mechanical gear stuff

the same as one with a 25 to one . Power is not effected by gear ratio's Torque can be changed with gear ratios.

The Power of the motor is about 95% of the rating on the motor. The 5% loss is probably due to voltage drop.

Welcome back!!!!!

Welcome back!

The worm gear ratio of 50:1 is very high. At this steep angle the rolling will be largely overtaken by the friction (or sliding) I expect at this ratio, with even multi start, the power transmission efficiency to be less than 50%.

To know output of the motor we must know the load.

The efficiency of 5% to 2% is understated.

We make gear boxes with single stage reduction - worms (ratio :1) with multi start and the efficiency is only about 80% - Motor power 500KW.

We have switched over to planetary chain with efficiency 95% approx. And the effect even in our manufacturing shop is significant -

Gear Box No load power - with Worm drive = 60KW, with planetary = 12KW.

rate the motor based on load accordingly, and if the power is high and you are buing the gear box, think about other types of gears.

"We have switched over to planetary chain with efficiency 95% approx. And the effect even in our manufacturing shop is significant -"

That's interesting. Is the system as compact as a gear driven system of the same capacity?

Many in my pastime build telescope tracking systems using worm drives in order to match the Earth's Sidereal rate of rotation. Ratios above 50 to 1 are common.

As you pointed out, shear loads are considerable in our applications. However, the biggest problem is periodic errors caused by minute variations in the precision of the machined parts.

L.J.

I was working once on high ratio and high efficiency gear box, but did not pursue it, due to perceived little need.

If you care to list the following, I am willing to see if there is an alternative gear box available.

What is the power transmitted, input and output rpm, rough size & weight, purchase price, perhaps the make and the quantity of possible sales per year.

You might not know the last questions, but let me see your data. It might be worthwhile after all.

Regards

As the others have said, there is not enough information to answer the question. The basic definition of electrical power is the product of voltage and current. The basic definition of mechanical power is the product of force and distance divided by time. There are lots of variations on these basic definitions, but no power calculation can be made without all of the required values for the calculation.

A high gear ratio is normally used either to obtain very low speed and/or high torque. If the requirement is low speed, then why use such a high-speed motor?

I'm guessing that this is a very small motor, likely operating on DC. As someone else indicated, very small motors with high ratio gearboxes have notoriously low efficiency, which means that the mechanical power provided to the load will be a small fraction of the electrical energy required to run the motor.

Good answer, DKW, and it leads me to MY question. I am designing a turntable for a lady's group in my church, which, if successful, will most certainly see much more than the planned use. It needs to turn at about 1 RPM, the table is roughly 40 inch diameter, I can apply power at any point along the rim, or underside (so actual track diameter is more a function of available torque and calculated speed of rotation), and the whole thing, battery powered, needs to be able to "turn" a load of about 40 pounds. That's the current spec. Specs may change later, as it sees use.

I managed to purchase a "lazy susan" bearing ring set with a 1000 pound load capacity (way in excess of requirements, but inexpensive, and much better made than anything available from people like Williams Sonoma, or even Home Depot or Lowes.

So, I found a motor, with a large reduction ratio, and according high base RPM (no load, no gear motor speed). It is probably as inefficient as you all have said, but I could live with that. What I can't live with is the growl of the assembly, both that which is mechanically coupled to the turntable by the friction drive I tried, and that of the motor/gearbox assembly. I MIGHT be able to live with the motor/gearbox noise, but would prefer lower speed/more efficiency for longer battery life.

In addition, at least for version 1.0, it has to be low cost (I have about $120 dollars of my own in it now, and was castigated thoroughly by the young lady who asked me to design/build it, and who I babysat when she was 2-3 years old and her Dad and I were fishing buddies, for spending money I can't convince her I could afford), and it has to be fairly light weight. The current assembly weighs about 25 pounds and if it goes up much, the ladies won't be able to set it up when they need it.

Assuming, (and knowing the history of MY 38 years with this church, I'm certain it's a good assumption) this THING finds more widespread use, all those specs might change. But then, so will the funding, storage requirements, etc., and MAYBE someone else will do the redesign anyway. Then it will all be their problem.

Any advice you can give me for power sources? I'm about tapped out, after 6 months of online and local research. And I have several HD, Lowes, and Ace Hardware, as well as Hobby Lobby, and many unaffiliated hobby stores I've visited and checked with. I've also checked some of the available Used and Surplus parts sources in print and online, but I'm certain there are a lot of which I'm unaware.

Anybody wish to weigh in with advice? I'd most appreciate it. If necessary I'll move this to another thread so I don't hijack this one. Though this does appear to be a similar trail.

Thanks.

Micahd

"Any advice you can give me for power sources?" When you say "power sources", my immediate thoughts turn to battery vs. AC adapters, but since you already mentioned 'battery', I assume that by 'power source' you mean the motor/gearing/drive system.

During the last year or so, I happen to have set up a couple of turntables of roughly that size, that can rotate even slower (around 3 min per revolution) and must rotate at a very consistent speed, as they are used for welding. Unfortunately, these are devices that require a forklift to move; just the motor on each of them weighs the 25 lb. that you mention...

On the other hand, besides the gear reductions, we also use voltage reduction. The motors are rated at 2500 RPM @ 90VDC, but we are applying something like 5VDC, so the motors rotate around 100 RPM, and gearing does the rest. These are brushed motors with many windings, so they do still run smoothly at that low voltage. Cheaper motors might not.

You mention rumble; that means something in the system is out of round or out of balance. Running the motor at a lower speed should help reduce that, but if you already have the desired table speed, this would make it run too slowly...

You also mention friction drive. If this is akin to the old inside rim-drive phonograph turntables, then an idler wheel with softer rubber contact surface would reduce the transfer of vibration from the motor to the table.

Obviously I have no idea of what machine tools you may have at your disposal, but one low-cost possibility that comes to mind would be to drill a series of equally-spaced holes close to the rim. These holes could be driven by pins in a small gear-like pinion, or they could hold pegs that are driven by the pinion. At 1 RPM, these should be virtually silent.

Depending on the housing of the apparatus, other possibilities could include belt or chain drives. Look at old phonographs for ideas...

Thank you. I've seen the pin drive idea, but couldn't find a photo. Your description gives me enough to work on, so I'll try it. The Smithsonian used to have a whimsy Machine in their Air and Space art gallery with a silent string driving a 20 foot diameter table, but it's apparently in storage now where I can't study it. It would have worked well too. But its reduction ratio had to be on the order of 2000 to 1, or so, and it's applied torque was so low I saw a toddler stop it with his fingers once (his parents weren't watching). It took a good 5 minutes to get back up to speed , so it had to also have horrendous slip at that ratio with a friction drive.

I had to try it...

Here's a bottom isometric view of one possibility, with a detail:

Here, the table is 40" in outside diameter, with a 1/4" thick rim and top. The table pins, in green, are 1/4" in diameter and 3/4" long, with 1/2" exposed. There are 120 of them, at 3.0° spacing, on a 39" diameter circle.

The drive wheel is 2" in diameter, with 8 - 1/4" pins @ 45° spacing, each extending 0.4" beyond the disc. The drive wheel center is 18.3" from the table center.

This will give a 15:1 speed reduction from the drive wheel to the table.

I could provide more details if needed.

Thank you. Provide more detail? I think not. That would remove my excuse for not starting right now. And since I'm in the middle of a move, I have to wait till later. So I'll get back to you on it, and my thanks.

MicahD

I saw a 50:1 worm gear drive at 6500 RPM once. It was definitely 1.3 HP. And I'm unanimous in that.