Ball Bearing


Series 40 Ball Bearing Orbit Block™, Ratchet Cheek Block, Anti-Clockwise

Cheek Block, Auto, anti-clockwise rotation, requires 2 x 4mm (5/32") fasteners


Up to 14:1 holding power - highest available.

Smooth easing of sheets.

Anti-clockwise rotation.

Fully automatic, load sensing ratchet engagement.

Recessed underside to suit curved mounting surface.

Low mounting points for maximum strength.


Product Specifications
Max. Rope diameter (in)5/16
M.W.L. (lb)385
Sheave diameter (in)1 9/16
B.L. (lb)1100
Weight (oz)1.3

Product Information

Awesome ratchet block holding power

Quite simply, Ronstan Ratchet Orbit blocks™ have the highest holding power available. The sophisticated NC-machined sheave features Generation 2 of our patented sheave cross-hole geometry. The Series 40 delivers up to 14:1 holding power, almost double that of our nearest competititor.

The unique sheave design has 8 gripping faces which directly resist loaded line movement. Traditional designs have an angled resistance to line movement.  Our Generation 2 design has straight resistance faces which both distribute the load and minimise rope wear. These faces are offset from the radial line, to draw the rope down into the gripping area when under load.


Smooth easing of sheets

With auto models the sheet runs out smoothly and freely as soon as the ratchet mechanism disengages. When engaged, and with manual models, the sheave cross-hole geometry eliminates the 'shuddering' ease-out that you can expect from traditional v-groove ratchet blocks.

Technical Information


  • Dinghy mainsheet systems.
  • Mainsheet fine tune systems on sportsboats & small keel boats.
  • Mainsheet systems on sportsboats using RF7 mainsheet swivel cleat unit.
  • Spinnaker and job sheets on dinghies - especially modern asymmetric classes.
  • Control line applications on larger yachts.



  • Sheave: Anodised Aluminium.
  • Ball Bearings: High compression strength carbon black Acetal.
  • Frame/Cheeks: Toughened, glass fibre reinforced Nylon.
  • Rope Link: UV stabilised, multi-strand impregnated SK75 Dyneema®.


Resource Files

We found other products you might like!

Need some advice?

Send us a

Find a