Gears and Power Transmission Catalog
Comprehensive catalog of gearing and rotary/linear power transmission: gear geometries (spur, helical, herringbone, bevel, hypoid, worm, planetary, harmonic strain-wave, cycloidal RV), AGMA/ISO/DIN quality grades, tooth standards (involute pressure angles, module/DP), material + heat-treatment paths, complete reducer families (helical inline, helical-bevel right-angle, worm, planetary, cycloidal RV, harmonic), rack-and-pinion linear drives, ball/lead/roller screws, and the OEM ecosystem with flagship product lines. Module/DP cross-reference throughout; SI metric primary, US-customary DP retained where the AGMA tradition uses it.
1. Gear Fundamentals — Quick Reference
Quantity Symbol Unit Definition / Formula Module (metric) m mm m = d / z (pitch diameter / tooth count) Diametral pitch (US) DP teeth/in DP = z / d_in; DP × m_mm ≈ 25.4 Circular pitch p mm p = π·m = π·d/z Pressure angle α deg Most common 20° involute; also 14.5° (heritage), 25° (high-load) Addendum a mm a = m (standard) Dedendum b mm b = 1.25·m (standard) Tooth depth h mm h = a + b = 2.25·m Base diameter d_b mm d_b = d · cos α Centre distance a_c mm a_c = (d₁ + d₂)/2 = m·(z₁ + z₂)/2 Helix angle β deg Helical / herringbone / worm wheel Gear ratio i — i = z₂/z₁ = n₁/n₂ = T₂/T₁ (ideal) Lewis bending stress σ_b MPa σ_b = W_t / (F·m·Y); Y = Lewis form factor AGMA bending stress σ_F MPa per AGMA 2001-D04 / ISO 6336-3 AGMA pitting (contact) σ_H MPa per AGMA 2001-D04 / ISO 6336-2 Pitch line velocity v m/s v = π·d·n / 60 000 (d in mm, n in rpm) Backlash j_t mm Per AGMA 2002 or DIN 3967; tangential clearance at pitch point
Standard module series (ISO 54, preferred): 0.5, 0.6, 0.8, 1, 1.25, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 10, 12, 16, 20, 25, 32, 40, 50. Secondary: 0.7, 0.9, 1.125, 1.375, 1.75, 2.25, 2.75, 3.5, 4.5, 5.5, 7, 9, 11, 14, 18, 22, 28, 36, 45.
Standard diametral pitches (US, AGMA): 0.5, 1, 1.25, 1.5, 1.75, 2, 2.25, 2.5, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 16, 18, 20, 24, 32, 48, 64, 72, 80, 96, 120, 150, 200.
2. Gear Type Master Classification
Type Axes Tooth form Ratio per stage Efficiency Service Spur Parallel Straight cut, parallel to axis 1:1 to ~7:1 98–99.5% General industrial, low-noise constraints absent Helical Parallel Helix β = 8–30° 1:1 to ~10:1 96–99% Smooth + quiet (HVAC, machine tools, auto transaxle) Double-helical / herringbone Parallel Two opposing helices, no thrust 1:1 to ~10:1 97–99% High-power marine, turbines, mill drives Bevel (straight) Intersecting 90° Straight-cut on cone 1:1 to ~6:1 94–98% Right-angle low-speed Bevel (spiral, Gleason / Klingelnberg / Oerlikon) Intersecting 90° Curved teeth on cone 1:1 to ~8:1 95–98% Right-angle high-speed, smooth (rear-axle differentials, helicopter mains) Bevel (Zerol) Intersecting 90° Curved with zero spiral angle 1:1 to ~6:1 95–98% Bevel without axial thrust Hypoid Offset 90° Curved cone with axis offset 2:1 to ~50:1 90–96% RWD/AWD car axles (lower drivetrain hump), heavy truck Worm + worm wheel Skew 90° Helical worm + concave wheel 5:1 to 100:1 (1-start to 4-start) 50–95% (depends on lead angle) Hoists, conveyors, packaging; self-locking option Planetary (epicyclic) Parallel concentric Sun + 3–6 planets + ring 3:1 to 12:1 per stage; combined to 1000:1+ 95–98% per stage Compact high-ratio; servo, robotics, wheel hubs Harmonic / strain-wave Concentric Wave generator + flexspline + circular spline 30:1 to 320:1 per stage 60–90% Zero-backlash precision servo (robot wrists, satellite gimbals) Cycloidal / RV Concentric Eccentric cam + cycloidal disc + pin gear 30:1 to 260:1 per stage (RV); 10:1–87:1 (Fine Cyclo) 70–93% Shock-tolerant high-ratio precision (robot bases, indexers) Magnetic Parallel / coaxial Permanent magnet pole interaction up to ~100:1 95–99% Hermetic, contactless, debris-tolerant; emerging Face gear (Crown) Intersecting Spur pinion mates to disc-face teeth 1:1 to ~6:1 94–98% Helicopter transmissions (BAE/Westland/Boeing)
3. Spur, Helical, Herringbone — Quality Grades
3.1 AGMA 2000-A88 (legacy, inch) and AGMA 2015-1-A01 (current, metric ISO-aligned)
Quality grades for parallel-axis cylindrical gears.
