Mechanisms

It is used to change 1 kind of motion into another

To simplify our tasks by making use of our effort more effectively

Linear, Rotary, Reciprocating & Ocillating

To transfer, convert and control motion

It is a system that allows some of its parts to be controlled for a specific purpose

Input motion, process (the internal control mechanism that would result in the desired output) & output

Open loop & closed loop

The output is completely dependent on the input and the input is not affected by the output as there is no feedback loop

the output is measured continuously and fed back to the input through a feedback loop and the input is adjusted accordingly by the system to achieve the desired output

they are flexible, takes up less space & are lighter

their flexibility makes it less applicable when precision is required, they produce only tension forces, it cannot be used to push a load.

It is a rigid bar resting on a pivot called the Fulcrum and arranged such that Effort is used to move a Load.

1st class (Load, Fulcrum, Effort), 2nd class (Fulcrum, Load, Effort) & 3rd class (Fulcrum, Effort, Load)

It is the measure of how much a simple machine multiply a force. The larger the MA the lesser the effort is needed to lift a load.

$\frac{Length \ of \ Effort \ Arm}{Length \ of \ Load \ Arm} = \frac{Load \ (Output \ Force)}{Effort \ (Input \ Force)}$

It is when 2 or more levers are joined together

Change the direction & type of a motion, Increase the amount of a force & amplify movement

Bellcrank

A specially shaped piece of material fitted to rotating shaft, when it rotates, the follower on top of it moves up and down

Rotary to Reciprocating

Rotary to Oscilating

The distance between the highest and lowest points of the cam

Dwell is the period when the follower does not move

A wheel with teeth around its edge

Controlling speed, transmitting turning force, changing direction of rotations of motors

Gear fixed to shaft vs 2 or more gears fixed to 1 shaft

Simple gears in mesh vs compound gears in mesh

Gear that is powered vs gear that is moved

By adding an idle gear in the middle of the 2

Speed is lower but turning force (torque) is higher at output

Speed is higher but turning force (torque) is lower at output

The number of turns the driver rotates to the driven

Count the number of teeth in the driver and driven and put them in a ratio and simplify

$\frac{No.\space of \space teeth \space on \space B}{No. \space of \space teeth \space on \space A}\times\frac{No. \space of \space teeth \space on \space D}{No. \space of \space teeth \space on \space C}$

Gears meshed at 90 degrees

Hand drills and chuck and chuck key of drilling machines

A worm gear looks like a screw thread attached to a drive shaft

The worm can only drive the worm wheel, since the worm is single tooth, it has a large speed reduction and torque increase

Tension adjuster in guitars and winch

Consists of a straight toothed rack that mesges with a toothes wheel called a pinion

Rotary to linear

A wheel with saw-shaped teeth around its rim. A pawl is a small tooth that engages the ratchet

When the ratchet wheel rotates, the pawls slides up and drops into each
tooth of the ratchet. The pawl prevents the ratchet from turning in the opposite direction

A wheel that rotates about an axel

Lifting to make it easier to lift a load and driving to transmit power from 1 shaft to another

Fixed to a wall or ceiling

The pulley is free to move together with the load. One end of the rope is fixed and support the weight of the load

Uses a combination of fixed and moveable pulleys, has both directional and mechanical advantage

Number of pulleys in the system

$\frac{Mechanical \ Advantage} {Velocity \ Ratio} \times 100\%$

Load / Effort both in Newtons

No, generally efficiency in a machine may be lost through fricton, heat and sound

A flexible rubber belt in tension used to transmit power between the driver and driven pulleys

Economical when the driver and driven shafts are separated by long distances, lubrication free and low maintenance, the shafts do not need to be parallel

By connecting the belt in a cross drive without needing an additional component

Flat, Vee and Tooth

Easy to install & low cost to manufacture ; Cannot transmit large load & belt slip more frequent

Conveyors in manufacturing and food industries

Belt does not slip easily (wedge effect) & can transmit larger load than flat belt ; Harder to install and higher manufacturing cost

Drilling machine with step/cone pulleys

No belt slippage & useable in high load applications ; Higher manufacturing cost

Used in place of sprocket and chain in bicycles and in vehicle engine drive systems

Diameter of driven / Diameter of driver

As belt is made of rubber, it stretches over time causing the belt to slack, reducing the tension between the driving and driven shaft, resulting in belt slippage and loss of efficiency

Using a tensioner pulley with a weight attached

The tensioner pulley is incorporated with a slot and locking screw which
can be adjusted to tension up the belt.

Moving the motor away from driven shaft by mounting the motor on a slide base and adjusting screw

Sprockets are strudy wheels with teeth that lock onto a chain. as the sprocket spins, the chain transmits power between the driver and driven shafts

No slippage & useable in high load applications ; high manufacturing cost & higher maintenance as mating parts requires lubrication to prevent wear

In bicycle drive systems and in forklifts to carry loads