Planetary Gearbox vs. Cycloidal Gearbox Technology – Component Case Studies

Planetary vs cycloidal gearboxes

Why Use a Cycloidal Gearbox or Planetary Gearbox?
Understanding Servo Gearbox Technology
Understanding Planetary Gearbox Technology – Principle of Operation
Planetary Gearbox Advantages & Disadvantages
Planetary Gearbox Commercial Variations
Understanding Cycloidal Gearbox Technology – Principle of Operation
Cycloidal Gearbox Advantages & Disadvantages
Cycloidal Gearbox Commercial Variations
Industries and Applications for Each Technology
Contact Us for Q & A

Why use a Cycloidal Gearbox or Planetary Gearbox?

Inertia matching
Speed reduction
Torque magnification
Bearing support for application loads

Servo Gearbox Technology

Planetary Gearbox
Right Angle Gearbox
Custom Drive Packages and Designs

Zero Backlash Cycloidal Gearbox / Speed Reducers
Custom Drive Packages and Designs

Understanding Planetary Gearbox Technology – Principle of Operation

planetary gearbox technology principle of operation photo

Planetary Gearbox Technology – Principle of Operation – Servo MotorPlanetary Gearbox - Servo Motor

The sun gear is attached to the input shaft which connects directly to the servo motor

Planetary Gearbox Technology – Principle of Operation – Satellite (Planet) Gears

planetary gearbox technology -operation satelite planet

The sun gear engages with the satellite (planet) gears and transmits its rotary motion to them.

 Planetary Gearbox Technology – Advantages

planetary gear

High torque density
Load distribution and sharing between planet gears
Smooth transmission
High efficiency
Low input inertia
Low backlash
Low cost

Planetary Gearbox Technology – Disadvantages

Necessary backlash increases with wear
Maximum practical single stage reduction ratios 10:1
>100:1 requires 3 stages
Through holes are not practical

Planetary Gearbox Technology – Commercial Variations

Gear Tooth Design
Straight teeth
Helical teeth
Gear Finishing Process and Precision
Skiving/carbide re-hobbing
Heat Treating Methods
Plasma/ion or gas nitriding
Through hardening
Output Shaft Bearing Support
Deep groove ball bearings
Angular contact ball bearings
Taper roller bearings
Satellite Carrier Design
Straddled gear support
Cantilevered gear support

Cycloidal Gearbox Technology Basics – Principle of Operation

The mechanism is comprised of the following major moving parts:

High speed input shaft
Single or compound cam
Cam followers or rollers
Slow speed output shaft

Cycloidal Gearbox Technology – Principle of Operation – Ratio

Cycloidal Gearbox Basics - Ratio

Cycloidal Gearbox Technology –Principle of Operation – First Track

Cycloidal Gearbox Technology – Principle of Operation-First Track

The first track of the cycloidal cam lobes/teeth engage with cam followers located in the reducer housing. Cylindrical cam followers act as teeth of the internal gear. The number of cam followers exceeds the number of cam lobes/teeth.

Cycloidal Gearbox Technology – Principle of Operation – Second Shaft

Cycloidal Gearbox Technology – Second Shaft

The second track of the cam lobes/teeth engages with the cam followers on the output shaft and transforms eccentric rotation of the cam into concentric rotation of the output shaft producing increased torque and reduced speed

Cycloidal Gearbox Technology Basics – Principle of Operation – Input Shaft

Cycloidal Gearbox Technology – Principle of Operation - Input ShaftThe input shaft is attached to the eccentric drive member that induces eccentric rotation of the cycloidal cam

Cycloidal Gearbox Technology – Advantages

cycloidial gearbox technology

Zero backlash stays constant through life
Rolling vs. sliding contact
Very low wear
High shock load capacity
High torsional stiffness
Flat, pancake design
Ratios in excess of 200:1 in the same package size are possible
Quiet operation

Cycloidal Gearbox Technology –Disadvantages

Cycloidal Gearbox DisadvantagesLow reduction ratios (below 25:1) impractical
Lower efficiency
Large diameter
Higher input inertia

Cycloidal Gearbox Technology – Commercial Variations

Cycloidal Gearbox Commercial Variations

Single vs. compound cycloidal stage speed reduction
Rollers vs. cam followers
Cantilevered vs. fully supported rollers/cam followers
Single, dual and triple cam arrangements
Cross roller vs. angular contact ball bearing support of loads
Large diameter thru-holes

Gearbox Industry Applications by Technology

Cycloidal Gearbox Applications                     Planetary Gearbox Applications

Cycloidal Gearbox Applications: Indexers, Machine Tool, Robotic Positioners, Antenna Drives, Robot Axes, Pan & Tilt Systems, Tool Changers

Planetary Gearbox Applications: Linear Actuators, X-Y Gantry Systems, Textile Machines, Packaging Machines, Conveying, Materials Handling, AGV’s

Both Cycloidal and Planetary Applications: Paper Manufacturing, Rack and Pinion, Printing, Semiconductor, Food Processing, Bottle Manufacturing, Automotive, Tire Manufacturing

Gearbox Technology Summary:

Two common technologies for use in servo applications

Planetary offers
Low ratios
Low backlash
High torque density
High efficiency

Cycloidal applications
High ratios
Lowest backlash
Compact design
High capacity output bearings

Principle of operation of both technologies

Broad applications for use with servo motors

Contact us to discuss your planetary or cycloidal gearbox technology needs!

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