AGMA 2000 AGMA 2015 (= ISO 1328-1) Class Typical service Q15 / Q14 A2 / A3 Master / Precision Metrology master gears Q13 / Q12 A4 / A5 High-precision Aerospace, instruments, servo Q11 / Q10 A6 / A7 Precision industrial Machine tools, robotics Q9 / Q8 A8 / A9 Commercial General industrial drives, gear motors Q7 / Q6 A10 / A11 Lower commercial Slow agricultural, hand tools Q5 / Q3 A12 / A13 Coarse Construction, rough machinery
3.2 ISO 1328 / DIN 3961-3964 alignment
ISO 1328-1:2013 (cylindrical involute gear flanks) grades 0–12 (0 best, 12 worst): pitch deviations, profile (form, slope, total), helix (form, slope, total), runout.
ISO 1328 DIN 3961 Use 2–4 2–4 Master / metrology 5 5 Aerospace transmissions, turbine main reduction 6 6 Industrial robotics, machine tools 7 7 Servo gear motors, precision automation (most common precision grade) 8 8 General industrial gearbox 9 9 Bulk material handling, agricultural 10–12 10–12 Hand tools, low-speed coarse
3.3 Bevel + hypoid
AGMA 2009-B01 / ISO 17485 — bevel gear quality grades 4–11 (lower = more precise).
3.4 Worm
AGMA 2011-A98 / DIN 3974 / ISO/TR 10828 — worm gearing quality.
4. Tooth Geometry — Pressure Angle and Profile
Profile Pressure angle Era / use Involute 14.5° composite 14.5° Heritage (pre-1940 US clock/instrument); still appears in repair Involute 20° full-depth 20° Workhorse global standard (ISO 53, AGMA 201/207) Involute 20° stub 20° (shorter addendum 0.8m) Heavy-load, off-highway Involute 25° full-depth 25° High bending strength, larger fillet radius; aerospace + heavy industrial Cycloidal curved (epicycloid + hypocycloid) Clocks, watches, pump rotors Circular arc (Wildhaber-Novikov) — Convex/concave mating; high contact load; Russian/Soviet heritage Gleason spiral bevel curved Most US/Western bevel + hypoid (Gleason face-milling) Klingelnberg cyclo-palloid curved German bevel (continuous indexing face-hobbing) Oerlikon (Spiroflex) curved Swiss/German bevel (continuous indexing) Beveloid (conical involute) varies Used as small-angle correction (eg ZF transaxle marine drive)
4.1 ISO 53 basic rack profile
Standard reference rack (basic rack) per ISO 53:1998: α = 20°, a = m, b = 1.25m, root fillet ρ = 0.38m, tip relief and protuberance per ISO 21771.
5. Materials — Gear Steels and Alternatives
5.1 Case-Carburized (most common for high-power gearing)
Grade Spec Composition (key) Core HRC Surface HRC Service SAE 8620 AISI 8620 / DIN 21NiCrMo2 / EN 805M20 0.18-0.23 C, 0.4-0.7 Mn, 0.4-0.7 Ni, 0.4-0.6 Cr, 0.15-0.25 Mo 28-35 58-62 Auto transmissions, light industrial SAE 4320 AISI 4320 / DIN 18NiCrMo7 0.17-0.22 C, 1.65-2.0 Ni, 0.4-0.6 Cr, 0.2-0.3 Mo 30-38 58-62 Truck axles, industrial gear drives SAE 9310 AISI 9310 (AMS 6260/6265) 0.08-0.13 C, 3.0-3.5 Ni, 1.0-1.4 Cr, 0.08-0.15 Mo 34-42 60-64 Aerospace transmission (helicopter, turboprop GTF) 16MnCr5 DIN 16MnCr5 / EN 16MnCr5 0.14-0.19 C, 1.0-1.3 Mn, 0.8-1.1 Cr 30-40 58-62 European automotive + industrial 17CrNiMo6 DIN 17CrNiMo6 / EN 18CrNiMo7-6 0.15-0.21 C, 1.4-1.7 Ni, 1.5-1.8 Cr, 0.25-0.35 Mo 30-40 58-64 Wind turbine planetary, marine, heavy industrial 20MnCr5 DIN / EN 20MnCr5 0.17-0.22 C, 1.1-1.4 Mn, 1.0-1.3 Cr 30-40 58-62 European workhorse automotive Pyrowear 53 Carpenter Pyrowear 53 (AMS 6308) C-Cr-Mo-Ni-V “hot hardness” 38-44 60-62 Aerospace high-temp transmissions (oil starvation tolerance) CSS-42L Latrobe (Ferrium) CSS-42L secondary-hardening martensitic 42-46 64-68 High-power-density aerospace
