Ball Bearing


Series 30 Ball Bearing Orbit Cheek Block

Single sheave cheek block. Requires 2 x 4mm (5/32") fasteners.


Base suits curved mounting base.


Highest working load in its class.

Low friction 2-stage ball bearing system provides consistent performance over the full working load range.


Product Specifications
Max. Rope diameter (in)5/16
M.W.L. (lb)660
Sheave diameter (in)1 3/16
B.L. (lb)1320
Weight (oz)0.7
Fastener Ø (in)5/32

Product Information

Ball Bearing Orbit Blocks™ boast the highest strength-to-weight ratio available. This is achieved through all-composite reinforced polymer materials and multiple attachment options. Their precision design provides the optimum number of ball bearings for minimum friction while weight reduction is achieved through the use of fibre-reinforced composites in the block head, cleat arms and beckets.


Kilogram for kilogram of working load BB Orbit Blocks™ are the world’s lightest. To gain peak performance, we engineered out the heavy steel load straps, head post, shackle and cleating accessories. Through extensive research and development, we replaced virtually all metal components with high-tech polymers and fibre equivalents. Weight and bulk are further reduced in the different block configurations. The ball bearing single and becket block has a through-sheave becket arrangement. The result? The lowest weight possible. Multi-sheave blocks have only single intermediate cheeks and an ultra-light and efficient head arrangement. Other brands just link together their single blocks with a heavy steel channel across the top of the block, with unnecessary extra cheeks adding extra weight and bulk not found in Ronstan Orbit Blocks™.

Highest working load in its class
The proven Ronstan 2-stage bearing system (Series 30 and larger) features high compression grade Acetal ball bearings and a secondary full-contact bearing. This gives minimum friction across the full working load range. The sheave and bearing system is supported by a fibre-reinforced load frame, computer modelled and optimised using advanced stress analysis methods. 

Technical Information


  • Mainsheet systems and spinnaker sheets on dinghies to 5m (16ft).
  • Halyard, vang and backstay applications on boats to 5m (16ft).
  • Control line applications on larger yachts.
  • Primary lead blocks on dinghies and catamarans.



  • Sheave: High compression strength carbon black Acetal.
  • Ball Bearings: High compression strength Acetal.
  • Frame/Cheeks: Toughened, glass fibre reinforced Nylon.


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