The WGP Drum Shape Gear Coupling with Brake Disc integrates a flat, independently replaceable brake disc for caliper brakes per JB/T7001, covering 14 sizes from 710 N·m to 160,000 N·m at up to 4000 RPM. With brake disc diameters D0 from 315–1000 mm and Y, J1, Z1 bore options, it is the preferred coupling for crane travel drives, VFD hoists, and conveyor emergency stops where disc braking is specified.
Crowned-tooth gear coupling with an integral flat brake disc for caliper disc brakes. Two functions in one unit: precision torque transmission plus a replaceable disc braking surface.
The WGP drum shape gear coupling with brake disc is a dual-function power transmission component combining a crowned-tooth gear coupling with an integral flat brake disc designed for caliper-type disc brakes. Conforming to JB/T7001, the WGP is the member of the WG coupling family selected when caliper disc braking — rather than shoe braking — is required at the drive shaft.
The defining feature of the WGP is its flat, replaceable brake disc. Unlike the WGZ (which carries a cylindrical drum for shoe brakes) or the NGCL (a drum-brake coupling with a different base design), the WGP's flat disc is purpose-built for the clamping action of a caliper brake assembly. This makes the WGP the natural choice for crane travel motions, hoist drives with variable speed control, precision positioning drives, and any application where disc brakes are preferred over shoe brakes for their faster response, more consistent braking torque, and superior heat dissipation.
The WGP consists of two main assemblies: the crowned-tooth gear coupling body (identical in principle to the WG base series) and a bolted-on flat brake disc. The gear coupling transmits torque through two crowned gear meshes. The brake disc — a flat, annular steel plate with precisely machined braking surfaces on both faces — provides the friction interface for a caliper disc brake assembly that clamps against the disc to decelerate or hold the drivetrain.
The key distinction from the WGZ (cylindrical drum) and NGCL (integral brake drum) types is the disc geometry. A flat disc allows a floating caliper to apply even clamping pressure across the full friction pad contact area, generating consistent braking torque that is relatively insensitive to minor disc runout. Cylindrical shoe brakes are more sensitive to drum eccentricity and require periodic shoe adjustment as the lining wears. Disc brakes also dissipate heat more effectively because both faces of the disc are exposed to cooling air during rotation.
The gear coupling element uses the same crowned tooth geometry as the WG base series — the barrel-shaped external tooth profile that produces a self-centring Hertzian contact ellipse regardless of shaft misalignment. This eliminates the destructive edge loading found in straight-tooth couplings under the same conditions, extending tooth service life and protecting adjacent bearings from misalignment-induced cyclic radial forces.
The WGP brake disc bolts onto the coupling half hub using high-strength fasteners. It is a separate, replaceable component — when the disc surface wears beyond the serviceable limit, the disc is unbolted and replaced without disturbing the coupling hubs or requiring shaft realignment correction. Each WGP size accepts multiple standard disc diameters (D0 options), allowing the brake disc size to be matched to the required braking torque without changing the coupling size.
When selecting a caliper brake to match a WGP coupling, specify D0 as the disc diameter and S as the minimum caliper mounting clearance.
The WGP's gear coupling element accommodates angular misalignment of 1.0 to 1.5 degrees per mesh, radial parallel offset, and axial displacement through axial sliding of the crowned teeth within the outer sleeve. The axial displacement capability is particularly important when the caliper brake is applied — brake clamping generates a small axial thrust on the disc and hub. The WGP's crowned tooth mesh absorbs this axial reaction within the gear clearance, preventing it from being transmitted to motor or gearbox bearings as an axial loading event.
