Introduction to
Mechanisms
Mechanisms are essential in understanding how things work. This
presentation will cover slide crank and pin, rack and pinion, and ratchet
mechanisms, including their components, diagrams, and applications.
Slide Crank and Pin Mechanism
Definition and Components
Uses and Applications
The slide crank and pin mechanism consists of a
This mechanism is commonly found in engines,
sliding block, crank, and connecting pin. It's used
pumps, and reciprocating saws due to its ability to
to convert rotational motion into reciprocating
convert circular motion to linear motion efficiently.
motion.
Rack and Pinion Mechanism
Definition and Components
The rack and pinion mechanism involves a gear
set comprising a circular gear and a linear gear.
It's used to convert rotational motion into linear
motion.
Uses and Applications
This mechanism is commonly utilized in steering
systems of vehicles and in some types of
elevators due to its simple and reliable
operation.
Main Types of Rack and Pinion Gears
Straight Teeth
Straight teeth have a tooth axis perpendicular to the rotation axis.The straight cut gears are used in racing cars as torque is
an aspect that is much needed in racing.
Helical Tooth Gears
Helical tooth gears are frequently quieter and more efficient than straight tooth gears
because they allow continuous engagement over the tooth length. Helical gears are
commonly used in industrial machinery, such as conveyor belts, mixers, and pumps
Roller Pinion
Roller pinion drives employ bearing-supported rollers that mesh with the rack’s teeth to
Ratchet Mechanism
1
Definition and Components
A ratchet mechanism consists of a gear and a pawl. It allows motion in only
one direction, preventing backward movement.
2
Uses and Applications
Ratchet mechanisms are commonly found in hand tools such as wrenches
and socket sets, allowing for efficient tightening and loosening of bolts and
fasteners.
Spring Blade Ratchet
This ratchet shown below uses flat springs as drive and holding pawls with proper heattreatment ,this type of drive will give long life under light loading.
Cam Driven Ratchet
This type of ratchet as shown below the cam can be design so that the drive pawl has little
kinetic energy when it strikes the wheel: this reduces impact & overtravel.