Description
WPKA Hollow Shaft Single Speed Worm Gear Reducer — Direct Shaft-Mount Drive for Mixers, Agitators & Feeders
Conventional shaft couplings introduce misalignment tolerance, require precise mounting, and add a maintenance touchpoint to every driven machine. The WPKA hollow shaft worm gear reducer resolves this problem by replacing the solid output shaft with a precision-bored hollow shaft that slides directly over the driven machine shaft — creating a compact, rigid, alignment-free connection that eliminates the coupling entirely from the drive chain.
Available in 12 frame sizes (40–250 mm) with ratios from 1/5 to 1/60, the WPKA is the hollow shaft worm gearbox of choice for agitator shafts, feeder screws, conveyor rollers, and any application where a direct-fit, coupling-free output connection reduces machine complexity and installation time. The foot-mounted cast iron housing ensures the same heavy-duty durability as the solid-shaft WPA series. About Ever-power | Request a Quote
Technical Specifications
Full dimensional data for all WPKA sizes. S = hollow bore diameter; W×Y = keyway width × depth in bore. Input shaft: HS = shaft diameter; U = shaft length; T×V = keyway. Reference input speed 1500 r/min. All dimensions in mm.
| Size | Ratio | A | AB | B | CC | H | HL | M | N | E | F | G | Z | HS | U | T×V | S(bore) | W×Y(keyway) | Wt(kg) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 40 | 1/5–1/60 | 143 | 87 | 85 | 40 | 138 | 40 | 90 | 100 | 70 | 80 | 13 | 10 | 25 | 12 | 4×2.5 | 16 | 6×18.8 | 5 |
| 50 | 175 | 108 | 105 | 50 | 176 | 50 | 120 | 140 | 95 | 110 | 15 | 12 | 30 | 12 | 4×2.5 | 20 | 6×22.8 | 7.5 | |
| 60 | 198 | 120 | 110 | 60 | 204 | 60 | 130 | 150 | 105 | 120 | 20 | 11 | 40 | 15 | 5×3 | 25 | 8×28.3 | 11 | |
| 70 | 231 | 140 | 130 | 70 | 236 | 70 | 150 | 190 | 115 | 150 | 20 | 15 | 40 | 18 | 5×3 | 30 | 8×33.3 | 15.5 | |
| 80 | 261 | 160 | 150 | 80 | 268 | 80 | 170 | 220 | 135 | 180 | 20 | 15 | 50 | 22 | 7×4 | 35 | 10×38.3 | 22 | |
| 100 | 322 | 190 | 160 | 100 | 336 | 100 | 193 | 270 | 155 | 220 | 25 | 15 | 50 | 25 | 7×4 | 40 | 12×43.3 | 36 | |
| 120 | 371 | 219 | 175 | 120 | 430 | 120 | 233 | 320 | 180 | 260 | 30 | 18 | 65 | 30 | 7×4 | 45 | 14×48.8 | 62 | |
| 135 | 422 | 249 | 210 | 135 | 480 | 135 | 253 | 350 | 200 | 290 | 30 | 18 | 75 | 35 | 10×4.5 | 60 | 18×64.4 | 80 | |
| 155 | 497 | 295 | 256 | 155 | 531 | 135 | 275 | 390 | 220 | 320 | 35 | 21 | 85 | 40 | 12×5 | 70 | 20×74.9 | 114 | |
| 175 | 534 | 314 | 282 | 175 | 600 | 160 | 310 | 430 | 250 | 350 | 40 | 20 | 85 | 45 | 14×5.5 | 80 | 22×85.4 | 150 | |
| 200 | 580 | 342 | 320 | 200 | 666 | 175 | 360 | 480 | 290 | 390 | 40 | 22 | 95 | 50 | 14×5.5 | 85 | 22×90.4 | 215 | |
| 250 | 705 | 420 | 400 | 250 | 800 | 200 | 460 | 560 | 380 | 480 | 45 | 28 | 110 | 60 | 18×7 | 110 | 28×90 | 360 |
* S = hollow output bore diameter (mm). W×Y = keyway dimensions in output bore. The driven shaft diameter must match S within h6/H7 tolerance for correct interference fit.