| Feature | WGP (this product) | WGZ (shoe brake) | WG (no brake) | Jaw Coupling |
|---|---|---|---|---|
| Braking Component | Flat disc — caliper brake | Cylindrical drum — shoe brake | None | None |
| Brake Wear Component Replacement | Disc replaceable without coupling removal | Drum integral; shoes replaced at brake | N/A | N/A |
| Braking Response Speed | Fast — caliper engages instantly | Moderate — shoe pivot geometry | N/A | N/A |
| Heat Dissipation | Excellent — both disc faces cooled | Good — drum exposed to air | N/A | N/A |
| Crowned Tooth Gear Mesh | Yes — 1.0–1.5 deg tolerance | Yes — 1.0–1.5 deg tolerance | Yes — 1.0–1.5 deg tolerance | Up to 1 deg (elastomer) |
| Preferred Application | Crane travel, VFD-controlled hoists, precision positioning | Heavy hoisting, mine winders, large cranes | Standard horizontal drives | Light–medium duty |
The WGP is one of five variants in the WG coupling family. All share the same crowned gear mesh core. The following comparison clarifies where the WGP fits and when to choose each variant.
| Factor | WG | WGP | WGC | WGZ | WGT |
|---|---|---|---|---|---|
| Standard | JB/T8854.2 | JB/T7001 | JB/T7002-93 | JB/T7003-93 | JB/T7004 |
| Braking Feature | None | Flat disc — caliper | None | Drum — shoe brake | None |
| Shaft Orientation | Horizontal | Horizontal | Vertical | Horizontal | Horizontal |
| Intermediate Shaft | No | No | No | No | Yes |
| Sizes Available | 24 | 14 | 14 | 14 | 24 |
| Choose When... | Standard horizontal, no brake | Caliper disc brake required; VFD drives; precise stopping | Vertical shaft drives | Heavy hoisting; shoe brake system | Distant shafts; axle withdrawal needed |
All specifications are from the WGP catalogue per JB/T7001. Dimensions in millimetres. D0 lists the available brake disc diameter options for each coupling size. Weight and inertia are calculated without the brake disc; add brake disc values separately from the disc table.
| Type | Torque (N·m) |
Speed (rpm) |
Bore d1,d2,dz (mm) |
Y | J1, Z1 | D0 Options (mm) |
D | D2 | D4 | B | F | N | Inertia (Kg·m²) |
Weight (Kg) |
Lubricant (Kg) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| WGP1 | 710 | 4000 | 12 – 42 | 32–112 | –/44/84 | 315 | 122 | 98 | 60 | 58 | 30 | 38 | 0.0078 | 5.62 | 0.11 |
| WGP2 | 1250 | 4000 | 22 – 56 | 52–112 | –/60/84 | 315 | 150 | 118 | 77 | 68 | 30 | 38 | 0.022 | 9.62 | 0.12 |
| WGP3 | 2500 | 3550 | 22 – 63 | 52–142 | –/60/107 | 355 | 170 | 140 | 90 | 80 | 30 | 49 | 0.047 | 16.6 | 0.20 |
| WGP4 | 4500 | 2500 | 30 – 80 | 82–172 | –/84/132 | 400 / 450 / 500 | 200 | 160 | 112 | 90 | 30 | 45 | 0.098 | 25.3 | 0.28 |
| WGP5 | 7100 | 2500 | 30 – 90 | 82–172 | –/84/132 | 400 / 450 / 500 | 225 | 180 | 128 | 100 | 30 | 45 | 0.174 | 34.7 | 0.45 |
