GearsTerm 2

Key Concepts:

• Various types of gears, such as spur gears, bevel gears, rack-and-pinion gears and worm gears, are used in machines.

• Gears transmit motion from one position to another.

• Gears can increase or reduce velocity.

• Gears can increase or reduce turning force.

• Bevel gears and worm gears change the direction of rotary movement.

• Rack-and-pinion gears change rotary motion to linear motion and vice versa.

GearsClick on the block

https://www.youtube.com/watch?v=49IOAHJ-V4I

Gearshttps://www.youtube.com/watch?v=kUPjcKF3hA8&t=1s

Click on the block

Spur-gear systems

• Spur gears are used to transmit motion from one position to another.

Equal-sized spur gears counter-rotate

Spur-gear systems

• Driver gear refers to the gear that is driven by the engine.

Spur-gear systems

• An idler gear can be used to synchronise the motion of spur gears.

Idler gear synchronise

Idler gear

Bevel-gear systems• The shafts of the two bevel gears are mounted at a 90° angle to each

other. Thus, bevel gears changes the turning direction at 90°.

Changes the turning direction at 90°.

90°

Click on the blockhttps://www.youtube.com/watch?v=s0kat1CUmpk

Bevel-gear systems

Garage door Motor’s “Diff”

Bicycle Hand drill Hand whisk

Rack-and-pinion gear systemhttps://www.youtube.com/watch?v=_L41jg9h-S0

Rack-and-pinion gear system• A rack-and-pinion gear system converts rotary motion into linear motion.

Pinion gear

RackRotary motion Linear motion

Worm-gear systems• Worm gears are widely used in the industry because they can produce extremely large reductions

in velocity and a large increase in turning force.

Velocity ratio:

VR= 𝑵𝒖𝒎𝒃𝒆𝒓 𝒐𝒇 𝒔𝒑𝒖𝒓𝒔 𝒐𝒏 𝒕𝒉𝒆 𝒘𝒉𝒆𝒆𝒍 𝒈𝒆𝒂𝒓

𝑵𝒖𝒎𝒃𝒆𝒓 𝒐𝒇 𝒔𝒑𝒖𝒓𝒔 𝒐𝒏 𝒕𝒉𝒆 𝒘𝒐𝒓𝒎 𝒈𝒆𝒂𝒓

VR= 𝟑𝟎

𝟏

VR= 30:1

Click on the block

Worm gear

Worm wheel

30 Teeth

Worm-gear systems

Cork screw

Shifting spannerWorm gear on guitar / Violin

Lifting system

Bench viceBench vice

Summary: