JHCC Posted November 3, 2018 Share Posted November 3, 2018 Saw this interesting drive unit for a 2x? grinder for sale at my local industrial surplus place. I didn’t buy it (I’m not in the market, since I bought the 2x90), but I’m posting here for reference and discussion. The drive wheel is attached to a gear reducer (don’t know the ratio), which is run by a belt and pulleys from a small motor. The motor is only 1/4 hp (which struck me as on the low side) and runs at 1725 rpm. Would gearing down to a slow speed offset the low power of the motor, especially if it’s set up for one dedicated task (such as running a fine grit or buffing belt)? Quote Link to comment Share on other sites More sharing options...
Daswulf Posted November 3, 2018 Share Posted November 3, 2018 Or is it for grinding/sanding belts at all? Could have run a flat belt to drive something else. Quote Link to comment Share on other sites More sharing options...
JHCC Posted November 3, 2018 Author Share Posted November 3, 2018 Seems odd to set up a V-belt drive to run a gear drive to run a flat-belt drive, but I suppose stranger things happen. Quote Link to comment Share on other sites More sharing options...
Jim Coke Posted November 3, 2018 Share Posted November 3, 2018 Greetings JHCC, That set up is a typical drive system for a method of updating a drill press with flat belt drive to a motorized unit. It also applies to various other small machines . Great find if you have a use for it. Belt grinder not so much. Forge on and make beautiful things Jim Quote Link to comment Share on other sites More sharing options...
JHCC Posted November 3, 2018 Author Share Posted November 3, 2018 Very interesting. Thank you! Quote Link to comment Share on other sites More sharing options...
rockstar.esq Posted November 6, 2018 Share Posted November 6, 2018 The gear reduction would increase the effective torque of that motor. I agree with Jim that a drill press would be the most likely application. Quote Link to comment Share on other sites More sharing options...
stevomiller Posted November 10, 2018 Share Posted November 10, 2018 Yes as Rockstar stated, torque will move as the inverse of RPM (for a given starting HP/Torque input at a given RPM). Using direct gears, cogs and roller chain, pulleys and belts, whatever: increase point of us RPM, torque will go down by the inverse of the ratio. Slow the RPM at point of use, and torque increases by the inverse of the ratio. Example: Double point of use RPM (2x1) gives you 1/2 the torque. Halve the point of use RPM (1/2) gives you 2x1 the torque. All this is assuming no frictional losses in the transmission, which is impossible. Different methods of power transfer (pulleys and belts, gear to gear, sprockets with roller chain) all have some frictional power loss, and they are all different from each other. Quote Link to comment Share on other sites More sharing options...
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