| WGP6 | 10000 | 2000 | 32 – 100 | 82–212 | –/107/167 | 450 / 500 / 560 / 630 | 245 | 200 | 145 | 112 | 30 | 44 | 0.293 | 51.3 | 0.65 |
| WGP7 | 14000 | 1700 | 32 – 110 | 82–212 | –/107/167 | 450 / 500 / 560 / 710 | 272 | 230 | 160 | 122 | 30 | 44 | 0.530 | 68.0 | 0.80 |
| WGP8 | 20000 | 1700 | 55 – 125 | 112–212 | –/107/167 | 500 / 560 / 630 / 710 | 290 | 245 | 176 | 136 | 30 | 44 | 0.71 | 79 | 0.95 |
| WGP9 | 25000 | 1600 | 65 – 140 | 142–252 | 107/202 | 560 / 630 / 710 / 800 | 315 | 265 | 190 | 140 | 30 | 58 | 1.05 | 106.5 | 1.30 |
| WGP10 | 40000 | 1600 | 75 – 160 | 142–302 | 107/242 | 630 / 710 / 800 | 355 | 300 | 225 | 165 | 30 | 58 | 1.74 | 159.0 | 1.60 |
| WGP11 | 56000 | 1400 | 85 – 180 | 172–302 | 132/242 | 710 / 800 / 900 | 412 | 345 | 256 | 180 | 40 | 58 | 3.67 | 215.0 | 2.00 |
| WGP12 | 80000 | 1400 | 120 – 200 | 212–352 | 167/282 | 710 / 800 / 900 | 440 | 375 | 288 | 207 | 40 | 58 | 6.40 | 303.0 | 3.40 |
| WGP13 | 112000 | 1400 | 140 – 220 | 252–352 | 202/282 | 800 / 900 | 490 | 420 | 320 | 235 | 50 | 58 | 10.45 | 291.0 | 4.40 |
| WGP14 | 160000 | 1200 | 160 – 260 | 302–410 | 242/330 | 900 / 1000 | 545 | 462 | 362 | 265 | 50 | 65 | 17.48 | 523.0 | 6.60 |
Notes: Weight and inertia are calculated without the brake disc — add brake disc values from the separate disc table. The C, C1, C2 axial clearance values vary by D0 selected; base table value plus K/2 for the chosen disc. N = S – K/2 (value shown is for maximum D0 for that coupling size).
| D0 Brake Disc Diameter (mm) |
T Thickness (mm) |
K Hub Height (mm) |
S — D5MAX (mm) |
Disc Weight I (Kg) |
Disc Weight II (Kg) |
Inertia I (Kg·m²) |
Inertia II (Kg·m²) |
Compatible WGP Sizes |
|---|---|---|---|---|---|---|---|---|
| 315 | 15 | 10 | 42 | 8.5 | 6.7 | 0.116 | 0.110 | WGP1, WGP2 |
| 355 | 15 | 10 | 54 | 11.4 | 9.9 | 0.192 | 0.178 | WGP3 |
| 400 | 15 | 14 | 54 | 15.2 | 12.4 | 0.320 | 0.287 | WGP4, WGP5 |
| 450 | 15 | 16 | 54 | 19.7 | 15.6 | 0.550 | 0.462 | WGP4, WGP5, WGP6, WGP7 |
| 500 | 15 | 18 | 54 | 25.0 | 20.0 | 0.830 | 0.712 | WGP4, WGP5, WGP6, WGP7, WGP8 |
| 560 | 15 | 18 | 54 | 30.7 | 25.6 | 1.280 | 1.127 | WGP6, WGP7, WGP8, WGP9 |
| 630 | 15 | 20 | 54 | 38.8 | 33.0 | 2.060 | 1.826 | WGP6, WGP8, WGP9, WGP10 |
| 710 | 15 | 20 | 54 | 46.5 | 39.4 | 3.320 | 2.912 | WGP7, WGP8, WGP9, WGP10, WGP11, WGP12 |
| 800 | 15 | 24 | 70 | 67.8 | 52.7 | 5.870 | 4.810 | WGP9, WGP10, WGP11, WGP12, WGP13 |
| 900 | 15 | 24 | 70 | 86.6 | 70.3 | 9.300 | 7.852 | WGP11, WGP12, WGP13, WGP14 |
| 1000 | 20 | 30 | 80 | 128.8 | 115.1 | 17.400 | 15.65 | WGP14 |
Note: D5MAX (S) is the maximum outer diameter of the caliper brake body that can be accommodated at the given D0. Disc weights shown are for Type I and Type II caliper configurations. Bolts connecting disc to coupling must be Grade 8.8 minimum.
