Ronstan Series 55 Ball Bearing Orbit Block™ - Single - Becket - Swivel Head RF55110

Series 55 Ball Bearing Orbit Block™ - Single - Becket - Swivel Head

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 fiber-reinforced load frame. The design was computer modelled to be stress optimised. The Dyneema® Link is produced from FSE Robline SK75 fiber, which is 10 times stronger and lighter than steel, and provides the final connection from the block to the load point.

Features:

• 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 unlimited block rotation
• Stainless steel shackle head for ultimate durability and compatibility with harsh fixing points
• Ultra low profile integrated becket

Applications:

• Mainsheet systems on dinghies, sportsboats and small keelboats to 9M(30')
• Spinnaker sheets on dinghies, sportsboats and small keel boats to 9M(30')
• Halyard, Vang and Backstay application on boats to 8M(26')
• Control line applications on larger yachts
• Ideal use for mainsheet systems and spinnaker sheets on dinghies, sportsboats and small keel boats to 9M(30')
• Also ideal with halyard, vang and backstay applications on boats to 8M(26')
• Spinnaker sheets on sportsboats and small keel boats (lateral lead blocks)
• Control line applications on larger yachts

Materials:

• Ball bearings - High compression strength carbon black Acetal
• Stage 2 bearing - Carbon fiber reinforced, PTFE impregnated Nylon
• Frame/Cheeks - Toughened, glass fiber reinforced Nylon
• Rope Link: UV stabilized, multi-strand impregmented SK75 Dyneema®
• Sheave: Carbon fiber reinforced, PTFE impregnated Nylon
• Head fitting: Grade 316 stainless steel.

Specifications:
Sheave Ø: 55mm(2-5/32")
Max. Rope Ø: 10mm(3/8")
M.W.L.: 500kg(1,100lbs)
B. L.: 1,000kg(2,200lbs)
Weight: 88g(3.1oz)

Shipping
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Processing and dispatch
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Delivery and tracking
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Duties, taxes, and support
International customers are responsible for any customs duties, taxes, and fees charged by the destination country. If these charges are refused and a shipment returns to us, the carrier’s return cost and any re-entry customs fees will be deducted from the refund. If your order is late or you need help, contact cs@qualityboatparts.com and we will assist you.

Quality Boat Parts is a reseller. Many items include a manufacturer’s warranty, and all warranty service is handled directly by the manufacturer. We do not manage or administer warranty claims on behalf of customers.

Warranty terms, coverage, and duration are set by each manufacturer. Issues involving defects, repairs, or replacements must be addressed with the manufacturer’s support team. When available, the warranty period is listed on the product page. If it is not shown, contact us or the manufacturer for details before purchasing.

To start a claim, the customer must contact the manufacturer and follow their process. Keep your proof of purchase and original packaging, and register the product if the manufacturer requires it, as these are often needed for warranty service.

We are happy to help you find the right contact or documentation, but we cannot decide outcomes or intervene in claim resolutions. For guidance, email cs@qualityboatparts.com.