When using my Kobalt CMS, I notice a large spark from the motor compartment
when I turn off the saw. Sometimes it looks like it fills the whole
compartment. Is this a sign the brushes need replaced?
Puckdropper
--
"The potential difference between the top and bottom of a tree is the
reason why all trees have to be grounded..." -- Bored Borg on
rec.woodworking
To email me directly, send a message to puckdropper (at) fastmail.fm
On Sun, 27 Sep 2009 17:10:33 -0500, "Leon" <[email protected]>
wrote:
>
>"krw" <[email protected]> wrote in message
>news:[email protected]...
>>
>> Nope. Not any more. The engine controls recycle fumes back to the
>> tank. Tanks have been sealed for decades.
>
>Yes the engine compartment does recycle fumes back to the tank but there is
>a lot of AIR that goes with it. Additionally there are lots of peole
>driving around with lost gas caps, check engine lights and all. And again,
>the tank is not sealed when you open it up to fill it with gas. There is
>just way too much of a chance of the perfect combination for the electric
>motor to set off an explosion if there was not a fool proof way to arrest
>the spark. How that is accomplished even the Olds factory rep could not
>explain when I was the service sales manager back in the 80's.
Nonsense. There is no air in there at all, even without a gas cap the
vapor pressure of the gas will push any out.
>>>
>>>But gasolinr does on a Gm electric fuel pump. My fuel pump in on my 1975
>>>Olds failed. I dropped the tank and replaced the pump, it is attached to
>>>the tank unit/gas gauge float assembly. I cut it open and the thing was
>>>spottless inside but the brushes were totally worn out. Gasoline went in
>>>one end of the motor and exited on the other. On one end of the motor was
>>>the plastic pump.
>>
>> Sure. No one was arguing that point. It's hardly dangerous.
>
>Obviousely but the simple explanation has not yet been explained to me.
Explanation for what?
"dpb" <[email protected]> wrote in message
news:[email protected]...
> Leon wrote:
>> "dpb" <[email protected]> wrote in message
>> news:[email protected]...
>>> While perhaps it is relatively common, it's still highly unlikely to be
>>> a problem. If there's enough fuel to crank and start the engine,
>>> there's enough to suppress the spark and have high enough vapor pressure
>>> to prevent flammability at any temperature above about -10F. Remember
>>> the flashpoint of gasoline is -40C (which iirc is the magic point
>>> where -40C=-40F???).
>>
>> The problem is though people run out of gas, people run over things on
>> the highway, Houston Freeways, that bounce up and puncture the bottoms of
>> the tanks. Tanks commonly run dry with the pump running.
>>
>>
>>
>>
>>> About the only time above about 0F one could get a real problem would be
>>> an essentially dry tank w/ residual vapor and run the pump dry. I'd
>>> think that if vehicles were so poor condition as to be left w/ empty
>>> tanks and no lid there would be little likelihood of them being cranked
>>> in any near-term time frame. Hence the evaporation over a period of
>>> time would likely imo serve to remove even the vapors.
>>
>> That is possible but GM has been using a fuel tank pump since the "early
>> 70's I worked directly and exclusively with GM vehicles for 17 years
>> and never ever heard of a problem. And I am not in doubt that what
>> works, "works" effectively. I was and still am curious as to exactly
>> what makes the set up "fool proof".
>
> I don't think it is totally fool-proof except that the conditions for
> flammability are much more limited than you think owing to the high vapor
> pressure that does, as another poster noted, keep positive pressure in the
> tank as long as there's any fuel surface at all.
>
> And, I'd venture that most of the cases you're talking about there's still
> a residual of fuel in the tank, only that it is below the pickup level.
>
> Added to that that the brushes are undoubtedly built to be non-arcing so
> that there really isn't a continuous ignition source, the conditions just
> aren't satisfied.
>
> --
That makes sense to me.
According to a table I have, for 100 octane gasoline vapor, when mixed with
air, the explosive (flammable) range is from 1.4% to 7.6%. vapor/air
mixture, - a condition which, as you say, would rarely be met.
"dpb" <[email protected]> wrote in message
news:[email protected]...
> Leon wrote:
> ...
>
>> If there is a hole in the bottom of the tank, it is absolutley below the
>> pick up level. ...
>
> But are the pumps mounted in a well? Are there not formed hollows/ridges
> for structural rigidity in the tanks? Even if it leaks to the point of
> not running, I'd expect there to be a little gas in almost all cases left
> in such areas. If the tanks were a perfect sphere and you punched a hole
> at the very bottom, all the liquid would run out, yes. But there still
> wouldn't be air intrusion in most cases, only almost pure vapor.
>
>>
>>> Added to that that the brushes are undoubtedly built to be non-arcing so
>>> that there really isn't a continuous ignition source, the conditions
>>> just aren't satisfied.
>>
>> That may be the case. Non arcing brushes and again the brushes were in a
>> strongly built contained steel enclosure behind a steel ball check ball.
>
> So, there's the design feature(s) you're after which are simply part of
> the design. I'm not saying the pumps are built w/ no thought of
> preventing an ignition source; only that I'm convinced there's no
> secondary protective device or system other than the base design and the
> physics of gasoline combustibility.
>
> --
It may also be that even when the fuel/air ratio conditions for combustion
are met, the arcing from the brushes may not provide a high enough
temperature to instigate ignition. (The article in the url below gives an
ignition temperature of 600F for gasoline vapor.)
http://tinyurl.com/yanzowk
"Leon" <[email protected]> wrote in message
news:[email protected]...
> Vapor literally does not exist with out air, vapor is simply difused
> matter suspended in air.
It might seem so, but that is not the case.
Gasoline vapor is heavier than air. With air given a vapor density of 1, the
vapor density of gasoline is between 3 and 4.
In an undisturbed tank, vented to the outside, as gasoline evaporates, the
vapor will displace the air.
In the case where all of the gasoline has been drained and air has entered
the tank, the remaining vapor will be concentrated at the bottom.
"LDosser" <[email protected]> wrote in message
news:[email protected]...
> "litteratuer" <takenonotice@all> wrote in message
> news:[email protected]...
>> "Leon" <[email protected]> wrote in message
>> news:[email protected]...
>>
>>> Vapor literally does not exist with out air, vapor is simply difused
>>> matter suspended in air.
>>
>> It might seem so, but that is not the case.