Product Structure — Hollow Output Shaft Design
The WPKA replaces the solid output shaft of the WPA with a through-bored worm wheel shaft. The bore is precision-ground to an H7 tolerance and fitted with an internal keyway, allowing the driven shaft to be located both radially (by the bore) and rotationally (by the key) in a single assembly step. A set screw or shrink-disc can provide additional axial retention.
| Output Type | Precision hollow bore H7 with internal keyway — no coupling required |
| Bore Tolerance | H7 — mates with shaft ground to h6 or js6 for precise alignment |
| Housing | FC25 grey cast iron, same footprint as WPA series |
| Input Shaft | Standard solid shaft with keyway — 5 direction positions (A–E) |
| Worm Pair | 20CrMnTi worm (≥58 HRC) + ZCuSn10Pb1 bronze wheel |
| Axial Retention | Set screw standard; shrink disc optional for higher torque or reversing loads |
✅ Key Features & Benefits
Coupling-Free Direct Shaft Mount
The H7 precision hollow bore mates directly to the driven shaft — no coupling, no hub, no adapter plate. The shaft simply slides into the bore, the key transmits torque, and the assembly is complete. This eliminates the coupling misalignment that accounts for a disproportionate share of bearing and seal failures in indirect-drive gearboxes. Keywords: hollow shaft worm gearbox, direct shaft mount worm reducer.
Simplified Machine Design & Build
Eliminating the coupling reduces part count, assembly time, and alignment tooling requirements. For OEM machine builders, this translates directly into lower machine BOM cost and faster production assembly — particularly valuable when the same drive configuration is repeated across a production line of dozens of machines.
Rugged FC25 Cast Iron Housing
Identical material and dimensional specification to the WPA solid-shaft series — FC25 grey cast iron providing outstanding impact resistance and vibration damping. The WPKA delivers the same heavy-duty durability in the same compact foot-mounted footprint, with hollow shaft as the only structural difference.
Precision Worm & Wheel for Smooth Torque
Ground 20CrMnTi worm and ZCuSn10Pb1 bronze wheel to ISO 1328 Grade 7 tolerances deliver smooth, low-noise (≤72 dB(A)) torque at transmission efficiencies of 60–90% depending on ratio. High-ratio self-locking (≥1/30) is also available for agitator positioning applications.
Wide Bore Size Range
Hollow bore diameters range from 16 mm (size 40) to 110 mm (size 250), covering the vast majority of industrial shaft diameters used in mixer, agitator, and feeder applications. Output torques from 17 Nm to over 2,300 Nm span the full industrial requirement spectrum.
Five Input Shaft Directions
Standard positions A through E allow the WPKA to accept input from any direction, accommodating horizontal, inclined, and vertical motor positions in machine layouts where space constraints prevent standard motor placement.
Industry Applications
The WPKA hollow shaft worm reducer excels wherever a coupling-free output shaft connection reduces machine complexity:
Industrial Mixers & AgitatorsChemical, paint, food, and pharmaceutical mixing vessels where the hollow shaft slides directly onto the impeller shaft, eliminating the coupling and simplifying the mixer gearbox head assembly.
Screw & Auger FeedersBulk powder and granule feeders in plastics, food processing, and cement production where the WPKA mounts directly over the conveyor screw shaft without a separate coupling hub.
Conveyor Roller DrivesLive-roller conveyor sections where the WPKA’s hollow bore accepts the roller shaft end, providing a clean, low-profile drive arrangement without protruding coupling hardware.
Animal Feed & Livestock EquipmentFeed conveyor drives, mixing drum drives, and silo discharge screw drives in agricultural facilities where simple, robust coupling-free gearbox mounting is preferred for ease of field maintenance.
Cosmetics & Personal CareCream and lotion mixing vessel drives, filling machine feed screws, and blending paddle drives in cosmetics manufacturing requiring smooth, quiet, compact drive integration.
Waste & Recycling EquipmentShredder pre-feed conveyors, rotary trommel screen drives, and compactor screw drives where hollow shaft mounting simplifies integration into custom machine frames.
Quality Control & Certification
ISO 9001:2015 & CE
Full ISO 9001:2015 QMS with CE Declaration of Conformity per shipment. The hollow bore is dimensionally verified to H7 tolerance using calibrated plug gauges at final inspection — ensuring correct shaft-to-bore fit without on-site reaming or modification.
Bore Tolerance & Concentricity Test
Each WPKA unit is verified for bore diameter to H7 tolerance (go/no-go gauge) and bore-to-shaft concentricity (≤0.05 mm TIR) relative to the gearbox output centreline. This ensures the driven shaft runs true within the bore without inducing additional bearing loads.
Material Standards
Housing: FC25 cast iron (≥250 MPa). Worm shaft: 20CrMnTi (≥58 HRC). Worm wheel bore: precision-bored worm wheel hub. Full material mill certificates available on request for food and pharmaceutical industry compliance documentation.
