Block double Orbit with swivel head and becket 55mm
Ronstan
Article number :  RF55210
Ultra Lightweight
Low friction 2-stage Orbital ball bearing system
Highest working load in its class
Low profile and compact
High performance cleating
Swivel shackle head for unlmited block rotation.
Stainless steel shackle head and compatibility with sharp fixing points.
Ultra low profile integrated beckets.
Sheave Ø 55 mm
Max. Rope Ø 10 mm
Max. Cable Ø mm
Pin Ø 5 mm
M.W.L. 750* kg
B. L. 1500 kg
Weight 172 g
Product Information
Lightweight
Kilogram for kilogram of working load, BB and RT Orbit Blocks are the worlds 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. The Dyneema® Link is produced from FSE Robline SK75 fibre, which is 10 times stronger and lighter than steel, and provides the final connection from the block to the load point.
Holding power 20:1
Applications
Mainsheet systems on dinghies, sportsboats and small keelboats to 9m (30ft)
Halyard, Vang and Backstay application on boats to 8m (26ft)
Control line applications on larger yachts
Mainsheet systems and spinnaker sheets on dinghies, catamarans, sportsboats and small keel boats to 9m (30ft)
Halyard, vang and backstay applications on boats to 8m (26ft)
Control line applications on larger yachts
Materials
Ball bearings - High compression strength carbon black Acetal
Stage 2 bearing - Carbon fibre reinforced, PTFE impregnated Nylon
Frame/Cheeks - Toughened, glass fibre reinforced Nylon
Rope Link: UV stabilised, multi-strand impregmented SK75 Dyneema®
Head fitting: grade 316 stainless steel
Ball Bearings: high compression strength carbon black Acetal