PSC Series Precision Planetary Gear Units for Robots

Schaeffler recently introduced the PSC Series Precision Planetary Gear Units for Robots, and is available from Pacific International Bearing Sales Inc.

PSC Series precision planetary gear units are built for robotic motion where accuracy, repeatability, and reliability matter especially under real loads and long duty cycles.

This overview explains what they are, what makes them “precision,” what specs to pay attention to, and how teams typically integrate them into robots and automation systems.

Here’s the practical breakdown.

Quick summary: The PSC Series is Schaeffler’s precision planetary gearbox line for robots, designed for high torque density, very low torsional backlash, and high torsional/tilting rigidity supporting accurate motion in industrial and collaborative robotics.

Key takeaway: PSC gear units are built around “precision under load”: low backlash plus rigid bearing arrangements help maintain positioning accuracy and consistent motion in demanding robotic applications.

Quick promise: With the right size/configuration (solid vs hollow shaft, pinion choice, sealing), PSC gear units can improve positioning, repeatability, and overall drivetrain performance in robotic systems without overcomplicating integration.

Quick Facts — PSC Series Precision Planetary Gear Units

• Precision planetary gearboxes designed specifically for robotics applications
• Integrated helical input stage + proprietary tooth technology for very low backlash
• Torsional backlash listed as ≤ 0.1 arcmin
• Efficiency listed as ≥ 90% (over 90% under full load)
• Design intended for long operational life up to 20,000 hours
  

What is the PSC Series?

The PSC Series is a set of precision planetary gear units for robots, introduced by Schaeffler and positioned for applications that need high accuracy, repeatability, and reliable performance.

What it includes / key components:

• Integrated helical gear stage at the input
• Proprietary tooth technology to support extremely low, consistent backlash
• Rigid bearing arrangement to provide high torsional and tilting rigidity
• Solid shaft and hollow shaft configurations, plus motor attachment options
  

Who it’s for:

• Industrial robot and automation builders focused on precision and repeatability
• Collaborative robots (cobots) that need controlled, predictable motion
• Systems that benefit from compact torque-dense drivetrain packaging
  

Who it’s not for:

• Projects where precision/backlash isn’t meaningful to performance outcomes
• Systems where gearbox size/rigidity requirements aren’t aligned with the mechanism constraints
  

Note: PSC is presented in the draft as a “precision” option where low torsional backlash and rigidity are core differentiators, not nice-to-haves.

What to expect (results, timeline, or outcome)

You can expect tighter positioning control, better repeatability, and more stable motion behavior, especially in applications where loads and forces vary over time.

Outcome profile (practical view):

• During motion: low backlash supports more predictable positioning and command execution
• Under load: rigidity helps reduce deflection and maintain accuracy
• In continuous operation: efficiency (≥ 90%) supports stable operation and lower energy loss versus lower-efficiency drivetrains
  

What changes outcomes most:

• Correct sizing (torque, rigidity needs, duty cycle)
• Correct configuration (solid vs hollow shaft, sealing, pinion choice)

Mechanical integration quality (alignment, mounting stability)

Overview of PSC Series Precision Planetary Gear Units

The PSC Series precision planetary gear units are a significant advancement in drive technology, tailored for robotic applications. The PSC Series precision planetary gear units enhance positioning accuracy, repeatability, and overall performance, making them an ideal choice for industrial and collaborative robot (cobot) applications.

The PSC Series integrates a helical gear stage at the input and unique tooth technology to ensure minimal torsional backlash throughout the operating life. This design feature is crucial for maintaining high precision and reliability in robotic movements and operations. The gear units boast a torsional backlash of ≤ 0.1 arcmin, highlighting their exceptional precision.

A standout feature of the PSC Series is its rigid bearing arrangement, which provides high torsional and tilting rigidity. This rigidity is essential for supporting significant forces and tilting moments encountered in robotic applications. These gear units have a compact design that offers a high torque density within a minimal envelope.

The versatility of the PSC Series is reflected in its wide range of variants, including nine different sizes with both solid and hollow shaft designs and various motor attachment options. This flexibility allows for extensive customization to match the required torque and speed ranges for diverse applications, from small cobots to large industrial robots.

Schaeffler offers a design intended for a long operational life of up to 20,000 hours, the PSC Series gear units are built to endure the demands of continuous use in harsh industrial environments. Schaeffler’s rigorous engineering standards and quality control measures support this longevity.

