GEAR DESIGN Part IV GEAR FORMS Lec 9

GEAR DESIGN Part “IV” (GEAR FORMS) Lec. 9 Dr. Ameer Ali Kamel Prod. Eng. & Mech. Design Dept. Faculty of Engineering

GEAR SHAPES Gear 1 Gear 2 Washer Parallel sides key Pin 2

Holes keyway Gear 2 Extended Hub Gear 3 3

Gear 3 4 Gear 4

Gear 4 5 Gear 5

Build-in gear Gear 1 6 Disc Form Gear 2 Disc & Holes Form Gear 3

Build-in web Gear 4 7 Build-in web& Holes Gear 5

Large Gear Wheels 1. Taper shaft end and nut Gear Tapered shaft end Gear Washer Keyway Thread 8 Nut

2. Shoulder and nut Shoulder 9

3. Shoulder and face plate 2 Screws 10

3. Shoulder giphead key 11

Compound Gears Gear 1 12 Gear 2

Compound Gears Gear 1 13 Gear 2

Compound Gears Flange with 4 Holes Gear 1 14 Gear 2

Compound Gears Gear 1 Gear 2 Gear 3 15

Some Special Gears (1). Two directional gear train Design 40 - Gear Two Directional (2). Non-circular gears Design 41 - Gear Non-circular gears (3) Change speed gears Design 42 - Gears changes speed 16

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Spur Gear reduction Unit. -Single Stage. - Spur gear. -Speed ratio 4 to 10. -Pinion. -Gear is disc with reduction weight holes. - Glass oil –level indicator. 18

-Single Stage. - bevel gear. -Two perpendicular shafts -Speed ratio 4 to 10. -Pinion is over-hanged. -Gear is Keyed. - Glass oil –level indicator. 19

Gear & Pulley construction Gear and pulley masses are subjected to shear stress due to torque. The following relationships can be considered. 1. Single raw webs are used for gears or pulleys with width “B”: B ≤ 300 mm 2. Double raw webs are used for: B ≥ 300 mm 20 B

a’ L = (1. 5 : 2 ) * d d : Shaft bore diameter. L : Hub length d 1 = 1. 7 d d 1 : Hub external diameter. No. of Webs “i” i = (1/7) √ Dmax : Gear or pulley external diameter 21 B

a’ Dimensions of web section P: Acting force For gear P = torque / (d 1/2) For Pulley P = (T 1 – T 2) a = 0. 4 h a’ = 0. 75 a h’= 0. 75 h 22 B

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EN D 26