Question (from a layman) about torque

I recently used a surplus windshield wiper motor in a drum coffee roaster application. The drum has an 11 inch diameter, and the motor
can reliably do about 5 pounds of coffee beans. It's coupled with a pulley that's almost 1:1 just now.
The drum has agitation vanes inside which are optimized to keep the beans tossing about, but the simple picture is that they're being lifted on a 5" radius (on average).
The drum's size easily allows for a 10 - 12 pound batch, but the motor I've been using can't handle that at all.
What this layman needs is a bit of guidance on how to understand what kind of torque specifications I should look for in a gearmotor that will do the trick.
I'd be glad of any tips!
TIA
- S
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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.

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snipped-for-privacy@gmail.com wrote:

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



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snipped-for-privacy@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.
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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:

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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.

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snipped-for-privacy@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
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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.
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Paul M wrote:

How about roasting a bunch of lawyers instead of Godzilla? ;-)
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Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
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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
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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. :-)
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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
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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.
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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
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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.
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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
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"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

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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?
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"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)
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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
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