Farm Collector

Rise of the Self-Oiling Windmil

For the farmer in the early 1900s, a windmill was almost as good
as a hired hand … except when maintenance was needed. Then, the
labor-saving device – with working parts located as much as 80 feet
in the air – fast became a nuisance. Self-oiling systems, first
devised in about 1910, changed all that.

Having worked in the well and water-related
business, as well as with vintage pieces in our museum (Little
Village Farm, Dell Rapids, S.D.), I have become quite involved with
windmills. They are rather interesting pieces. Unlike most
mechanical items, they require only minimal annual service. And, if
you forget to maintain a windmill, it will keep working right
along, none the worse for wear, for several years.

Early windmills were termed “direct stroke.” For each revolution
of the wheel, water was lifted. Later, back-geared mills were
devised. These made 3 to 3-1/2 revolutions for each pumping cycle.
The theory behind that technology was that more water would be
pumped, on average, as the geared-down units run in lighter

Initially, windmill mechanisms were exposed to the elements,
with either grease cups to fill, or boxings with lids. The boxings
contained a cotton waste into which oil was poured, providing
lubrication for a short time. The majority of these mills employed
babbitt for bearings, babbitt being fairly tolerant of lack of

Self-oiling mills were introduced in 1910 with “The Little
Giant” from the Elgin (Ill.) Wind Power & Pump Co. This unit at
least kept the gears and bearings oiled and protected, but left the
stroking components exposed to face the elements.

In 1915, Aermotor, another major player, devised a
less-than-stellar design for oiling the top works. In that design,
a bent spring arrangement was supposed to flick oil around. It
didn’t. We have a Model 502 in the museum and you can readily see
why this plan did not work.

Aermotor solved the problem quickly with its Model 602,
manufactured from 1916 to 1933. The new design worked well, and
many rebuilt models remain in use today. Aermotor’s Models 702 and
802 are similar in construction to Model 602. The upper works are
oiled with a wire ring that contacts the large gears, picking up
oil as it turns. The turning motion then deposits oil on the
crosshead area, giving it adequate lubrication. On the 802, babbitt
bearings were replaced by composite bearings, which can run without

James Dockal at the Aermotor factory in San Angelo, Texas, notes
that in his nearly 20-year career at Aermotor (beginning in 1986),
he has yet to see a case of failure resulting from the new style
bearings. Motor cases manufactured there are produced with ductile
iron, making them stronger and, because ductile iron is not porous,
less prone to leakage. It’s worth noting that all Aermotor
windmills come with a seven-year warranty.

The front windwheel shaft bearing on an Aermotor gets its oil
from a spout-like washer held against the small gear with a spring.
This spout sends oil down a galley to the front, and it returns to
the main housing via a galley below the shaft.

In the 1920s, Baker Manufacturing Co. introduced a “ham bone”
model (so named because the unit’s cast iron case resembled a ham
bone). This unit was totally enclosed, with a tin cover securely
bolted to it. The cover was removed when changing oil or servicing
parts. Baker also used a large gear to splash oil around, plus a
sleeve-type pump which worked with each stroke to move the oil to
the top works. From there the oil traveled down, getting out to the
front bearing on the wind-wheel. From that bearing, oil then
returned (via a galley in the casting) to the main motor housing,
beginning the cycle anew.

Duplex Manufacturing, which manufactured the “Andrew” in
Superior, Wis., in 1929-30, had a really nice oiling system with a
cast iron scraper running on top of the internal gear. As the gear
turned, oil was scraped off and down into the various galleys. This
mill also featured a removable front hub, enabling assembly of the
fan on flat ground. It could then be hoisted up into place and
installed on the motor with three bolts. This mill was probably too
expensive for the times. You see few of these, even though they
were high quality mills.

Dempster Manufacturing Co. (still an active manufacturer of
windmills, based in Beatrice, Neb.) had yet another approach to
self-oiling systems in the years leading up to 1920. When you open
the “helmet” (the mill’s tin top is referred to as a helmet) you’ll
see a threaded sleeve on the fan shaft. That carries oil to the
front bearing, a galley below returning it to the main case. This
unit also has oil collectors on the crank gears, which get oil to
the crosshead lubricating upper parts.

Windmill oil is a light, non-detergent oil, roughly 5 weight, as
it must flow readily under all conditions. We have a decades-old
can of genuine Aermotor oil in our museum, and when you shake the
can, you would think it contained water. Ideally, you’d change the
oil in your windmill’s engine annually. Drain the motor, clean out
any grit or dirt on the bottom, make sure galleys to the front
bearing are open, check the helmet for bullet holes (if you find
holes, solder a patch, or fill it with a bolt … if you don’t patch
those holes, water comes in, and oil goes out), add new oil and
bolt on the helmet. Not much work for pumping lots of water!

For more information: A Field Guide to American
by T. Lindsay Baker

Jim Lacey is an antique farm equipment enthusiast and
collector in South Dakota. Contact him at (605) 428-5979.

  • Published on Jun 1, 2005
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