Caged Ball Profile Rail Design Considerations

Nook's NARC / NHRC Linear Guide Series uses the O-type arrangement for the four row ball circulation design. The contact angle between the rail and ball is 45 degrees, and can realize the 4 directional load effects. NARC / NHRC linear guide blocks have a longer length to allow for a greater Mr value to increase the rigidity and static moment capability. In addition, runner blocks feature a larger ball bearing, which allow them to outperform competitor's models by 10% to 30% regarding load capapbilities. The products have characteristics of high load, high moment, and high stiffness.


The Caged Ball Chain Design provides lower friction and lower noise than traditional profile rail block designs. The benefit of a caged ball design prevents the bearings from incidental contact, which reduces friction, wear and noise.

Rotational Ball Chain:

  • Reduces noise
  • Higher speed in motion
  • Prolong service life
  • Prolong re-lubrication period

A uniquely patented ball chain design provides a flexible link between the block and bearings. This gives the ball chain enough space to rotate and move in the circulation channel and overcome the friction of the curvature. In addition, the space between upper and bottom parts have oil storage functions, increasing the re-lubrication interval and service life.


Inner oil storage and oil supply system design

Inner Lubrication Storage Pad design does not increase length of runner block and contacts directly with ball bearings. Lubrication oil can be injected through lubrication holes. The Lubrication Storage Pad can save enough lubrication oil to ensure long term lubrication effects, conforming to environment protection needs and lowering maintenance costs. Excellent performance when used in short stroke.

Multi-position lubrication port

The lubrication fittings can be moved from the top, bottom or side of the runner block. An o-ring seal is used for easy/clean lubrication.


Using two stainless steel reinforcement plates on each end increases the rigidity of the end caps.

The clearance between the rail profile with the seal design is below 0.3mm, reinforcing the steel plates while having scraper functions.

The NARC / NHRC type uses the stainless steel reinforcement plates to strengthen the bottom retainer, while increasing X-axis direction force capacity, and increasing operation speed.


Stainless steel reinforcement plate

With clearance between rail profile of no more than 0.3mm, the plate can scrape large items such as iron fillings to protect the end seals.

Inner seals

The newly designed inner seals, slant inward at a 45 degree angle. This protects against foreign objects from sliding into the rails while maintaining low friction. It also allows the lubrication oil to be maintained inside the runner block and prolong the re-lubrication interval.

Bottom seals

The bottom seals can prevent foreign objects from entering the bottom and prevent lubrication from leaking out. The full sealing design reduces the amount of oil usage, prolongs the re-lubrication interval and the service life.

End seals

The Nook double lip type end seals can prevent foreign objects from entering from the side and prevent lubrication oil and grease from leaking. The flexibility of the TPU material has better friction resistance ability and better prevents cracking characteristics than typical NBR plastic.

Standard seals (B): Suitable for most conditions, with slight contact with the rail, having both scraping function with low friction.

Reinforcement seals (S):Seal comes in direct contact with the rail surface, thus having better dustproof and lubrication retention. Nook recommends using this type of seal in enviroments that are exposed to long periods of high dust. The friction will be higher than standard seals.

Comparison of friction of seals The friction will be highest on new linear rails. After a short period of operation, friction will reduce to a constant level.

Figure 1