>>
>> Gasoline vapor is heavier than air. With air given a vapor density of 1,
>> the vapor density of gasoline is between 3 and 4.
>>
>> In an undisturbed tank, vented to the outside, as gasoline evaporates,
>> the vapor will displace the air.
>> In the case where all of the gasoline has been drained and air has
>> entered the tank, the remaining vapor will be concentrated at the bottom.
>>
>
>
> And some fool will try to weld the 'empty' tank ....
Sadly, it does happen.
Many years ago a young neighbor of mine was using an oxy-acetylene torch to
cut open a fuel tank which he had emptied some time beforehand and thought
was safe. It exploded, leaving him with serious permanent brain damage.
Friend of mine was working on a gas tank from a 1979 Ford Bronco washed
the gas tank out several times was trying to solder the tank and all of
a sudden there was a big bang what had happened the tank actually
expanded,he finished soldering it but we had a hellova time getting it
back onto the truck as it had expanded so much. Dan
On Sep 28, 8:38=A0am, "Leon" <[email protected]> wrote:
> "krw" <[email protected]> wrote in message
>
> news:[email protected]...
>
>
>
> > On Sun, 27 Sep 2009 17:10:33 -0500, "Leon" <[email protected]>
> > wrote:
>
> >>"krw" <[email protected]> wrote in message
> >>news:[email protected]...
>
> >>> Nope. Not any more. =A0The engine controls recycle fumes back to the
> >>> tank. =A0Tanks have been sealed for decades.
>
> >>Yes the engine compartment does recycle fumes back to the tank but ther=
e
> >>is
> >>a lot of AIR that goes with it. =A0Additionally there are lots of peole
> >>driving around with lost gas caps, check engine lights and all. =A0 And
> >>again,
> >>the tank is not sealed =A0when you open it up to fill it with gas. =A0T=
here is
> >>just way too much of a chance of the perfect combination for the electr=
ic
> >>motor to set off an explosion if there was not a fool proof way to arre=
st
> >>the spark. =A0How that is accomplished even the Olds factory rep could =
not
> >>explain when I was the service sales manager back in the 80's.
>
> > Nonsense. =A0There is no air in there at all, even without a gas cap th=
e
> > vapor pressure of the gas will push any out.
>
> Obviousely clueless.
Wrong again. Unlike you, I'm not guessing.
"litteratuer" <takenonotice@all> wrote in message
news:[email protected]...
>> --
>
> That makes sense to me.
>
> According to a table I have, for 100 octane gasoline vapor, when mixed
> with air, the explosive (flammable) range is from 1.4% to 7.6%.
> vapor/air mixture, - a condition which, as you say, would rarely be met.
And rarely is the event that I am talking about. Rarely does not equal
absolutley not, and with millions upon millions of these vehicled out there
you still don't hear of a problem. There has to be a stop gap safe guard
that takes care of those rare situations such as when there is an accident
with a ruptured tank and no explosion by fault of the fuel pump. There are
simply way too many conditions that can and do occour that would create the
right rare situation.
"dpb" <[email protected]> wrote in message
news:[email protected]...
>
> While perhaps it is relatively common, it's still highly unlikely to be a
> problem. If there's enough fuel to crank and start the engine, there's
> enough to suppress the spark and have high enough vapor pressure to
> prevent flammability at any temperature above about -10F. Remember the
> flashpoint of gasoline is -40C (which iirc is the magic point
> where -40C=-40F???).
The problem is though people run out of gas, people run over things on the
highway, Houston Freeways, that bounce up and puncture the bottoms of the
tanks. Tanks commonly run dry with the pump running.
>
> About the only time above about 0F one could get a real problem would be
> an essentially dry tank w/ residual vapor and run the pump dry. I'd think
> that if vehicles were so poor condition as to be left w/ empty tanks and
> no lid there would be little likelihood of them being cranked in any
> near-term time frame. Hence the evaporation over a period of time would
> likely imo serve to remove even the vapors.
That is possible but GM has been using a fuel tank pump since the "early
70's I worked directly and exclusively with GM vehicles for 17 years and
never ever heard of a problem. And I am not in doubt that what works,
"works" effectively. I was and still am curious as to exactly what makes
the set up "fool proof".
"dpb" <[email protected]> wrote in message
news:[email protected]...
Snip
>
> I will agree it _is_ something of a mental twist that the very volatility
> of gasoline is in fact the property that mitigates the fire hazard
> suppressant from the fuel pump when the tank is low (although I presume
> the pumps are mounted in a well or at least at the lowest point in the
> tanks in order to keep them submerged until absolutely all fuel that can
> be picked up has been. I suppose one could even raise the inlet pipe a
> little to ensure that; don't know if they do or not.)
>
> hth....
>
> -dpb
While the explanation is valid and works for 99.999% of the time my question
is about the other .0001 percent of the time. When the lost gas cap is
never replaced and the car is parked and sits for several months with little
fuel. Eventually some one cranks it up and the tank has little fuel to
submerge the pump.
And if you think that is not common, repositions of abandoned cars filled
the bill at the dealerships and many were often stripped.
Because the fuel pump is relatively tiny and totally enclosed, IIRC there
was a check ball valve on the inlet side, perhaps in some instances of a low
fuel condition there is an actual flash when the pump motor in energized,
but the flash is contained with in the motor casing. I do recall the motor
housing being rather substantial compared to most electric motors found on
automobiles.
Thanks for the time spent gathering the information.
"dpb" <[email protected]> wrote in message
news:[email protected]...
>
> I don't think it is totally fool-proof except that the conditions for
> flammability are much more limited than you think owing to the high vapor
> pressure that does, as another poster noted, keep positive pressure in the
> tank as long as there's any fuel surface at all.
Ok you and he are both missing the point. I realize that the with and
absence of air the possibility of an explosion is nil. I am specifically
looking at the situation where there is air present, ie. a rupture in the
tank where air absolutely will displace the gasoline that is leaking out.
We saw this all the time in the shop. Car died on the freeway, completely
empty tank.
> And, I'd venture that most of the cases you're talking about there's still
> a residual of fuel in the tank, only that it is below the pickup level.
If there is a hole in the bottom of the tank, it is absolutley below the
pick up level. Out of the millions of vehicles built with this
configuration you have to know that there will be a deviation that will
negate the situation that relies on the lack of air to prevent an explosion.
Because I have not ever heard of a tank explosion caused by an electronic
fuel pump I know that the system works under normal conditions but normal
conditions do not always exist.
