Glossary 353
O
oblique drawing: A type of pictorial drawing
that features one side of the object as the
front image. (5)
Occupational Safety and Health
Administration (OSHA): An agency of the
US Department of Labor, whose mission is to
ensure safe and healthful working conditions
for all workers. (15)
ohm (Ω): The base unit of measurement of
resistance. (8)
ohmmeter: A meter that is used to measure
resistance. (8)
Ohm’s law: The law that defi nes the
relationship between voltage, current, and
resistance. (8)
open-channel fl owmeter: A type of fl owmeter
that measures the fl ow in a channel rather
than in a pipe. (15)
operation process chart: A type of chart used to
study all operations in the manufacture of an
entire product. (14)
operations engineer: An engineer who controls
and maintains large systems, such as
manufacturing facilities, railroad systems,
and traffi c systems. (16)
operation sheet: The way the operation name,
machine, and tooling are recorded and
communicated. (14)
optimization: The process of creating the most
optimal solution within the specifi cations
and constraints. (1)
oral presentation: The spoken delivery of a
report to an audience. (6)
OR gate: A gate that provides an output of 1 if
either or both of the inputs are 1. (12)
orthographic drawing: A drawing with true
shape that shows what a part will look like
from a given direction. See also multiview
drawing. (2)
oscilloscope: An electrical test device whose
screen can show the exact shape of a wave
and, therefore, any possible distortion. It can
measure voltage, frequency, pulses, and the
timing of multiple signals. (8)
P
parallel circuits: Circuits that have more than
one load and multiple paths for current
fl ow. (8)
Pascal’s law: The law that states that all fl uids
exert the same amount of pressure in all
directions when in a limited space. (10)
patent: An exclusive right that is granted by a
government to the creator of a new product
or design so others cannot produce it
without permission. (16)
perspective drawing: A type of pictorial
drawing that shows an object from a specifi c
point of view and simulates what the eye
sees. (5)
pictorial drawing: A drawing that shows a
single view of an object in a way that makes
it look 3-D as your eye would see it. (2)
piers: The main vertical columns that transfer
the load of the bridge into the ground. (9)
piping and instrumentation diagram: A detailed
type of plan diagram that shows every
detail of plant layout and design, including
all chemical fl ows, instrumentation,
temperature, control systems, location of all
equipment, and everything else needed to
build and maintain the facility. (15)
pitch: The up-and-down movement of the nose
and tail. (13)
plant layout: The arrangement of facilities
whose design is based on the location of the
materials that will be made into products
and how they are moved through the plant,
equipment layout, utility location, and traffi c
fl ow. Layout is also based on the economics
of construction and operation, the specifi c
requirements of the processes that will take
place, the convenience of the maintenance
that will be necessary, possible future
expansion, and safety. (14, 15)
plasticity: The deformation that occurs from the
yield point to the fracture point. (7)
pneumatic system: A system that uses air
instead of fl uid to transmit power. (10)
polarity: The positive or negative condition at
the power supply terminal. (8)