeroid dudes, trust your castings less than I trust my 55 year old Uk castings, particularly when it comes to things like flywheel bursting force....

Might not be appropriate, might not be useful, but, folks I knew who were racing used to paint their highly stressed bits in the hardest and most brittle enamel paints they could find, the paint cracking was an early visual clue.

Wheeltappers used to do just that to loco and railway wheels, cracked, porous and damaged wheels didn't sound the same as sound ones, those flywheels will speak to you and after a couple of months of daily tapping you'll learn that sound

Use your ears and your eyes, this is no good to non and ex smokers, but at various stages of a job we would always sit down, look at the job (or the machine running) and smoke a leisurely cigarette, can't tell you how many times I caught a mistake that way.

Onan generators sucked ( JIC threads suck too IMHO), while big cats with gleaming black paint and show chrome covers looked the dogs bollocks, but that white onan paint job was a godsend for spotting problems.... dark green lister isn't the best colour on the planet, when mine is re-done it will be a light blue...

and finally esther

run aways and near misses are god's way of telling you your maintenance sucked big time, don't bank on getting a second warning.

------------------------------------

which kinds reminds me of an old chief engineers ticket question

Q What steps do you take when the main steam line fractures?

A Fucking big ones, up the companionway ladder. (out of the engine room)
--
Original Lister CS 6/1 Start-o-matic 2.5 Kw (radiator conversion)
3Kw 130 VDC Dynamo to be added. (compressor + hyd pump)
Original Lister D, megasquirt multifuel project, compressor and truck alternator.
Current status - project / standby, Fuel, good old pump diesel.

Joe

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Re: "Run away" diesels
« Reply #1 on: February 09, 2006, 07:02:53 PM »
Guy,
Thanks for the detailed info...I'll have to work on an intake shut-off of some type...I can't seem to find my leather cricket ball at he moment.... :)

Joe
Nothing is easy...if it were...anybody could do it.

2005 Power Solutions  6/1-ST5

Tom

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Re: "Run away" diesels
« Reply #2 on: February 09, 2006, 07:15:21 PM »
Hi Guy,

Instead of doing all that heavy duty work to the intake manifold to stop a runaway, why not just rig up a spring loaded latch to hold the exhaust valve open? Tie a string to it and there you go.
Tom
2004 Ashwamegh 6/1 #217 - ST5 just over 3k hours.

GuyFawkes

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Re: "Run away" diesels
« Reply #3 on: February 09, 2006, 07:18:25 PM »
it was kind of a general run away thing rather than lister specific, but I still prefer sealing the intake and depriving the engine of oxygen to hoping the exhaust valve stays open and deprives it of compression
--
Original Lister CS 6/1 Start-o-matic 2.5 Kw (radiator conversion)
3Kw 130 VDC Dynamo to be added. (compressor + hyd pump)
Original Lister D, megasquirt multifuel project, compressor and truck alternator.
Current status - project / standby, Fuel, good old pump diesel.

SHIPCHIEF

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Re: "Run away" diesels
« Reply #4 on: February 10, 2006, 03:29:29 AM »
BruceM has been running a thread on shutdowns. He uses a combination of battery voltage and compressed air. As a retired electrical engineer, I anticipate he will gin up a simple and elegant control computer. :)
I fully support safety devices. Listeroids DON'T HAVE ANY.

Scott E
Ashwamegh 25/2 & ST12
Lister SR2 10Kw 'Long Edurance' genset on a 10 gallon sump/skid,
Onan 6.5NH in an old Jeager Compressor trailer and a few CCK's