>
> Added to that that the brushes are undoubtedly built to be non-arcing so
> that there really isn't a continuous ignition source, the conditions just
> aren't satisfied.
That may be the case. Non arcing brushes and again the brushes were in a
strongly built contained steel enclosure behind a steel ball check ball.
"dpb" <[email protected]> wrote in message
news:[email protected]...
> Leon wrote:
> ...
>
>> If there is a hole in the bottom of the tank, it is absolutley below the
>> pick up level. ...
>
> But are the pumps mounted in a well?
No. They are typically flat and generally tilt towards a low end of the tank
for all the gunk to collect at. The pump is suspended by the tank unit up
from that position. There are ridges for rigidity on some tanks but those
ridges generally run in a direction so as to drain to the low spot of the
tank and the low spot is typically the forward end facing towards the front
of the vehicle. This allows for more ground clearance under the back of the
vehicle. That area is also the most vulnerable and typically will be the
damaged/ruptured area when a driver drives over an obstacle.
Are there not formed
> hollows/ridges for structural rigidity in the tanks? Even if it leaks to
> the point of not running, I'd expect there to be a little gas in almost
> all cases left in such areas. If the tanks were a perfect sphere and you
> punched a hole at the very bottom, all the liquid would run out, yes. But
> there still wouldn't be air intrusion in most cases, only almost pure
> vapor.
I would say that a pint of fuel could collect, maybe depending ont he
damaged area but if the damage is located on the front bottom it is likely
very very little will remain. Keep in mind a puntcture on the bottom of the
tank will act exactly like a can of juice. Hold the juice can and poke a
hole in it from the bottom. Juice will come out and as it comes out air
will replace the leaking juice otherwise the fluid would not drain.
Gasiline works the same way.
>
>>
>>> Added to that that the brushes are undoubtedly built to be non-arcing so
>>> that there really isn't a continuous ignition source, the conditions
>>> just aren't satisfied.
>>
>> That may be the case. Non arcing brushes and again the brushes were in a
>> strongly built contained steel enclosure behind a steel ball check ball.
>
> So, there's the design feature(s) you're after which are simply part of
> the design. I'm not saying the pumps are built w/ no thought of
> preventing an ignition source; only that I'm convinced there's no
> secondary protective device or system other than the base design and the
> physics of gasoline combustibility.
Yeah I am sure there is a secondary back up measure there are countless
others in the fuel lines and in the old days the carburetors had
preventatice features to limit fuel flow.
Leon wrote:
> "krw" <[email protected]> wrote in message
> news:[email protected]...
...
>> ... There is no air in there at all, even without a gas cap the
>> vapor pressure of the gas will push any out.
>
> Obviousely clueless.
Not quite, no...not _exactly_ "none" wrt to air but the high vapor
pressure (very low flash point) of gasoline _is_ the key. To save
having to dig up the flammability and explosive mixture data, the most
cogent explanation I found on the web quickly was at a site discussing
the Flight 800 explosion that went on to compare the situation w/ jet A
and an airline tank and the fuel pump in automobile tank and gasoline.
From that site--
> Cars contain fuel pumps and wiring inside the fuel tanks - why
> don't they blow up more often?
>
> Gasoline tank vapor spaces are almost never flammable while Jet A
> tanks in airplanes will always pass through a flammable regime during
> normal flight operations.
>
> The ullage of gasoline fuel tanks in automobiles is almost always too
> rich to be flammable except at very low temperatures. This is due to the
> much lower flash point (about -40 C) of gasoline in comparison to Jet A.
> The vapor space in a partially-filled gasoline tank does not become
> flammable until the temperature has dropped below about 10F and a
> serious hazard will exist below 0 F down to about -40 F for a typical
> gasoline (Reid Vapor Pressure (RVP) of 9.5 psi, flammability limits
> between 1.4 and 7 % by volume). [See W.F. Marshall and G. A. Schoonveld,
> SAE Transactions, Vol. 99, No. 4, 594-617, 1990]
>
> For this reason, the probability that a fuel tank containing liquid
> gasoline has a flammable vapor space is extremely small in most climates
> except in the artic regions. The exception to this is when the tank is
> removed for servicing and the fuel is drained from the tank. Since
> gasoline has such a high vapor pressure, the tank can have a flammable
> vapor space even if there is no liquid fuel visible inside that tank.
> For example, the complete vaporization of about 1-2 tablespoons of
> gasoline will result in a flammable mixture inside a 15-gallon capacity
> automobile tank. This is the reason why welding on or near "empty" gas
> tanks is extremely hazardous and thorough purging of the tank with
> steam, carbon dioxide, nitrogen, or other inert gas is required before
> repair work is started.
>
> The in-tank fuel pumps in modern fuel-injected vehicles are designed
> to run submerged in fuel, as are the fuel pumps in aircraft, and the
> fuel circulates through the pump, including the sparking
> brush-commutator system. Unless the gasoline tank is almost
> completely emptied of fuel, this will not pose a hazard since there
> will be only fuel and not a fuel-air mixture within the pump. So in
> order for an in-tank fuel pump to pose an ignition hazard, the tank
> must be "run dry" under very cold conditions so that flammable vapor
> surrounds the commutator.
In short, the answer is that the high vapor pressure of gasoline does
create an atmosphere that is too rich for explosion even when the tank
is uncapped if there is any liquid fuel at all in the tank at anything
above very cold ambient temperature.
I will agree it _is_ something of a mental twist that the very
volatility of gasoline is in fact the property that mitigates the fire
hazard suppressant from the fuel pump when the tank is low (although I
presume the pumps are mounted in a well or at least at the lowest point
in the tanks in order to keep them submerged until absolutely all fuel
that can be picked up has been. I suppose one could even raise the
inlet pipe a little to ensure that; don't know if they do or not.)
hth....
-dpb
--
Leon wrote:
> "dpb" <[email protected]> wrote in message
> news:[email protected]...
> Snip
>
>> I will agree it _is_ something of a mental twist that the very volatility
>> of gasoline is in fact the property that mitigates the fire hazard
>> suppressant from the fuel pump when the tank is low (although I presume
>> the pumps are mounted in a well or at least at the lowest point in the
>> tanks in order to keep them submerged until absolutely all fuel that can
>> be picked up has been. I suppose one could even raise the inlet pipe a
>> little to ensure that; don't know if they do or not.)
>>
>> hth....