5.2 Nitrided
Grade Spec Composition Core HRC Surface HV (depth) Service SAE 4140 AISI 4140 / 42CrMo4 0.38-0.43 C, 0.8-1.1 Cr, 0.15-0.25 Mo 28-35 600-700 HV (0.3-0.5 mm) General industrial, hydraulic-driven gear 31CrMoV9 DIN 31CrMoV9 0.27-0.34 C, 2.3-2.7 Cr, 0.15-0.25 Mo, 0.10-0.20 V 30-38 850-1000 HV (0.4-0.7 mm) Heavy industrial gearboxes, ring gears Nitralloy 135M AMS 6470 / EN 41CrAlMo7-10 0.30-0.40 C, 1.4-1.8 Cr, 0.9-1.4 Al, 0.15-0.25 Mo 32-40 1100-1200 HV (0.4-0.6 mm) Aerospace + gun barrels (highest nitride hardness) 34CrNiMo6 DIN / EN 34CrNiMo6 0.30-0.38 C, 1.3-1.7 Ni, 1.3-1.7 Cr, 0.15-0.30 Mo 30-36 600-700 HV Marine + heavy gearing
5.3 Through-Hardened + Induction / Flame Hardened
Grade Use AISI 4340 (Q+T) Heavy industrial through-hardened pinions 42CrMo4 (Q+T HB 269-321) EU industrial gear quality AISI 4150 / 4145 Heavy ring gears, large modules; flame-hardened tooth flanks AISI 1045 / C45E Commercial gears, induction-hardened ADI (Austempered Ductile Iron, ASTM A897 / ISO 17804) Grade 5 (1400 MPa) Increasingly displaces gear steel for medium-size industrial (lighter, quieter, lower cost)
5.4 Bronzes (worm wheels)
Grade Spec Service CuSn12 (Phosphor Bronze) DIN GZ-CuSn12 / SAE 65 / UNS C90700 Standard centrifugal-cast worm wheel rim CuSn12Ni GZ-CuSn12Ni / UNS C91700 Higher load, marine CuAl10Fe5Ni5 (Nickel-Aluminum Bronze) UNS C95800 Heavy industrial, sea water CuZn25Al5 (Manganese-Aluminum Brass) special Hoist worm wheels
5.5 Plastics + Composites
Material Use PA66 (Nylon 6/6) + glass fill Light industrial, automotive accessories POM (Acetal, Delrin) Office equipment, small gear trains PEEK (Victrex) High-temp + chemical (450 series) PEEK + carbon fiber High-load polymer gears (Igus iglidur, SDP/SI) Phenolic (woven cotton, Bakelite Norplex Micarta) Heritage industrial pinions (low noise) UHMW-PE Light low-load Filament-wound CFRP / GFRP composite gears Aerospace, motorsport (Apex Dynamics composite range, Schaeffler Cevolution)
6. Heat Treatment Pathways for Gears
Process Surface HRC Case depth Distortion Throughput Gas carburizing (Ipsen, AFC-Holcroft, Aichelin) 58-62 0.5-3 mm Moderate (oil quench) Industrial batch / continuous (10-200 kg/hr) Low-pressure (vacuum) carburizing + high-pressure gas quench (ALD ModulTherm, Ipsen TurboTreater) 58-62 0.4-2 mm Lowest Aerospace + premium industrial Plasma (ion) carburizing 58-62 0.3-1.5 mm Low Specialty Carbonitriding (combined C + N) 58-62 0.1-0.7 mm Moderate Smaller gears, pinions Gas nitriding (NH₃, 500-560°C) 850-1100 HV 0.2-0.7 mm Lowest (no quench) Final-machined gears; no post-machining required Plasma (ion) nitriding 900-1200 HV 0.1-0.5 mm Lowest Selective masking possible (Eltro, Rübig) Salt-bath nitrocarburizing (Tenifer/Tufftride, QPQ) 600-700 HV 0.01-0.05 mm Lowest Wear surfaces (auto cams, gear noses) Induction hardening (Inductoheat, EFD, EMA Indutec) 55-62 0.5-5 mm Moderate (tooth-by-tooth or full contour) Large pinions + ring gears Flame hardening 50-58 1-6 mm Moderate Very large gears (mill drives, dragline ring gears) Through-hardening (Q+T) 30-50 full section Moderate Through-hardened pinions, bronzes excluded
Post-treatment grinding (form + flank): MAAG, Gleason TAG 400/800, Reishauer RZ series, Höfler Promat / Cylindrical, Niles ZE/ZP, Kapp-Niles KX, Klingelnberg P 65/100, Liebherr LGG.