Why Choose Ever-power for WPKA Hollow Shaft Gearboxes
We supply WPKA hollow shaft worm gearboxes to mixer OEMs, conveyor equipment builders, and agricultural machinery manufacturers in Korea, Mexico, Germany, Australia, and over 60 countries worldwide. Our in-house internal grinding capability ensures every hollow bore is machined to H7 tolerance in a single clamped operation — maintaining concentricity and eliminating multi-step machining errors.
- ✅ In-house internal grinding — H7 tolerance hollow bores machined to ≤0.05 mm TIR
- ✅ Custom bore sizes — non-standard bore diameters for specific shaft sizes on request
- ✅ Shrink-disc output option — available for high-torque or reversing load applications
- ✅ OEM batch supply — consistent bore dimensions across large production batches
- ✅ 20+ years export experience — Korea, Mexico, Germany, Australia and beyond
⭐ Customer Reviews
“We switched our entire agitator gearbox range to WPKA hollow shaft units three years ago. The coupling-free direct shaft mount has eliminated our most common field service call — coupling misalignment — completely. The bore tolerance is consistently H7; our shafts fit perfectly every single time.”
David C., Production Engineer
Industrial Mixer OEM, Queensland, Australia
“We use WPKA-100 and WPKA-120 units on our animal feed mixing drums. The hollow shaft design is perfect for our drum shaft diameter, and the self-locking at 1/40 ratio provides useful passive positioning for the mixing cycle. Consistent quality from Ever-power across multiple orders.”
Ji-hoon P., Senior Engineer
Feed Equipment Manufacturer, Gyeonggi, South Korea
“WPKA gearboxes are now our standard specification for roller conveyor drives. The hollow bore mounts directly over the roller shaft — no coupling, no extra hardware. Our assembly time per drive point dropped from 45 minutes to under 15. Excellent quality and competitive pricing.”
Roberto M., Design Engineer
Conveyor Systems Builder, Monterrey, Mexico
“Good quality WPKA units for our industrial paint mixer range. The H7 bore tolerance is correct and our shafts fit cleanly. We requested a custom bore diameter for one model and Ever-power delivered to specification on the first attempt. Minor packaging improvement would be appreciated for ocean freight, but overall very satisfied.”
Thomas B., Technical Manager
Mixing Equipment OEM, Hamburg, Germany
❓ Frequently Asked Questions
How do I specify the correct hollow bore diameter for my driven shaft?
The hollow bore diameter (S column in the specification table) must match your driven shaft diameter exactly. The WPKA bore is machined to H7 tolerance — your shaft should be ground to h6 or js6 tolerance for a precision sliding fit. If your shaft diameter falls between standard WPKA bore sizes, contact us: custom bore diameters are available for OEM orders with MOQ of typically 5–10 units.
How is the WPKA secured axially on the driven shaft?
Standard supply includes a set screw in the hub that locks against the shaft keyway for light axial loads. For heavier axial loads, cyclic loading, or reversing duty, we recommend specifying the optional shrink disc variant, which clamps the hollow bore onto the shaft through interference compression — providing much higher axial and torsional holding capacity without keyway stress concentrations.
What is the difference between the WPKA and the WPA?
The WPKA and WPA are identical in housing dimensions, input shaft dimensions, gear ratio options, and torque ratings. The sole difference is the output: the WPA has a solid output shaft with external keyway; the WPKA has a hollow output bore with internal keyway. Choose WPA when your machine has a separate coupling and driven shaft; choose WPKA when you want to mount the gearbox directly onto the driven shaft without a coupling.
Can the WPKA handle bidirectional (reversing) operation?
Yes — the worm gear pair handles bidirectional rotation, and the hollow bore keyway transmits torque in both directions equally. For reversing applications, ensure the axial retention method (set screw or shrink disc) is adequate to prevent the gearbox from walking along the shaft during direction changes, particularly if axial forces are present.
What is the maximum shaft length that can pass through the WPKA hollow bore?
The maximum usable shaft insertion depth is governed by the through-bore length (LL dimension, which is the same as the worm wheel hub width). For size 50, this is approximately 77 mm; for size 135, approximately 170 mm. A longer shaft can pass through the bore without issue as long as it does not contact internal gearbox components. Contact us with your shaft through-length requirement and we will confirm.
Eliminate the Coupling — Enquire About WPKA Today
Simplify your mixer, agitator, or conveyor drive by mounting the gearbox directly onto the driven shaft. Our engineers will confirm bore size availability, shrink-disc options, and provide a fast quotation.
