Question (from a layman) about torque

1. windshield washer motor may not like running continuously - you want a
continuous duty motor
2. if I understand it right, you want to lift 12 pounds by 10 inches - to be
conservative, assume all the weight is at the extreme end of your 5 inch
radius, so you have 12X5 inch pounds of torque (e.g. 60 inch pounds or 5
foot pounds) of torque needed when the weight is exactly horizontal.  I'd
probably add another 100% to that and look for 10 foot pounds of torque.




--
Posted via a free Usenet account from http://www.teranews.com

scott.marquardt@gmail.com wrote:

Has it gotta be a wiper or 12vdc motor?
Why not press into service a washing machine motor or the likes ?

--
Cheers ............. Rheilly P

scott.marquardt@gmail.com wrote:


You might find a copy of the Bosch electric motor (aftermarket program)
catalogue useful. I have a printed copy, it may be available for
download or you may have to request one from a Bosch rep. Basically
lists all sorts of motors which I think derive from automotive
applications but which have a wider use. It give sizes, duty, voltage
and power consumption figures, torque curves. It may be helpful as you
might find the same or equivalent motor and may be able to find a more
powerful alternative.

Regarding William Noble's comment about duty cycle,  those listed which
appear to be windscreen types are listed S1 duty (continuous) which
makes sense as it rains a lot in some parts of the world.

It might be worthwhile looking at a motor from a truck as they have
larger wipers but are likely to be 24V, at least they are typically in
the UK. Also the wiper motors are often only intended to run in one
direction and don't run as well in reverse so that may be worth checking
in your app.

The power of google, searching for "bosch electric motor aftermarket" got

http://aa.bosch.de/advastaboschaa/Category.jsp?ccat_id 6&language=en-GB&publication=1

as the first hit and you can search through their online literature
about the various motors.

Hope that helps.

David Billington wrote:

I think you guys missed the point, he has a wiper motor, and wants to know
how to select a commercial gearmotor replacement that will be suitable.

scott.marquardt@gmail.com wrote:

Adding to what Roger said about gearing down to reduce
RPM:  when you gear down to reduce speed, you multiply
the torque that the motor can deliver by the same ratio
as you geard down the rpm.  So, for example, say you
gear down to reduce the speed to 1 tenth.  That makes
your motor effectively 10 times stronger. A 100 RPM
motor capable of delivering 1 foot pound of torque geared
down to 10 RPM will deliver 10 foot pounds of torque through
the gears.  There will be some loss due to friction,
so the actual delivered torque will be something a bit
under 10 foot pounds.

Ed

proclaimed to the world:


This reminded me of my past in the US Navy. I took care of the main
engine controls on the last conventional powered aircraft carrier
built. It has four main engines consisting of huge GE steam turbines.
The reduction gears tower above you. All that turbine torque reduced
down to less than 100 rpm to a 30 inch drive shafts. There is no
clutch or reverse. A separate turbine drives the whole thing in
reverse. Anyway, the weight of the drive shafts and span between
bearing blocks made it necessary to slowly turn the shafts while in
port to keep the shafts from sagging. We "jacked" the turbine,
reduction gears and main shaft with a fractional HP electric motor.
Because we could connect the jacking motor to a huge ring gear on one
of the turbine's larger rotors, there is little gearing loss.

One night while looking down into the dry dock, I had a vision of the
worlds largest barbecue pit, with a tied and spittled Godzilla slowly
turning over the fire. In this application the jacking gear would have
to be sped up or the big lizard would get burnt on one side. I don't
remember the exact turn rate anymore. I knew then. It's somewhere
around 2 RPD.

Paul M wrote:

   How about roasting a bunch of lawyers instead of Godzilla? ;-)


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

Paul M wrote:

I'm not sure that the stated reason for "jacking" is correct. Many power
plants use gas turbines to run peaking generators for short-term loads
When those are idle, they are kept moving slowly by "turning gear"
(different industry, different name). The purpose is not to prevent the
steel shafts of alternator and turbine from taking a set, but to keep
oil from being squeezed out of the lower parts of the bearings by steady
unidirectional pressure. Some modern installations use pumps to force
oil flow even when the shafts are stationary. This has the advantage
that recovery from power failure is simpler and safer.

Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

proclaimed to the world:


From my experience, I suspect that rotor warping is as much a reason
for turning those gas turbines. I've do some work with gas turbines in
both the power generation and marine industries. BTW "turning gear" is
also used in the marine field, more so in the merchant marines than
Military. I know the Brits have some odd names for things too.