7. Reducer Families — Industrial Gear Motors
7.1 Helical Inline (R / SK / G / NORD blocs)
OEM Country Flagship line Ratio range Torque Notes SEW-Eurodrive DE R series (R07-R187), DR..N motor 1.3:1 to 30 000:1 50-58 000 Nm Global market leader; “Movigear” mechatronic NORD Drivesystems DE SK series (SK 02-SK 1182 helical bevel) 1.6:1 to 30 000:1 60-242 000 Nm UNICASE single-casting; NORDBLOC inline Lenze (Schaefer) DE g500-H helical 1:1 to 5000:1 70-19 000 Nm Servo + standard Bonfiglioli IT C series helical, A series helical-bevel 1.2:1 to 10 000:1 50-105 000 Nm A 90/110 ring (wind yaw) Sumitomo Drive (SM Cyclo) JP Hyponic K, Paramax 5:1 to 17 950:1 50-1 100 000 Nm (Paramax) Heavy industrial Paramax 9000 Brevini (Dana) IT E / S helical, Posired 2:1 to 35 000:1 70-150 000 Nm + planetary Flender (Siemens) DE H/B (helical/bevel), MOTOX gear motor 1.25:1 to 22 400:1 100-2 600 000 Nm Industrial workhorse (mill drives, cement) Hansen Industrial BE/IN P4 / M4 helical 1.25:1 to 71:1 1200-1 500 000 Nm Heavy industrial Falk (Rexnord, now Regal Rexnord) US Quadrive / Drive One 5:1 to 250:1 300-1 300 000 Nm Heavy industrial, mill drives David Brown Santasalo UK/FI Series M / 2 / 3 / 4 / Q 1.25:1 to 1000:1 1000-2 500 000 Nm Marine, mining, steel mill Voith Turbo DE Vorecon (variable speed), BHS turbo gears up to 100 MW — Gas/steam turbine + heavy industry Renold (Holroyd) UK RXG, SMSR 5:1 to 50 000:1 up to 600 000 Nm Industrial, marine, mining
7.2 Helical-Bevel Right-Angle (K / SK 92xx / A series)
Combines bevel input + helical output stages; orthogonal in/out.
OEM Flagship SEW K (K07-K187), W (W..) shaft-mount NORD SK 92xx-SK 102xx UNICASE helical-bevel Bonfiglioli A 05-A 80 Flender KB / BK Lenze g500-B Sumitomo Hyponic K with bevel input
7.3 Worm Gear Motors (S / SK / W)
OEM Flagship Notes SEW S series (S37-S97) Ratio 7:1 to 7000:1 NORD SK 1S-SK 9082 Single + double stage worm Bonfiglioli VF / W series Standard frame compatibility Boston Gear (Altra) 700 series, Centric worm US workhorse Renold XK Heavy hoist + conveyor
7.4 Planetary (Servo + Industrial)
OEM Country Flagship Backlash Ratio Service Apex Dynamics TW AB / AF (precision), PG (servo), PE (economy) <3 / <8 arcmin 3:1 to 1000:1 Servo + machine tool Stober DE PHQ / PHV / SMS / KFS (helical-planetary) 1-7 arcmin (PHV: <1) 3:1 to 1000:1 High-precision servo (machine tool, robotics) Wittenstein alpha DE TP+ / SP+ / NP / NPS / cyber <1 (TP+ HIGH Torque) / <6 arcmin 3:1 to 1000:1 Precision servo, robotics Neugart DE PLE / PLN / PLPE <8 arcmin (PLPE) 3:1 to 100:1 Servo Bonfiglioli MP / TR / TQ IT mobile machinery planetary — up to 12 000 Nm Wheel drive (skid-steer, telehandler) Brevini ED / EP / EM (Dana) IT Posired planetary — up to 800 000 Nm Heavy industrial (winches, slewing) Comer Industries PG IT PG / PGA / PGRF — up to 800 000 Nm Wind yaw + pitch, mining Spinea TwinSpin SK T / E / M (precision reducer combining cycloidal + planetary) <0.5 arcmin 35:1 to 192:1 Precision robotics Reggiana Riduttori (Brevini) IT RR / RA — 3:1 to 6000:1 Mobile + industrial Anaheim Automation, Nidec-Shimpo, Tamagawa JP/US various — — — ZF Servoplan DE KPA series — up to 500 000 Nm Heavy mobile Pulsar (Bonfiglioli) IT up to 2 600 000 Nm — — Mill drives, kilns
7.5 Cycloidal — Nabtesco RV + Sumitomo Fine Cyclo
OEM Series Ratio Output torque Backlash Service Nabtesco RV-N (compact), RV-E (industrial), RV-C (hollow shaft), RV-iA (integrated motor) 27:1 to 260:1 110-58 800 Nm <1 arcmin Robot S1-S3 axes (base, shoulder, elbow); world leader for industrial robot joints Nabtesco GH (precision planetary-cycloidal) up to 192:1 — <0.5 arcmin Robotics Sumitomo Drive Fine Cyclo F2C-A / F2C-C / F3C / F3C-A (hollow shaft) 11:1 to 87:1 39-15 700 Nm <1.5 arcmin Robot wrists, indexers Sumitomo Cyclo 6000 (industrial), Cyclo BBB / HBB 6:1 to 658 503:1 (cascaded) up to 1 800 000 Nm — Heavy industrial; very high single-stage shock tolerance Spinea TwinSpin H / G 31:1 to 251:1 up to 6500 Nm <0.5 arcmin Robot joints Onvio SDS/SDR cycloidal up to 230:1 — — Robotics
7.6 Harmonic Strain-Wave
OEM Series Ratio (single-stage) Torque Hollow shaft Service Harmonic Drive LLC / SE CSF / CSG (high torque) 30:1 to 320:1 0.9-7600 Nm optional Robot wrists, satellite, semiconductor Harmonic Drive SHD / SHF / SHG (hollow) 30:1 to 160:1 0.9-7600 Nm yes Robot joints with cable routing Harmonic Drive HFUS / HFUC component sets 30:1 to 320:1 — — OEM integration Harmonic Drive FHA / RSF integrated servo actuators 50:1 to 160:1 — — Plug-and-play robot joint Nidec-Shimpo EVO series strain-wave 30:1 to 160:1 — — Robotics Leaderdrive LSS / LSD 30:1 to 320:1 — — China challenger Cone Drive HDU / HDD 30:1 to 160:1 — — US (Tesla Optimus supplier)
Operating principle (harmonic): elliptical wave generator deflects thin flexspline cup with z₁ teeth into mesh with rigid circular spline z₂ = z₁ + 2; one input rev → output advance = 2 teeth → ratio z₂ / 2. Zero backlash via tooth-engagement preload.
