Ronstan RF74100 Series 75 Core Block Single with Universal Bearing

The Ronstan RF74100 Series 75 Core Block is a high-performance single block designed for demanding sailing applications. Featuring Ronstan's innovative 2-stage Universal Bearing system, this block delivers exceptional performance across the full working load range while handling both dynamic and high static loads with ease.

Universal Bearing System:

The advanced 2-stage bearing technology ensures minimal friction under all conditions. Stage 1 uses Acetal ball bearings for smooth operation under moderate loads, while Stage 2 employs a sliding Acetal bearing on a polished stainless steel race to maintain low friction performance under heavy loads. The ball bearings also function as an integrated thrust bearing, preventing sheave-to-cheek contact and eliminating friction even when line lead angles aren't perfect—especially important for cheek block applications.

Key Features:

• Class-leading performance with contemporary, sleek styling
• Less than half the friction of competing blocks
• Universal head with full 3-axis articulation and 360° rotation on brass bearing washer
• Head posts can be locked at 0° or 90° using a 2.5mm hex key
• Lightweight alloy cheek plates with cut-away design for easy rinsing and debris removal
• Flared block throat and reduced cheek-to-sheave gap minimize rope wear
• Central hub hole serves as becket take-off or tie-up point
• High-quality forged grade 316 stainless steel shackle included

Applications:

• Mainsheet, halyard, and spinnaker sheet systems on boats up to 14M (46')
• Control line applications on larger yachts
• Racing and cruising applications requiring reliability and durability

Construction Materials:

• Sheave: UV-stabilized Acetal
• Cheek body: Aluminum alloy
• Ball bearings: High-compression carbon black Acetal
• Shackle, head post, and hub: Grade 316 stainless steel

Specifications:

• Sheave diameter: 75mm (3")
• Maximum rope diameter: 14mm (9/16")
• Pin diameter: 8mm (5/16")
• Maximum working load: 1,500kg (3,300 lbs)
• Breaking load: 3,000kg (6,600 lbs)
• Weight: 354g (12.5 oz)