Introducing Onvio’s Dojen™ Zero Backlash, Cycloidal Gearbox / Speed Reducer

Onvio’s Dojen™ cycloidal gearbox / speed reducers

Onvio’s Dojen™ cycloidal gearbox / speed reducers

Today’s servo motors continue to provide higher speeds and increased torque capacity in each frame size. Dynamic performance, backlash and torsional stiffness become ever more crucial to motion control systems.

Onvio’s Dojen™ cycloidal gearbox / speed reducers provide the highest precision available offering TRUE ZERO BACKLASH, high torsional stiffness and unmatched positioning accuracy.

Onvio has manufacturing locations in the United States and Mexico. By employing world class manufacturing standards we are able to control all aspects of the manufacturing process which means we will deliver the right product on time. You can count on it. 

True Zero Backlash Unique Cam Design Balanced Cam for Higher Speeds
400% Shock Load Capacity Allows for More Than 50 Standard Ratios Low Inertia
Exceptional Torsional Stiffness Same Low Profile Design High Safety Factor
Rigid Bearing Construction Regardless of Ratio Input Speeds to 6000 rpm
Smooth, Quiet Operation Integral Output Bearing Great for High Reversing Applications

Experience Ultimate Performance with Onvio’s  Dojen™
Zero Backlash, Cycloidal Gearboxes

In applications that demand the greatest positioning accuracy, highest torsional stiffness, and lowest backlash, Onvio’s Dojen™, with its compact axial design, is the only choice.

Choose from the following options:

Nine Frame Sizes

  • Diameters from 4 inches up to 19 inches
  • Output Torques from 100 Lb-in to over 100,000 Lb-in
  • Input speeds to 8,000 RPM

Widest Ratio Range Available

  • 49 Ratios Available
  • 9:1 up to 256:1
  • Stacking stages not required


  • Add Onvio’s Right angle reducer for applications where axial space is crucial
  • Add a planetary stage and create ratios of 256,000:1 and beyond
  • Motor attaches easily using one of two available standard interface designs

Input Configurations

  • Hollow bore input shaft for close mounting motor
  • Straight shaft for use with a timing belt
  • Thru-holes for passing wires
  • Optimal integrated brushless servo motor

Zero Backlash Cycloidal Gearbox / Speed Reducers Ultimate Performance

Onvio Cycloidal Gearbox / Reducers are designed with cantilevered needle bearing cam followers and rollers—not with pins and bushings found in other cycloidal gearbox designs. This allows for a controlled pre-load between the cam and cam followers, assuring zero backlash.  Pre-load is maintained throughout the design life of the reducer.

Every cam follower is in contact at all times, the load is equally shared. This guarantees consistently high torsional rigidity independent of load position.

With a high capacity output bearing and output flange, Onvio’s cycloidal gearbox can support most loads.  Machine designs are simplified thus increasing reliability and reducing overall package size.

Dojen™ Zero Backlash, Cycloidal Gearboxes / Speed Reducer Features

  • All steel construction for operation in wide range of temperatures.
  • One-piece dual reduction cam provides a wide range of ratios in a compact, low profile design.
  • Hollow bore input and clamp collar provide quick motor installation with no backlash.
  • Dynamically balanced counterweight for high speed input.
  • Integral four point contact ball bearing offers precision and high capacity.
  • Output flange design allows for direct connection to load, simplifying machine designs.
  • Full compliment needle bearing provides high capacity and assures zero backlash.
  • Improved spring loaded lip seal provides better sealing and can be operated in washdown.