7.7 RV Operating Principle
Nabtesco RV: input shaft → spur reduction stage → two/three eccentric cranks → two cycloidal discs phased 180°/120° → pin-gear ring → output. Two-stage = high single-package ratio + shock load shared across many pin contacts.
8. Large Industrial Gear Drives
Application Typical drive Torque range Cement mill main Flender Combiflex / SEW MGF 1-12 MNm Rotary kiln Flender / David Brown / Hansen P4 0.5-5 MNm Crusher (gyratory, cone) Flender / Falk Quadrive up to 5 MNm SAG / ball mill Flender MAAG SYMETRO, ABB GMD (gearless) up to 28 MW Sugar mill David Brown, Renold up to 2 MNm Hot strip rolling mill Voith MAAG, SHW up to 25 MNm output Marine main reduction RENK, Voith, Falk, MAAG up to 100 MW Wind turbine main gearbox (3-stage planetary + helical) Winergy (Flender), ZF Wind Power, Moventas (Yaskawa), NGC 3-15 MW Wind turbine yaw drive Bonfiglioli, Brevini, Comer 1-50 kNm Wind turbine pitch drive Bonfiglioli, Brevini, Comer, Liebherr 1-30 kNm Helicopter main rotor transmission Sikorsky, Bell, Airbus Helicopters in-house + Howmet —
9. Rack and Pinion — Linear Drives
OEM Country Flagship Module range Backlash Accuracy Atlanta Drive Systems DE Performance / Precision / High-Performance racks m 1.5 to 25 <1-6 arcmin DIN 5 to DIN 10 quality Güdel CH TrackMotion FP / FH m 3 to 12 <2 arcmin DIN 6-7 Wittenstein alpha DE TP+ rack + cynapse pinion, value rack m 1.5 to 12 <1.5 arcmin (cynapse) DIN 5-6 Andantex / RedeX FR TwinDrive (preloaded twin pinion eliminates backlash) m 3 to 25 zero (preloaded) DIN 5 Apex Dynamics TW precision rack PR series m 1 to 16 <4 arcmin DIN 5-7 Neugart DE WPLE rack m 2 to 8 <8 arcmin DIN 6 GAM Enterprises US EPL-W rack m 2 to 10 <4 arcmin DIN 6 Stober DE ZTR rack m 2 to 10 <2 arcmin DIN 5-6 Nidec-Shimpo JP PHJ rack — — —
Helical (β = 19° 31′ 42″) preferred over straight-cut for smoothness, load capacity, and continuous tooth contact ratio > 1.
10. Ball Screws
OEM Country Flagship Lead accuracy (per 300 mm) Service NSK JP HMS / Standard Stock / S Series rolled / HTF (high-load) / EPB (peripheral ball-circulation) C0 (3.5 μm) to C10 Machine tool, semiconductor, robotics THK JP BIF / BNFN / BNK / SBN / DIK / EPC (end cap) C0 to C10 Workhorse machine tool ballscrew supplier Bosch Rexroth DE SHE / FSI / SEM-E / EM C1 (4 μm) to C10 Industrial automation HIWIN TW R series, FSI, FSC, FSV (precision) C0 to C10 Cost-competitive machine tool + automation Schaeffler INA DE KGT, KGM (preloaded) C1 to C7 Industrial automation Schaeffler INA (Bosch) DE KSEM — — PMI (Precision Motion Industries) TW FSV / FSI / SFI rolled, SFK ground C0 to C10 TW machine tool KSS (Kuroda Precision) JP GS / SS series C0 to C7 High-precision machine tool, semiconductor Steinmeyer DE ETA+ / ETA / KGT high-load C0 (1.2 μm) World’s most precise (lithography, metrology) Eichenberger Gewinde CH Carry / Speedy (rolled) C5 to C10 Cost-effective ground + rolled Nook Industries (Altra) US XPR / SPR / Powerac C3 to C10 US-built Thomson (Regal Rexnord) US Glide screws + ball screws C3 to C10 Mil-Spec + industrial Kuroda Jena Tec UK/DE precision ground C0-C3 Aerospace + medical
Preload classes: light (Z0, 2-5% of dynamic load), medium (Z1, 5-7%), heavy (Z2, 8-10%). Dynamic load rating Ca per ISO 3408-5; static rating C0a.
