Rack and Pinion : It is a pair of gears which convert
rotational motion into linear motion. The circular pinion engages
teeth on a rack (flat bar). Rotational motion applied to the
pinion will cause the rack to move to the side, up to the limit
of its travel.
Radial Bearing : It is a bearing with rolling contact
in which the direction of action of the load transmitted is
radial to axis of the shaft.
Radial Drill : It is a drilling machine in which the
drill spindle can be moved along a horizontal arm that itself
can be rotated about a vertical pillar.
Radial-flow Turbine : It is a turbine in which the gases
flow primarily in a radial direction.
Radial Locating : It is one of three locating problems
in tooling to maintain the desired relationship between the
workpiece, the cutter, and the body of the machine tool. The
other two locating problems are concentric and plane locating.
Radial Rake : It is the angle between the cutter tooth
face and a radial line which is passing through the cutting
edge in a plane perpendicular to the cutter axis.
Radiant-type Boiler : It is a water-tube boiler in which
boiler tubes form the boundary of the furnace.
Ram-type Turret Lathe : It is a horizontal turret lathe
in which the turret is mounted on a ram or slide that rides
on a saddle.
Rankine Efficiency : The efficiency of an ideal engine
which is operating on the Rankine cycle under specified conditions
of steam temperature and pressure.
Ratchet Coupling : It is a coupling between two shafts
which uses a ratchet to allow the driven shaft to be turned
in one direction only and also to permit the driven shaft to
overrun the driving shaft.
Rated Horsepower : It is the normal maximum, allowable,
continuous power output of an engine, turbine motor or other
Ratio of Expansion : The ratio of the volume of steam
in the cylinder of an engine when the piston is at the end of
a stroke to that when the piston is in the cutoff position.