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Engineman1
 
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Default stopping a diesel

I wrote:
A friend just bought a yacht with twin Hino diesels. They are started by a key
switch but when they you want to shut them off you have to press a stop button
until the engines quit, then turn the keys off. I don't have much experience
with diesels but years ago when I had a job repairing forklifts I ran into a
similar situation. This seems to me to be unnecessarily complicated. After all,
most diesel powered cars turn on and off with a key switch. I have asked many
people this question but have gotten answers that didn't seem plausible. So now
I'm asking the experts. Thoughts?

Some of the replys I got:

Some diesels have a normally open fuel solenoid in the injection pump. You
need to apply power to the solenoids to stop the flow of fuel. The shut down
may be a solenoid the pushed the injection rack to a position that causes the
pump to stop delivering fuel. Either way you need a few seconds of power
applied to the kill wire. Simplest, least problematic it a plain old normally
open push button. One nice feature of a shut down like this is the engine does
not need any electrical power to run, once it is running it will go 'till it
runs out of fuel or is intentionally shut down. It increases the dependability
somewhat by not needing power to run.

This is, to me, a hazard. I ran turbocharged diesel alternators in the army.
50kw 3 phase 230 volts. one of them had lost it's electronic control panel
before I arrived, and the starting method was to tie the fuel solenoid up with
some wire then bridge the terminals on the starter with the cap from an
antitank mine. started up every time.

What this tells me is that it occurred often enough for a "most effective
way" to be discovered. :-) I'm glad it worked in the Navy. When I was in the
Army, I heard of a runaway deuce and a half engine. The mechanic took off his
field jacket and threw it over the intake. The engine ate the jacket buttons,
zipper and all. Diesels do not have any air controls. Power level of the engine
is determined by the amount of fuel entering the engine. The governors of these
engines have a throttle control and a fuel cutoff lever. The cutoff lever can
be electric or manual, your choice. Many engine manufacturers have emergency
air shutoff valves as an option, which are very important. Diesels will run
quite happily on their own lube oil. I would not own a diesel without one. A
runaway is a virtual bomb. Wait until that diesel runs away by consuming it's
own lube oil. You have never been really frightened until you share a bilge
with this engine.

Modern diesel automobiles that I have encountered (and, indeed, modern
tractors and whatnot) have fuel solenoids that shut off the flow of diesel to
stop the vehicle when you shut the key off. A mechanical diesel (as opposed to
an electronic-injection diesel) will run as long as it has fuel, unless
something makes it stop. Every diesel will have a kill-switch under the hood in
case you lose electrical power - without power you can't move the solenoid to
shut off the fuel. If the solenoid is sprung then you might have a situation
where without power the spring returns the solenoid and the fuel shuts off.
That, to me, is not a good thing. I've made it home in my old diesel truck with
a frozen battery and without enough power to run the turning indicators or
anything else, but the engine ran fine to get me home. If it had have stopped
dead somewhere I would have not been amused. A diesel of an older design may
not have a solenoid but rather a spring-return lever that acts both as the
emergency kill switch and the usual method of stopping the engine via a
cable-pull from the operator's position. In the case of these Hinos, if they're
similar to the Hinos that I have dealt with, they will be mechanically injected
and definitely of the 'run until they're out of fuel' variety, so they have to
be stopped manually. I haven't yet seen a Hino with a compression release, so I
would strongly suspect that the button you're pushing is attached to a solenoid
that pushes against a spring-return lever on the injector pump to kill the
engine. The old Mercedes 240's & 300's start and stop with the ignition key but
"off" is not electric. The key off position closes a vacuum valve that is part
of the switch assembly, connected by hose to a diaphram-actuated fuel shutoff
on the injection pump. So it is not dependent on the electrical system but if
there is a major vacuum leak, in addition to the door and gas cap locks and I
forget what else stops working, there is a red shutoff lever under the hood.
Wait until that diesel runs away by consuming it's own lube oil. You have never
been really frightened until you share a bilge with this event. The diesel I
have shuts down by cutting off the fuel flow to the injectors. There is a
solenoid that, when energized, retracts and lets the fuel cutoff level move to
the run position. When de-energized the same solenoid moves the fuel level to
the stop position and holds it there. Works nice. For emergency shutdown use a
board over the air intake.

