Rise of the Self-Oiling Windmil

Innovative systems eliminated dreaded maintenance chore


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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 winds.

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 lubrication.

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 oil.

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 Windmills by T. Lindsay Baker.

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