Custom Bore, Non-Standard D0, and Special Disc Configurations Available
Need a non-standard shaft bore, a D0 outside the catalogue range, or a disc surface treatment for high-temperature or corrosive environments? Our engineering team accommodates custom specifications. Send your caliper brake model and shaft drawing for a comprehensive assessment within 24 hours.
Crane drives experience simultaneous peak torque loading — when a heavy load is lifted or a bridge decelerates rapidly — and brake clamping stress. The WGP's crowned teeth distribute these combined peak stresses as Hertzian contact ellipses rather than edge-concentrated line contacts, significantly reducing maximum tooth surface stress.
When a caliper disc brake applies to a WGP coupling, the clamping force generates a small axial thrust and bending moment at the coupling hub. The WGP's crowned tooth accommodates axial brake reaction through the mesh sliding clearance, and minimises bending moment transmission through its self-centring contact geometry — protecting bearings from the incremental loading events that accumulate into premature fatigue failure on high-cycle brake drives.
The WGP offers two independent maintenance advantages. First, the replaceable brake disc means disc wear does not require coupling disassembly or shaft realignment. Second, the built-in lubrication port allows tooth mesh re-lubrication without disassembly at 6–12 month intervals.
WGP1 and WGP2 are rated to 4000 RPM — allowing direct connection to standard IEC 4-pole motors running at 50 Hz. The flat disc geometry of the WGP is inherently better balanced than a cylindrical drum at high speeds. For VFD-controlled drives operating across a wide speed range, the WGP maintains dynamic stability from zero to maximum speed without requiring rebalancing as disc wear occurs within normal service limits.
WGP couplings and brake discs are manufactured from forged alloy steel blanks — 42CrMo4 for WGP8 and above, 45# carbon steel for smaller sizes. The coupling crowned teeth are CNC hobbed to DIN Class 7 accuracy. Tooth flanks are carburised and quenched to HRC 58–62 surface hardness. The brake disc is machined to flat disc parallelism within 0.05 mm across the braking face width, with surface roughness of Ra 1.6–3.2 μm for consistent caliper pad wear-in.
Each WGP coupling and its matched brake disc are dimensionally verified as a system before dispatch — coupling concentricity, disc flatness, and bolt circle register are all measured and recorded. This system-level inspection ensures the disc runs true within the caliper clearance, preventing vibration from disc runout.
ISO 9001:2015 certification covers the complete WGP manufacturing and inspection process. CE marking applies to applicable sizes. Every shipment includes material mill certificates with heat number traceability, heat treatment records, Rockwell hardness test certificates, disc flatness measurement records, and dimensional inspection reports.
Our engineers respond in technical English, review caliper brake and coupling system drawings, verify D0 disc selection against braking torque requirements, and verify bore compatibility with your motor and gearbox data sheets.
WGP couplings are available from a single piece, including replacement brake discs as standalone spares. Standard items ship within 15–20 working days; replacement discs for standard D0 sizes typically ship within 7–10 working days from finished goods stock.
Non-standard D0 diameters, alternative disc thicknesses, hardened and ground disc surfaces, special bore configurations, and modified hub bolt patterns are all achievable to customer drawings. Contact us with your drawing.
As the manufacturer of the complete WG family (WG, WGP, WGC, WGZ, WGT), RP supplies all variants from a single source. Projects requiring WGP on hoist drives and WG on travel drives are handled with one engineering team, one procurement order, and one combined documentation package.
Customer Profile: A major integrated steelworks operating six ladle cranes lifting 80–130 tonne molten steel ladles, each with VFD-controlled hoist drives.
Challenge: The existing drum-and-shoe brake coupling arrangement was generating inconsistent stopping positions after VFD ramp-down. Shoe brakes were applying unevenly due to thermal expansion of the drum surface, causing positioning errors of 15–25 mm at the ladle set-down point.