>>
>> -dpb
>
>
> While the explanation is valid and works for 99.999% of the time my question
> is about the other .0001 percent of the time. When the lost gas cap is
> never replaced and the car is parked and sits for several months with little
> fuel. Eventually some one cranks it up and the tank has little fuel to
> submerge the pump.
> And if you think that is not common, repositions of abandoned cars filled
> the bill at the dealerships and many were often stripped.
While perhaps it is relatively common, it's still highly unlikely to be
a problem. If there's enough fuel to crank and start the engine,
there's enough to suppress the spark and have high enough vapor pressure
to prevent flammability at any temperature above about -10F. Remember
the flashpoint of gasoline is -40C (which iirc is the magic point where
-40C=-40F???).
About the only time above about 0F one could get a real problem would be
an essentially dry tank w/ residual vapor and run the pump dry. I'd
think that if vehicles were so poor condition as to be left w/ empty
tanks and no lid there would be little likelihood of them being cranked
in any near-term time frame. Hence the evaporation over a period of
time would likely imo serve to remove even the vapors.
--
dpb wrote:
...
> While perhaps it is relatively common, it's still highly unlikely to be
> a problem. If there's enough fuel to crank and start the engine,
> there's enough to suppress the spark and have high enough vapor pressure
> to prevent flammability at any temperature above about -10F. Remember
> the flashpoint of gasoline is -40C (which iirc is the magic point where
> -40C=-40F???).
>
> About the only time above about 0F one could get a real problem would be
> an essentially dry tank w/ residual vapor and run the pump dry. I'd
> think that if vehicles were so poor condition as to be left w/ empty
> tanks and no lid there would be little likelihood of them being cranked
> in any near-term time frame. Hence the evaporation over a period of
> time would likely imo serve to remove even the vapors.
And if your contention is that it is _possible_ under specific
circumstances and there's no failsafe protection against that very
dilute vapor case that is in the flammability region then yes, it is
possible.
I hadn't actively thought about the Arctic conditions increasing risk, I
don't know if there's anything done for the really cold areas out of the
ordinary or not. I'd guess not; rely on folks in inclement weather
areas having enough sense to keep adequate fuel on hand I'd guess.
--
Leon wrote:
> "dpb" <[email protected]> wrote in message
> news:[email protected]...
>> While perhaps it is relatively common, it's still highly unlikely to be a
>> problem. If there's enough fuel to crank and start the engine, there's
>> enough to suppress the spark and have high enough vapor pressure to
>> prevent flammability at any temperature above about -10F. Remember the
>> flashpoint of gasoline is -40C (which iirc is the magic point
>> where -40C=-40F???).
>
> The problem is though people run out of gas, people run over things on the
> highway, Houston Freeways, that bounce up and puncture the bottoms of the
> tanks. Tanks commonly run dry with the pump running.
>
>
>
>
>> About the only time above about 0F one could get a real problem would be
>> an essentially dry tank w/ residual vapor and run the pump dry. I'd think
>> that if vehicles were so poor condition as to be left w/ empty tanks and
>> no lid there would be little likelihood of them being cranked in any
>> near-term time frame. Hence the evaporation over a period of time would
>> likely imo serve to remove even the vapors.
>
> That is possible but GM has been using a fuel tank pump since the "early
> 70's I worked directly and exclusively with GM vehicles for 17 years and
> never ever heard of a problem. And I am not in doubt that what works,
> "works" effectively. I was and still am curious as to exactly what makes
> the set up "fool proof".
I don't think it is totally fool-proof except that the conditions for
flammability are much more limited than you think owing to the high
vapor pressure that does, as another poster noted, keep positive
pressure in the tank as long as there's any fuel surface at all.
And, I'd venture that most of the cases you're talking about there's
still a residual of fuel in the tank, only that it is below the pickup
level.
Added to that that the brushes are undoubtedly built to be non-arcing so
that there really isn't a continuous ignition source, the conditions
just aren't satisfied.
--
Leon wrote:
> "litteratuer" <takenonotice@all> wrote in message
> news:[email protected]...
>>> --
>> That makes sense to me.
>>
>> According to a table I have, for 100 octane gasoline vapor, when mixed
>> with air, the explosive (flammable) range is from 1.4% to 7.6%.
>> vapor/air mixture, - a condition which, as you say, would rarely be met.
>
> And rarely is the event that I am talking about. Rarely does not equal
> absolutley not, and with millions upon millions of these vehicled out there
> you still don't hear of a problem. There has to be a stop gap safe guard
> that takes care of those rare situations such as when there is an accident
> with a ruptured tank and no explosion by fault of the fuel pump. There are
> simply way too many conditions that can and do occour that would create the
> right rare situation.
I don't think there's any evidence to support that hypothesis that the
conditions can be made right so easily as you suppose--in fact, I think
the evidence clearly demonstrates the opposite--that is, despite the
number of vehicles, the conditions under which the fuel pump is an
ignition source _and_ the tank vapors are in an explosive mixture state
is simultaneously, are, simply not events that occur with any frequency
at all.
Again, all these scenarios you've brought up simply don't lead to
nothing but a dilute air:vapor mix in just the right
proportions--there's still far to much fuel.
Again, I don't think it is impossible, only highly improbable.
--
--
Leon wrote:
...
> If there is a hole in the bottom of the tank, it is absolutley below the
> pick up level. ...
But are the pumps mounted in a well? Are there not formed
hollows/ridges for structural rigidity in the tanks? Even if it leaks
to the point of not running, I'd expect there to be a little gas in
almost all cases left in such areas. If the tanks were a perfect sphere
and you punched a hole at the very bottom, all the liquid would run out,
yes. But there still wouldn't be air intrusion in most cases, only
almost pure vapor.
>
>> Added to that that the brushes are undoubtedly built to be non-arcing so
>> that there really isn't a continuous ignition source, the conditions just
>> aren't satisfied.
>
> That may be the case. Non arcing brushes and again the brushes were in a
> strongly built contained steel enclosure behind a steel ball check ball.
So, there's the design feature(s) you're after which are simply part of
the design. I'm not saying the pumps are built w/ no thought of
preventing an ignition source; only that I'm convinced there's no
secondary protective device or system other than the base design and the
physics of gasoline combustibility.
--
Leon wrote:
> "dpb" <[email protected]> wrote in message
> news:[email protected]...
>> Again, I don't think it is impossible, only highly improbable.