I appreciated the explanations and stories and I'm not criticizing anyone but I
still don't have a definite answer. I liked the jacket story best. A solenoid
controlled shutoff makes the engine independant of the electrical system.(for
shutoff at least) but some engines die hard. Since there doesn't seem to be any
hard and fast reason for a separate shutoff button, I am thinking of converting
my friend's boat to keyswitch start and stop for safety reasons,.
He's technologically impaired (he had a VCR for 2 years before I pointed out
to him that it was one of those that can't be programmed-he was surprised when
he found out that he could push the scan button on his car radio to find
stations automatically and he has a cellphone but carries phone no's on a piece
of paper.
I'm thinking of bypassing the stop button with a normally closed relay which
when the keyswitch is turned on will open and release the solenoid which is
stopping the fuel supply. When the key is turned off the solenoid will be
energised and cut off the fuel. Since we don't want to run the batteries dead
over a long period we'd have a time delay relay to cut off the power to the
solenoid and itself after say, 5 minutes. This I hope is a simple method of
accomplishing this purpose with easily obtained materials and not having to
make major changes to the system, or is there a loophole in ny logic?
Engineman1



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Eric R Snow
 
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Default stopping a diesel

SNIP
He's technologically impaired (he had a VCR for 2 years before I pointed out
to him that it was one of those that can't be programmed-he was surprised when
he found out that he could push the scan button on his car radio to find
stations automatically and he has a cellphone but carries phone no's on a piece
of paper.
I'm thinking of bypassing the stop button with a normally closed relay which
when the keyswitch is turned on will open and release the solenoid which is
stopping the fuel supply. When the key is turned off the solenoid will be
energised and cut off the fuel. Since we don't want to run the batteries dead
over a long period we'd have a time delay relay to cut off the power to the
solenoid and itself after say, 5 minutes. This I hope is a simple method of
accomplishing this purpose with easily obtained materials and not having to
make major changes to the system, or is there a loophole in ny logic?
Engineman1


Not to be flippant, but since he carries phone numbers on a piece of
paper maybe the best solution would be to print the start and shutoff
instructions on a card, laminate it, and post it above the ignition
switch. Even better, engrave it on a piece of brass or that laminated
plastic used for name plates. It seems that he would understand this
better and anybody who is competent to service the boat won't find
anything unusual when it needs to be serviced away from home.
ERS
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Jon Elson
 
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Default stopping a diesel



Engineman1 wrote:

I'm thinking of bypassing the stop button with a normally closed relay which
when the keyswitch is turned on will open and release the solenoid which is
stopping the fuel supply. When the key is turned off the solenoid will be
energised and cut off the fuel. Since we don't want to run the batteries dead
over a long period we'd have a time delay relay to cut off the power to the
solenoid and itself after say, 5 minutes.

This may burn out the solenoid, and you won't be able to shut it off
except by
the manual override. Why on earth do you need 5 minutes for a Diesel to
stop
turning? It should stop in 5 seconds, easily! Maybe set the time delay
for 10 seconds
or so.

This I hope is a simple method of
accomplishing this purpose with easily obtained materials and not having to
make major changes to the system, or is there a loophole in ny logic?


Well, yes. If the solenoid needs to be activated AFTER the key is off,
then the
timer needs to be powered all the time. So, the TIMER will run the
battery down.
That will take longer that the solenoid would, but in a couple of days
the battery
will be dead. Hmm, I suppose there could be some relay arrangement that
would
keep the timer powered on until it was done, then turn it off, also.

Jon

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Greg O
 
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Default stopping a diesel


"Gary Coffman" wrote in message
...

Sounds to me like you're just adding complications, ie more things that
can go wrong.

Gary


I agree!
What ever happened to KISS - Keep It Simple Stupid!
Greg




  #6   Report Post  
Old Nick
 
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Default stopping a diesel

On 25 Sep 2003 06:01:35 GMT, (Engineman1) wrote
something
.......and in reply I say!:

AFAICS In the event of an electrical failure, you have a fail to
unsafe mode setup. The fuel can still flow.

It's interesting that people have described both types of solenoid. I
reckon I would rather one that failed to dead engine than one where I
could not stop the engine. Once an engine has stopped, then I can work
out hos to get fuel back. I suppose in a boat, heading through a reef
passage, this may be different. But there are the odd few other
thikngs that could stop the engine as well,,,,

I'm thinking of bypassing the stop button with a normally closed relay which
when the keyswitch is turned on will open and release the solenoid which is
stopping the fuel supply. When the key is turned off the solenoid will be
energised and cut off the fuel. Since we don't want to run the batteries dead
over a long period we'd have a time delay relay to cut off the power to the
solenoid and itself after say, 5 minutes. This I hope is a simple method of
accomplishing this purpose with easily obtained materials and not having to
make major changes to the system, or is there a loophole in ny logic?
Engineman1



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The rest sit around and make snide comments.

