Horse Power, Actual.
The rate of activity of a machine, as actually developed in condition
for use. It is less than the indicated or total horse power, because
diminished by the hurtful resistances of friction, and other sources of
waste. It is the horse power that can be used in practise, and which in
the case of a motor can be taken from the fly-wheel.
Horse Power, Electric.
The equivalent of a mechanical horse power in electric units, generally
in volt-amperes or watts; 745.943 watts are equivalent to the activity
of one British horse power; 735.75 are equivalent to one metric horse
power. The number 746 is usually taken in practical calculations to give
the equivalency.
[Transcriber's note: Contemporary values are: Mechanical (British)
horsepower = 745.6999 Watts; Metric horsepower = 735.49875 Watts]
Horse Power, Indicated.
The horse power of an engine as indicated by its steam pressure, length
of stroke, and piston area, and vacuum, without making any deduction for
friction or hurtful resistances. The steam pressure is in accurate work
deduced from indicator diagrams.
Horse Power, Hour.
A horse power exerted for one hour, or the equivalent thereof. As the
horse power is a unit of activity, the horse power hour is a unit of
work or of energy. It is equal to 1,980,000 foot pounds.
H. P.
Abbreviation for "horse power."