A pneumatic hand held percussive drill designed as a boring
tool.
Jack hammer
A hand held rock drill worked by compressed
air.
Jet
A stream of vapor, gas or liquid coming out fast from a narrow
orifice.
Joule
A measurement. The international unit of energy. One joule is
equal to one WATT - second or 0.737 foot pounds.
Joule effect
The conversion of mechanical, electrical or magnetic energy
into heat.
Joule Thompson
effect
When a perfect gas flows through a throttling with constant
inlet and outlet pressures, the temperature of the gas is the same
before and after it flows through the throttling. There is a
temperature drop, however, during the passage of gas through the
throttling device itself. At this point internal energy is
transformed into kinetic energy with an accompanying temperature
drop. However, for real gases there is a sustained change in
temperature, even though the energy content of the gas remains
constant. This is called the Joule Thompson effect.
Jounce
The compression of an air actuator (air spring) below its
design height.
Journal
That part of a shaft or axle that rotates or angularly
oscillates in or against a bearing or about which a bearing
rotates or angularly oscillates.
Journal bearing
A sliding type of bearing having either rotating or
oscillatory motion and in conjunction with which a journal
operates. In a full or sleeve type bearing, the bearing surface is
360 degrees in extent. In a partial bearing, the bearing surface
is less than 360 degrees in extent.