Pancake Series Cycloidal Gearbox

Cycloidal Gearbox – Overall Dimensions

Cycloidal Gearbox Pancake Series DimensionsCycloidal Gearbox Diagram

 (Housing) InstallationCycloidal Gearbox Base-(Housing)-Installation

Load Installation

Cycloidal Gearbox load Installation

Pancake Series Cycloidal Gearbox – Performance RatingCycloidal Gearbox Pancake Series Performance Specs

  1. Additional ratios available. See ratio table for a complete list.

Additional Ratios Available

Pancake Series Additional Ratios Available

Ratios: Onvio’s cycloidal gearbox offers the most ratios with the widest range available. The  unique cam design allows all ratios to be achieved without stacking stages, so the reducer’s package size never changes.  The – and + indicators that precede the reduction indicate the
rotation of the output shaft relative to the direction of the input shaft. In negative ratios, the output shaft rotates opposite the input shaft. In positive ratios, the output shaft rotates in the same direction as the input shaft.

M-24 Series – Cycloidal GearboxM24 series Cycloidal Gearbox Diagram
– Dimensions
Special features of the high torque M-24

  • 3 times the power in the same diameter
  • Full complement output bearing
  • Higher ratios—up to 256:1
  • Higher input speeds—up to 4500 rpm
  • Greater positioning accuracy (±330 arc seconds)
  • Thru-hole capability


M-24 Series – Cycloidal Gearbox – Overall Dimensions

m24 series cycloidal gearbox overall dimensions

Base (Housing) Installation

m24-series cycloidal gearbox base (housing) - installation

Load Installation

m24-series cycloidal gearbox load insullation

M-24 Series Cycloidal Gearbox – Performance Ratings

Performance Specifications

m-24-cycloidal gearbox series-performance-specifications

  1. Additional ratios available. See ratio table for a complete list.

Ratios: Onvio’s cycloidal gearbox / speed reducer offers the most ratios with the widest range available. The unique cam design allows all ratios to be achieved without stacking stages, so the reducer’s package size never changes. The – and + indicators that precede the reduction indicate the rotation of the output shaft relative to the direction of the input shaft. In negative ratios, the output shaft rotates opposite the input shaft. In positive ratios, the output shaft rotates in the same direction as the input shaft.

Additional Ratios Available

m-24-performance series cycloidal gearbox additional ratios available

Additional Specification

Back Driveability

One of the unique features of Dojen™ cycloidal gearbox technology is it’s ability to be used as a speed increaser as well and as a speed reducer. This “backdriveability” is a necessary feature in reduction applications that have high inertial loads.

m24 cycloidal gearbox performance series backdrivability

 Input Torque Variables

Cycloidal gearbox Input Torque Variables

Tare Torque: Tare torque is the friction from the preload, bearings, grease, etc. The tare torque is the amount of torque it takes to continuously operate the reducer at 1,500 RPM input speed.

Motor Bearing Dynamic Radial Loads

Onvio’s unique collet input shaft gives designers the shortest axial package available. The motor shaft is close coupled with the reducer input shaft. When this design is used, the motor bearing is very close to the reducer’s input shaft. We remove the rear support bearing in order to avoid too many bearings in a row. Under load, the motor bearing will see a radial load from the reducer input. The following chart provides the radial load at rated output torque. The load varies with the amount of output torque and the relationship is linear.

Dynamic Radial Loads for Standard Ratios

Cycloidal gearbox - Dynamic Radial Loads for Standard Ratios

If the motor bearing can not support the reflected radial load, Onvio offers an added support bearing and male input shaft. Please refer to page 10 for standard dimensions. Contact Onvio application engineering for additional ratios or for assistance.

Efficiency, Lubrication, and Temperatures

Typical Efficiency vs. Load



The Dojen cycloidal gearbox is grease lubricated and sealed for life. However, in some high cycle applications or in environments that can prematurely cause lubricant to breakdown, we recommend purging old grease with fresh new grease. The reducer is equipped with grease ports on the outer diameter.  Contact Onvio customer service for lubrication procedures and available equipment.

Grease Chart

Cycloidal Gearbox Grease Chart

1 May require derating the cycloidal gearbox / reducer. Contact our application department for details.
Onvio also offers specialty lubrication for use is semiconductor applications, food processing, etc. Contact our application department for details.