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  #7   Report Post  
Rick
 
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Default stopping a diesel

Engineman1 wrote:

...is there a loophole in ny logic?


Do you know if the fuel solenoid is engergized to run or to stop?

Rick


  #8   Report Post  
Engineman1
 
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Default stopping a diesel

In article , Rick
writes:

Do you know if the fuel solenoid is engergized to run or to stop?

Rick


The solenoid has to be energized to stop the engine.

I may not do anything to my friend's boat but just as an exercise in elementary
circuit logic I'm using Turbocad and trying to design the simplest circuit to
allow an engine to be controlled entirely by the key switch.
My parameters a no modifications to the fuel injector or engine, no solid
state components, IE no 555 chips, nand gates, and gates ETC. I'd like my
device to be just an add on, keeping the kill button active and using the
existing key switch.
My circuit would consist of dpdt relays and time delay relays. Since the boat
may not be used for a month or more at a time, the system cannot have any
devices which would drain the battery during nonuse without any extra switches
to turn off. So far this last requirement has been my biggest hurdle.

I wrote:

A friend just bought a yacht with twin Hino diesels. They are started by a key
switch but when they you want to shut them off you have to press a stop button
until the engines quit, then turn the keys off. I don't have much experience
with diesels but years ago when I had a job repairing forklifts I ran into a
similar situation. This seems to me to be unnecessarily complicated. After all,
most diesel powered cars turn on and off with a key switch. I have asked many
people this question but have gotten answers that didn't seem plausible. So now
I'm asking the experts. Thoughts?

On 25 Sep 2003 06:01:35 GMT, (Engineman1) wrote:
I'm thinking of bypassing the stop button with a normally closed relay which
when the keyswitch is turned on will open and release the solenoid which is
stopping the fuel supply. When the key is turned off the solenoid will be
energised and cut off the fuel. Since we don't want to run the batteries dead
over a long period we'd have a time delay relay to cut off the power to the
solenoid and itself after say, 5 minutes. This I hope is a simple method of
accomplishing this purpose with easily obtained materials and not having to
make major changes to the system, or is there a loophole in ny logic?
Engineman1


Sounds to me like you're just adding complications, ie more things that

can go wrong.

Gary





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DoN. Nichols
 
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Default stopping a diesel

In article ,
Engineman1 wrote:
In article , Rick
writes:

Do you know if the fuel solenoid is engergized to run or to stop?

Rick


The solenoid has to be energized to stop the engine.

I may not do anything to my friend's boat but just as an exercise in elementary
circuit logic I'm using Turbocad and trying to design the simplest circuit to
allow an engine to be controlled entirely by the key switch.
My parameters a no modifications to the fuel injector or engine, no solid
state components, IE no 555 chips, nand gates, and gates ETC. I'd like my
device to be just an add on, keeping the kill button active and using the
existing key switch.
My circuit would consist of dpdt relays and time delay relays. Since the boat
may not be used for a month or more at a time, the system cannot have any
devices which would drain the battery during nonuse without any extra switches
to turn off. So far this last requirement has been my biggest hurdle.


Hmm ... I would opt for a solenoid which had to be energized to
allow fuel to reach the engine. I'm presuming that when the engine is
running, there is a generator to keep the batteries charged. Under
those circumstances, the relay and solenoid power consumption is less of
a problem.

Turning on the key should pull in the solenoid valve (with or
without the help of a relay, depending on how much current the solenoid
valve happens to draw.

Anything with a time delay relay to turn off the fuel with a
apply-power-to-shut-off solenoid valve would either need a continuous
power drain for at least one relay, or a mechanically latching relay to
*hold* it off once the time delay is past. (There are old time delay
relays which operate with a heater and a bi-metalic strip in a vacuum
envelope if you *absolutely* want to avoid solid-state devices. But
they draw *lots8 more current than a well-designed solid-state timer.
If you want a minimum current way to operate the solenoid, I would go
for a power-to-fuel-flow solenoid, and a logic circuit (including
counter-timer) build around CMOS logic, which can draw *extremely* low
power at slow clock speeds -- except for the driver to a solid-state
relay, which is why the apply-power-to-flow option is preferred.