Solution: We supplied 6× WGP11 couplings (56,000 N·m, 140 mm bore, D0 = 800 mm) matched to the existing caliper brake actuators. The flat disc geometry eliminated the thermal runout issue causing inconsistent shoe brake contact.
Result: Ladle set-down positioning accuracy improved to within 3–4 mm immediately. The correction step was eliminated, improving throughput by approximately 4%. Brake inspection interval extended from 3 months to 12 months.
Customer Profile: A container terminal operating 12 rubber-tyred gantry (RTG) cranes with VFD-controlled bridge travel drives.
Challenge: Drum brake couplings on the bridge travel drives were experiencing premature lining wear during wet seasons — moisture absorption in the shoe linings was closing the effective brake gap, causing drag braking and lining wear rates 3–4× higher than normal. Each replacement required taking the RTG out of service for a half-shift.
Solution: We supplied 12× WGP7 couplings (14,000 N·m, 90 mm bore, D0 = 500 mm). The disc brake geometry is unaffected by moisture-related lining swell, eliminating the seasonal wear variation entirely.
Result: Brake-related maintenance events dropped from an average of 3.8 per crane per year to 0.7 per crane per year. Estimated total maintenance saving across the 12-crane fleet: USD $180,000 over the first two years.
Customer Profile: An aluminium smelter operating pot room overhead cranes for anode replacement and metal tapping, performing 600–800 brake cycles per shift at ambient temperatures exceeding 60°C at crane level.
Challenge: Existing drum shoe brake assemblies were experiencing thermal fade — as drum temperature rose through a shift, effective brake force decreased by up to 25%, requiring operators to compensate manually.
Solution: We supplied 8× WGP9 couplings (25,000 N·m, 110 mm bore Z1 taper, D0 = 710 mm) with high-temperature rated caliper brake pads for continuous operation to 200°C. The disc brake's open geometry dissipates heat from both disc faces during rotation, keeping working temperature lower than an enclosed drum at equivalent braking energy.
Result: Thermal fade was eliminated. Brake performance measurements at end of shift showed less than 3% torque variation from start-of-shift baseline, versus 18–25% with the previous drum shoe arrangement. The cranes have since completed 30 months without brake-related safety observations or unplanned stoppages.
The WGP is a crowned-tooth gear coupling (JB/T7001) with an integral flat brake disc for caliper-type disc brakes. Available in 14 sizes from WGP1 (710 N·m) to WGP14 (160,000 N·m), with brake disc diameters D0 from 315 mm to 1000 mm.
The WGP has a flat brake disc for caliper disc brakes. The WGZ has a cylindrical brake drum for shoe brakes. Disc brakes (WGP) offer faster response, better heat dissipation, and more consistent braking torque in wet or high-temperature conditions, and are compatible with VFD-controlled drives. Shoe brakes (WGZ) typically provide higher braking torque per unit of actuator force and are preferred for heavy hoisting applications where large braking torque is the primary design requirement.
The required D0 is determined by the braking torque calculation: braking torque = caliper clamping force × pad friction coefficient × D0/2 × number of pad contact faces. Each WGP coupling size supports multiple D0 options. The WGP size is selected first based on transmission torque, then D0 is chosen to meet the required braking torque. Our engineering team can perform this calculation with your application data.
Yes. The brake disc is a bolted-on component that can be replaced independently of the coupling hubs. When ordering a replacement disc, specify the WGP size and D0 diameter. We supply replacement discs as standalone items with the same dimensional inspection records as new coupling assemblies.
N is the axial distance from the coupling face to the nearest edge of the caliper mounting clearance envelope (N = S - K/2). It defines where the caliper brake body must be positioned relative to the coupling flange face — critical for crane structural designers specifying the caliper mounting bracket position.
Tell us your transmission torque, required braking torque, shaft bore dimensions, and caliper brake model. Our engineering team confirms the right WGP size and D0 disc diameter, and provides a competitive factory-direct quotation within 24 hours — including brake disc weight and inertia data for your system dynamics calculation.
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