The Question:
We have purchased a Little Giant Power Hammer for our antique Power Show and was wondering what size electric
motor goes on it. The model number is 8682. clutch flywheel is 13" in diameter and is totally outside of the castings.
What RPM motor it takes and what size pulley.
Thank you
The Answer:
That serial number pretty much has to be for a 25# Little Giant. It was mfr'd in 1953.
It should look like figure #4 on this page: http://www.spaco.org/lgid.htm
You say that the "clutch flywheel" is 13" in diameter. Then the crankplate (flywheel in the front) must be a couple
of inches less in diameter, right? If this is not true, we need to talk more.
A 1 1/2 hp to 2 hp motor will run it just fine.
The design speed for this machine was 375 rpm on the crankshaft. People usually use a double sheave vee pulley
on the motor
and run the two "B" width vee belts on the outer surface of the clutch Pulley.
So, since the vee belts running on the clutch pulley would add about one inch to the OD of that pulley, its
effective diameter
becomes about 14 inches.
Assuming we find a 1725 rpm motor, we now need to find the correct size for the motor pulley.
The ratio of motor speed to crankshaft speed = 1725/375 = 4.6.
So we need that same ratio for pulleys.
So: 14 inches / 4.6 = 3.04 inches for the motor pulley, measured at its rim.
There will always be some slippage, maybe 5%, so that brings the required pulley size to about 3.2 inches in diameter.
Going a little faster (close to 400 rpm) won't hurt, so a pulley diameter of 3 1/2" should be okay.
But if you are a little worried about untrained people running it wide open and possibly hurting themselves,
you might consider a 3" pulley instead.
The hammer can be run in either direction.
You can see a nice setup that Roger Rice uses on the opening page of the
Little Giant Website
I think Sid sells kits to do all this if you don't want to make your own motor drive.
You can call him at: 402-873-6603 in Nebraska City, NE.