Technical Specifications and Performance

The PSC Series precision planetary gear units by Schaeffler are designed to deliver exceptional performance in robotic and industrial applications. These gear units are engineered with cutting-edge technology to ensure high precision, durability, and operational efficiency. Below is a detailed examination of their technical specifications and performance features.

Design and construction. The PSC Series gear units include an integrated helical gear stage at the input. This design ensures minimum torsional backlash and improves the overall precision of the gearbox. The gear teeth are designed using proprietary tooth technology, which contributes to extremely low and consistent torsional backlash across the whole operational life.

Torsional rigidity is an important consideration for the PSC Series gear units. It is defined as the ratio of the torsional torque exerted on the gearbox from the outside to the resulting torsion angle at the output. Torsional rigidity is measured in Nm per arcminute. The gear units have a high torsional rigidity due to their sturdy design and rigid bearing arrangements.

Tilting rigidity refers to the gear unit’s ability to resist bending moments resulting from external forces. The PSC Series gearboxes exhibit high tilting rigidity due to their robust design and precise engineering. This parameter is measured in Nm/arcmin, ensuring that the gearbox can handle significant forces without compromising performance.

The synchronous running accuracy of the PSC Series is a measure of the maximum transmission error, defined as the fluctuation amplitude of the output rotary motion. It is given in angular seconds (arcsec). The gear units maintain high synchronous running accuracy by minimizing transmission errors, which is crucial for applications requiring precise motion control.

The efficiency of the PSC Series gear units is a testament to their advanced engineering. Efficiency is defined as the ratio of output to input power and is typically less than 1 due to power losses from friction. The PSC Series achieves an efficiency of ≥ 90%, making them highly effective for continuous industrial operations.

Precision Planetary Gearboxes

Gearbox mounting kits from Schaeffler can be integrated directly into the system. These kits are available in several versions, each designed to cater to different needs and operational environments.

These mounting kits include a separate input pinion as standard, which is supplied loose. The transmission ratio is determined by whether a plug-in pinion (ER) or slip-on pinion (AR) is used.

The hollow shafts are particularly suitable for the passage of supply cables, ensuring that the gearboxes can be adapted to meet specific operational needs.

The three-stage construction with a solid shaft is a key configuration of the PSC Series gearboxes. This design is focused on maximizing torque handling and ensuring robust performance in demanding applications.

Technical specifications:

The following table provides detailed specifications for the PSC Series precision planetary gearboxes with solid shafts, illustrating their nominal torque capacities, input pinion types, and critical dimensions. 

Gearbox Dimensions:

The solid shaft version is designed to handle high torque and precise motion control, making it particularly suitable for applications that require robustness and accuracy. The detailed construction and precise measurements ensure that the gearboxes can withstand significant forces without compromising performance.

For more information or to discuss custom orders, please get in touch with us at [email protected] 

Integration and Applications in Robotics

The PSC Series Precision Planetary Gear Units by Schaeffler are designed to seamlessly integrate into robotic systems, providing the high performance and reliability required for advanced robotic applications. These gear units offer exceptional precision, rigidity, and efficiency, making them ideal for various robotic uses ranging from industrial automation to service robots.

Mechanical Compatibility and Mounting Options:

The PSC Series gear units are engineered with a range of mounting options to ensure mechanical compatibility with various robotic platforms. The gearboxes can be easily integrated into robotic arms, joints, and other moving parts, thanks to their compact design and versatile mounting kits. The available configurations include solid shaft and hollow shaft versions, catering to different mechanical requirements:

• Solid shaft version – ideal for applications requiring high torque and rigidity. This version ensures a robust connection to the robotic components, minimizing deflection and maintaining precise positioning.
• Hollow shaft version – this configuration is particularly useful for robots that require cable routings through the gear unit, such as articulated arms and collaborative robots (cobots). The hollow shaft allows for the passage of electrical cables, pneumatic lines, or hydraulic hoses, simplifying the design and reducing external clutter.

Electrical and Control Integration:

The integration of PSC Series gear units into robotic systems extends beyond mechanical aspects. These gear units are designed to work seamlessly with various motor types and control systems commonly used in robotics. The high precision and low backlash of the gear units ensure accurate transmission of motion commands, enhancing the overall control and performance of the robot.