My stated reason for jacking the turbine and power transmission system
in a marine propulsion system is only one of several. There may be
more but here are the ones I know of.

1. Drive shaft sag
2. Lubrication
3. Warping of the turbine due to temperature variation.

Lubrication was never a big issue that I knew of other than making
sure that the pumps were on and you had pressure at the bearings
before you started jacking. There were several conditions we keep the
engine in which had to do with the amount of time it took to turn
screws under power. The most "shut down" state was with no oil to the
bearing, no jacking. With a completely cold main engine turbine it
took around a day to warm it up to the point where the throttle valve
was cracked open. I remember a few times where we pushed the edge of
safely when we had to get underway unexpectedly. Shaft sag posed the
possibility of the longest delay. We kept logs of when and how long we
jacked and had a setup to measure the shaft sag. There are times when
it is unavoidable and the shafts had to stay in the same position.
They do not sag all at once of course. I saw a graph of shaft sag once
and remember that sag is a curve with sag decreasing with time. After
several weeks the shafts are as bent as they are going to get. It
takes several weeks of straightening to get underway. This is
unacceptable for a combat ship, so they jack the shaft as a rule, only
letting it set when necessary, such as when in overhaul.

It might be a good idea for me to add that the jacking gear was
sometimes used intermittently.Some ships had two speeds.  We might
want to keep the shaft stationary most of the time, so we would jack
the shafts 180 degrees ever few days. The longest shaft is over 200
ft. I was told that this shaft has 2 1/2 twists in it when under full
load. I find this difficult to believe, but the guy who told me was
pretty credible, as he was one of the naval engineers working on
refurbishing the bearing blocks for the shaft. It gives you a better
idea of the flexibility of these shafts.

Keep on questioning things Jerry. It gives me the opportunity to
babble more. :-)

Paul M wrote

interesting information and


I stand corrected.

I have a collimator that fastens into the bore of my rifle and provides
a target for the scope. I can remove the scope from the barrel and the
barrel from the receiver, then align the scope to the collimator's
projected image at reassembly and it is dead on *provided the barrel is
right-side up and level when the adjustment is made.* The weight of the
barrel and collimator flexes the barrel enough to throw the sight line
off otherwise.  My barrel is about two feet long and 3/4" in diameter,
with a 15/64" (.22 cal.) bore, yet it flexes enough to throw the sights
way off is not used gingerly.

I drove a '50 jaguar XK-120 that had such a hard-grabbing clutch that
nobody I knew, not even the dealer's mechanic, could slip the clutch a
bit without chattering vigorously. (That's why it sold cheap.) The drive
shaft was about 1.25" at the clutch spline, tapering uniformly down to
3/4" at the differential. My way to start the caw was sliding my foot
sideways off the pedal so the clutch didn't have time to chatter, and
rely on the drive shaft's windup to absorb the shock. The shaft probably
wound up two turns before the car moved an inch, then unwound, returning
the stored energy to forward momentum. Properly playing the accelerator
avoided oscillation. That car started like a goosed antelope!

Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

proclaimed to the world:


I hope the car had head rests. I would imagine that having your head
against the rest made the start a bit better. Forget the coffee.

BTW a fine clutch and gearbox is a real joy. Coupled to a beefy engine
it really is a treat. I really should have become a rally racer.

 Paul M <PaulMatWiredogdotcom> wrote:


My son has a one year old Mazda 6. I have a 15 yr old Jeep. I can beat
him off the line for the first 50 feet or so. He then smokes me. Torque
is what makes the Jeep jump out ahead.

Al

to the world:


In younger years I had a Suzuki 380 motorcycle. It was a hot 2 stroke
back in the 70's. I used to street drag race with it against all the
Hondas around then. The Honda 360 and 550 were really popular four
stroke bikes back then and had more torque than most. The two strokes
were laughed at then but they had a lot of top end. For me to beat a
550 Honda, I had to due a burnout start, hell to get off the line, I
had to do this. On the start the Honda would get maybe twenty feet
ahead while I was leaning over the handle bars, leaving a cloud of
smoke with the tire. Once I got moving a bit, I would lean back and
transfer weight to the tire. The bike would squat, the front wheel
would come up and the tire would stick. It was like being shot from a
cannon. At around 150 ft off the line, I would shoot by the Honda like
it was standing still.

Now I have a old Honda CX500 touring bike with lots of torque. Torque
is better than speed for day after day pleasure in driving.

