Worm - Worm Gear as a Speed Increaser
Worm - Worm Gear as a Speed Increaser
(OP)
I know it's not common nor recommended, but I've seen it done before -if you open the head box of a portable grinder/cutter you'll see the wormgear being used as a driver and the large lead angle worm as the driven.
In my application, power is minor -less than 0.05 HP, but the speed increase of around 20:1 is essential. I appreciate if somebody can tell me where I can buy those.
In my application, power is minor -less than 0.05 HP, but the speed increase of around 20:1 is essential. I appreciate if somebody can tell me where I can buy those.





RE: Worm - Worm Gear as a Speed Increaser
RE: Worm - Worm Gear as a Speed Increaser
RE: Worm - Worm Gear as a Speed Increaser
Here is a starting place:
http://www.wmberg.com/prgears.html
RE: Worm - Worm Gear as a Speed Increaser
RE: Worm - Worm Gear as a Speed Increaser
Thanks for your replys. I've checked wmberg, all what they have is low lead angle and hence can't be back-driven.
As for the high speed motor; it doesn't work for my application as there's no motor. The high speed is not a target by itself. We need to trasform a low speed high torque hand driven motion to a "higher" speed motion resisted by a fly wheel.
Thanks again for your contribution.
RE: Worm - Worm Gear as a Speed Increaser
I have seen worm-drive saws, but the worm drive is used to reduce the speed, not increase it. Layout is similar to the grinders.
RE: Worm - Worm Gear as a Speed Increaser
You can run helical gears at 90 degrees apart. Are you sure that is not what you saw?
I would worry about the efficiency of your speed increaser. Is there no motor that runs at the speed you want? Try searching for spindle motors/drives.
An alternate speed increaser would be a two stage spur gear or belt drive. A 4:1 ratio and a 5:1 ratio together would be more efficient than any worm drive.
JHG
RE: Worm - Worm Gear as a Speed Increaser
Similarly Peugeot used a worm drive back axle with ratios of 4:1 or 5:1 up till about 1975 with no problems when the wheels were driving the engine. With good hydrodynamic lubrication conditions, an hourglass shaped worm and several teeth in contact, the drive can be very smooth with high efficiency.
However a 20:1 ratio would probably need 2 stage gearing to keep the helix angle high. With a very small motor, lube oil sliding viscosity losses might be high.
Jeff
RE: Worm - Worm Gear as a Speed Increaser
RE: Worm - Worm Gear as a Speed Increaser
"http://www.schafergear.com/chicagogear/gear_catalo..."
"http://www.calsmall.ne.jp/KHKCat_en/tocf_KHK.htm"
"http://www.ohiogear.com/"
RE: Worm - Worm Gear as a Speed Increaser
I would check their suitability for the application with the manufacturer.
But at 20:1 your final output shaft will be running at 70,000 rpm if your drive motor is a 2 pole induction motor at 60hz. If this is what you are looking for you will have some lubrication and bearing problems to consider. The whole 37W might turn into heat.
It may be that something like a 100mm dia rubber wheel driving a 5mm dia shaft might be more suitable, but I don't have any experience of this type of drive.
Jeff
RE: Worm - Worm Gear as a Speed Increaser
Thank you for your valuable contributions. The mechanism will be driven by hand, hence the high rpm is not a concern.
RE: Worm - Worm Gear as a Speed Increaser
An average person can put out 100W continously - BUT does this apply to arms alone (ie. no leg power)? - I don't know. So getting a 37W steady output via arms alone could be a problem if the coversion efficiency really stinks.
RE: Worm - Worm Gear as a Speed Increaser
http://www.whitemountainexports.com/other_tool3.ht...
From a google search using - hand tool grinder
RE: Worm - Worm Gear as a Speed Increaser
RE: Worm - Worm Gear as a Speed Increaser
Apparently, Harmonic drives can be back driven. I have been told that they are used this way. The smallest ratio of a harmonic drive is around 60:1, so it will not work in takoot's application.
I am trying to wrap myself around the input torque. This can be surprisingly high if you did not sit down and work out the effect of the speed increase. Inertia increases by the square of the gear ratio.
My gut feeling about this is that this mechanism should be made as efficient as possible.
JHG
RE: Worm - Worm Gear as a Speed Increaser
Jeff
RE: Worm - Worm Gear as a Speed Increaser
According to my machine design book, worm gears are very efficient at lead angles between thirty and sixty degrees. The whole process is massively affected by friction, not surprisingly.
By messing with the worm diameter, I suppose you can get just about any ratio you want out of an efficient worm drive. Unfortunately, most high ratio worm drives are meant for people like me who want something that _cannot_ be back driven. You could make a custom worm gear set, but this is getting as expensive as all the other options being thrown around here.
I suspect that an off-the-shelf two-stage spur gear drive will do the job and cost the least money. As you noted, we get around all sorts of workmanship issues by buying a packaged drive.
JHG