• Servo motors – the gear units can be paired with servo motors to achieve precise control over speed and position. The high torsional rigidity and low backlash of the PSC Series ensure that the servo motors can operate at their full potential, providing smooth and accurate motion.
• Stepper motors -when integrated with stepper motors, the gear units help in maintaining consistent torque output and precise positioning, which is essential for tasks requiring repetitive and accurate movements.
• Advanced control systems – the compatibility with advanced robotic control systems allows for seamless integration of the PSC Series gear units. The precise feedback provided by the gear units’ low backlash and high rigidity improves the accuracy of motion control algorithms, enhancing the robot’s performance in complex tasks.

Applications in Robotics

Industrial Robotics:

In industrial robotics, the PSC Series gear units are widely used due to their ability to handle high loads and maintain precision over long operating periods. They are essential components in the following applications:

• Robotic arms and manipulators – the high torque and rigidity of the PSC Series gear units make them ideal for robotic arms and manipulators used in assembly lines, welding, and material handling. The precise motion control ensures accurate placement and manipulation of objects.
• Automated guided vehicles – the gear units contribute to smooth and precise navigation, enabling the vehicles to follow predefined paths accurately and handle varying load conditions without compromising performance.
• CNC machines and automated machining – the PSC Series gear units provide the necessary precision and rigidity for CNC machines and automated machining centers, ensuring high-quality production with minimal errors.

Service Robotics:

Service robots, which operate in environments ranging from healthcare to domestic applications, benefit significantly from the integration of PSC Series gear units. The gear units provide the necessary performance characteristics for tasks that require both precision and reliability:

• Medical robots – in medical applications, such as surgical robots and diagnostic machines, the gear units ensure precise control and smooth operation. The low noise generation and high efficiency are particularly beneficial in sensitive environments.
• Cleaning and maintenance robots – for robots used in cleaning and maintenance, the robust design and high efficiency of the PSC Series gear units ensure long operational life and reliable performance, even in demanding conditions.
• Entertainment and educational robots – in the entertainment and educational sectors, the gear units enable robots to perform complex movements and interactive tasks with high precision, enhancing user experience.

Collaborative Robots (Cobots):

Collaborative robots, designed to work alongside humans, require gear units that offer both high performance and safety. The PSC Series gear units meet these requirements through their precise control and ability to handle varying loads and forces:

• Assembly and inspection – in collaborative assembly and inspection tasks, the gear units ensure that the cobots can perform delicate operations with high accuracy and repeatability.
• Pick-and-place operations – the high precision and low backlash of the gear units make them ideal for pick-and-place operations, where precise positioning and handling of objects are crucial.

Emerging Technologies and Future Trends:

The PSC Series gear units are also well-suited for emerging technologies and future trends in robotics, such as:

• Autonomous vehicles – the precision of the gear units enhances the performance of autonomous vehicles, providing accurate control over steering and movement.
• Advanced AI and machine learning applications – in robotics powered by AI and machine learning, the gear units provide the necessary precision and control to execute complex algorithms and tasks with high accuracy.
• Integration with IoT – the compatibility with Internet of Things (IoT) devices allows for real-time monitoring and control of the gear units, enabling predictive maintenance and optimization of robotic systems.

Step-by-step: How to choose and integrate PSC gear units

Use this workflow to pick the right PSC setup and reduce integration surprises.

1. Define the robotics use case (arm joint, cobot axis, AGV drive, machining automation, etc.).
2. Determine torque and rigidity needs based on loads and motion accuracy goals.
3. Choose shaft type: Solid shaft for high torque/rigidity emphasis. Hollow shaft if you need cable/line routing through the gear unit
4. Select mounting kit options as needed (seals, protective sleeve, lubrication requirements).
5. Plan motor pairing (draft references servo motors and stepper motors as common pairings).
6. Choose the input pinion type because it affects the transmission ratio: plug-in pinion (ER) vs slip-on pinion (AR).
   Confirm key dimensions for your chosen unit (draft provides example dimension tables for PSC..-V-E variants).
7. Validate control performance: low backlash + high rigidity should support more accurate motion control behavior.
8. Document the configuration (size, shaft type, pinion, sealing) for serviceability and future scaling.
   

Maintenance tip: For long duty cycles, keep configuration documentation (pinion type, seal choice, shaft version) consistent across builds—this makes replacement, servicing, and scaling much easier.

