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Appendix — Glossary
single-pole, double-throw (SPDT) switch — a three-terminal electri-
cal switch or relay that connects one terminal to either of two other
terminals.
single-pole, single-throw (SPST) switch — a two-terminal electrical
switch or relay that opens or closes one circuit.
slave control panel — a secondary derrick lower control panel that
is congured as a remote terminal of the master panel. The slave
panel is used in conjunction with a master panel to provide dual sta-
tion lower controls.
slave cylinder — a cylinder in which motion of the piston is produced
by the transfer of hydraulic uid from a master cylinder, resulting in
corresponding motion.
slide frame — the structure on a pressure digger used to support the
auxiliary engine, hydraulic reservoir, control station, and pivot weldment.
The slide frame can be extended horizontally from its stowed position
to adjust the distance of the kelly bar from the rotate frame.
slide pad — a rectangular block used as a bearing between extend-
ible boom or outrigger sections, usually composed of a non-metallic
material.
slip ring — an assembly of one or more conductive, rotating rings and
stationary brushes used to provide a continuous electrical connection
between rotating and stationary conductors. Commonly used at the
centerline of rotation of units equipped with continuous rotation.
slug face — the extreme end of the cable slug which is secured to the
cylinder rod or adjusting stud.
SMA connector — metal connector used for connecting ber optic
components.
snatch block — a device which has a means of attachment to connect
it to a boom or load, and which can be opened to receive a winch line
around an internal sheave.
snubber valve — a two-port valve with a manually adjustable orice
that restricts the ow of uid through the valve.
socket head — a cylindrical cap screw head design containing a
hexagonal (six-sided) female socket into which an Allen wrench can
be inserted to turn the cap screw.
solenoid — a coil of insulated wire that produces a magnetic eld within
the coil when electrically energized. When attached to a hydraulic valve,
the magnetic eld acts upon the valve to move internal valve parts.
solenoid valve — a valve which is actuated by a solenoid to controlling
the ow of hydraulic uid.
speed reducer — see gearbox.
spherical bearing — a bearing with a spherically shaped inner race
that is allowed to move freely inside a stationary outer race to accom-
modate misalignment.
splicer platform — a berglass platform equipped with a door and
latch.
spline — one of a number of equally spaced, load carrying teeth that
have been cut on the outside diameter of a shaft or inside diameter of
a bore, parallel to the shaft or bore centerline.
spool — a moving, cylindrically shaped part of a hydraulic valve that
moves to direct ow through the valve.
spring lockouts — a mechanical system which is engaged to keep
a vehicle’s suspension system from exing during operation of the
unit.
sprocket — a wheel with teeth along the circumference which are
shaped so as to engage with a chain, used to support and guide the
chain at a point of change in the direction of motion of the chain.
SSU (Saybolt Second Universal) — the unit of measure for Saybolt
universal viscosity.
stability — a condition of a mobile unit in which the sum of the mo-
ments which tend to overturn the mobile unit is less than the sum of
the moments tending to resist overturning; the mobile unit’s ability to
resist tipping.
stabilize — to provide adequate stability for a mobile unit to allow
operation of the vehicle-mounted device(s).
stabilizer — a device used to assist in stabilizing a mobile unit, such
as an outrigger, torsion bar or spring lockout.
stake — to slightly deform the threads of a fastener or material at the
joint between two components by placing the blade of punch or chisel
on the threads or joint and tapping on the handle with a hammer. The
deformed material serves to prevent loosening of the components.
stall torque — the torque produced by a rotating device such as a
motor or gearbox at zero rotational speed.
standard option — an option which can be ordered from a standard
order form and can be supplied without additional engineering work.
start/stop control module — an electrical device that relays sig-
nals from the unit’s remote start/stop system to the component(s) or
system(s) being controlled, such as the secondary stowage DC pump
and/or vehicle ignition system.
static mixer — a tube with no moving parts used to combine two or
more uids.
stationary frame — the structure attached to the subbase of a pressure
digger that supports the outriggers and rotate frame.
stationary hood — normally non-removable part of the disc housing
in which the discharge chute attaches.
stationary platform — a platform which can not be rotated about a
vertical axis to change its position in relationship to the boom tip.
stow — to place a component such as a boom or digger derrick auger
in its rest position.
strainer — a coarse lter.
strainer basket — a coarse, basket shaped lter which is mounted in
the ll hole of a reservoir and projects into the reservoir.
strand — 1: one of the groups of individual bers or wires within a
synthetic winch line or wire rope. 2: see suspension strand.
strand carrier — a device used to support and transport strand reels
on a vehicle.
strand reel — a reel or spool used for carrying suspension stand.
street side — the side of a vehicle toward oncoming trafc when the
vehicle is traveling forward in the normal direction in a lane of trafc.
stroke — 1: total linear movement in either direction of a piston or
plunger. 2: to change the displacement of a variable displacement
pump or motor.
subbase — a structural mounting interface between the pedestal and
the vehicle frame. It provides torsional stiffness and strength in addition
to that which would be provided from the vehicle frame alone.
subweldment — a smaller welded subassembly used within a more
complex welded structure.
suction lter — a lter located in a hydraulic system suction line or at
the outlet of a hydraulic reservoir which cleans uid owing from the
reservoir to the pump inlet.
suction line — the hydraulic line connecting the pump inlet port to
the reservoir outlet.
surge — a momentary rise of pressure in a circuit.
surge brake system — a surge brake system is entirely self-contained
on the trailer and is activated when the tow vehicle decelerates. The
momentum of the trailer pushes the surge brake housing forward. This
drives the push rod that is connected to the coupler into the master
cylinder. Brake uid is then forced out of the master cylinder into the
wheel cylinders or pistons that apply the trailer brakes. The entire
activation process is completed in less than one second.
suspension strand — a type of wire rope which is used to support
the weight of an attached communication cable suspended between
poles or other overhead support structures.
swage — to taper or reduce the diameter of a rod, tube or fastener by
forging, squeezing or hammering.
synthetic winch line — a winch line made from nonmetallic synthetic
bers which are formed into strands that are then braided together to
make a complete rope.
T-stand — a “T” shaped weldment for mounting lower controls to the
vehicle.
tachometer — an instrument used for displaying the speed of rotation
of an engine output shaft.
tailshelf — the rear portion of the mobile unit above and behind the
rear axle.
tailshelf tools — see lower tool circuit.
tank — the hydraulic reservoir.
telescopic — having sections that slide within or over one another to
change overall length.
tension spring — springs controlling downward force of the upper
feed roll.
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