The WG Drum Shape Gear Coupling is a high-rigidity, compact crowned-tooth gear coupling with a built-in lubrication port, available in Type I (WG1–WG24) and Type II (WG1–WG14), spanning 24 sizes from 710 N·m to 1,250,000 N·m at up to 7500 RPM per JB/T8854.2 and JB/ZQ4186. With Y, J1, and Z1 bore options and a design that forms the foundation of the WGP, WGC, WGZ, and WGT brake/vertical coupling family, it is the preferred base coupling for mining, steel, power generation, and cement drives requiring high torque density and field-maintainable lubrication.
High-rigidity, compact crowned-tooth gear coupling with built-in lubrication port. The foundation of the WG family — 24 sizes, two construction types, massive torque range, and Z1 taper bore option.
The WG drum shape gear coupling is a heavy-duty, high-rigidity crowned-tooth gear coupling built for the most demanding horizontal shaft drive applications in mining, steel, power generation, cement, and bulk material handling. It is the base coupling of the WG family — sharing its core gear mesh geometry with the WGP (brake disc), WGC (vertical installation), WGZ (brake drum), and WGT (intermediate shaft) variants.
What sets the WG apart from other drum shape gear coupling series is its combination of two distinct construction types, a wide 24-size range spanning three orders of magnitude in torque capacity, and a built-in lubrication port that enables field re-lubrication without coupling disassembly.
The WG is a moveable rigid coupling that transmits torque through two crowned (barrel-shaped) gear meshes — one on each side of the coupling. Each coupling half consists of a hub with external crowned teeth and a sleeve with internal straight teeth. Torque flows: shaft → hub (crowned external teeth) → sleeve (straight internal teeth) → opposite hub → opposite shaft.
The crown radius machined into each external tooth profile is the defining technical feature that distinguishes the WG from a straight-tooth gear coupling. In a straight-tooth design, torque is transmitted through a line contact running the full tooth width — when shaft angular misalignment is present, this contact shifts to the tooth edge, generating stress concentrations that cause accelerated wear.
The WG's built-in lubrication port on the outer sleeve is a practical engineering detail that separates it from couplings requiring partial disassembly for lubrication. Grease or oil is injected directly into the gear mesh space through the nipple port with the coupling stationary — no sleeve removal required.
The WG is offered in two structural variants for WG1 through WG14: Type I features a single continuous outer sleeve, while Type II incorporates an inner bore collar with longer hub engagement length for applications requiring greater bore depth or higher interference fit area.
For WG15 through WG24 — the largest sizes — only Type I is available, as the outer dimensions make the Type II split construction impractical. These large sizes serve the heaviest mining and steel mill applications.
| Feature | WG (this product) | Jaw Coupling | Disc Coupling | Rigid Flange |
|---|---|---|---|---|
| Torque Range | 0.71–1250 KN·m | Low–Medium | Medium | High |
| Angular Misalignment | 1.0–1.5 deg per mesh | Up to 1 deg | Up to 1 deg | Near zero |
| Shock Load Tolerance | Excellent | Good (elastomer) | Poor | Transmitted fully |
| Z1 Taper Bore | Yes — standard option | Limited | No | No |
| Built-in Lubrication Port | Yes — standard | No (no lube) | No | No |
| Axial Displacement | Yes (built-in) | Limited | Yes | No |
| Two Construction Types | Yes — Type I & Type II | No | No | No |
All five WG-family variants share the WG crowned gear mesh as their core transmission element. The choice between them depends on your application's braking requirements, shaft orientation, and shaft spacing.