kpgv

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Re: "Run away" diesels
« Reply #5 on: February 10, 2006, 07:03:33 AM »
Hi All,
This is Great Stuff!!!
Regarding stopping and/or preventing a "runaway", I am very interested to hear ideas of causes, and proposed solutions.
I am pretty sure that a fire hose, or a hand-full of ball bearings will stop one of these, BUT those seem like things one might do IF they haven't worked the problem in ADVANCE, and they just don't have the energy or good sense to clear out. Is "Wrecking" it that much better than it "Wrecking" itself? :o
I like the "Air starvation" flapper, and the exhaust valve "open" compression release.
I have been thinking about another method to stop one of these.
I'm thinking of putting a disc brake on the crankshaft. A disc/caliper combination from a pickup with a master cylinder energized with a "reverse air" actuator (like the Westinghouse "air brakes" the railroads use) which can be remotely and/or automatically applied in a very tame and non-destructive manner. A 2" steel shaft will easily carry 50 BHP in torsion, and if you work out a gradual method to apply the "brake", there shouldn't be any damage, and I am certain that this method WILL stop the engine regardless of fuel, air, whatever.
The other question is what the "definition" (quantitative) of "over speed" is, to apply this, or any emergency shutdown/stopping mechanism or device.
The better the governor tracks, the closer you can cut it and catch a runaway before it gets hairy. It'll be a personal decision based on the individual machine and application.

Kevin

sid

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Re: "Run away" diesels
« Reply #6 on: February 10, 2006, 02:02:17 PM »
I have never tried it on a diesel but I have had good luck stopping a gas engine with freon//  of course most of the time it was my fault for letting the freon loose...on a diesel I think a co2 fire extinguisher would get rid of most of the oxygen//that takes away the bang //at least it should slow it down enough for you to run a safe distance away and watch the fire works from outside//  any comments????
15 hp fairbanks morris1932/1923 meadows mill
8 hp stover 1923
8 hp lg lister
1932 c.s bell hammer mill
4 hp witte 1917
5 hp des jardin 1926
3 hp mini petters
2hp hercules 1924
1 1/2 briggs.etc

GuyFawkes

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Re: "Run away" diesels
« Reply #7 on: February 10, 2006, 02:46:28 PM »
Hi All,
This is Great Stuff!!!
Regarding stopping and/or preventing a "runaway", I am very interested to hear ideas of causes, and proposed solutions.
I am pretty sure that a fire hose, or a hand-full of ball bearings will stop one of these, BUT those seem like things one might do IF they haven't worked the problem in ADVANCE, and they just don't have the energy or good sense to clear out. Is "Wrecking" it that much better than it "Wrecking" itself? :o
I like the "Air starvation" flapper, and the exhaust valve "open" compression release.
I have been thinking about another method to stop one of these.
I'm thinking of putting a disc brake on the crankshaft. A disc/caliper combination from a pickup with a master cylinder energized with a "reverse air" actuator (like the Westinghouse "air brakes" the railroads use) which can be remotely and/or automatically applied in a very tame and non-destructive manner. A 2" steel shaft will easily carry 50 BHP in torsion, and if you work out a gradual method to apply the "brake", there shouldn't be any damage, and I am certain that this method WILL stop the engine regardless of fuel, air, whatever.
The other question is what the "definition" (quantitative) of "over speed" is, to apply this, or any emergency shutdown/stopping mechanism or device.
The better the governor tracks, the closer you can cut it and catch a runaway before it gets hairy. It'll be a personal decision based on the individual machine and application.

Kevin

Runaway is always excess, eg unmetered, fuel, where "fuel" = "anything she is hot enough to burn" and NOT "just diesel fuel"

the ONLY two (non destructive)  ways to stop a runaway are cut the "fuel" (see above) supply, and / or cut the oxygen supply

the mega disk brake idea I don't trust, this ain't like stalling a car in top gear, this is like trying to stall the car in top gear AFTER it has already exceeded the top speed it ever did and the revcounter and speedo are both bouncing against the stops, anyone who thinks their brakes will stand up to that has never gone production vehicle racing, by the 3rd or 4th corner your production brakes have faded badly, by the end of the first lap they are near gone.

wrecking it internally is preferable to it wrecking itself only if you have no humans livestock or property within 100 yards IMHO

governor has practically nothing to do with a runaway, unless perhaps the rack is manually jammed wide open, which even then will prolly only over rev, but still within safety limits for short periods of time < 60 seconds

I have NEVER seen a runaway as a result of metered fuel through a governor except on things like detroits, which happened when the control arms on the 4 banks (16v71 motor, 2 blowers and 4 turbos) were mixed up....) with the two following caveats

1/ shitty engine designs with injector and return lines hidden inside the rocker cover deciding to take a leak

2/ the excess revolutions causing extra lube oil heating and in an already worn motor with worn rings and worn guides

As far as overspeed goes

Lister CS is a CONTINUOUS duty engine, things like car engines are not, so when rating them for continuous duty you need to drop the RPM by 15%

My original 5/1 Lister CS is 650 rpm, I'm personally not happy with the higher rpm versions out there, bhp is simply a function of rpm which is why you get 600 cc japanese motorcycle engines rated at higher bhp that 8 cylinder gardner diesels pulling 40 ton trucks.