11. Lead Screws (ACME, Tr) and Roller Screws
11.1 Lead Screws
OEM Flagship Material Helix Linear (Roton) RSU / RSA acme steel + bronze nut Nook Industries Stainless + plated steel acme + Tr — Thomson (Regal Rexnord) Glide screws (PEEK + acetal nut) — Igus dryspin lead screw (lubricant-free polymer nut) high-helix Eichenberger Speedy rolled trapezoidal — Kerk Motion (now Haydon Kerk Pittman / Ametek) KFI / NRT high-helix stainless + advanced polymer nut
11.2 Planetary Roller Screws (PRS) and Recirculating Roller Screws
OEM Country Flagship Service SKF SE SR / SRT planetary roller High-load servo electric cylinders (replacing hydraulics) Rollvis CH RV / RVI inverted planetary roller World leader for premium PRS Ewellix (former SKF Linear, now standalone) SE SR / SLS / RSL recirculating — GSA / Schaeffler INA DE PWG planetary roller — Rexroth (Bosch) DE PLSA / PLSC — Exlar (Curtiss-Wright) US GS / GSX / GSM roller screw electric cylinders Heavy-duty servo actuators Tolomatic US RSX / RSA / ERD electric rod actuators Hydraulic replacement
PRS load capacity ~3× ballscrew at same diameter; lead 1-25 mm; life 10-100× ballscrew; preferred for high-cycle high-load servo applications.
12. Chain and Belt Power Transmission
12.1 Roller Chain (ANSI B29.1 / ISO 606 / DIN 8187 8188)
ANSI ISO Pitch (mm) Tensile strength (kN, typical single-strand) 25 04C 6.35 3.5 35 06C 9.525 7.9 40 08A 12.7 13.9 50 10A 15.875 21.8 60 12A 19.05 31.3 80 16A 25.4 55.6 100 20A 31.75 87.0 120 24A 38.1 125 140 28A 44.45 169 160 32A 50.8 222 200 40A 63.5 347 240 48A 76.2 500
Manufacturers: Tsubaki, Renold, Diamond Chain (Timken), Rexnord, Senqcia (Hitachi), Donghua, Iwis, KMC, Wippermann.
12.2 Synchronous Belts
Profile Pitch (mm) Notes MXL 2.032 Office / instruments XL 5.08 Light industrial L 9.525 Industrial H 12.7 Heavy industrial XH 22.225 Very heavy industrial HTD 3M / 5M / 8M / 14M 3-14 Curvilinear; higher load than trapezoidal GT2 / GT3 (Gates PolyChain GT, Carbon GT) 8M / 14M Highest load + life PowerGrip GT3 (Gates) 2GT-14M Industrial servo + robotics Mulco / Megadyne RPP 3-14 EU industrial
Manufacturers: Gates, ContiTech, Megadyne, Optibelt, Mitsuboshi, Bando, Mitsuboshi-Belting, Goodyear EPG (Veyance/Continental).
12.3 V-Belts and Wedge Belts
Classical: A, B, C, D, E (US); Z, A, B, C, D (EU)
Narrow / wedge: 3V, 5V, 8V (US); SPZ, SPA, SPB, SPC (EU per ISO 4184)
High-performance: Gates Super HC, Optibelt Super X-Power, ContiTech XPB-XPZ
13. Couplings — Adjacent (see couplings-taxonomy)
Type Application OEMs Disc-pack flexible (lamina) API 671 turbomachinery, pump-motor, gear-motor Rexnord/Falk Thomas, John Crane Metastream, KTR Radex N, Stromag, Ringfeder Gear coupling (single + double flex) High torque, mill drives, marine Renold, Lovejoy, Falk Steelflex, Voith Hirth Elastomeric (jaw, tire, sleeve) General industry, vibration damping Lovejoy, KTR ROTEX, Falk Steelflex, Vulkan Grid (Steelflex) Industrial pump-motor Falk Steelflex, Lovejoy Bellows (welded metal) Servo, encoder, optics R+W BK series, Rotex GS, Ringfeder Magnetic coupling Sealless pump drive Magnetic Technologies, Dexter, HKD, Sumitomo Magnoseal Shrink disc (locking assembly) Keyless shaft connection Ringfeder, Etp Transmission, KTR Clampex, Stüwe Universal joint (Cardan) Non-aligned rotary Spicer (Dana), GWB, BPW, Stieber Constant-velocity (Rzeppa / tripod) Auto half-shaft, robotics GKN Driveline, NTN, Hyundai-Wia
14. Lubrication of Gears
14.1 ISO VG Grade vs Pitch-Line Velocity (per AGMA 9005-F16)
ISO VG Typical service VG 32 High-speed gearing v > 20 m/s, fan, fluid coupling VG 68-100 Medium-speed industrial gear motor VG 150-220 General industrial gearbox (most common) VG 320-460 Heavy-duty slow-speed (mill drives, cement) VG 680-1500 Slow-speed bull gears (open gears, exposed pinions)
14.2 Gear Oil Categories
Spec Use R&O (Rust & Oxidation) — AGMA 9005 R&O Light-load enclosed gearing EP (Extreme Pressure) — AGMA 9005 EP (sulfur-phosphorus additives) Industrial gear (most common) Compounded (animal/synthetic fat-doped) Worm gears (improves boundary lubrication) Synthetic PAO (polyalphaolefin) Wide temperature range, longer drains Synthetic PAG (polyalkylene glycol) Worm gears — significant friction reduction (worm efficiency +5-15%) Synthetic PFPE Extreme temp / chemical (semiconductor, aerospace)
Common products: Mobilgear SHC (PAO), Klüber Klübersynth GH 6 (PAG), Castrol Tribol 1710 (PAO), Shell Omala S4 GX (PAO), Mobil SHC 600 series (PAO), Total Carter SH (PAO), Petro-Canada Enduratex EP.