| Feature | WG | WGP | WGC | WGZ | WGT |
|---|---|---|---|---|---|
| Full Name | Standard drum gear coupling | With brake disc (flat disc) | Vertical installation type | With brake drum (cylindrical) | With intermediate sleeve (spacer) |
| Standard | JB/T8854.2 / JB/ZQ4186 | JB/T7001 | JB/T7002-93 | JB/T7003-93 | JB/T7004 |
| Braking Feature | None | Flat brake disc for caliper brakes | None | Cylindrical drum for shoe brakes | None |
| Shaft Orientation | Horizontal | Horizontal | Vertical — purpose designed | Horizontal | Horizontal |
| Intermediate Shaft | No | No | No | No | Yes — for distant shafts |
| Number of Sizes | 24 (WG1–WG24) | 14 (WGP1–WGP14) | 14 (WGC1–WGC14) | 14 (WGZ1–WGZ14) | 24 (WGT1–WGT24) |
| Lubrication Port | Yes | Yes | Yes | Yes | Yes |
| Choose When... | Standard horizontal drive, no braking needed | Caliper braking required (e.g. crane hoists, VFD drives) | Vertical shaft drive (pumps, fans, agitators) | Shoe brake system required (hoists, cranes) | Motor and gearbox are far apart, or axle withdrawal needed |
All specifications are from the WG product catalogue per JB/T8854.2 and JB/ZQ4186. Dimensions in millimetres. Where two values appear for C and weight, the first is Type I and the second is Type II. WG15–WG24 are Type I only.
| Type | Torque (N·m) |
Speed (rpm) |
Shaft Bore d1,d2,dz (mm) |
Y | J1, Z1 | D | D1 | D2 | D3 | D4 | B | B1 | F | Inertia I (Kg·m²) |
Inertia II (Kg·m²) |
Weight I (Kg) |
Weight II (Kg) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| WG1 | 710 | 7500 | 12–42 | 32–112 | –/44/84 | 122 | 115 | 98 | 88 | 60 | 116 | 100 | 30 | 0.008 | 0.0063 | 5.6 | 4.86 |
| WG2 | 1250 | 6700 | 22–56 | 52–112 | –/60/84 | 150 | 145 | 118 | 108 | 77 | 136 | 104 | 30 | 0.021 | 0.016 | 9.78 | 7.48 |
| WG3 | 2500 | 6300 | 22–63 | 52–142 | –/60/107 | 170 | 165 | 140 | 125 | 90 | 160 | 108 | 30 | 0.047 | 0.033 | 16.7 | 12.2 |
| WG4 | 4500 | 5600 | 30–80 | 82–172 | –/84/132 | 200 | 195 | 160 | 145 | 112 | 180 | 116 | 30 | 0.098 | 0.073 | 25.6 | 19.6 |
| WG5 | 7100 | 5300 | 30–90 | 82–172 | –/84/132 | 225 | 215 | 180 | 168 | 128 | 200 | 126 | 30 | 0.175 | 0.126 | 35 | 26.1 |
| WG6 | 10000 | 5000 | 32–100 | 82–212 | –/107/167 | 245 | 230 | 200 | 185 | 145 | 224 | 134 | 30 | 0.295 | 0.213 | 51.6 | 38 |
| WG7 | 14000 | 4500 | 32–110 | 82–212 | –/107/167 | 272 | 265 | 230 | 210 | 160 | 244 | 148 | 30 | 0.53 | 0.35 | 68.6 | 45 |
| WG8 | 20000 | 4250 | 55–125 | 112–212 | –/107/167 | 290 | 272 | 245 | 225 | 176 | 272 | 162 | 30 | 0.71 | 0.46 | 79.5 | 55.8 |
| WG9 | 25000 | 4000 | 65–140 | 142–252 | 107/202 | 315 | 305 | 265 | 245 | 190 | 280 | 176 | 30 | 1.05 | 0.77 | 106.5 | 80.5 |
| WG10 | 40000 | 3550 | 75–160 | 142–302 | 107/242 | 355 | 340 | 300 | 280 | 225 | 330 | 196 | 30 | 1.87 | 1.54 | 158.8 | 121.8 |
| WG11 | 56000 | 3000 | 85–180 | 172–302 | 132/242 | 412 | 385 | 345 | 325 | 256 | 360 | 224 | 40 | 3.66 | 2.77 | 214 | 167 |
| WG12 | 80000 | 2800 | 120–200 | 212–352 | 167/282 | 440 | 435 | 375 | 360 | 288 | 414 | 250 | 40 | 6.39 | 4.75 | 302 | 142 |
| Type | Torque (N·m) |
Speed (rpm) |
Bore Range (mm) |
Y Range | D | D2 | D4 | B | F | Inertia I (Kg·m²) |
Weight I (Kg) |
|---|---|---|---|---|---|---|---|---|---|---|---|
| WG13 | 112000 | 2500 | 140–220 | 252–352 | 490 | 425 | 320 | 470 | 50 | 10.44 | 390 |
| WG14 | 160000 | 2300 | 160–260 | 302–410 | 545 | 462 | 362 | 530 | 50 | 17.46 | 522 |
| WG15 | 224000 | 2100 | 160–270 | 302–470 | 580 | 488 | 400 | 560 | 50 | 24.91 | 677 |
| WG16 | 280000 | 1900 | 180–300 | 302–470 | 650 | 560 | 440 | 600 | 50 | 43.22 | 939 |
