Who pays follow-up

I'll throw a few things out there based on my experience with v-belts. We
have literally thousands of v-belts on a wide variety of equipment. Our
mechanics have become very picky about which belts they use. Sometimes we
run into a change that the manufacturer has made that causes the same brand
and part numbered belt to do strange things. We've seen things such as a
change in the composition of the rubber of the belting material causing
additional friction and "pulley climb" and changes in the number of layers
of reinforcing fabric and changes to the hardness of the belts causing
problems because it is either more or less flexible than the previous belt.

Do you still have the old belt(s)? Are the belts that were being thrown off
worn, chaffed, or stretched unusually? Polished or shiny spots on the sides
of the belt will indicate slipping. Cracks and fraying will indicate that
the belt was either overtight and/or old when installed. Do they lay flat
when you simply lay them on the floor? Twisted belts can indicate
misalignment. I'm just wondering if there was something wrong with those
specific belts. How old where they when installed? Brand and part number
identical to the latest 3 hour belt? Can you measure them to check them
against the original length and what the belt number states?

Could either pulley have slipped on the shafts? Do you have room to run a
straight edge across and between the faces of each pulley to check for
alignment?

Too tight? Too loose? Rule of thumb tension is a deflection mid way
between the pulleys of 1/2 the thickness of the belt, but check your MM.

Jim

"Viperdoc" wrote in message
...
Threw the belt again after twenty minutes in IMC on the way to the
avionics shop. Destination was VMC, so elected to continue rather than
turn around or land, and the other alternator was handling the load
easily.

Avionics guy fixed the radar (took three guys around 30 minutes). Belt
replaced.

Flew 1.5 hours back- no problems. After return I tightened belt again, and
then flew another 1.6 hours doing LNAV/VNAV approaches in IMC (much
smoother than ILS).

Checked belt again, which appeared tight. So, last belt has now gone over
three hours, where the others have all thrown in less than 30 minutes.

What gives- can a new belt stretch so much that it gets thrown that
easily, or should I still suspect that the engine is detuned and has a
sticking counterweight?

The engine shop quoted a cost of over $3,000 as a minimum to change the
counterweight bearings, plus any costs associated with finding something
wrong with the cylinders.

All of the belts that were thrown no longer lay flat- they looked like they
were stretched on one side. This, I was told, was due to some of the cords
being broken on one side versus the other.

One episode found the belt actually inside out on the pulleys, but still in
place. Yet, the overall alignment looks good to everyone who has inspected
the system.

The only difference so far is that at the last belt change, we noted that
the lower (non-tensioning) alternator bolt was very loose.

I bought two spares, and one of them is now on the plane. I forget the
source, and didn't save any of the old belts, but clearly they were all
"warped" and didn't lay flat.

Again, this was attributed to "whipping" of the belts by two mechanics, as a
result of the engine being detuned due to a sticking crankshaft
counterweight.

I again questioned why this should occur all of a sudden after changing the
belt at annual, since the previous belt had gone for hundreds of hours
without any indication of a problem. No one had a good answer for this, so
somehow the logic of the crankshaft counterweights being the source of the
problem is a little suspicious.
"Jim Burns" wrote in message
...
I'll throw a few things out there based on my experience with v-belts. We
have literally thousands of v-belts on a wide variety of equipment. Our
mechanics have become very picky about which belts they use. Sometimes we
run into a change that the manufacturer has made that causes the same
brand and part numbered belt to do strange things. We've seen things such
as a change in the composition of the rubber of the belting material
causing additional friction and "pulley climb" and changes in the number
of layers of reinforcing fabric and changes to the hardness of the belts
causing problems because it is either more or less flexible than the
previous belt.

Do you still have the old belt(s)? Are the belts that were being thrown
off worn, chaffed, or stretched unusually? Polished or shiny spots on the
sides of the belt will indicate slipping. Cracks and fraying will
indicate that the belt was either overtight and/or old when installed. Do
they lay flat when you simply lay them on the floor? Twisted belts can
indicate misalignment. I'm just wondering if there was something wrong
with those specific belts. How old where they when installed? Brand and
part number identical to the latest 3 hour belt? Can you measure them to
check them against the original length and what the belt number states?

Could either pulley have slipped on the shafts? Do you have room to run a
straight edge across and between the faces of each pulley to check for
alignment?

Too tight? Too loose? Rule of thumb tension is a deflection mid way
between the pulleys of 1/2 the thickness of the belt, but check your MM.

Jim

"Viperdoc" wrote in message
...
Threw the belt again after twenty minutes in IMC on the way to the
avionics shop. Destination was VMC, so elected to continue rather than
turn around or land, and the other alternator was handling the load
easily.

Avionics guy fixed the radar (took three guys around 30 minutes). Belt
replaced.

Flew 1.5 hours back- no problems. After return I tightened belt again,
and then flew another 1.6 hours doing LNAV/VNAV approaches in IMC (much
smoother than ILS).

Checked belt again, which appeared tight. So, last belt has now gone over
three hours, where the others have all thrown in less than 30 minutes.

What gives- can a new belt stretch so much that it gets thrown that
easily, or should I still suspect that the engine is detuned and has a
sticking counterweight?

The engine shop quoted a cost of over $3,000 as a minimum to change the
counterweight bearings, plus any costs associated with finding something
wrong with the cylinders.

("Viperdoc" wrote)
Again, this was attributed to "whipping" of the belts by two mechanics, as
a result of the engine being detuned due to a sticking crankshaft
counterweight.

I again questioned why this should occur all of a sudden after changing
the belt at annual, since the previous belt had gone for hundreds of hours
without any indication of a problem. No one had a good answer for this, so
somehow the logic of the crankshaft counterweights being the source of the
problem is a little suspicious.


