Series 40 Ball Bearing

Orbit Block™


  •  Ultra Lightweight
  •  Low friction 2-stage Orbital ball bearing system
  •  Highest working load in its class
  •  Low profile and compact
  •  High performance cleating

  Product No. Desc. Sheave ØMax. Rope ØMax. Cable ØPin ØM.W.L.B. L.Weight
 RF45101 RF45101 Single 409--32570033
 RF45110 RF45110 Single, becket, swivel head 4094325*65044
 RF45111 RF45111 Single, becket 409--32570036
 RF45130 RF45130 Single, Becket, Cleat, Swivel Head* 4094325650105
 RF45140 RF45140 Single, becket, swivel shackle head, stand-up 409325*65054
 RF45151 RF45151 Cheek Block 409--32570032
 RF45201 RF45201 Double 409--500100067
 RF45501 RF45501 Fiddle 40 + 229--32570047
 RF45511 RF45511 Fiddle, becket 40 +229--32570048
 RF45521 RF45521 Fiddle, cleat* 40 + 229--325700108
 RF45531 RF45531 Fiddle, becket, cleat* 40 + 229--325700109

These blocks have been specifically designed and optimised for use on racing sailboats and the conditions encountered in this unique application.  They should not be assumed suitable for other non-marine or industrial applications. For further details on associated risks see   Orbit Block Usage and Considerations



Kilogram for kilogram of working load, BB and RT Orbit Blocks™ are the world’s lightest. The unique orbital design allows the bearing to only be in the active areas of the floating sheave. This minimises the mass of the inactive return race and hub.

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. This gives a 30% weight saving advantage over the nearest competitor. Other brands just link together their single blocks. This results in unnecessary double cheeks between each sheave, held together by a heavy steel channel across the top of the block.


Highest working load in its class

The orbital ball-bearing arrangement gives the largest possible bearing race diameter. This maximises load performance. The proven Ronstan 2-stage bearing system features high compression grade acetal ball bearings and a secondary full-contact bearing. This gives minimum friction across the full working load range.

The floating sheave and bearing system is supported by a fibre-reinforced load frame. The design was computer modelled to be stress optimised.   User Instructions
For comprehensive details including user instructions, and for spare part tables, and fastener sizes view in various languages using the following links BB & RT OrbitBlock™ User Instructions  (English),  BB & RT OrbitBlock™ User Instructions (French), BB & RT OrbitBlock™ User Instructions (German)


  • Mainsheet systems on spinnaker sheet on dinghies to 5m (16ft)
  • Spinnaker sheets on dinghies, sportsboats and small keel boats to 5m (16ft)
  • Halyard, vang and backstay applications on boats to 8m (26ft)
  • Control line applications on larger yachts


  • Ball Bearings - High compression stregnth carbon black Acetal.
  • Stage 2 Bearing - Glass fibre reinforced, MoS2 impregnated Nylon
  • Frame/Cheeks - Toughened, glass fibre reinforced Nylon
  • Sheave - Carbon fibre reinforced, PTFE impreganated Nylon


  Range aaDescription
  BB & RT Orbit Block™ Accessories,