>>
>
>
> Ok, and I'll end with this, I think. What keeps the improbable scenario
> from exploding? Those improbable scenario's actually do not explode.
They would. That the don't is indicative of just how improbable they
are (because they simply don't happen).
--
"litteratuer" <takenonotice@all> wrote in message
news:[email protected]...
> "Leon" <[email protected]> wrote in message
> news:[email protected]...
>
>> Vapor literally does not exist with out air, vapor is simply difused
>> matter suspended in air.
>
> It might seem so, but that is not the case.
>
> Gasoline vapor is heavier than air. With air given a vapor density of 1,
> the vapor density of gasoline is between 3 and 4.
>
> In an undisturbed tank, vented to the outside, as gasoline evaporates, the
> vapor will displace the air.
> In the case where all of the gasoline has been drained and air has entered
> the tank, the remaining vapor will be concentrated at the bottom.
>
And some fool will try to weld the 'empty' tank ....
dpb wrote:
> Leon wrote:
> ...
>
>> ... Vapor literally does not exist with out air, vapor is simply
>> difused matter suspended in air.
>
> Not necessarily--there are other gaseous materials other than O, N,
> etc., that are the constituents of air.
Or, more visible way to think of it, if were to start w/ a liquid in a
closed container w/ a movable wall and if retract that wall creating a
vacuum there will become a new equilibrium of two phases--liquid and
gas. The concentration will be dependent on the specific liquid.
There's no air needed...
--
"litteratuer" <takenonotice@all> wrote in message
news:[email protected]...
> "LDosser" <[email protected]> wrote in message
> news:[email protected]...
>> "litteratuer" <takenonotice@all> wrote in message
>> news:[email protected]...
>>> "Leon" <[email protected]> wrote in message
>>> news:[email protected]...
>>>
>>>> Vapor literally does not exist with out air, vapor is simply difused
>>>> matter suspended in air.
>>>
>>> It might seem so, but that is not the case.
>>>
>>> Gasoline vapor is heavier than air. With air given a vapor density of 1,
>>> the vapor density of gasoline is between 3 and 4.
>>>
>>> In an undisturbed tank, vented to the outside, as gasoline evaporates,
>>> the vapor will displace the air.
>>> In the case where all of the gasoline has been drained and air has
>>> entered the tank, the remaining vapor will be concentrated at the
>>> bottom.
>>>
>>
>>
>> And some fool will try to weld the 'empty' tank ....
>
>
> Sadly, it does happen.
>
> Many years ago a young neighbor of mine was using an oxy-acetylene torch
> to cut open a fuel tank which he had emptied some time beforehand and
> thought was safe. It exploded, leaving him with serious permanent brain
> damage.
How could anyone tell?
Sorry, that was thoughtless and cruel, but it's the mood I'm in at the
moment.
"litteratuer" <takenonotice@all> wrote in message
news:[email protected]...
> "dpb" <[email protected]> wrote in message
> news:[email protected]...
>> --
>
>
> It may also be that even when the fuel/air ratio conditions for combustion
> are met, the arcing from the brushes may not provide a high enough
> temperature to instigate ignition. (The article in the url below gives an
> ignition temperature of 600F for gasoline vapor.)
And there in lies the probable answer as a fowled spark plug will spark but
not necessarily ignite the fuel mixture. Gasoline running past the brushes
keeps every thing cooled down under normal operating conditions. And with
electrical wiring running into the fuel tanks even for the tank units to
measure the level of fuel you have to know that sooner or later there is
going to be a short and that does not seem to present a problem either.
that has veen a fact long before electric fuel pumps wer even being used.
There is absolutely air in the tank otherwise the tanks would colapse or
fuel would not exit. Fuel vapor may be too dense to burn unless the
conditions are right. Vapor literally does not exist with out air, vapor is
simply difused matter suspended in air.
Either way I believe your explanation that the spark in not hot enough is
the stop gap safety measure. That is indeed a constant vs air and vapor
conditions around the fuel pump.
>
> http://tinyurl.com/yanzowk
>
>
>
>
"krw" <[email protected]> wrote in message
news:[email protected]...
> On Sun, 27 Sep 2009 17:10:33 -0500, "Leon" <[email protected]>
> wrote:
>
>>
>>"krw" <[email protected]> wrote in message
>>news:[email protected]...
>>>
>>> Nope. Not any more. The engine controls recycle fumes back to the
>>> tank. Tanks have been sealed for decades.
>>
>>Yes the engine compartment does recycle fumes back to the tank but there
>>is
>>a lot of AIR that goes with it. Additionally there are lots of peole
>>driving around with lost gas caps, check engine lights and all. And
>>again,
>>the tank is not sealed when you open it up to fill it with gas. There is
>>just way too much of a chance of the perfect combination for the electric
>>motor to set off an explosion if there was not a fool proof way to arrest
>>the spark. How that is accomplished even the Olds factory rep could not
>>explain when I was the service sales manager back in the 80's.
>
> Nonsense. There is no air in there at all, even without a gas cap the
> vapor pressure of the gas will push any out.
Obviousely clueless.
"litteratuer" <takenonotice@all> wrote in message
news:[email protected]...
> "Leon" <[email protected]> wrote in message
> news:[email protected]...
>
>> Vapor literally does not exist with out air, vapor is simply difused
>> matter suspended in air.
>
> It might seem so, but that is not the case.
>
> Gasoline vapor is heavier than air. With air given a vapor density of 1,
> the vapor density of gasoline is between 3 and 4.
>
> In an undisturbed tank, vented to the outside, as gasoline evaporates, the
> vapor will displace the air.
> In the case where all of the gasoline has been drained and air has entered
> the tank, the remaining vapor will be concentrated at the bottom.
>
Disturbed, I suspect that a shaken tank would not qualify as undisturbed.
There is an awful lot of shoshing around going on in there when the vehicle
is moving and if there is a hole in the bottom of the tank from a damaging
impact the vapors will "grain out" after the fuel.
"dpb" <[email protected]> wrote in message
news:[email protected]...
>
> Again, I don't think it is impossible, only highly improbable.
>
Ok, and I'll end with this, I think. What keeps the improbable scenario
from exploding? Those improbable scenario's actually do not explode.
"Leon" <[email protected]> wrote in
news:[email protected]:
>
> "Puckdropper" <puckdropper(at)yahoo(dot)com> wrote in message
> news:[email protected]...