Common problems and fixes

Common Issues

• Inconsistent positioning → alignment/mounting instability → Verify mounting surfaces and alignment; ensure the gearbox is securely located per its mounting requirements.
• Unexpected cable routing complexity → solid shaft chosen where routing is needed → Use hollow shaft configuration to pass cables/lines through the unit.
• Environmental wear/contamination → sealing not matched to conditions → Choose appropriate seal option (NBR vs optional Viton) and protective sleeve if needed.
• Performance doesn’t match precision goals → configuration doesn’t match application (size/rigidity/torque) → Re-check required torque/range and select the correct PSC size/variant.
• Wrong ratio behavior → pinion selection mismatch → Confirm ER vs AR pinion choice (ratio determined by pinion type).
  

Mistakes to Avoid

• Assuming one configuration fits every robot type (cobot vs large industrial robots differ)
• Ignoring cable routing needs until late-stage design
• Selecting seals/lubrication without considering the operating environment
• Overlooking pinion type choice even though it impacts ratio
• Skipping validation under real loads (precision claims matter most under load)
  

FAQ

What is the PSC Series in simple terms?

The PSC Series is a line of precision planetary gear units designed for robotic applications, focusing on high accuracy, repeatability, and reliable performance under load. It’s presented with very low torsional backlash and high rigidity as core features.

What does “torsional backlash ≤ 0.1 arcmin” mean?

It means the gearbox is designed to have extremely low rotational “play” (backlash), which supports more accurate positioning and repeatability. The draft lists PSC gear units at ≤ 0.1 arcmin torsional backlash.

What is torsional rigidity, and how is it measured here?

Torsional rigidity is described as the ratio of torque applied to the gearbox to the resulting torsion angle at the output, measured in Nm per arcminute. The draft describes measuring it by loading the gearbox bidirectionally up to nominal torque and recording the torsion angle.

What’s the difference between the solid shaft and hollow shaft versions?

The solid shaft version is positioned as ideal for high torque applications, while the hollow shaft version is described as useful when you need cable/line routing through the gear unit to simplify integration and reduce external clutter.

How efficient are PSC gear units?

The draft lists efficiency as over 90% under full load and also states PSC achieves ≥ 90% efficiency, which supports continuous industrial operation with lower friction losses.

How long are PSC gear units designed to last?

The draft states PSC gear units are intended for a long operational life of up to 20,000 hours in harsh industrial environments.

What motors and control systems are PSC gear units used with?

The draft describes pairing PSC gear units with servo motors for precise speed/position control and with stepper motors for consistent torque output and repetitive positioning needs, and notes compatibility with advanced robotic control systems.

How is transmission ratio determined for these gear units?

The draft states the mounting kits include a separate input pinion and that the transmission ratio is determined by whether a plug-in pinion (ER) or slip-on pinion (AR) is used.

What robotics applications are these commonly used in?

The draft lists industrial robotics (arms/manipulators, AGVs, CNC/automated machining), service robotics (medical, cleaning/maintenance, entertainment/education), and cobots (assembly/inspection, pick-and-place).

Can PSC gear units support future robotics trends like IoT and AI?

The draft frames PSC gear units as suitable for emerging trends like autonomous vehicles, AI/ML-driven robotics, and IoT integration for monitoring and predictive maintenance.

One-Minute Summary

• PSC is a precision planetary gearbox series built for robotics performance needs.
• It’s positioned around very low backlash (≤ 0.1 arcmin) and high rigidity.
• Efficiency is listed at ≥ 90% (over 90% under full load).
• Variants include solid/hollow shaft designs, seal options, and pinion selection that impacts ratio.
  Applications span industrial robots, service robots, cobots, and emerging robotics systems.
  

Key Terms

• Torsional backlash: rotational play in the gearbox; lower values support precision.
• Arcmin (arcminute): an angular unit used here to express backlash and rigidity-related angles.
• Torsional rigidity (Nm/arcmin): torque-to-angle stiffness measure for gearbox twist under load.
• Tilting rigidity: resistance to bending moments from external forces.
• Synchronous running accuracy (arcsec): measure tied to maximum transmission error, expressed in angular seconds.
• Helical input stage: a helical gear stage at the input, referenced as part of the PSC design.
• Pinion (ER / AR): input pinion type referenced as determining transmission ratio.

NBR / Viton seals: seal material options referenced for durability in different conditions.

You can order Schaeffler’s PSC Series gear units and other precision products from Pacific International Bearing Sales. By selecting from our comprehensive online shop, you can ensure you are equipping your robotic systems with the best in precision engineering.