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Roller Pinion Gear System

Supplier: Norman G. Clark

Nexen offers an advanced new technology that revolutionizes rotary motion.


The Roller Pinion Gear system (RPG) provides zero backlash, very high positional accuracy, 99% efficiency,high rigidity, low maintenance, corrosion resistance, and long life. This opens up new design possibilities and provides the capability to achieve much higher levels of performance in machine designs.

The Roller Pinion System features a rack with patented tooth design combined with a pinion consisting of bearing supported rollers to ensure precision and reduce maintenance. Offering better performance and longer life than traditional rack and pinion or ball screw systems, the Nexen Precision Roller Pinion System has sizes ideal for a variety of linear motion applications.

Accurate Positioning

The RPG system features an innovative ring gear and roller pinion technology that provides extremely accurate positioning. The Roller Pinion Gear system also offers backlash-free performance in both directions by maintaining opposing contact with two or more teeth at all times.

High Speed Capability

The RPG system maintains accurate positioning at peripheral speeds as high as 11 m/sec (36.1 ft/sec). Even at these speeds, the extremely-low friction design does not create heat or wear on components.


  • Gantry Systems
  • Machine Tools
  • Material Handling
  • Transfer Equipment
  • Robotics
  • Inspection Equipment
  • Packaging Machinery

Eliminates Many of the Short Comings of Other Rotary Drive Technologies the RPG’s unique design eliminates many of the limitations of current rotary drive systems like:

  • Spur Gears: Backlash limits positional accuracy, tooth meshing can be noisy and introduce vibration that can affect control systems, and tend to have high wear and maintenance.
  • Chain Drives: Backlash limits positional accuracy, tooth meshing can be noisy and introduce vibration that can affect control systems, and tend to have high wear and maintenance due to stretch.
  • Belt Drives: Limited by low accuracy, backlash, low load capacity, belt stretch, and low rigidity.
  • Direct Drive Rotary Stages: Limited by low torque capacity, high cost, and strong magnetic fields.
Zero Backlash/High Precision

The RPG’s innovative meshing action provides backlash of less than 3.2 µm [0.00013 in.] and positional accuracy up to ± 30 µm [± 0.00118 in.] tangentially at the meshing pitch circle due to an extremely precise manufacturing and inspection process. Each tooth profile is precisely measured to ensure that high positional accuracy is maintained.


The RPG system can achieve tangential meshing pitch circle speeds, up to 11 m/s (36.1 ft/s), while providing high positional accuracy.


Due to the smooth, backlash free way that the rollers engage the teeth, the RPG system is very quiet with 62 dB at low speeds and 75 dB at full speed. This is much lower than traditional gear systems with their tooth slap.


The RPG system has very low maintenance. Typically lubrication is required every two million pinion revolutions or six months.

Surface Treatments

The RPG system has the Raydent surface treatment, providing stainless steel-like performance without the related high cost and low wear characteristics. Raydent is not a typical blackening or surface treatment coating that can break down and flake off. Instead, Raydent is a cryogenic process that permeates the metal surface and permanently bonds with it forming a ceramic oxide surface layer 1 millimeter deep without causing significant surface buildup. Raydent will not flake off and is highly resistant to acids, alkalies, and solvents.