| WG17 | 355000 | 1800 | 200–320 | 352–470 | 690 | 600 | 460 | 650 | 50 | 56.27 | 1041 |
| WG18 | 450000 | 1700 | 220–360 | 352–550 | 750 | 650 | 510 | 700 | 60 | 88.17 | 1381 |
| WG19 | 560000 | 1600 | 240–380 | 410–550 | 775 | 690 | 535 | 745 | 60 | 108.8 | 1526 |
| WG20 | 710000 | 1500 | 260–400 | 410–650 | 825 | 730 | 580 | 785 | 60 | 164.4 | 2081 |
| WG21 | 800000 | 1300 | 280–440 | 470–650 | 925 | 825 | 620 | 810 | 60 | 242.7 | 2460 |
| WG22 | 900000 | 950 | 320–460 | 470–650 | 950 | 850 | 665 | 820 | 60 | 297 | 2775 |
| WG23 | 1000000 | 900 | 360–500 | 550–650 | 1030 | 900 | 710 | 880 | 60 | 384.8 | 3148 |
| WG24 | 1250000 | 850 | 380–520 | 550–800 | 1060 | 925 | 730 | 900 | 70 | 477.8 | 3766 |
Note: Torque values are in N·m (divide by 1000 for KN·m). Y column shows the bore length range for Y type shaft holes. J1/Z1 bore lengths are longer — refer to catalogue table C1/C2 values. Type II data applies to WG1–WG14 only.
Custom Bore, Type Selection & Shaft Fit Available
Need a specific Y, J1, or Z1 bore diameter not listed in the standard range, a custom keyway, or Type II construction for a larger size? Our engineering team evaluates custom requests and provides solutions. Contact us.
Crusher and mill drives experience torsional shock peaks of 2–4× nominal torque during material ingestion and blockage events. The WG's crowned tooth distributes these peaks as a Hertzian contact patch rather than concentrating them at a tooth edge — significantly reducing peak tooth stress under shock loading.
A misaligned straight-tooth coupling generates cyclic bending moments at 2× running frequency, loading motor and gearbox bearings with parasitic radial forces that accelerate bearing fatigue. The WG's crowned tooth self-centres under load, generating substantially lower parasitic radial force transmission.
The WG's lubrication port is more than a convenience — it fundamentally changes the maintenance workflow. Re-lubrication requires only the injection of fresh grease through the port with the coupling stationary — no guards to remove, no sleeve to pull, no shaft disassembly. This directly translates to shorter planned maintenance windows and fewer unplanned outages from lubrication-related failures.
WG1 is rated to 7500 RPM — the highest speed in the drum shape gear coupling family — making it suitable for direct 2-pole motor coupling on 50 Hz supplies. The crowned tooth profile generates significantly less heat at speed by avoiding the scrubbing action of edge-loaded straight teeth under misalignment.
WG couplings are manufactured from forged alloy steel blanks — 42CrMo4 for WG8 and above, 45# carbon steel for smaller sizes. The crowned external tooth profiles are CNC hobbed to DIN Class 7 accuracy or better, with tooth flanks carburised and quenched to 58–62 HRC surface hardness.
The lubrication port is drilled and tapped after all machining is complete, with thread-form verified for compatibility with standard grease nipple specifications. All bores are finish-machined to H7 or js6 tolerance after heat treatment.
ISO 9001:2015 quality management certification covers all WG manufacturing operations from raw material receipt through to finished goods dispatch. CE marking applies to applicable sizes. Products manufactured to JB/T8854.2 and JB/ZQ4186.
Our engineers communicate in technical English, review drivetrain drawings, verify coupling size selection, and validate bore and keyway specifications against customer shaft data sheets.