Say what you want, the CS design was never designed for 800+ rpm, too much reciprocating mass IMHO, if you want a 1000 rpm motor go and buy one....

So, back to the plot.

__IF__ you are talking about a 650 rpm lister, I'd treat 800 rpm as an absolute maximum intermittent peak rpm, and 900 as a "strip the bastard down and check EVERYTHING before even considreing restarting it" rpm, and I'd set my auto intake valve to trip at 750, esp for a generator.

------------------------

Those of you who have stripped one KNOW how heavy the rods and so on are, and they are going up and down very fast (work out peak piston speeds some time) but what people often fail to realise is doubling the rpm quadruples the forces, trebling the rpm is nine times the forces.....

I have NO DATA of any kind on a 5/1 destruct rpm, but considering human rated elevators have only a factor of eight safety factor I'd assume it was lower than that, and guess somewhere in the region of 1750 rpm for a sorted engine, and 1500 for a worn one, and lower than that for a clone.

-----------------------

either way, +100 rpm is more than enough for a "last ditch" automatic non disengageable and non-over-rideable guaranteed to work mechanical shutdown system.

The IDEAL shutdown system would be one activated by the increased air flow in the inlet literally sucking a robust and well sealing valve shut

One thing I do know is when she starts revving it's too late to start planning, and for those confused by it all a hand held hatchet mounted on the engine bearers somewhere in quick release style and taken to the injection pressure lines pronto is a cheap solution, chop, see it's a clean cut and not a mere crack, drop hatchet and run, don't stand there looking at it.
--
Original Lister CS 6/1 Start-o-matic 2.5 Kw (radiator conversion)
3Kw 130 VDC Dynamo to be added. (compressor + hyd pump)
Original Lister D, megasquirt multifuel project, compressor and truck alternator.
Current status - project / standby, Fuel, good old pump diesel.

kpgv

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Re: "Run away" diesels
« Reply #8 on: February 10, 2006, 09:01:08 PM »
Hi Guy and List,
I ran across this in "Mc Master-Carr":

Bronze Ball Valves with Spring-Return Handle 
 • Maximum Pressure:
  W.O.G. (water, oil, inert gas): 600 psi @ 100° F
  W.S.P. (working steam pressure):
  150 psi @ 365° F
• Vacuum Rating: 29" Hg
• Temperature Range: -20° to +450° F
• Ports:  1/4" to  1/2": Full;  3/4" to 2": Standard 
       These valves automatically close when the spring-return ("deadman") handle is released. Body is bronze, ball is chrome-plated brass, stem is blowout-proof Type 316 stainless steel, seats and packing are carbon/graphite-filled PTFE, and body seal is PTFE. Handle is Type 300 series stainless steel with a vinyl grip.
     Connections: NPT female. 
Pipe  End-to-   
Size  End Lg.  Each   
 
 1/4" 2 1/4"  4171K21  $59.36 
 
 3/8" 2 1/4"  4171K22    59.36 
 
 1/2" 2 1/4"  4171K23    59.36 
 
 3/4" 3"  4171K24    66.48 
 
 Pipe  End-to-   
Size  End Lg.  Each   
 
1" 3 3/8"  4171K25  $70.99 
 
1 1/4" 4"  4171K26    91.77 
 
1 1/2" 4 3/8"  4171K27  109.17   ;D ???
 
2" 4 11/16"  4171K28  128.45     ;D ???

I was thinking one of these in the inlet pipe with the handle held open by a quick release tied to your "shutdown" sensor/trigger system might do the job without a big fab job. ???

Kevin
 
 
« Last Edit: February 10, 2006, 09:39:52 PM by kpgv »

BruceM

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Re: "Run away" diesels
« Reply #9 on: February 10, 2006, 10:48:06 PM »
This has been a very helpful thread for me, thanks Guy, Scott, Kevin, Sid, Tom.  (Sorry if I missed someone.)

