RF55521 - Series 55 Ball Bearing

Lightweight 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. 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. High performance cleating Both Ronstan BB and RT Orbit Blocks feature strong, lightweight fibre-reinforced cleat arms. They have a wide range of adjustment and calibration marks, perfect for selecting your preferred cleating angle settings. The race-proven carbon-fibre reinforced Ronstan C-Cleat give secure rope holding with low entry and exit efforts, and are fitted with fairleads for fast action from any angle. Fiddle block flexibility Becket fiddle blocks use a Dyneema Link attachment for the sheet termination and are suitable for both spliced and un-spliced lines. If you need additional purchase, a becket take-off can be simply added to any fiddle block version just by adding a Dyneema Link.

Sheave Ø 55 + 35 mm
Max. Rope Ø 10 mm
Max. Cable Ø - mm
Pin Ø - mm
M.W.L.500 kg
B. L.1000 kg
Weight231 g