General gear terms and definitions 317
Spur and Helical Gears: Formulae and definitions Helical Gear Spur Gear Term Definition formulae formulae 318
Spur and Helical Gears: Formulae and definitions Helical Gear Spur Gear Term Definition formulae formulae 319
Tolerances - spur gears 24 DP and finer 320
Tolerances - spur gears, metric pitch Total Tooth comp to Quality gs Quality fs error tooth Max Min Max Min comp ind ind ind ind error reading reading reading reading 321
Tolerances - Spur Gears 4 DP to 20 DP Max Min Pitch indicator indicator DP reading reading Tolerance 322
Spur gear durability and efficiency Abbreviation Terms Unit To be found in 323
Spur gear durability and efficiency Ruling Surface Core Thru Material BS No. Condition Section VPN BHN st BHN Sc Sb 324
Helical gear durability No. IN MATING GEAR teeth Rack 400 300 200 150 100 80 70 60 50 40 35 30 28 26 24 22 20 19 18 17 16 15 14 13 12 11 10 325
Spur and helical gear durability Hours 0.1 1 5 10 40 100 150 200 400 500 600 1000 1500 2000 3000 5000 10000 20000 25000 rpm No. No. teeth in gear being designed teeth 400 300 200 150 100 80 70 60 50 40 35 30 28 26 24 22 20 19 18 17 16 15 14 13 12 11 10 326
Spur and helical gear durability Hours 0.1 1 5 10 40 100 150 200 400 500 600 1000 1500 2000 3000 5000 10000 20000 25000 rpm No. IN MATING GEAR teeth Rack 400 300 200 150 100 80 70 60 50 40 35 30 28 26 24 22 20 19 18 17 16 15 14 13 12 11 10 327
Spur and helical gears: assembly data, backlash calculations Indicator Centre Total No. PCD Reading Dist Centre Comp. Gear fp* Teeth DP Inches Max. Min. Tolerance Dist. Error Maximum Equivalent Centre Distance c Probable Max. Probable Max. Angular increase over norm. B/Lash - fp* c x 2tan PA) B/Lash. in Mins. 328
Simple calculation for strength Material Value of M plastic 5,000 bonze 10,000 cast iron 12,000 0.2% carbon steel natural 20,000 0.2% carbon steel case hardened 25,000 0.4% carbon steel natural 25,000 0.4% carbon steel case hardened 30,000 329
Rack tooth strength 330
Straight bevel gear: Formulae and definitions (Gleason System) Term Definition Pinion Gear 331
Straight bevel gear: Formulae and definitions (Gleason System) Term Definition Pinion Gear 332
Material Factors Character of load on driven machine Prime Mover Uniform Medium Heavy Shock Shock Gear Pinion Material Minimum Minimum Factor Material Hardness Material Hardness Cm 300 333
Straight bevel gear: Torque, efficiency, assembly data 334
Right-angled gear systems -characteristics maximum pitch line velocity Class Type Power-to- efficiency Ratio max. Com- Aero- type of mounting weight ratio range % range HP (per -mercial space contact sensitivity mesh) ft/min ft/min OFFSET COPLANAR 1 straight bevel medium high 97-99.5 1:1 to 8:1 500 1000 10000 line critical 3 directions 2 Coniflex bevel ¹ medium high 97-99.5 1:1 to 8:1 500 1000 10000 line critical 3 directions 3 spiral bevel very high 97-99.5 1:1 to 8:1 5000 8000 25000 line critical 3 directions 4 Zerol bevel ¹ high 97-99.5 1:1 to 8:1 1000 1000 10000 line critical 3 directions 5 Revacycle bevel ¹ high 97-99.5 1:1 to 8:1 100 1000 line critical 3 directions 6 Face gear medium high 97-99.5 3:1 to 8:1 200 4000 5000 line critical 1 direction 7 Beveloid ² low 97-99 1:1 to 8:1 150 4000 5000 point not critical 8 crossed helical low 50-95 1:1 to 100:1 100 4000 10000 point not critical 9 cylindrical worm medium high 50-98 3:1 to 400:1 750 5000 10000 line sensitive 2 directions 10 double enveloping worm medium high 50-98 3:1 to 100:1 1000 4000 10000 line or area critical 3 directions 11a hypoid low ratio high 85-98 1:1 to 10:1 1000 6000 10000 line critical 3 directions 11b hypoid high ratio medium high 50-90 10:1 to 50:1 500 6000 10000 line critical 3 directions 12 Face gear medium high 70-98 3:1 to 8:1 200 4000 5000 line critical 2 directions 13 Spiradrive 3 (spiroid) medium high 50-98 9:1 to 400:1 500 6000 10000 line sensitive 2 directions 14 planoid high 70-98 1.5:1 to 8:1 1000 4000 10000 line critical 3 directions 15 ZTA Spiradrive 3 medium high 50-98 3:1 to 400:1 500 6000 10000 line sensitive 2 directions 16 Beveloid ² low 70-98 1:1 to 8:1 150 4000 5000 point not critical 1 Zerol, Coniflex & Revacycle Gleason Works 2 Bevaloid Vinco Corp 3 Spiradrive, ZTA Spiradrive Davall Gears Ltd registered trade names 335
Worm gear: Formulae and definitions (BS. 721) Term Definition Worm Wheel 336
Worm gear: Torque capacity and effciency 337
Bearings choice - spur and helical gears Tf tanpa Tf Tf tan 338
Bearing choice - straight and spiral bevel gears 339
Bearing choice - straight and spiral bevel gears Driving Member Value of seperating component Spiral hand Rotation* of radial load Driving Member Spiral hand Rotation* Value of axial thrust 340
Bearing choice - worm gearing 341