WG couplings are available from a single piece. Standard sizes ship within 15–20 working days ex-works; custom bore configurations add 5–10 working days. Volume pricing applies for orders of 5 or more identical units.
As the manufacturer of the complete WG family — WG, WGP, WGC, WGZ, and WGT — RP can supply all variants from a single source. If your project requires WG couplings for standard drives and WGT for distributed drive arrangements, we manufacture and supply the complete mix from one order.
Customer Profile: A large iron ore producer operating a 47 km overland conveyor system with 12 drive stations using various coupling brands accumulated over 15 years.
Challenge: The mixed coupling inventory was creating a spares management problem — different coupling brands required different lubricants, different re-lubrication tools, and different maintenance procedures. Coupling failures were occurring at unpredictable intervals across the fleet.
Solution: We supplied 12× WG10 couplings (40,000 N·m, 150 mm bore, Type I) across all 12 drive stations, standardising the entire fleet to a single coupling family with identical maintenance procedures and a single lubricant specification.
Result: In the 30 months since standardisation, total coupling failures across all 12 drives fell from an average of 8–10 per year to zero. The maintenance team reduced coupling-related spares inventory by 67%.
Customer Profile: A cement manufacturer operating a 3.5 m diameter ball mill with a 2250 kW main drive.
Challenge: The existing disc-pack coupling had failed three times in 18 months due to disc fatigue from combined angular and axial misalignment caused by kiln thermal growth. Each failure resulted in 48 hours of unplanned downtime.
Solution: We supplied a WG15 coupling (224,000 N·m, 240 mm bore, Type I). The WG15's crowned tooth profile handles 0.7 degrees of misalignment continuously without stress concentration — well within the coupling's rated angular tolerance.
Result: The WG15 has operated for 26 months without failure or intervention beyond scheduled lubrication. The estimated saving from three avoided replacement outages represents a significant operational benefit.
Customer Profile: An integrated steel mill performing a major refurbishment of a 5-stand hot strip rolling mill, requiring new couplings on all stands.
Challenge: The existing straight-tooth gear couplings on stands 3–5 were experiencing tooth spalling every 6–8 months due to severe torque reversals from the rolling pass cycle. The customer required a solution demonstrating a minimum 3-year service life.
Solution: We supplied 6× WG17 couplings (355,000 N·m, 280 mm bore, Type I) — one driving and one non-driving for each of the three stands — with custom keyways matched to the customer's spindle drawing.
Result: All six WG17 couplings completed 28 months of continuous production without tooth failure or unplanned replacement. The 3-year service life target was met with margin.
The WG is a high-rigidity, compact crowned-tooth gear coupling with a built-in lubrication port. It is available in Type I (WG1–WG24) and Type II (WG1–WG14), covering 24 sizes from 710 N·m (0.71 KN·m) to 1,250,000 N·m (1,250 KN·m) at up to 7500 RPM.
Both Type I and II share the same outer diameter, torque rating, and shaft bore options. Type I has a single continuous outer sleeve. Type II adds an inner bore collar with a longer hub engagement length — increasing the effective bore engagement area for applications that require higher interference fit or greater bore depth for keys.
The WG has a standard grease nipple port on the outer sleeve that allows EP-grade grease or gear oil injection directly into the tooth mesh space without disassembly. Re-lubrication can be performed with the machine stationary during a brief planned stop.
Both are crowned-tooth gear couplings. The WG has an integral lubrication port and two construction types (I and II); it is the base of the WG family including brake and vertical variants. The GIICLZ has an intermediate shaft spacer between two coupling halves and uses a different sleeve assembly design — suited to applications requiring larger shaft separation.
WGP, WGC, WGZ, and WGT share many sizes with the WG base series but have size-specific limits. WGP, WGC, and WGZ are available up to 14 sizes due to the additional brake or vertical installation components. WGT is available in its own size range for distributed drive applications.
The WG accommodates angular misalignment of 1.0 to 1.5 degrees per tooth mesh. With two meshes in the WG design, the total system can tolerate up to approximately 3 degrees of combined angular offset — the same as the GIICLZ series.
Send us your torque requirement, shaft dimensions, required construction type (I or II), and application details. Our engineering team confirms the right WG size and provides a competitive factory-direct quotation within one business day.
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