Of course -- there is the problem of making it survive the
electrical glitches which are often present in motor systems.

Good Luck,
DoN.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---
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Engineman1
 
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Default stopping a diesel

Subject: stopping a diesel
From: Engineman1
To: rec.crafts.metalworking
Date: 9/26/2003

In article , Rick
writes:

Do you know if the fuel solenoid is engergized to run or to stop?

Rick


The solenoid has to be energized to stop the engine.

I may not do anything to my friend's boat but just as an exercise in elementary
circuit logic I'm using Turbocad and trying to design the simplest circuit to
allow an engine to be controlled entirely by the key switch.
My parameters a no modifications to the fuel injector or engine, no solid
state components, IE no 555 chips, nand gates, and gates ETC. I'd like my
device to be just an add on, keeping the kill button active and using the
existing key switch.
My circuit would consist of dpdt relays and time delay relays. Since the boat
may not be used for a month or more at a time, the system cannot have any
devices which would drain the battery during nonuse without any extra switches
to turn off. So far this last requirement has been my biggest hurdle.

I wrote:

A friend just bought a yacht with twin Hino diesels. They are started by a key
switch but when they you want to shut them off you have to press a stop button
until the engines quit, then turn the keys off. I don't have much experience
with diesels but years ago when I had a job repairing forklifts I ran into a
similar situation. This seems to me to be unnecessarily complicated. After all,
most diesel powered cars turn on and off with a key switch. I have asked many
people this question but have gotten answers that didn't seem plausible. So now
I'm asking the experts. Thoughts?

On 25 Sep 2003 06:01:35 GMT, (Engineman1) wrote:
I'm thinking of bypassing the stop button with a normally closed relay which
when the keyswitch is turned on will open and release the solenoid which is
stopping the fuel supply. When the key is turned off the solenoid will be
energised and cut off the fuel. Since we don't want to run the batteries dead
over a long period we'd have a time delay relay to cut off the power to the
solenoid and itself after say, 5 minutes. This I hope is a simple method of
accomplishing this purpose with easily obtained materials and not having to
make major changes to the system, or is there a loophole in ny logic?
Engineman1


Sounds to me like you're just adding complications, ie more things that

can go wrong.

Gary



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jim rozen
 
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Default stopping a diesel

In article , Engineman1 says...

My circuit would consist of dpdt relays and time delay relays.


Ah, oops. Most of the present time delay relays (the
square white ones, with the black knob on top) are
solid state inside. They have semiconductors inside.
You have to go back to the older, all-glass tube type
time delay relays to achieve your goal then.

I think there's at least one member of the ng here
who would be first (second?) to point out that relays
and mechanical switches have a poorer fail rate in
the field than properly designed solid state circuitry.
Even more so for consumer grade, unsealed relays
that are pressed into service in marine applications.

If you want reliable, you need to be able to figure
out a way to do this without electricity. No solenoid.

Jim

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jim rozen
 
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Default stopping a diesel

In article , Gary Coffman says...

The key thing you want reliable here is for the boat's engine to *run*
until you tell it to stop. So it should be designed to passively run until
you actively tell it to stop.


This is how aircraft magneto ignitions work. The coil wire
gets grounded to kill the spark. If anything along the way
goes open, the motor keeps on running.

Jim

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jim rozen
 
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Default stopping a diesel

In article , Engineman1 says...

In article , jim rozen
writes:

I think there's at least one member of the ng here
who would be first (second?) to point out that relays
and mechanical switches have a poorer fail rate in
the field than properly designed solid state circuitry.
Even more so for consumer grade, unsealed relays
that are pressed into service in marine applications.


I have several motion detector out door light activators that have mechanical
relays, also it seems that most turnsignal flashers also have them.
Is Cu cheaper than Si?


The photocell controllers I use for my porch lights are all
solid state. I think at some point (above 5 or 10 amps)
the triac to control this current becomes more expensive
than a cheap relay to do the same thing.

My suspicion is that if you take apart a failed consumer
grade motion sensor light, that had a mechanical relay
in it, it's the relay that ultimatly failed. Because
consumer grade stuff cuts right to the profit margin,
they skimp on components. The difference in cost between
a one year MTBF relay, and a 20 year MTBF relay is a
lot.

For a marine application where lives might be at
stake, it makes sense to look at all the failure
modes and figure out a motor control setup that
does the utmost to keep the engine running when
it's needed. If that means using a manual shutdown
by the engine then that's still best.

Jim

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