Standard Operating Temperatures

For normal, steady-state operation: 32°F to 150°F
Requires heatsinking/cooling: 150°F to 212°F

Input Shafts

Cycloidal Gearbox Collet Input ShaftCollet Input Shaft

  • Perfect for direct mounting in close quarters to a servo motor.
  • No keyways, no backlash.
  • Specify motor shaft diameter when ordering.
  • Motor sleeves provided for any motor shaft diameter smaller than the maximum shaft diameter.
  • Eliminates costly couplings.

Collet Input Chart (For direct coupling of motor shaft)

Collet Input (For direct coupling of motor shaft)

Straight Input ShaftsCycloidal Gearbox Straight Input Shaft

  • Has fully supported input shaft.
  • Removes radial load from motor bearings.
  • Ideal for shaft-to-shaft couplings, pulleys, gears, etc.
  • Allows reducer to be used as a speed increaser in
    specified ratios.
  • Both metric and inch sizes.
  • Thru-holes available for routing wires, etc.

Straight Input Shaft Chart

Straight Input Shaft



Additional Options

  • Face mounted pulleys
  • Large diameter thru-holes for passing wires, coolant lines, etc.
  • Full complement output bearing that can handle even higher loads
  • Eccentric pilot for installation and preload of rack and pinion drives
  • Nickel plated finish for use in high corrosive and vacuum environments
  • Custom input and output shafts
  • Stacked reducers for ratios over 50,000:1

Motor InterfacesMotor Interfaces

Onvio offers three standard types of servo flanges that can be machined for use with almost any servo or stepper motor. They include square flanges, round flanges, and foot mounts. They can be made of either steel or aluminum.


Motor Interfaces


These flanges are used to interface our speed reducer to various brands of motors. Here’s a partial list of brands.


  • Allen Bradley
  • Baldor
  • Control Technique
  • Danaher
  • Electrocraft
  • Emerson
  • Fanuc
  • Global Servos
  • Giddings & Lewis
  • IMS
  • Indramat
  • Industrial Drive
  • Infranor
  • Kollmorgen
  • Lenze
  • Mavilor
  • MCG
  • Moog
  • Oriental Motor
  • Pacific Scientific
  • Parvex
  • PMI Motion Technologies
  • Reliance Electric
  • Rockwell Automation
  • Siemens
  • Yaskawa

One of our applications engineers will be pleased to provide you with the proper CAD drawing— by mail, fax, CD, or over the internet.

Round Face Mount Flange

Round Face Mount Flange

Foot Mount

Foot Mount

Cycloidal Gearbox Installation Chart

Warning: Never loosen the stud nuts of a Onvio reducer. They are factory precision set.
Attempting to adjust these nuts in the field will void the warranty.


  • Torque: 1Nm = 8.85 Lb In
  • Stiffness: 1Nm/arc min = 8.85 Lb In/arc min
  • Inertia: 1Kgcm2 = 8.85 x 104 Lb In sec2
  • Weight: 1Kg = 2.2 Lbs
  • Force (Bearing Loads): 1 Newton = .2248 Lbs
  • Dimensional: 1mm = .03937 inches

Cycloidal Gearboxes are Easy to Order.  Use the chart below to create your part number.

Onvio’s unique interface design offers an oversized pilot and slotted holes. The motor bearing is free of side load, resulting in longer life and better performance.

Simplified ordering and shortened delivery time because Onvio offers standard flanges for almost any motor. Match the motor mounting dimensions with the proper flange and insert the corresponding letter into the catalog number when ordering.

How to order High Torque and Hollow Shaft Cycloidal GearboxesHow to order Standard Cycloidal Gearboxes

Use the form below to order your Cycloidal Gearbox and/or set up a conference call with Onvio’s Engineered Solutions Group

Step 1 of 2

  • Tell Us What You Need

  • The more detail, the better/easier/faster we can get you what you need.
  • Please provide urgency level of the request.