9
Appendix — Glossary
nontransferable boom ares — boom ares that are permanently
attached to the boom tip of a digger derrick.
nontransferable upper controls — an upper control panel on a digger
derrick that is permanently attached to the upper boom tip.
normally closed switch — a switch which is closed to allow current
to ow through it when it is not actuated, and opens to interrupt current
ow when actuated.
normally closed valve — a two-way valve which is closed to block
uid from owing through it when it is not actuated, and opens to allow
ow when actuated.
normally open switch — a switch which is open to prevent current
from owing through it when it is not actuated, and closes to allow
current ow when actuated.
normally open valve — a two-way valve which is open to allow uid
to ow through it when it is not actuated, and closes to block ow
when actuated.
nozzle — a tube-like device for accelerating and directing the discharge
ow of uid.
NPT — National Pipe Thread.
NPTF — National Pipe Thread Fluid, a pipe thread form which is
modied from the NPT form to improve the resistance to uid leakage
through the threads in a connection.
O-ring — a ring of material with a circular cross section that is used
as a gasket, usually made of synthetic rubber.
ohmmeter — an instrument used to measure the resistance in ohms
between two points in an electrical component or circuit.
on/off circuit — circuit that supplies constant electrical power to a
solenoid or other component when a relay or switch is closed and
removes the power when the relay or switch is opened.
one-man platform — a platform designed to carry one person. It is
usually 24″ wide x 30″ wide or 24″ wide x 24″ wide.
open center — a directional valve design in which pump output re-
turns freely to the reservoir when the valve spool(s) is in the center
or neutral position.
open circuit — an electric circuit that has innitely high resistance,
resulting in no current ow. An open circuit may be caused by a loose
connection, broken wire, corrosion or poor contact where an electrical
component is grounded to the unit structure.
operational area — the area surrounding a chipper effected by chip
discharge, noise, or any chipper operations.
operator — a person trained, authorized and engaged in the opera-
tion of the unit.
optical ber — a thin strand of transparent glass or plastic used to
transmit signals using light throughout the length of the strand.
orice — a restriction in a hydraulic or pneumatic circuit, the length of
which is small in respect to its diameter.
OSHA — Occupational Safety and Health Administration.
out and down outrigger — an outrigger that has independently-
controlled horizontal and vertical extendible outrigger legs.
outboard bearing — a bearing which supports the end of a gearbox
output shaft farthest from the gearbox.
output signal — a radio wave intended to pass communication from
a source to a destination.
outrigger — a structural member, which when properly extended or
deployed on rm ground or outrigger pads, assists in stabilizing the
mobile unit.
outrigger controls — the controls for operating the outriggers.
outrigger cylinder — the hydraulic cylinder which extends and retracts
or unfolds and folds an outrigger leg.
outrigger interlock system — a system which requires all outriggers
to be extended to a specied position before other unit functions are
allowed to operate.
outrigger interlock valve — a valve which prevents above rotation
sense line signals from reaching the pump until the outriggers have
been lowered.
outrigger leg — 1: the moveable structural component of an outrigger
which extends or unfolds to position the outrigger shoe on the ground,
and which retracts or folds to return the outrigger shoe to the stored
position. 2: the stationary structural component of an extendible outrig-
ger from which the moveable outrigger leg extends.
outrigger motion alarm — an audible warning system to alert person-
nel that outriggers are being lowered or moved.
outrigger pad — a portable piece of rigid material which is placed
under an outrigger shoe to increase the contact area with the ground
surface when the ground surface is not rm enough to support direct
contact from the outrigger shoe.
outrigger shoe — the component of an outrigger that is attached to
the moveable leg and that contacts the ground or outrigger pad to
stabilize the mobile unit.
outrigger signal valve — a valve used to provide a signal to the pump
when the outriggers are being operated and to allow a separate signal
system to control the aerial device operation.
outrigger spread — the distance between the outer edges on xed
shoes, or between pin centerlines on pivoting shoes, of opposite outrig-
gers which have been extended or deployed to a given position.
over travel — movement of a mechanism beyond its normal stop-
ping point.
overcenter aerial device — a type of articulating-boom aerial device
on which the upper boom can unfold from the stored position to beyond
a vertical position.
overframe — an outrigger weldment mounting position located above
the vehicle chassis frame.
overload — the condition existing when a load greater than the rated
capacity or design lead is applied to a unit or component.
override — the takeover of boom movement control functions from
the platform controls by the activation of the lower control station
controls.
overtighten — to torque a threaded fastener beyond the recommended
torque value.
oxidation — the reaction of a substance with oxygen.
paddle — part of the disc assembly which propels chipped debris into
the discharge chute.
panic bar — a safety system which when manually activated stops
movement of the feed roll(s) on a chipper.
parallel link — the secondary load-carrying structure of an elevator
lift.
particle count — a visual count of the numbers of particulate contami-
nants in a quantity of a hydraulic uid.
passage — a machined or cored uid conducting path that lies within
or passes through a component.
payload — any tools, materials, fuel and occupants carried by the
mobile unit that are not permanently attached.
pedestal — the stationary base of a unit that supports the turntable
and is attached to the subbase or vehicle frame.
pedestal mount — a mounting conguration for an aerial device in
which the turntable is mounted on a pedestal consisting of a box-like
structure.
penetration — the distance the vehicle frame is lifted after the outrig-
gers contact the ground surface.
phase — a conductive wire or cable used for transmitting high voltage
electrical current. The phrase “phase to phase” can be referenced as
any two conductors of a three-phase electrical power line system.
pilot operated — condition in which a valve is actuated by hydraulic
uid pressure.
pilot operated check valve — a check valve that can be opened
to allow ow in the normally blocked direction by applying hydraulic
pressure to a pilot port.
pilot pressure — auxiliary pressure used to actuate or control hydraulic
components.
pilot valve — an auxiliary valve used to control the operation of
another valve.
pin — a cylindrical structural device used to allow a pivoting joint or
to connect mating parts.
pin retainer — a device which is used to hold a pin in place in an
assembly.
pinch point — a particular location in which a human body or a part
of the body may become pinched or pinned between moving mechani-
cal parts.
To Next Page
Loading...