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: