Wind Engines
Operation
The distinct advantage of wind engines is their ease of use. Unlike custom windmills that had to be manually turned into the wind, wind engines automatically turn the sails into the wind. In fact, an operator is not required to make adjustments of any kind to keep the engine operating at peak efficiency. Regardless of weather conditions, wind engines are built to be self-regulating—they even brake if strong gales prevent safe operation.
Maintenance
Aside from a periodic visual inspection, not much maintenance
is required to operate a wind engine—which is exactly how it’s
designed to function. Many are so well built that
“tune-ups” are virtually unheard of. All that is required
of the operator is ensuring that the contact points are
well-lubricated with gear oil. On early wind engines, this
required operators to climb the tower every few days to oil the
gearbox. Although this design was still a vast improvement
from operating a custom windmill (that required daily
maintenance with several large gears), it was not uncommon to
hear of people losing their balance and falling to their death.
When safety became the top priority of manufacturers, designs
were modified to make maintenance trips less daunting (or, at
the very least, less frequent). One short-lived model was
the “tilting tower” design, in which the tower, centrally
balanced on a hinge, flipped the windmill so that the gearbox
could be oiled from the ground. Another design was the
“pull-the-wire” concept, in which the operator released more oil
into the gearbox from the ground by releasing small amounts from
a larger reservoir (of course, the tower still had to be climbed
to refill that reservoir).
Ultimately, an innovation of the Elgin Windmill Company
prevailed. “Self-oiling” gearboxes required fewer than one
oil change per year. These operated with totally enclosed
gearboxes that contained the oil within and protected the gears
from weathering. It did not take long for windmill
manufacturers to borrow this design, which continues to prevail.
An Aermotor gearbox oiling diagram,
designed to "last for many years."
Diagram from Aermotor Windmill
Speed Control
Halladay’s original patent called for four spring-hinged
“self-furling” sails, which could, like modern wind turbines,
turn upon their axes to alter the surface area exposed to the
wind. The sails were not mounted directly to the gearbox
but rather to a set of axles: as the hub increased in rotational
velocity, a spring control turned those axles to expose less
surface area to the wind. If the velocity dropped, the
sails turned back to their normal position.
When engine designs changed to employ rigid annular sails
instead, Halladay addressed the speed control issue with the
pivoting sectional wind wheel. The sectional wheel
similarly operated on a set of springs, but rather than turn the
thin, individual slats of wood out of the wind, each of the six
sections of the wheel opened to allow wind to pass through as
demonstrated below:
Demonstration of a pivoting wind wheel. As the wind speed (and pressure) increases, it activates controls that automatically fan the sections of the wheel open, allowing air to pass through the sails rather than turn them. This operation was present on both vaned and vaneless models.
Illustration by Tom Haskell
While Halladay successfully sold his “standard” wind engine
models across the Midwest, the problem of speed had to be
addressed on models with a solid, non-pivoting wheel. To
keep the mill from spinning out of control, a second, smaller
vane was added. While the main tail vane sits
perpendicular to the wind wheel and keeps the gearbox in the
wind, the smaller vane operates parallel to the sails.
If the wind is strong enough to push the small vane, it swings
the gearbox out of the wind (this is not unlike the manual
motion of “quartering” the cap of a custom windmill).
Pumping
There are several design patents in relation to the
construction of the gearbox and mechanisms, but the basic
principle involves a simple geared crank to create a mechanized
water pump. Once the annular sails are facing the eye of
the wind, they will turn the wind shaft. The wind shaft
passes through a smaller gear (akin to a spur gear) and into a
bearing at the end of the gear box (on some models, this may
turn an additional gear to activate the self-oiling feature).
The spur gear on the wind shaft turns a larger toothed gear next
to it. The larger gear is attached to the pumping rod via
a pitman arm; the arm converts the rotary motion of the gear
into a vertical motion for the pumping rod. The best way
to think about the motion within the gearbox is that of an
automobile engine—rather than the vertically-moving piston
turning the crankshaft (that turns the wheels of the car), the
crankshaft turns to move the piston.
The stand pipe contains the chambers and check valves necessary
to bring water to the surface. The downward motion of the
pump forces the check valve to open, allowing water inside the
chamber. As the pump moves upward, the weight force from
the water closes the check valve, bringing water with it.
This process continues as long as the engine is running.
