Ronstan RF55110 Series 55 Orbit Ball Bearing Single Block with Becket and Swivel Mount

The Ronstan RF55110 Series 55 Orbit Block features an innovative orbital ball bearing design that delivers exceptional performance for sailing applications on boats up to 30 feet. This single block with integrated becket and swivel head mount combines ultra-lightweight construction with a maximum working load of 1,100 lbs, making it the lightest block in its class while maintaining superior strength.

Key Features:

• Ultra-lightweight design at just 3.1 oz with 1,100 lb working load capacity
• Two-stage orbital ball bearing system minimizes friction across full load range
• Through-sheave becket arrangement for lowest possible weight
• Swivel shackle head in 316 stainless steel allows unlimited block rotation
• 55mm diameter sheave accommodates rope up to 10mm (3/8 inch)
• Fiber-reinforced, stress-optimized load frame
• Dyneema SK75 fiber link provides exceptional strength-to-weight ratio
• Low profile and compact design for easy installation

Construction:

• Sheave and bearings: Carbon fiber reinforced, PTFE-impregnated nylon with high-compression acetal ball bearings
• Frame and cheeks: Toughened, glass fiber reinforced nylon
• Head fitting: Marine-grade 316 stainless steel
• Rope link: UV-stabilized multi-strand SK75 Dyneema

Ideal Applications:

• Mainsheet and spinnaker sheet systems on dinghies, sportsboats, and small keelboats to 30 feet
• Halyard, vang, and backstay applications on boats to 26 feet
• Control line systems on larger yachts

Specifications:

• Maximum Working Load: 1,100 lbs (500 kg)
• Breaking Load: 2,200 lbs (1,000 kg)
• Sheave Diameter: 55mm (2-5/32 inches)
• Maximum Rope Diameter: 10mm (3/8 inch)
• Weight: 3.1 oz (88g)

The RF55110's orbital bearing design positions the bearing only in active areas of the floating sheave, eliminating unnecessary mass from the inactive return race and hub. This engineering innovation delivers 30% weight savings compared to competitors while maintaining the highest working load in its class.