The question that faces many of us in the old
engine hobby is: What can we have our engines doing besides just
idling? Most of us have probably been amazed from time to time at
the creative engineering we have observed at engine shows. This is
in addition to the factory designed pumps, grain shellers, wood
saws, light plants, etc.
Here in the north, where the show season is short, we have a lot
of time to attempt to be creative. During the winter of 2005/2006,
my attempt to put an engine to use resulted in this
Massey-Harris-powered AC generator.
This engine was made by Cushman to be sold in Canada as a
Massey-Harris. It is identical to a Cushman Cub. I bought it from
an antique dealer in Quebec, Canada, as a non-running unit in the
late summer of 2005. The work needed to get it running involved a
thorough fuel system cleaning with acetone, as the old gas had
turned to rusty gum. Two other small problems were setting the
ignition timing from an extremely advanced position (causing it to
kick back even with the timing lever fully retarded), and fixing a
broken speed adjusting screw (which held the governor on wide open
throttle). That was all that was required to get it running. It
appears to have nearly all of its original green paint and all of
the silk-screened Massey-Harris lettering with scrolled pinstripes
on the front of the block. The addition of a new muffler (with no
modifications to the engine exhaust port) from a Kohler-powered
John Deere lawn tractor makes for a quiet-running unit.
The 115-volt, 2-kilowatt AC generator was originally belted to a
single-cylinder Wisconsin air-cooled engine that was not running.
The tag on the generator says, “Montgomery Ward Powerlite.” Vintage
is unknown, but probably 1950s.
Both engine and generator had V-belt pulleys attached when
acquired, so the question was: How could a 2 HP throttle-governed
engine that is rated to run at 750 RPM operate an AC generator that
attains standard output voltage at 3,600 RPM? We all know the
answer to that: Given enough time and money, most anything can be
accomplished!
Once the correct pulley diameters were figured out, I had
planned to just change the engine pulley to keep the cost down and
the project as simple as possible. But a mechanic friend happened
to be around while I was laying out the project and he thought out
loud about the procedure. He said, “Why don’t you make a line shaft
between them to increase the ‘cool factor’ and have more action
visible?” After the math was refigured so the original pulleys
could be used as is, the line shaft idea was developed.
The line shaft was made from 3/4-inch cold-rolled round rod with
a standard 3/16-inch keyway cut 4 inches in from each end. (Both
ends could therefore have pulleys on them.) The pillow blocks and
bearings were purchased locally. The zerk-type grease fittings were
replaced with our familiar turndown style grease cups for a vintage
look to the line shaft. The line shaft was placed in such a
position that the belts are the same size, both adjustable through
slots in the pillow block mountings and the bracket on the
generator.
The cart was made from some donated oak. I purchased 8-inch
diameter cast iron wheels, riding on 3/4-inch diameter axles.
Bolsters were fabricated from 1/4-by-3-inch flat steel with a
steerable front axle, and 1/2-inch round rod for the handle. The
generator is bolted through the wood right to the rear axle for
static grounding.
Upon initial startup and testing, it was found that by setting
engine speed to 650 RPM, the generator operates at its required
3,600 RPM, with output at 120 volts AC.
To answer the question about what size pulleys you are looking
at, the engine has a 6-inch diameter pulley driving a 3-inch pulley
on the line shaft. The 11-inch pulley on the inside of the line
shaft drives a 4-inch pulley on the generator. The line shaft
pulley sizes were derived using the formula printed in an original
Hercules Gas Engine Operating Instructions that came with each new
Hercules engine purchased. The end results were verified with a
mechanical tachometer that contacts the center of the shaft.
My mechanic friend was present at the inaugural run. He said it
had the “cool factor.”
Contact Bob Naske at: 2059 State Highway 29, Johnstown, NY
12095; pulleypower@frontiernet.net
