Wheel and Axle
• In this machine a wheel or
spoke is locked to a central
Gadget Anatomy Lab axle so that when one is
turned the other must turn.
• A longer motion at the edge
of the wheel is converted to a
Pre-lab Survey shorter more powerful motion
at the axle.
• In reverse, a short powerful
force at the axle will move
the wheel's edge a greater
Pulley System Wedge
• A single pulley simply • A wedge converts motion
reverses the direction of a in one direction into a
force. splitting motion that acts
• When two or more pulleys at right angles to the
are connected together, blade.
they permit a heavy load
to be lifted with less force. • Nearly all cutting
machines use the wedge.
• The trade-off is that the
end of the rope must move • A lifting machine may use
a greater distance than the a wedge to get under a
• A lever is a stiff rod that
• A screw is a central rotates around a pivot point
core with a thread or or fulcrum.
groove wrapped • Downward motion at one
around it to form a end results in upward
helix. motion at the other end.
• While turning, a screw • Depending on where the
converts a rotary pivot point is located, a
motion into a forward lever can multiply either
or backward motion. the force applied or the
distance over which the
force is applied.
• are toothed or pegged
wheels meshed together to
Other Elements of Machines transmit motion and force.
• In any pair of gears the
larger one will rotate more
slowly than the smaller
one, but will rotate with
• Each gear in a series
reverses the direction of
rotation of the previous
Bevel Gears Worm Gear
• a combination of a gear
meshed with the threads of
• mesh at an angle & • This combination changes
change the the direction of turning
direction of rotation motion by ninety degrees.
• Worm gears also decrease
the speed of turning from
screw to gear and increase
Ratchet Rack and Pinion
• a device that allows a wheel to • A single gear, the pinion, meshes
turn in only one direction. with a sliding toothed rack.
• The ratchet wheel has specially • This combination converts rotary
shaped teeth. motion to back and forth motion.
• A bar on a pivot called the
• Windshield wipers in cars are
"pawl" is fixed above the ratchet
wheel. powered by a rack and pinion
• The pawl slides over the teeth of
the ratchet in one direction, but – A small pinion at the base of the
wiper meshes with a sliding rack
blocks the motion of the teeth if
the wheel turns in the other
Chains and Belts Cam
• a wheel with shaped bumps on
• A chain or belt it.
connects two • Cams are often connected to
rods, levers, or springs.
separated wheels so
• In the gravity trip hammer
that one turns, the
shown here, the bumps on the
other will turn in the turning cam push down on the
same direction. end of the lever making it raise
the hammer again and again.
Let’s Look Hand Powered Drill
• Which elements of
machines do you see
in each gadget?
– Bevel Gears
at some examples – Worm Gear
and test your memory… – Screw
– Rack and Pinion
– Wheel and Axle
Simple Machines – Crank and Rod
Wing-Handle Corkscrew Scissor Style Jack
• Which elements of • Which elements of
machines do you see machines do you see
in each gadget? in each gadget?
– Pulley – Screw
– Wheel and Axle – Cam
– Screw – Pulley
– Rack and Pinion – Gears
– Lever – Lever
– Cam – Wedge
• Now, go to the lab station and begin your
Gadget Anatomy Lab
• Straighten up area when finished… and I
MEAN do it right!!!!! Everything should
look like it did when you got here.
Including lab stools.