14.3 Open Gear Lubricants
Spec Use AGMA 9005-F16 OG (open gear) Mill / dragline ring gears, kiln girth gears Spray-applied bitumen-based or synthetic graphited Heavy industrial open drives
Common: Klüberfluid C-F, Mobiltac, Shell Malleus GL (graphited), Whitmore Surgear.
15. Standards Summary
Standard Topic AGMA 2000-A88 Cylindrical gear quality (inch, legacy) AGMA 2001-D04 Strength rating cylindrical gears (US) AGMA 2003-C10 Strength rating bevel + hypoid (US) AGMA 2009-B01 Bevel gear classification AGMA 2015-1-A01 Cylindrical gear quality (metric, harmonized with ISO 1328) AGMA 6011-J14 High-speed helical gearing AGMA 925-A03 Effect of lubrication on gear surface distress AGMA 9005-F16 Industrial gear lubrication ISO 1328 Cylindrical gear accuracy ISO 6336 Cylindrical gear load capacity (parts 1-6) ISO 10300 Bevel gear load capacity ISO 14635 FZG scuffing test ISO 17485 Bevel gear accuracy ISO 21771 Gear geometry (basic terms) ISO 21773 Profile + helix modifications ISO 23509 Bevel gear geometry ISO 3408 Ballscrew (parts 1-5) DIN 867 Basic rack profile for involute cylindrical gear DIN 3960-3964 Gear terminology, tolerances DIN 3974 Worm gear tolerances DIN 3990 Cylindrical gear capacity (now superseded by ISO 6336) JIS B 1702 Spur + helical gear accuracy (JP equivalent of ISO 1328) API 613 Special-purpose gear units for petrochem API 677 General-purpose gear units GOST 1643 Cylindrical gear tolerances (RU/CIS)
16. OEM Summary
Company HQ Strengths Flagship lines SEW-Eurodrive DE Global leader industrial gear motors R / K / S / F / W series, MOVI-C NORD Drivesystems DE UNICASE single-casting reducers SK 02-SK 1182, NORDBLOC.1 Lenze DE Servo + standard gear motors g500-H / g500-B Flender (Siemens) DE Heavy industrial + wind H / B / Winergy, MOTOX, Combiflex, MAAG SYMETRO Stober DE High-precision servo planetary PHQ / PHV / SMS Wittenstein alpha DE Premium servo planetary + rack TP+ / SP+ / cyber Neugart DE Servo planetary PLE / PLN / PLPE Bonfiglioli IT Industrial + mobile + wind C / A / 300M / TR / RR Brevini (Dana) IT Heavy planetary + slewing Posired, RR Comer Industries IT Wind yaw + pitch + mobile PG series David Brown Santasalo UK/FI Heavy industrial (marine, mill) M / Q series, Naval Renold UK Industrial gear + chain RXG, SMSR Voith Turbo DE Variable + turbomachinery Vorecon, MAAG, BHS turbo gears Hansen Industrial (TBWES Sumitomo JV) BE/IN Heavy industrial P4 / M4 Falk (Regal Rexnord) US Heavy industrial US Quadrive, Drive One Boston Gear (Altra Motion) US Industrial gear + clutch + couplings 700-series, Centric, ORC clutch Martin Sprocket & Gear US Stock gears + sprockets + couplings huge stock inventory Browning (Regal Rexnord) US Pulleys, sheaves, gears broad industrial Power Transmission Solutions (PTS / Emerson, now Regal Rexnord) US broad US industrial Browning, Morse, Rollway Tsubaki JP Chain + gear + reducer RS chain, EVOLVE chain, Cone reducer Sumitomo Drive (SM Cyclo) JP Cyclo + Hyponic + Paramax + Fine Cyclo Cyclo 6000, Hyponic, Paramax, Fine Cyclo F3C Nabtesco JP Precision RV gear for robotics RV-N / RV-E / RV-C / RV-iA / GH Harmonic Drive (LLC / SE) JP/US/DE Strain-wave reducers CSF / CSG / SHD / SHF / SHG / FHA KHK (Kohara Gear Industry) JP Stock gears + custom comprehensive catalog spur/helical/bevel/worm Cone Drive (Altra) US Right-angle + harmonic Cone Drive double-enveloping worm, Cone HDU strain-wave Hub City (Regal Rexnord) US Right-angle worm M series, IGB Apex Dynamics TW Servo planetary + rack AB / AF / PG / PE HIWIN TW Ballscrew + linear guides R series + FSI NSK JP Ballscrew + bearings HMS / HTF / EPB THK JP Ballscrew + linear guides + actuators BIF / BNFN / SBN Bosch Rexroth DE Ballscrew + linear systems SHE / FSI / EM Schaeffler INA DE Ballscrew + bearings + clutches KGT / KGM / KSEM KSS (Kuroda) JP Precision ground ballscrew GS / SS Steinmeyer