Pelton wheel
Overview
 
The Pelton wheel is an impulse turbine which is among the most efficient types of water turbines. It was invented by Lester Allan Pelton
Lester Allan Pelton
Lester Allan Pelton was an American inventor who contibuted significantly to the development of hydropower and hydroelectric power in the old West and world-wide. In the late 1870's he invented the Pelton water wheel, then the most efficient design of the impulse water turbine...

 in the 1870s. The Pelton wheel extracts energy from the impulse (momentum
Momentum
In classical mechanics, linear momentum or translational momentum is the product of the mass and velocity of an object...

) of moving water, as opposed to its weight like traditional overshot water wheel
Water wheel
A water wheel is a machine for converting the energy of free-flowing or falling water into useful forms of power. A water wheel consists of a large wooden or metal wheel, with a number of blades or buckets arranged on the outside rim forming the driving surface...

. Although many variations of impulse turbines existed prior to Pelton's design, they were less efficient than Pelton's design; the water leaving these wheels typically still had high speed, and carried away much of the energy.
 
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