Download Glossary

machine used to translate torque into linear force. It can also be defined as an
inclined plane wrapped around a shaft.
Screwdriver: A screwdriver, invented by Leonardo da Vinci, is a device
specifically designed to insert and tighten, or to loosen and remove,
screws. The screwdriver comprises a head or tip which engages with a
screw, a mechanism to apply torque by rotating the tip, and some way to
position and support the screwdriver. A typical hand screwdriver
comprises an approximately cylindrical handle of a size and shape to be
held by a human hand, and an axial shaft fixed to the handle, the tip of
which is shaped to fit a particular type of screw. A screw has a head with
a contour such that an
appropriate
Screw types:
screwdriver tip can be
(a) Slotted, (b) Phillips,
engaged in it in such a
(c) Pozidriv, (d) Torx,
way that the
(e) Hex key, (f) Robertson,
application of
(g) Tri-Wing, (h) Torq-Set,
sufficient torque to the
(i) Spanner
screwdriver will cause
the screw to rotate.
Sprocket: A sprocket is a gear or wheel with metal teeth that meshes with a
chain or track. Sprockets are used in bicycles, motorcycles, cars, tanks,
and other machinery. In the case of bicycle chains by varying the size
(and therefore, the tooth count) of the sprockets on each side of the chain,
modifying the overall gear ratio of the chain drive is possible. For
example, a 10-speed bicycle, by providing two different-sized driving
sprockets and five different-sized driven sprockets, allows up to ten
different gear ratios. The resulting lower gear ratios make the bike easier
to pedal up hills while the higher gear ratios make the bike faster to pedal
on flat roads.
Torque: A torque can informally be thought
of as "rotational force" or "angular force"
which causes a change in rotational
motion. A torque is defined by linear force
(F) multiplied by a radius (r).
Wrench: A wrench is a tool used to provide a
mechanical advantage in applying torque
to turn bolts, nuts or other hard-to-turn
items.
Glossary
Angular velocity: In physics, the angular
velocity is a vector quantity which
specifies the angular speed at which an
object is rotating along with the direction
in which it is rotating. The SI unit of
angular velocity is radians per second,
although it may be measured in other units
such as degrees per second, degrees per
hour, etc. When measured in cycles or
rotations per unit time (e.g. revolutions
per minute), it is often called the
rotational velocity and its magnitude the
rotational speed. Angular velocity is
usually represented by the symbol omega
(Ω or ω). The direction of the angular
velocity vector is perpendicular to the
plane of rotation, in a direction which is
usually specified by the right hand rule.
Axle: An axle is a central shaft for a
rotating wheel or gear. In some cases
the wheel or gear may be fixed to the
axle, with bearings or bushings
provided at the mounting points where
the axle is supported. An axle that is
driven by the engine or motor is called
a drive axle. A dead axle is not part of
the drivetrain but is instead freerotating. The rear axle of a front-wheel
drive car may be considered a dead
axle.
ω=
∆θ
∆t
∆θ
Angular velocity describes the
speed of rotation and the
orientation of the instantaneous
axis about which the rotation
occurs. The direction of the
angular velocity vector will be
along the axis of rotation; in
this case (counter-clockwise
rotation) the vector points
toward the viewer.
Train wheels are affixed to a straight
axle, such that both wheels rotate in
unison.
Bolt: A bolt is a cylindrical threaded fastener that passes through a work
piece and is held in place by a nut or a threaded hole on the other side.
Torque applied via an adjustable
end wrench
* Images and standard terminology provided, courtesy of Wikipedia.com
Chassis: The base frame of a motor vehicle. A chassis (pronounced:
chassey) consists of a framework which supports an inanimate object,
analogous to an animal's skeleton; for example in a motor vehicle or a
firearm. In the case of vehicles, the term chassis means the frame plus the
"running gear" like engine, transmission, driveshaft, differential, and
suspension. A body (sometimes referred to as "coachwork"), which is
usually not necessary for integrity of the structure, is built on the chassis to
complete the vehicle.
Drill bit: A drill bit is a cutting tool used to create cylindrical holes. Drill bits
are held in a tool called a drill, which rotates them and provides axial
force to create the hole.
Specialized bits are also
available for non-cylindricalshaped holes.
Drill press: A drill press is a
fixed style of drill, which
may be mounted on a stand
or bolted to the floor or
Some drill bits: Spade, lip and spur (brad point),
workbench. It consists of a
masonry bit, twist drill
base, column, table, spindle
and drill head, usually driven by an induction motor. The head has a set of
handles (usually 3) radiating from a central hub which, when turned, move
the spindle (and chuck) vertically, parallel to the axis of the column.
A drill press has a number of advantages over a hand held drill:
(a) less effort is required to apply the drill to the workpiece. The movement of the
chuck and spindle is by a lever working on a rack and pinion, this gives the
operator considerable mechanical advantage;
(b) the table may allow a vise or clamp to position and lock the work in place
making the operation secure;
(c) the angle of the spindle is fixed in relation to the table allowing holes to be
drilled accurately and repetitively.
Efficiency: In physics, mechanical efficiency is the effectiveness of a
machine. To show the effectiveness of a machine one must compare its
work input to its work output. Efficiency is often indicated by a
percentage, the efficiency of an ideal machine is 100%. Due to the fact
that energy cannot emerge from nothing and the Second law of
thermodynamics which states that the quality of energy will always
decrease (transforming from mechanical energy to thermal energy) the
mechanical efficiency of any machine will always be less than 100%.
Gear: a part, as a disk, wheel, or section
of a shaft, having cut teeth of such
form, size, and spacing that they mesh
with teeth in another part to transmit
or receive force and motion.
Gear ratio: The gear ratio is the
relationship between the number of
Two intermeshing gears.
teeth on two gears that are meshed (or
two sprockets connected with a
common roller chain) or the circumferences of two pulleys connected with
a drive belt.
Gear train: A gear train is a set or system of gears arranged to transfer
rotational torque from one part of a mechanical system to another.
Gear trains consist of: (1) Driving gears (attached to the input shaft), (2)
Driven gears (attached to the output shaft), and (3) Idler gears – which
are interposed between the driving and driven gear in order to maintain
the direction of the output shaft the same as the input shaft or to increase
the distance between the drive and driven gears. A compound gear train
refers to two or more gears used to transmit motion.
Nut: A nut is a type of hardware
fastener with a threaded hole. Nuts
are usually hexagonal to permit
tightening with a wrench, but may
also be square, winged, or
otherwise shaped. Along with a
bolt, nuts are designed to capture
and fasten objects together. Without
a nut the bolt would “slide out.”
needle-nose pliers
Lock jaw pliers, also called vise grips
Bolt with a nut
Pliers: Pliers are hand
tools, designed
primarily for gripping
objects by using
leverage. Pliers are
designed for numerous
purposes and require
different jaw
configurations to grip,
turn, pull, or crimp a
variety of things.
RPM: Revolutions per minute (abbreviated rpm, RPM, r/min) is a unit of
frequency, commonly used to measure rotational speed, in particular in the
case of rotation around a fixed axis. It represents the number of full rotations
something makes in one minute.
The International System of Units
(SI) unit for rotational velocity is
the radian per second.
Screw: A screw is a shaft with
a helical groove or thread
formed on its surface. Its
main uses are as a threaded
fastener used to hold objects
together, and as a simple
Screws come in a variety of shapes and sizes for
different purposes. U.S. Quarter coin (diameter 24
mm) shown for scale.