1. Product Overview: Hollow Shaft Planetary Gear Motors
Modern machine design prioritizes compactness and elegance. Passing power cords, hydraulic lines, or laser beams directly through the center of a rotating mechanism is often necessary. Ever Power, a premier drive innovator in the Netherlands, offers Hollow Shaft Planetary Gear Motors to solve this engineering challenge. These drives provide the massive torque of a planetary gear while leaving the center axis completely open.
Applicable Industries: Automated printing presses, packaging machinery, robotic wrist joints, and rotary indexing tables.
Core Advantages: Simplifies cable routing, eliminates the need for bulky external couplings, and allows for direct mounting onto the machine’s driven shaft, saving crucial space.
2. Technical Parameters
| Specification | Value Range | Unit / Note |
|---|---|---|
| Hollow Bore Diameter | 12 to 120 | mm (Clear-through) |
| Output Torque | 20 to 1,500 | Nm |
| Connection Method | Keyway or Shrink Disc | Shrink disc offers zero backlash |
| Reduction Ratio | 3:1 to 100:1 | 1 or 2 stages |
| Backlash | Less than 5 | Arcminutes (Precision Series) |
3. Working Principle & Structure
Creating a hollow planetary gearbox requires advanced structural engineering. Instead of a solid central sun gear, the motor drives an offset spur or helical gear stage that connects to a larger, hollow sun gear. The planet gears orbit this hollow sun gear, and the planet carrier itself is fashioned as a heavy-duty steel tube. This leaves the entire center axis unobstructed from the front of the gearbox through to the back. Dive deeper into specialized gear geometries at planetary gearboxes.
4. 5 Core Advantages
Cable Routing Efficiency
Pass power cables, air hoses, or optical fibers directly through the axis, preventing them from tangling as the machine rotates.
Direct Machine Mounting
The machine’s solid shaft slides directly into the hollow bore, eliminating the need for expensive, space-consuming external flexible couplings.
Zero Backlash Connection
Using a shrink disc clamping mechanism on the hollow shaft provides a 360-degree frictional grip, ensuring absolutely zero play between motor and machine.
High Torsional Stiffness
The large-diameter hollow carrier acts like a rigid pipe, resisting twisting forces much better than a solid, thin shaft.
Weight Reduction
Removing the solid core material lightens the overall drive unit, which is highly beneficial for dynamic moving gantry systems.
5. Structure & Material Technology
To compensate for the material removed from the center, the hollow carrier is machined from high-strength forged steel and supported by dual oversized angular contact bearings. This ensures the hollow tube does not deform under heavy radial or axial loads. The internal gears are precision hobbed and hardened, ensuring silent, smooth power delivery around the hollow center.
6. Typical Application Scenarios
Robotic Joints: The hollow bore allows pneumatic hoses and sensor wires for the robotic gripper to pass straight through the spinning “elbow” joint without getting tangled.
Rotary Indexing Tables: The motor mounts directly under the table. The hollow shaft allows a central stationary pillar to pass up through the table to mount fixed cameras or tools.
7. Selection Guide
Sizing a hollow shaft motor requires precision:
- Bore Diameter Requirement: Measure the maximum bundle thickness of your cables/hoses, or the exact diameter of the machine shaft you intend to insert.
- Shrink Disc vs. Keyway: We strongly recommend shrink discs for dynamic reversing applications (like robotics) to prevent keyway wallowing.
- Servo Match: Ensure the offset input flange matches your chosen servo or stepper motor dimensions.
8. Brand Comparison & Upgrades
Ever Power provides exceptional hollow-shaft engineering, matching the precision of legacy brands at a highly competitive price point.
| Competitor Brand / Series | Ever Power Equivalent | Advantage |
|---|---|---|
| Neugart – WPLN Hollow | EP-Hollow Precision | Identical low backlash; faster delivery on custom bore sizes. |
| Apex Dynamics – AD/ADR | EP-AD Flange Hollow | Equivalent torsional stiffness; highly competitive bulk pricing. |
9. Quality Certification & Service Promises
Manufactured under strict ISO 9001:2015 guidelines in the Netherlands, our precision drives are CE certified. Every hollow shaft unit is tested for concentricity runout to ensure it will not induce vibration into your machine shaft. Supported by our global 18-month technical warranty.
10. Engineer Field Notes: Global Case Studies
🇮🇹 Italy (Printing Machinery): “We saved almost 200mm of machine width by sliding the print roller shaft directly into the Ever Power hollow gearbox. It completely eliminated the need for external couplings.”
🇯🇵 Japan (Robotics): “Passing the camera fiber-optics straight through the gear axis prevented the cables from tangling during 360-degree spins. The zero-backlash shrink disc performed perfectly.”
🇺🇸 USA (Packaging Automation): “The compact integration allowed us to build a smaller, faster indexing table. Lead times from the Netherlands were exceptionally fast.”
Simplify Your Machine Design
Optimize space and cable management with Ever Power hollow shaft technology.
11. Frequently Asked Questions (FAQ)
Q: Is a shrink disc difficult to install?
A: Not at all. You simply slide your machine shaft into the bore, then tighten the bolts on the shrink disc collar in a circular pattern using a torque wrench. It squeezes the hollow tube onto your shaft securely.
Q: Does the hollow shaft rotate?
A: Yes, the hollow tube is the output shaft. Anything mounted rigidly inside it will rotate. If passing cables through, ensure there is enough slack on either end to accommodate the rotation, or use a slip ring.
