Roymech engineering encyclopedia

Machine Parts, Cams, Springs & Mechanisms

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Machine Elements & Mechanisms

Jump to: Cams-Flywheels-Mechanisms -Power Screws-Shock Absorbers-Springs


Cams are mechanical devices used to convert rotary motion into linear or oscillatory motion. They consist of a cam and a follower that rides on the cam's surface. As the cam rotates, the follower is subjected to different profiles of the cam, resulting in specific motions or actions.

Cams find applications in various mechanical systems, such as engines, automotive systems, manufacturing equipment, and machinery. They are commonly used to control valve movements in engines, operate feeding mechanisms in automatic machines, control the opening and closing of doors, and provide specific movements in various mechanical systems.

Cams can have the following profiles, including:

Displacement or translating cams: These cams provide linear motion to the follower as the cam rotates. The follower moves in a straight line parallel to the axis of rotation.

Oscillating or swinging cams: These cams provide oscillatory motion to the follower as the cam rotates. The follower moves back and forth in an arc.

Cylindrical or barrel cams: These cams have a cylindrical shape and provide a combination of linear and oscillatory motion to the follower.

Plate or disk cams: These cams have a flat plate or disk shape with specially shaped profiles to control the motion of the follower.



A flywheel is a mechanical device used to store rotational energy. It consists of a heavy rotating wheel or disc that is mounted on a shaft. The primary purpose of a flywheel is to maintain the rotational momentum of a system and provide consistent energy output.

Flywheels have several important functions and applications:

Energy Storage: Flywheels are often used to store energy in systems where a consistent or smooth output of energy is required. For example, in reciprocating engines, the flywheel helps to smooth out the fluctuating energy produced during the power strokes and deliver a more uniform output.

Inertia and Stability: The rotational inertia of a flywheel helps to maintain the speed and stability of a system. It resists changes in rotational motion, which can be important in various applications, such as in vehicles, machinery, and power transmission systems.

Power Compensation: Flywheels can compensate for fluctuations in power supply or demand. When there is excess power available, the flywheel can store it, and when there is a shortage, it can release the stored energy to meet the demand.

Motion Control: Flywheels are used in various applications to control or regulate the speed of rotational motion. They can act as speed regulators, providing a constant speed or limiting the acceleration rate.

Energy Recovery: Flywheels can also be used for energy recovery. For example, in hybrid vehicles or regenerative braking systems, the kinetic energy during deceleration or braking is converted into rotational energy and stored in the flywheel for later use.



Mechanisms are devices or systems that consist of interconnected components designed to achieve specific types of motion or transmit forces. They are used to convert one type of motion into another or to amplify or modify forces. Mechanisms are fundamental building blocks in engineering and are widely used in various machines, vehicles, and mechanical systems. Here are a few common types of mechanisms:

Linkages: Linkages are mechanisms composed of rigid links connected by joints. They enable the transformation of input motion into a desired output motion. Linkages can produce different types of motion, such as linear, rotary, oscillatory, or complex motions. Examples of linkages include the four-bar linkage, which is commonly used in machines and mechanisms like engines and steering systems, and the scissor mechanism, often found in lifting and cutting devices.

Gears: Gears are toothed wheels that mesh together to transmit rotational motion and torque between axes. They provide a mechanical advantage, allowing for speed reduction, speed increase, torque amplification, or direction reversal. Gears are commonly used in gearboxes, transmissions, clocks, and many other mechanical systems.

Belts and Pulleys: Belts and pulleys are used to transmit power and motion between rotating shafts. They consist of a belt that wraps around two or more pulleys. By changing the size of the pulleys, different speed ratios can be achieved. Belt and pulley systems are widely used in engines, conveyor systems, and many types of machinery.

Levers: Levers are simple mechanisms consisting of a rigid bar or beam that pivots around a fixed point called a fulcrum. They can be used to magnify or change the direction of a force. Levers are found in various applications, such as wrenches, seesaws, and lifting devices.


Power Screws

Power screws are mechanical devices used to convert rotary motion into linear motion or vice versa. They consist of a threaded screw and a matching nut or threaded hole, which allows the screw to move axially when rotated. Power screws are commonly used in applications that require precise linear motion or the transmission of large forces.

The primary advantage of power screws is their ability to provide high mechanical advantage and convert rotational motion into linear motion with relatively low friction.

Power screws have several applications, including:

Linear Actuators: Power screws are commonly used in linear actuators, which are devices that convert rotary motion into linear motion. Linear actuators with power screws find applications in robotics, automation, positioning systems, and industrial machinery.

Jacks and Lifts: Power screws are used in jacks and lifts to raise and lower heavy loads. They provide a mechanical advantage that allows for the application of large forces with minimal effort.

Presses: Power screws are utilized in presses to exert controlled force for tasks such as metal forming, forging, and assembly operations.

Positioning Systems: Power screws are integral components in precision positioning systems used in fields like optics, microscopy, and measurement equipment. They enable precise and repeatable linear motion for accurate positioning.

Power Screws

Shock Absorbers

In engineering, shock absorbers are devices or components designed to mitigate the effects of shocks, impacts, and vibrations in a mechanical system. They are commonly used to dampen and control motion, absorb energy, and reduce the transmission of forces to other components or structures.

The primary function of shock absorbers is to convert the kinetic energy generated by sudden movements or impacts into heat energy. By doing so, they help to dissipate the energy and provide a smoother, more controlled response, improving the overall performance, stability, and comfort of the system.

Shock absorbers are particularly important in applications where controlled motion, stability, and protection against sudden forces are critical. They are widely used in various fields, including automotive, aerospace, industrial machinery, robotics, and many other mechanical systems.

The engineering definition of shock absorbers encompasses their ability to:

Dampen Vibrations: Shock absorbers attenuate vibrations and oscillations by dissipating the energy generated during the system's motion. They help to reduce unwanted vibrations, which can affect performance, accuracy, and comfort.

Absorb Impacts: When a system encounters sudden impacts or shocks, such as hitting a pothole or encountering an obstacle, shock absorbers absorb the energy of the impact and dampen the resulting forces. They help to protect the system and its components from excessive stress or damage.

Control Motion: Shock absorbers provide controlled motion by regulating the speed and damping characteristics of a system. They play a crucial role in maintaining stability, ensuring tire contact with the road (in automotive applications), and improving handling and maneuverability.

Improve Comfort: In many applications, shock absorbers contribute to user comfort by reducing the effects of vibrations and shocks. This is particularly important in vehicles, where they enhance ride quality and passenger comfort.

Shock Absorbers


n mechanical design, springs are widely used components that store mechanical energy and provide various functions such as restoring forces, damping, vibration isolation, and motion control. They are flexible, elastic elements that deform under the application of a load and then return to their original shape when the load is removed.

Spring Types: There are several types of springs, each suited for different applications. Common types include:

Coil Springs: These are helical springs made of wire wound in a spiral shape. They are versatile and widely used in a range of applications.

Torsion Springs: Torsion springs exert a twisting force when subjected to a torque. They store and release energy by rotating about their axis.

Leaf Springs: Leaf springs are flat, elongated springs made from multiple layers of spring steel. They are commonly used in vehicle suspension systems.

Compression Springs: Compression springs are designed to resist compressive forces. They become shorter when compressed and exert a restoring force when the load is released.

Extension Springs: Extension springs extend in length under tensile forces. They provide restoring forces when stretched and are often used in applications where the spring needs to return to its original position.