MECHANISMS

They're classified in:

Transmitting Motion

Transforming Motion

Linear

Rotary

Rotary to Linear

Rotary to Reciprocating

LINEAR MOTION

Definition: Mechanisms that transmit motion and force in a straight line from one point to another.

Levers

A lever is a rigid bar that is supported by a fulcrum.

The Law of levers: F · d = R · r

There are 3 class of levers

Class 2: The resistance is between the fulcrum and the effort applied.

Class 3: The effort applied is between the fulcrum and the resistance.

Class 1: The fulcrum is between the effort applied and the resistance.

Fixed Pulleys

A fixed pulley is a wheel that has a groove around lt into which a rope, cham or belt fits It rotates around an axle that is fixed to an immobile surface.

Law: F=R

Movable Pulleys

A moveable pulley is a set of two pulleys — one is fixed while the other can move in a linear direction.

Law: F=R/2

Compound Pulleys

This ts a system of fixed and moveable pulleys, often called block and tackle

Block Law: F=R/2n

Tackle Law: F=R/2N

ROTARY MOTION MECHANISMS

Friction Drives

Pulleys whit Belt

Friction drives are made up of two or more wheels that are in contact

N1· D1 = N2 · D2 -> D1/D2 = N1/N2

They consist of two pulleys or wheels that are a certain distance apart. Their axles are parallel and they rotate simultaneously due to the effect of the belt.

Gear Mechanisms and Cogwheels

Cogwheels are sets of wheels that have teeth called cogs. The cogs fit into the spaces between the cogs of another wheel, so that one wheel moves the other.

N1 · Z1 = N2 · Z2 -> N1/N2 = Z1/Z2

Worm Gear

This is a screw that moves a helical cogwheel that is set perpendicular to the screw

N = N · Z / Z

Gear Mechanisms With a Chain

These are two cogwheels with parallel axles that are a certain distance apart, they rotate simultaneously by means of a metal chain or a toothed belt stretched over both wheels.

N1 · Z1 = N2 · Z2 -> Z1/Z2 = N2/N1

Gear Train

This is a system of more than two gears, connected together

N4/N1 = Z1/Z2 · Z3/Z4

Pulley Trains With Belts

Look at the diagram below. It's a system of pulleys, or wheels, with a belt formed by more than two wheels.

N4/N1 = D1/D2 · D3/D4

MECHANISMS THAT TRANSFORM MOTION

From Rotary Into Linear

From Rotary Into Reciprocating Motion

Nut and bolt system

Winch and crank handle

Rack and pinion system

This uses a pinion that is a small cogwheel, mounted on a rack that is a toothed belt or bar

L = P · Z · N

This consists of a bolt or threaded bar and a nut that has the same intenor diameter as the diameter of the bolt.

A winch and crank handle system consists of a drum that rotates and a crank handle that allows to pull or lift obiects.

F · d = R · r -> F = R · R · r / d

Crank-link-slider

Crankshaft

This is composed of a crank and a rod called a connecting rod or link. This rod has articulated Ioints at each end — one is connected to the crank and the other to the slider

This is a set of connecting rods attached to a jointed axle. Each of the joints of the axle acts as a crank

Cam

This is basically a rotating object that pushes a follower as it moves.

Eccentric cam

This consists of a wheel with an off centre rotation axle that doesn't coincide with the centre of its circumference.

OTHER MECHANISMS

Mechanisms for Controlling and Directing Motion

Mechanisms That Store Energy

The most typical mechanism of this type is the ratchet, which allows rotauon in one direction but impedes it in the opposite direction.

Springs are devices that absorb energy This energy can be released later, little by little or all at once.

Connecting Mechanism

Movable connections are used to connect shafts that can move along the axle or at an angle to each other

Fixed connections are used to make permanent connections
between axles and shafts

Clutches are mechanisms that allow axles or shafts to be connected or separated

Supports: Bushings and Bearings

In bushings the axle or the shaft is inserted in a plain circular piece that is placed inside a housing to provide a bearing surface.

Bearings are made up of two concentric nngs with balls or rollers between them.