Applying Roller Gear Cam Mechanism Technology

Linear drive systems that convert motor rotation into linear motion—such as cam-type rack and pinion, precision ball screws, and timing belts—come in various forms. Among these systems, the liner unit utilizing roller gear cam mechanism technology—renowned for its exceptional precision and high-speed performance—delivers outstanding accuracy, rigidity, and reliability. Developed ten years ago, the liner unit transforms the rotation of a servo motor through a screw-shaped cam, allowing the unit to move smoothly in a straight line along a rail. It is a product of Sankyo Seisakusho, the first company in Japan to domestically produce the roller gear cam mechanism, which has continued to pursue research and development under the theme of providing motion control. By adopting rolling transmission drive using high-rigidity rollers, the liner unit enables high-speed and stable transport even for heavy loads such as robots. It achieves travel speeds exceeding 200 meters per minute, significantly reducing transfer time. The system supports rapid acceleration and deceleration as well as high-speed operation, and by simply connecting rails, it can accommodate long strokes of over 10 meters.

▲Liner unit demonstration

Excellent load balance is another advantage. Thanks to the single integrated cam mechanism, the system operates smoothly, enabling seamless lifting and lowering of pallets, 180° rotation, and efficient transfer of heavy workpieces or robots. Compared with other mechanisms, it can reduce installation space by up to approximately 50%.

Achieving a Well-Balanced Combination of Functions Required for Linear Drive Systems

The most remarkable feature of this liner unit is its well-balanced design. It offers all key performance aspects: high speed, compact size, long stroke, high load capacity, and long service life.

▲Comparison of features with other mechanisms

In typical long-stroke drives, positioning accuracy is around ±50–100 µm, whereas the liner unit achieves ±15 µm. Thanks to the cam mechanism, it maintains high repeatability, stopping precisely at the intended position every time. Other linear drive systems have limitations: rack and pinion mechanisms experience play due to backlash between gear teeth, making precise positioning difficult. Precision ball screws can achieve accurate positioning but are prone to deflection, limiting long strokes to about 3 meters. The liner unit, on the other hand, is widely used in processes such as 10-meter-long vehicle transfers because it simultaneously delivers both long-stroke capability and high precision.

▲By simply connecting rails, long strokes of over 10 m (theoretically unlimited) are possible

High maintainability is another advantage of the liner unit. Thanks to smooth bearing-based rolling, wear is minimal, and lubrication is needed only about once every six months, ensuring stable operation over long periods. In the unlikely event of damage, the bearing unit can simply be removed and replaced with a new one, enabling quick maintenance and reducing overall downtime. The rolling transmission also keeps operating noise low.

Ideal for High-Speed Automated Transport Systems Requiring Long Strokes

Because the liner unit combines all the key functions expected of a linear drive system, it can be applied across a wide range of applications. Its adoption in new equipment is steadily increasing. Demand for long-stroke projects has also been growing consistently in Southeast Asia.

▲Featured at METALEX 2024 — Ueno (Thailand) booth showcasing Denso robots and Sankyo Seisakusho liner units

Amid labor shortages and workforce reductions, the introduction of robots and automated transport systems is accelerating on production floors. The liner unit, capable of long-stroke, high-precision operation and offering excellent maintainability, offers a highly rigid and reliable solution that meets these evolving needs.

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