>> "Lew Hodgett" <[email protected]> wrote in news:001c03e2$0$24199
>> [email protected]:
>
>>>
>>
>> I took the brushes out, blew out the sawdust in the brush chambers
>> and put them back. The big spark is gone, and I think I picked up a
>> little missing speed.
>>
>> I'll have to add that to the occasional maintenance list. It only
>> takes about 2 minutes.
>
>
> I suspect that the fix will be short lived. I think you are trying to
> fix a normal condition.
I'll keep an eye on it. I expect some sparks (nature of the beast), but
this was a rather large one that filled the motor chamber. Now it only
does it when I let go of the switch before it's come up to speed. (I'm
curious now. If it starts again I'll have to put an ammeter on there,
take a few readings, then clean the brushes.)
Puckdropper
--
"The potential difference between the top and bottom of a tree is the
reason why all trees have to be grounded..." -- Bored Borg on
rec.woodworking
To email me directly, send a message to puckdropper (at) fastmail.fm
krw wrote:
>
> The water going through turbines is hardly pure. I doubt water
> touches the generator windings themselves.
I've toured the Robert Moses power generation station in Niagara Falls a
number of times. The turbines are at the bottom of the dam to take
advantage of the water's pressure. The generators are on the top floor
of the structure to facilitate installation/replacement. The two are
connected by a massive shafts. You're correct, the water (hopefully)
doen't come near the generators.
--
Jack Novak
Buffalo, NY - USA
[email protected]
"Lew Hodgett" <[email protected]> wrote in news:001c03e2$0$24199
[email protected]:
>
> "Puckdropper" wrote:
>
>> When using my Kobalt CMS, I notice a large spark from the motor
>> compartment
>> when I turn off the saw. Sometimes it looks like it fills the whole
>> compartment. Is this a sign the brushes need replaced?
>
> Good place to start.
>
> Might not be seated properly.
>
> Lew
>
I took the brushes out, blew out the sawdust in the brush chambers and
put them back. The big spark is gone, and I think I picked up a little
missing speed.
I'll have to add that to the occasional maintenance list. It only takes
about 2 minutes.
Puckdropper
--
"The potential difference between the top and bottom of a tree is the
reason why all trees have to be grounded..." -- Bored Borg on
rec.woodworking
To email me directly, send a message to puckdropper (at) fastmail.fm
"DanG" <[email protected]> wrote in news:5opvm.443888$Ta5.188839
@newsfe15.iad:
> Read your owner's manual. Is this a saw with electric brake?
>
The saw indeed has an electronic brake. If that's normal behavior, I'll
let it be.
Puckdropper
--
"The potential difference between the top and bottom of a tree is the
reason why all trees have to be grounded..." -- Bored Borg on
rec.woodworking
To email me directly, send a message to puckdropper (at) fastmail.fm
"Puckdropper" <puckdropper(at)yahoo(dot)com> wrote in message
news:[email protected]...
> When using my Kobalt CMS, I notice a large spark from the motor
> compartment
> when I turn off the saw. Sometimes it looks like it fills the whole
> compartment. Is this a sign the brushes need replaced?
>
> Puckdropper
> --
> "The potential difference between the top and bottom of a tree is the
> reason why all trees have to be grounded..." -- Bored Borg on
> rec.woodworking
>
> To email me directly, send a message to puckdropper (at) fastmail.fm
Sounds like a normal condition when an electronic brake in engaged.
"-MIKE-" <[email protected]> wrote in message
news:[email protected]...
No, gas tanks do
>> not always have gasoline in them so being constantly submerged is not the
>> answer.
>
> I'm guessing the pump was low enough as to always be submerged, even when
> the tank was "empty?"
Nope, mentioned that above, of millions each year built this way there had
to be a few thousand that went with out caps and the gas evaporated.
>
> Reminds me of the Mythbusters episode in which they *could not* get a
> gasoline trail to ignite with a burning cigarette, like you see in the
> movies.
> Apparently, smoldering tobacco embers are not hot enough to ignite
> gasoline vapors.
>
> Another interesting fact from my electrical engineer friend who works
> for a huge electric producer...
> Those giant electric turbine generators are cooled with direct water
> immersion. Turns out pure H2O doesn't conduct electricity. It's all the
> minerals and other stuff in water that does.
>
>
> --
>
> -MIKE-
>
> "Playing is not something I do at night, it's my function in life"
> --Elvin Jones (1927-2004)
> --
> http://mikedrums.com
> [email protected]
> ---remove "DOT" ^^^^ to reply
Read your owner's manual. Is this a saw with electric brake?
--
______________________________
Keep the whole world singing . . . .
DanG (remove the sevens)
[email protected]
"Puckdropper" <puckdropper(at)yahoo(dot)com> wrote in message
news:[email protected]...
> When using my Kobalt CMS, I notice a large spark from the motor
> compartment
> when I turn off the saw. Sometimes it looks like it fills the
> whole
> compartment. Is this a sign the brushes need replaced?
>
> Puckdropper
> --
> "The potential difference between the top and bottom of a tree
> is the
> reason why all trees have to be grounded..." -- Bored Borg on
> rec.woodworking
>
> To email me directly, send a message to puckdropper (at)
> fastmail.fm
On Sun, 27 Sep 2009 16:25:49 -0500, "Leon" <[email protected]>
wrote:
>
>"krw" <[email protected]> wrote in message
>news:[email protected]...
>> On Sun, 27 Sep 2009 13:46:09 -0500, -MIKE- <[email protected]>
>> wrote:
>>
>> Even when the tank is "empty" it's not empty. It's full of gasoline
>> fumes, which without air (oxygen) aren't dangerous at all. ...and
>> there isn't any air in there either.
>
>Yeah, there is oxygen/air in there, every time you open the tank some gets
>in. Besides, the tank would collapse if it were totally sealed, Air has to
>displace the disappearing gasoline.
Nope. Not any more. The engine controls recycle fumes back to the
tank. Tanks have been sealed for decades.
>> The water going through turbines is hardly pure. I doubt water
>> touches the generator windings themselves.
>
>
>But gasolinr does on a Gm electric fuel pump. My fuel pump in on my 1975
>Olds failed. I dropped the tank and replaced the pump, it is attached to
>the tank unit/gas gauge float assembly. I cut it open and the thing was
>spottless inside but the brushes were totally worn out. Gasoline went in
>one end of the motor and exited on the other. On one end of the motor was
>the plastic pump.
