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

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

The Ronstan Series 55 Ball Bearing Orbit Block with Single Becket and Swivel Head is designed for high-performance marine rigging systems. Its ultra-lightweight construction is achieved through a unique orbital bearing design that minimizes mass while maximizing load capacity. The ball bearings are positioned only in the active sheave areas, reducing unnecessary weight and ensuring smooth operation under heavy loads. This innovative design results in a lightweight, compact, and highly efficient block suitable for various sailing applications.

Constructed with durable materials, the Series 55 Orbit Block features a 55mm sheave capable of handling ropes up to 3/8 inch (10mm) in diameter. Its high compression grade acetal ball bearings provide low friction and excellent load distribution, supporting a maximum working load of 1,100 lbs (500kg) with a breaking load of 2,200 lbs (1,000kg). The floating sheave and bearing system are supported by a fiber-reinforced load frame, which has been stress-optimized through computer modeling for maximum strength and durability. The Dyneema Link, made from FSE Robline SK75 fiber, offers a lightweight yet incredibly strong connection, being ten times lighter than steel and resistant to harsh marine environments.

The block features a stainless steel swivel shackle head that allows for unlimited rotation, ensuring flexibility in rigging configurations. Its low-profile, compact design makes it ideal for applications such as mainsheet systems, spinnaker sheets, halyards, and control lines on boats up to 30 feet (9 meters). The high-performance cleating and integrated becket provide reliable operation and easy handling during sailing maneuvers. The materials used—such as carbon fiber reinforced Nylon, PTFE impregnated Nylon, and Grade 316 stainless steel—ensure longevity and resistance to corrosion, making it suitable for demanding marine conditions. This block is an excellent choice for sailors seeking a lightweight yet robust solution for their rigging needs, offering the highest working load in its class with minimal weight and maximum efficiency.

Features:

• Ultra Lightweight construction for reduced weight and ease of handling

• Low friction 2-stage orbital ball bearing system ensures smooth operation under load

• Supports highest working load in its class, maximizing safety and performance

• Compact, low-profile design suitable for limited space applications

• High performance cleating for secure line control

• Swivel shackle head allows for unlimited rotation, increasing versatility

• Stainless steel shackle head for durability and compatibility with harsh environments

• Integrated becket for simplified line management