Al wrote:

The Jag belonged to a friend. It had the same weight, engine
displacement, and cylinder count (6) and as my father's '50 Dodge sedan.
Not much similarity beyond that.

Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

"Paul M" <PaulMatWiredogdotcom> wrote in message

On boats (submarines), we too had to run the turning gear.  But the drive
shaft was much shorter and sag wasn't much of an issue.  Steam turbine rotor
bending was more the concern, due to uneven heating (cold condenser below,
and sealing steam applied to the shaft's labyrinth seals).  If completely
'cold', like from an IMA or overhaul, we had to run the oil for a day or so
just to warm it up to the minimum for jacking (90 F IIRC, for 2190 turbine
oil).  Then put the turbine/gear on the the 'jack' for four hours before
bringing steam into the engine room and applying steam to the shaft seals,
or warming the engine.

Lubrication on relatively small turbines (just a couple of ton rotors) is a
matter of just having low-pressure oil supply and letting a dry shaft 'ride
up' one side of the journal.  It quickly pulls a film of oil under the
shaft.

Large commercial turbines (on the order of 50 ton) also have 'lift pumps'.
Along the with the low-pressure lubricating oil, a 'lift pump' supplies high
pressure oil (>100 PSI) to a special port in the lower half of the bearing
sleeve.  It is enough pressure to force an oil film under the shaft, even
when it isn't turning.  So prior to first starting the turning gear, the
lift pumps are used to 'break free' the shaft from the bearing sleeves.
Quite often, once the shaft is turning (with the turning gear), the lift
pumps can be secured as the oil film around the shaft is then enough to
allow continued turning with the small motor.

daestrom

On Sun, 19 Nov 2006 18:24:50 GMT, "daestrom"


I appreciate you posting this. My main duties involved the
instrumentation and controls of both the boilers and main engines, but
my rate was boiler tech. The shop I worked in had both boiler tech and
machinist mates. The main engines had very little controls. I am sure
this is the same with your sub. I did a lot of work on subs after I
got out of the Navy and worked as a private contractor. The steam
cycle remains the same as did the turbines which used the power
produced by whatever source, be it conventional or nuke. Anyway, I was
hesitant to post any info on main bearing lubrication with sketchy
memory. Jerry spends late nights checking all my facts.:-) (Just
kidding Jerry. I appreciate every question you pose.) Anyway I vaguely
remember the lift pumps and decided not to mention them fearing I
might not be accurate. Thanks for filling in the details. Do you
remember what the lift pump pressures were?

I remember one time where the labyrinth packing was damaged by someone
incorrectly jacking. I also remember uncoupling the main shaft so we
could jack the turbine while the shaft was down.

You don't happen to remember how big the shafts were on the sub, do
you? I remember on tridents and the sea wolf, the shafts appeared to
be much smaller. It seems a little silly today but this might still be
classified. Which class of sub did you serve on?

"Paul M" <PaulMatWiredogdotcom> wrote in message

Commercial turbine lift pumps run about 100 psi (relief set for 120).  But
they're positive displacement (little versions of a typical 'gear' pump), so
the exact pressure depends on the weight of the shaft and the
temperature/viscosity of the oil.


We had it 'both ways'.  The main reduction gear output could be disconnected
from the shaft so the turbines/gear could be jacked without turning the
shaft (a big-a__ clutch).  Then each turbine shaft had a 'hard' coupling
that could be disconnected between each turbine and the gear (port-starboard
main turbines fed one reduction gear).  That was in case a turbine was
damaged, you could spin the shaft from the opposite turbine at reduced
bells.


Don't know if it was ever classified, I'm sure the hp rating was.  As I
recall, they were only about 18" to 20" across, much smaller than your
carrier version (and shorter too).  The trickiest part of them was the
seals, we didn't use 'packing gland' type, but the 'mechanical seal' type in
order to adapt to changing depth/sea-pressure.

Tridents?  SeaWolf?  HA!!! Luxury liners!!  Try 'boring holes in the ocean'
in 'Permit' class.  Yes, those are the ones with *miles* of seawater piping
and were originally named 'Thresher' class.  ("fast and black, and never
come back")

daestrom
former EMC(SS)

daestrom wrote:

   ...


I remember Thresher being lost, and I remember how surprised some
experts were when she was ultimately found nearly intact. I recall a
seminar at which it was claimed that she was probably scattered in small
pieces over a wide area. "... never came back." Were there other losses?

Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