This sounds like a case for "House" ...or in your case, "Hangar". :-)

If it's easy to get at, and all other things being equal, can you swap
alternators with a known good one (meaning pulley)?


Montblack
http://www.fox.com/house/features/houseisms.htm
"Twenty-year olds fall in and out of love more often than they change their
oil filters. Which they should do more often."
- Fools For Love

"Take this four times a day. And stay off airplanes. They're flying
cesspools."
- Informed Consent

"Montblack" writes:



This sounds like a case for "House" ...or in your case, "Hangar". :-)

If it's easy to get at, and all other things being equal, can you swap
alternators with a known good one (meaning pulley)?

I've wondered about the whole idea of belt drive; given that you must pull
the prop to change same.

I've pondered a smooth pulley in place of the existing one, then a
rubber drive wheel on the alternator/vacuum pump etc.... I suppose
icing may be an issue, as well as having to locate the accessories
directly adjacent to the engine axis.

The other way would be driving the belt with the back of engine
pulley, but that has other issues...

BTW, Real Soon Now, Detroit is promising everything will be
electric-driven; water pump, power steering, air conditioning, you
name it. They'll build a starter/ alternator into the flywheel/bell
housing area. The engine won't idle; it will stop at red lights
and restart when you hit the gas...
--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

Dave,
My bonanza has a 70A alternator that is belt driven off the back of the
engine, IO470.

Toyota already offers what Detroit is promising - actually I think Ford
does too. My Camry Hybrid has electric power steering, electric power
assist brakes, electric AC, etc. The engine only runs when it needs
to. Very clever car. I've put about 1400 miles on it and so far so good.

Dave
M35

David Lesher wrote:
"Montblack" writes:



This sounds like a case for "House" ...or in your case, "Hangar". :-)

If it's easy to get at, and all other things being equal, can you swap
alternators with a known good one (meaning pulley)?

I've wondered about the whole idea of belt drive; given that you must pull
the prop to change same.

I've pondered a smooth pulley in place of the existing one, then a
rubber drive wheel on the alternator/vacuum pump etc.... I suppose
icing may be an issue, as well as having to locate the accessories
directly adjacent to the engine axis.

The other way would be driving the belt with the back of engine
pulley, but that has other issues...

BTW, Real Soon Now, Detroit is promising everything will be
electric-driven; water pump, power steering, air conditioning, you
name it. They'll build a starter/ alternator into the flywheel/bell
housing area. The engine won't idle; it will stop at red lights
and restart when you hit the gas...

dave writes:

My bonanza has a 70A alternator that is belt driven off the back of the
engine, IO470.

Sounds more sensible than pulling a prop.... Best belt setup I ever
saw was a Greyhound bus [!] w/ a ~250A/28vdc alternator. It was
driven by triple belt set, tensioned by an air cylinder/regulator.
When a belt broke:

a) close valve
b) push alternator to loosen
c) remove old belts if any; put on matched set of three.
d) open valve; air tightens belts to correct tension.
e) start bus, drive away.

Literally a 5 minute repair. Long part is getting belts from stockroom.


Toyota already offers what Detroit is promising - actually I think Ford
does too. My Camry Hybrid has electric power steering, electric power
assist brakes, electric AC, etc. The engine only runs when it needs
to. Very clever car. I've put about 1400 miles on it and so far so good.

The Grand Plan was 42VDC [More V == less A for same W] cars, with
a 15KV starter/alternator. It adds umph during passing situations.

No lamps, all LED's/HID headlights. Valve train controlled by the
FADEC-type system. So step on gas, starter spins a zero-compression
engine, then valves close, fuel's injected; alleged 0.5 sec restart
time at stoplight.

Big plus on all electric is location is flexible; why have the
compressor under the hood at all? [Think roof-rack AC system] Second
plus is no exposed shaft on AC compressor, hence no Freon leakage.

With hybrids, you can change the picture considerably. But lots
of weight added for more battery capacity.


--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

David Lesher wrote:


Sounds more sensible than pulling a prop....

When you guys do pull the prop to change a belt, do you ty-wrap a spare
belt to the engine, just in case?

"David Lesher" wrote in message
...

Valve train controlled by the
FADEC-type system. So step on gas, starter spins a zero-compression
engine, then valves close, fuel's injected; alleged 0.5 sec restart
time at stoplight.


Obvious, but never occurred to me. Thanks for information.

Taking the camshaft out of our IC engines is going to provide significant
performance improvement and additional capabilities. The Audi V12 racing
engine is diesel fueled with full electronic control of valves and
injectors. Common rail injection using VERY high fuel pressure. There may
be more use of 2 stroke?

On Tue, 3 Apr 2007 16:51:32 +0000 (UTC), David Lesher
wrote:

"Montblack" writes:



This sounds like a case for "House" ...or in your case, "Hangar". :-)

If it's easy to get at, and all other things being equal, can you swap
alternators with a known good one (meaning pulley)?

I've wondered about the whole idea of belt drive; given that you must pull
the prop to change same.

I've pondered a smooth pulley in place of the existing one, then a
rubber drive wheel on the alternator/vacuum pump etc.... I suppose
icing may be an issue, as well as having to locate the accessories
directly adjacent to the engine axis.

The other way would be driving the belt with the back of engine
pulley, but that has other issues...

BTW, Real Soon Now, Detroit is promising everything will be
electric-driven; water pump, power steering, air conditioning, you
name it. They'll build a starter/ alternator into the flywheel/bell
housing area. The engine won't idle; it will stop at red lights
and restart when you hit the gas...

Mine works that way now and it'son purpose.
Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com