DE Ultra-precision ballscrew ETA+ Rollvis CH Planetary roller screw RV / RVI SKF SE Roller screws + bearings + linear SR / SRT Exlar (Curtiss-Wright) US Roller-screw electric cylinders GSX / GSM Tolomatic US Electric rod actuators RSX / RSA / ERD Andantex / RedeX FR Preloaded rack & pinion TwinDrive Atlanta Drive Systems DE Rack & pinion drives Performance / Precision / High-Performance Güdel CH Gantry rack + linear modules + bearings TrackMotion FP / FH ZF Friedrichshafen DE Auto + commercial + wind + marine + industrial ZF Wind Power, Servoplan, EcoLife MAAG (Voith) DE/CH High-speed turbine gears MAAG-Pinion Eickhoff Antriebstechnik DE Wind + cement + mining wind 3MW-15MW planetary Moventas (Yaskawa) FI Wind turbine gearboxes Exceed, FusionDrive NGC (Nanjing High-Speed Gear) CN Wind turbine gearboxes global #1 wind gearbox supplier by volume Winergy (Flender Wind) DE Wind gearboxes + generators Hybrid Drive, FlenderOne Spinea SK TwinSpin cycloidal precision reducer T / E / M RENK (MAN) DE Marine + heavy industrial naval + rail ELBE (Voith) DE Cardan shafts Auto + industrial GKN Driveline UK/DE CV joints + driveline RWD, AWD, EV
17. Common Pitfalls
Selecting low-quality AGMA Q8 gearing for servo robotics: tooth-to-tooth pitch error stacks into positioning error; specify ISO 6 or 7 (= AGMA Q11-Q12) minimum for servo
Specifying worm gearing for continuous duty without considering efficiency: 30:1 worm at 50% efficiency dissipates half the input as heat in the gearbox — overheats and lubrication degrades
Misapplying self-locking worm assumption: worms are only reliably self-locking with lead angle < 5° and even then dynamic shock loads can back-drive; always include a brake for hoists
Carburized vs nitrided choice without accounting for distortion: carburized gears need post-grind; nitrided gears can ship as-machined but lower case depth limits torque density
Backlash from gearbox added to backlash from coupling: precision servo train backlash compounds — specify zero-backlash bellows / disc-pack coupling with zero-backlash reducer
Helix angle direction not specified on helical pair: thrust direction flips; bearing arrangement may not handle reversed thrust
Mounting RV reducer rigidly bolted between two stiff structures: thermal expansion + alignment error preloads pin gear unevenly; follow Nabtesco mounting torque + flatness spec
Choosing harmonic reducer for shock service: flexspline tooth root is the limit; cycloidal RV preferred for high impact loads
Lubricating worm gear with EP industrial oil: sulfur-phosphorus additives attack bronze worm wheel; use compounded oil or PAG synthetic
Open gear lubricant on enclosed gear motor: high-viscosity asphaltic oil churns + heats; use proper enclosed-gear oil
Specifying ballscrew lead too short for required linear speed: critical speed limit; consider larger lead + reduction, or roller screw, or hydraulic cylinder
Mismatched preload class on twin nuts: oversize preload reduces life dramatically (cube law) but underload allows backlash; balance per servo bandwidth requirement
Rack pinion mounted with module mismatch between two segments: pitch discontinuity at joint; specify Atlanta or Wittenstein matched rack segments
Synchronous belt running on under-sized pulley: jumping teeth; minimum recommended pulley tooth count varies by pitch (HTD 8M minimum ~22T)
Coupling specified with insufficient angular misalignment capacity: disc-pack typical 0.25-0.5°, gear coupling 0.5-1.5° per mesh, elastomer 0.5-1° — verify against installed alignment tolerance
Wind turbine gearbox failure mode (high-speed shaft bearing micropitting): use ISO 6336-22 micropitting check + low-additive oil + black-oxide bearings
ADI gear substituted for carburized steel without redesign: ADI core hardness + thermal capacity differ; AGMA derating factor applies
Adjacent