Sure. No one was arguing that point. It's hardly dangerous.
On 27 Sep, 19:46, -MIKE- <[email protected]> wrote:
> Those giant electric turbine generators are cooled with direct water
> immersion. Turns out pure H2O doesn't conduct electricity. It's all the
> minerals and other stuff in water that does.
Trouble with that is that water is viscous.
Best thing for cooling them is an internal flow of hydrogen, but that
really is a pain to work with.
On Sun, 27 Sep 2009 16:23:51 -0500, -MIKE- <[email protected]>
wrote:
>krw wrote:
>>> Another interesting fact from my electrical engineer friend who works
>>> for a huge electric producer...
>>> Those giant electric turbine generators are cooled with direct water
>>> immersion. Turns out pure H2O doesn't conduct electricity. It's all the
>>> minerals and other stuff in water that does.
>>
>> The water going through turbines is hardly pure. I doubt water
>> touches the generator windings themselves.
>
>I'm not talking about the water running through the tubes from a dam,
>that spin the turbines.
>He was specifically referring to steam powered generators, btw.
I was thinking more about hydro-electric turbines, which are also
water cooled.
>And yes, he said they use pure H2O.
Nothing is pure. ;-) In this case it has to be as close as possible
because of the process. If there were any impurities they would be
deposited in the "boiler". Not a good thing in a nuke, either. ;-)
"-MIKE-" <[email protected]> wrote in message
news:[email protected]...
> Leon wrote:
>> "-MIKE-" <[email protected]> wrote in message
>> news:[email protected]...
>>
>>
>> No, gas tanks do
>>>> not always have gasoline in them so being constantly submerged is not
>>>> the answer.
>>> I'm guessing the pump was low enough as to always be submerged, even
>>> when the tank was "empty?"
>>
>> Nope, mentioned that above, of millions each year built this way there
>> had to be a few thousand that went with out caps and the gas evaporated.
>>
>
> "Had to be?" Sounds pretty speculative. :-)
I was in the automotive service business from 1972 to 1995. I saw it all.
"-MIKE-" <[email protected]> wrote in message
news:[email protected]...
>>
>
> Sometimes my old Skil looks like one of those 4th of July sparklers inside
> the case.
> I don't know if it's normal or healthy... I just know I won't use it
> around open cans lacquer or paint thinner. :-)
You would probably do well to not use any thing that sparks around flamable
vapors.
I am still in wonderment having retired from the automotive industry how GM
prevented gas tank explosions. They used submerged electric fuel pumps and
the gasoline literally went through the motor and brushes. No, gas tanks do
not always have gasoline in them so being constantly submerged is not the
answer.
"Puckdropper" <puckdropper(at)yahoo(dot)com> wrote in message
news:[email protected]...
> "Leon" <[email protected]> wrote in
> news:[email protected]:
>
>>
>> "Puckdropper" <puckdropper(at)yahoo(dot)com> wrote in message
>> news:[email protected]...
>>> "Lew Hodgett" <[email protected]> wrote in news:001c03e2$0$24199
>>> [email protected]:
>>
>>>>
>>>
>>> I
>
> I'll keep an eye on it. I expect some sparks (nature of the beast), but
> this was a rather large one that filled the motor chamber. Now it only
> does it when I let go of the switch before it's come up to speed. (I'm
> curious now. If it starts again I'll have to put an ammeter on there,
> take a few readings, then clean the brushes.)
My Delta does it, at night with a not so well lit garage the motor becomes
pretty lit up when I release the switch.
"krw" <[email protected]> wrote in message
news:[email protected]...
> On Sun, 27 Sep 2009 13:46:09 -0500, -MIKE- <[email protected]>
> wrote:
>
> Even when the tank is "empty" it's not empty. It's full of gasoline
> fumes, which without air (oxygen) aren't dangerous at all. ...and
> there isn't any air in there either.
Yeah, there is oxygen/air in there, every time you open the tank some gets
in. Besides, the tank would collapse if it were totally sealed, Air has to
displace the disappearing gasoline.
>
> The water going through turbines is hardly pure. I doubt water
> touches the generator windings themselves.
But gasolinr does on a Gm electric fuel pump. My fuel pump in on my 1975
Olds failed. I dropped the tank and replaced the pump, it is attached to
the tank unit/gas gauge float assembly. I cut it open and the thing was
spottless inside but the brushes were totally worn out. Gasoline went in
one end of the motor and exited on the other. On one end of the motor was
the plastic pump.
"krw" <[email protected]> wrote in message
news:[email protected]...
>
> Nope. Not any more. The engine controls recycle fumes back to the
> tank. Tanks have been sealed for decades.
Yes the engine compartment does recycle fumes back to the tank but there is
a lot of AIR that goes with it. Additionally there are lots of peole
driving around with lost gas caps, check engine lights and all. And again,
the tank is not sealed when you open it up to fill it with gas. There is
just way too much of a chance of the perfect combination for the electric
motor to set off an explosion if there was not a fool proof way to arrest
the spark. How that is accomplished even the Olds factory rep could not
explain when I was the service sales manager back in the 80's.
>>
>>But gasolinr does on a Gm electric fuel pump. My fuel pump in on my 1975
>>Olds failed. I dropped the tank and replaced the pump, it is attached to
>>the tank unit/gas gauge float assembly. I cut it open and the thing was
>>spottless inside but the brushes were totally worn out. Gasoline went in
>>one end of the motor and exited on the other. On one end of the motor was
>>the plastic pump.
>
> Sure. No one was arguing that point. It's hardly dangerous.
Obviousely but the simple explanation has not yet been explained to me.
On Sun, 27 Sep 2009 13:46:09 -0500, -MIKE- <[email protected]>
wrote:
>Leon wrote:
>> "-MIKE-" <[email protected]> wrote in message
>> news:[email protected]...
>>> Sometimes my old Skil looks like one of those 4th of July sparklers inside
>>> the case.
>>> I don't know if it's normal or healthy... I just know I won't use it
>>> around open cans lacquer or paint thinner. :-)
>>
>>
>> You would probably do well to not use any thing that sparks around flamable
>> vapors.
>> I am still in wonderment having retired from the automotive industry how GM
>> prevented gas tank explosions. They used submerged electric fuel pumps and
>> the gasoline literally went through the motor and brushes. No, gas tanks do
>> not always have gasoline in them so being constantly submerged is not the
>> answer.
