26 Fluid Power
Middle Ages
During the Middle Ages following the fall of
the Roman Empire, the development of new tech-
nology was extremely slow in Western civiliza-
tion. In the Western countries of Europe, existing
Roman structures were allowed to gradually dete-
riorate as major emphasis was placed on defense,
conquest, development of monastic (religious)
orders, and support of the Crusades. The Islamic
world, however, continued to make progress on
public water supply systems, public baths, and
power-driven mills. Many of these ideas were
introduced in Europe during the twelfth and thir-
teenth centuries by returning Crusaders.
At first, waterwheels were just a means of turn-
ing millstones for grinding grain for local con-
sumption. Waterwheels began to be recognized
as an important source of power for other uses
during the fourth and fifth centuries. They were
slowly adapted for use in sawmills, paper mills,
iron mills, and mining operations. An example
of the slow, but pervasive, growth of water power
as a prime mover is that the earliest recorded use
in England was in the eighth century with over
5000 in use by the eleventh century, Figure 1-15.
Water mills were profitable operations and found
in every community that had a suitable stream.
Windmills continued to be developed in several
forms in the Near East, where easy access to water
was limited. Records indicate that windmills were
extensively used in Afghanistan and Persia, with
a number of designs developed to control speed.
Speed control was required because of strong winds
in the area. Use of wind power spread throughout
the Islamic world during the period.
The first recorded use of windmills in
Western Europe was during the twelfth century,
Figure 1-16. These mills were initially used for
grinding grain, but were gradually modified for
use in other applications, such as sawing lumber,
pumping water, and manufacturing. Holland and
the other “low countries” of Europe were prime
users of these mills because of their flat terrain
and consistent winds.
Windmills gradually developed with improve-
ments in design and increases in size. Power out-
put ranged from 4 to 5 horsepower for the average
mill to over 15 horsepower for larger mills. At the
peak of windmill use, Holland had over 8000 mills,
with many of them having sail spans as large as
100 feet.
Figure 1-15. Thousands of watermills have been
used throughout history as prime movers for
grinding grain and powering early machines.
Modern water turbines for electric generation
and fl uid power motors have evolved from these
early designs. (©2007 Jupiterimages and its
licensors. All rights reserved.)
Figure 1-16. Windmills have played an important
part in the development of civilization. Their use is
limited to coastal and plains areas with consistent
winds. This design was used on a farm from the
early to mid-1900s.