Tom's suggestion of decompressing the exhaust valve for an overspeed shut down is very appealing to me, since I plan to automate the decompression via a small air cylinder, and so this safety feature could be essentially "free".

Sequence/Logic  something like:  IF overspeed sence (700 rpm?) OR vibration switch THEN  shut down fuel rack actuato(fixed delay of 60 seconds) AND activate decompression valve (fixed delay 60 seconds).
An electronic tachometer integrating time between spokes should pick up the rpm excess in less than 1/3 of a revolution. I just have to see how much the difference there is for the one "fast" spoke every other cycle. No harm done doing and overspeed shutdown for a wandering governor adjustment.

Robbing the 6/1 engine of compression seems a pretty reliable "shut-her-down" to me.  Am I missing the boat? 

Bruce M


sid

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Re: "Run away" diesels
« Reply #10 on: February 10, 2006, 11:15:36 PM »
just  some extra input.. on a run away ..you will not have 60 seconds../also on that 3.5 mini petter. believe it or not that thing will keep running away with the decompression lever open///I know // but I have been there// I did not believe either..and i do not know how.. i was too scared to make checks on why/ I know you need the squeeze to get the bang but that thing proved me wrong// if it ever happen to you  i can promise you will have to change  your underwear// have fun//sid
15 hp fairbanks morris1932/1923 meadows mill
8 hp stover 1923
8 hp lg lister
1932 c.s bell hammer mill
4 hp witte 1917
5 hp des jardin 1926
3 hp mini petters
2hp hercules 1924
1 1/2 briggs.etc

GuyFawkes

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Re: "Run away" diesels
« Reply #11 on: February 10, 2006, 11:48:23 PM »

Robbing the 6/1 engine of compression seems a pretty reliable "shut-her-down" to me.  Am I missing the boat? 

Bruce M



runaway is excess "fuel" plus oxygen, I dislike the decompression idea because you are not cutting off either fuel or oxygen.

fuel is often impossible to cut off if it is bypassing guides or rings, so the only thing you can shut off is oxygen
--
Original Lister CS 6/1 Start-o-matic 2.5 Kw (radiator conversion)
3Kw 130 VDC Dynamo to be added. (compressor + hyd pump)
Original Lister D, megasquirt multifuel project, compressor and truck alternator.
Current status - project / standby, Fuel, good old pump diesel.

BruceM

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Re: "Run away" diesels
« Reply #12 on: February 11, 2006, 02:22:48 AM »
Guy, I don't understand how the engine can continue to run with no compression.  Even with ample fuel and air.

It's not normally done, but what's the technical downside?

Sid, the 60 seconds delay while holding the rack closed and the exhaust valve open would be to allow for the engine to spin to a stop, not delay before shutdown.  That should begin in a fraction of a second of overspeed being sensed. 




SHIPCHIEF

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Re: "Run away" diesels
« Reply #13 on: February 11, 2006, 03:33:24 AM »
I have strangled a Lister and it still ran! :-X I threaded a pipe plug into the intake!
It was an air cooled single that had been around the block a few times, so I presumed it got enough air to keep running by pulling it up past the rings!
On the other hand, it did slow down 8) So I guess it wouldn't overspeed.
Scott E
Ashwamegh 25/2 & ST12
Lister SR2 10Kw 'Long Edurance' genset on a 10 gallon sump/skid,
Onan 6.5NH in an old Jeager Compressor trailer and a few CCK's

BruceM

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Re: "Run away" diesels
« Reply #14 on: February 11, 2006, 05:45:42 AM »
There you go, Shipchief.  You should have decompressed- and you were the one who suggested it in my auto shutdown thread.  :)

So much for the sanctity of air cut off.

I've got the decompression via pneumo piston about half built this afternoon.  I needed some Lister therapy after "interfacing" with an incompetent power co. RFI investigator (while wearing my community service hat representing two different disabled folks).  Yesterday I "learned" that a non electric barbed wire steel T post fence under the power line was the problem, not the power company,  because when he held his low frequency broad band sniffer near the fence wire it was noisey.  Guess you'd have to be an EE with an EMC background to realize how stupid this was.  I had to put up with 5 hours of this blowhard, and I was wiped out and a wreck today.