>>
>
>I'm guessing the pump was low enough as to always be submerged, even
>when the tank was "empty?"
Even when the tank is "empty" it's not empty. It's full of gasoline
fumes, which without air (oxygen) aren't dangerous at all. ...and
there isn't any air in there either.
Liquid-fueled rocket and jet engines commonly use the fuel and
oxidizer as a coolant.
>Reminds me of the Mythbusters episode in which they *could not* get a
>gasoline trail to ignite with a burning cigarette, like you see in the
>movies.
>Apparently, smoldering tobacco embers are not hot enough to ignite
>gasoline vapors.
>
>Another interesting fact from my electrical engineer friend who works
>for a huge electric producer...
>Those giant electric turbine generators are cooled with direct water
>immersion. Turns out pure H2O doesn't conduct electricity. It's all the
>minerals and other stuff in water that does.
The water going through turbines is hardly pure. I doubt water
touches the generator windings themselves.
"Puckdropper" <puckdropper(at)yahoo(dot)com> wrote in message
news:[email protected]...
> "Lew Hodgett" <[email protected]> wrote in news:001c03e2$0$24199
> [email protected]:
>>
>
> I took the brushes out, blew out the sawdust in the brush chambers and
> put them back. The big spark is gone, and I think I picked up a little
> missing speed.
>
> I'll have to add that to the occasional maintenance list. It only takes
> about 2 minutes.
I suspect that the fix will be short lived. I think you are trying to fix a
normal condition.
Leon wrote:
> "Puckdropper" <puckdropper(at)yahoo(dot)com> wrote in message
> news:[email protected]...
>> "Lew Hodgett" <[email protected]> wrote in news:001c03e2$0$24199
>> [email protected]:
>
>> I took the brushes out, blew out the sawdust in the brush chambers and
>> put them back. The big spark is gone, and I think I picked up a little
>> missing speed.
>>
>> I'll have to add that to the occasional maintenance list. It only takes
>> about 2 minutes.
>
>
> I suspect that the fix will be short lived. I think you are trying to fix a
> normal condition.
>
Sometimes my old Skil looks like one of those 4th of July sparklers
inside the case.
I don't know if it's normal or healthy... I just know I won't use it
around open cans lacquer or paint thinner. :-)
--
-MIKE-
"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com
[email protected]
---remove "DOT" ^^^^ to reply
Leon wrote:
> "-MIKE-" <[email protected]> wrote in message
> news:[email protected]...
>> Sometimes my old Skil looks like one of those 4th of July sparklers inside
>> the case.
>> I don't know if it's normal or healthy... I just know I won't use it
>> around open cans lacquer or paint thinner. :-)
>
>
> You would probably do well to not use any thing that sparks around flamable
> vapors.
> I am still in wonderment having retired from the automotive industry how GM
> prevented gas tank explosions. They used submerged electric fuel pumps and
> the gasoline literally went through the motor and brushes. No, gas tanks do
> not always have gasoline in them so being constantly submerged is not the
> answer.
>
I'm guessing the pump was low enough as to always be submerged, even
when the tank was "empty?"
Reminds me of the Mythbusters episode in which they *could not* get a
gasoline trail to ignite with a burning cigarette, like you see in the
movies.
Apparently, smoldering tobacco embers are not hot enough to ignite
gasoline vapors.
Another interesting fact from my electrical engineer friend who works
for a huge electric producer...
Those giant electric turbine generators are cooled with direct water
immersion. Turns out pure H2O doesn't conduct electricity. It's all the
minerals and other stuff in water that does.
--
-MIKE-
"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com
[email protected]
---remove "DOT" ^^^^ to reply
krw wrote:
>> Another interesting fact from my electrical engineer friend who works
>> for a huge electric producer...
>> Those giant electric turbine generators are cooled with direct water
>> immersion. Turns out pure H2O doesn't conduct electricity. It's all the
>> minerals and other stuff in water that does.
>
> The water going through turbines is hardly pure. I doubt water
> touches the generator windings themselves.
I'm not talking about the water running through the tubes from a dam,
that spin the turbines.
He was specifically referring to steam powered generators, btw.
And yes, he said they use pure H2O.
--
-MIKE-
"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com
[email protected]
---remove "DOT" ^^^^ to reply
Leon wrote:
> "-MIKE-" <[email protected]> wrote in message
> news:[email protected]...
>
>
> No, gas tanks do
>>> not always have gasoline in them so being constantly submerged is not the
>>> answer.
>> I'm guessing the pump was low enough as to always be submerged, even when
>> the tank was "empty?"
>
> Nope, mentioned that above, of millions each year built this way there had
> to be a few thousand that went with out caps and the gas evaporated.
>
"Had to be?" Sounds pretty speculative. :-)
--
-MIKE-
"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com
[email protected]
---remove "DOT" ^^^^ to reply
Nova wrote:
> krw wrote:
>>
>> The water going through turbines is hardly pure. I doubt water
>> touches the generator windings themselves.
>
> I've toured the Robert Moses power generation station in Niagara Falls a
> number of times. The turbines are at the bottom of the dam to take
> advantage of the water's pressure. The generators are on the top floor
> of the structure to facilitate installation/replacement. The two are
> connected by a massive shafts. You're correct, the water (hopefully)
> doen't come near the generators.
Actually, large-capacity turbine-generators are typically H cooled to
enhance conductivity. One does not smoke in the vicinity... :)
<http://www.gepower.com/prod_serv/products/generators/en/hydrogen_cool.htm>
--
Electric brake shorts out the motor winding and it generates
current in the winding in reverse - generating voltage - and sparks
if the brushes are not smooth on. The short isn't hard, but soft
through a low resistance value.
Good find.
Martin
Leon wrote:
> "Puckdropper" <puckdropper(at)yahoo(dot)com> wrote in message
> news:[email protected]...
>> When using my Kobalt CMS, I notice a large spark from the motor
>> compartment
>> when I turn off the saw. Sometimes it looks like it fills the whole
>> compartment. Is this a sign the brushes need replaced?
>>
>> Puckdropper
>> --
>> "The potential difference between the top and bottom of a tree is the
>> reason why all trees have to be grounded..." -- Bored Borg on
>> rec.woodworking
>>
>> To email me directly, send a message to puckdropper (at) fastmail.fm
>
>
> Sounds like a normal condition when an electronic brake in engaged.
>
>