Gear Ratio for buffalo tumbler.

[AIRFRAMER]

Hello,
I built a Tumbler for Large Hides, Buffalo, Elk etc. The
tumbler is like a dryer, it is 6'long, 6'wide, making the circumference 18'. It is made with 2*4's & 3/4" plywood on the sides, I have it on a Metal Frame with Pillow Block Bearings on the sides for rotating, I am trying to use a Baldor 1.5 HP Electric Motor Single Phase, Farm Duty with 1725 RPM. I need to slow it down to 18 to 20 RPMs. I used a 1.5" pulley on the motor shaft & a 4'pulley (12'circum), on the tumbler itself and it still won't slow down, we tried to connect it to 120v kept popping circuit breakers, connected it to 220 works fine just can't seem to get it to slow down. The hides are pretty heavy also and i have to put in at least 150lbs of saw dust to help break the hides.

Thank You very much for any info.

 

[Philrock]

To get down to 18-20 rpm you need about a 91:1 ratio. You now have about a 35:1 ratio. There are many ways to increase the ratio, though a single stage drive seems impractical.

You could introduce a jackshaft (intermediate shaft) and have a 9:1 drive and a 10:1 drive. The belt on the low speed drive will have to be much heavier than the belt on the high speed drive.

If I were starting from scratch, I'd use a 3.6:1 belt drive from the motor into a 25:1 shaft mounted gearbox. The gearbox mounts directly on the dryer drive shaft.

Another possible approach would be to use a gearmotor with a 25:1 ratio, and connect its output to the dryer with a 3.6:1 chain drive.

 

[eromlignod]

You won't be able to change the speed of an AC motor by lowering the voltage. The speed is constant and is determined by the AC frequency (60 Hz). You could use a variable-frequency inverter drive to change your motor speed, but if you're going to just run at one speed, you should gear it down.

It sounds like you've already got your motor, but I would have probably used a gearmotor (motor with integral gearhead) to drive it. In lieu of this you could use an inline reducer in addition to your pulleys, a right-angle worm drive, or a jackshaft with an additional reduction of pulleys.

Don
Kansas City

 

[dvd]

Sounds like a fun project. I wish I was there. (I might want to be there even without the tumbler.)

The jackshaft arrangement sounds like the cheap way to use all of your existing components. I would recommend that you keep at least one v-belt drive in the system. A v-belt can slip at start up when your torque is highest.

You might also consider starting an empty tumbler and (safely) adding hides and sawdust so that you don't need as much starting torque.

You might post this on the electric motor site and ask if there is a cheap single frequency inverter that could be purchased to slow down your motor.

 

[diskullman]

The most economical way would be a belt drive to a jackshaft, and a chain drive to the tumbler.

Russell Giuliano