Ronstan 75mm Halyard Core BlockClass leading performance and sleek, contemporary styling
Excellent dynamic and high static load performance
Less than half the friction of the nearest competitor
Durable aluminum alloy cheek plates
Central hub hole can be used as a becket take-off or tie-up point
Suits direct attachment to mainsail headboard for 2:1 halyard
Removable 8mm (5/16”) threaded pin at head
Acetal roller on head pin to suit spliced line attachment
Alloy Rope/Wire sheave version also available
Sheave Ø - 3 in.
Max. Rope Ø - 9/16 in.
Max. Cable Ø - in
Pin Ø - 5/16 in.
M.W.L. - 330 lb.
B. L. - 6600 lb.
Weight - 8.6 oz.
Core Blocks™ are a true all round solution. A tuned 2-stage bearing system provides excellent performance across the full working load range with an integrated thrust bearing feature and the resilience to handle high dynamic or static loads. Acetal sheave, alloy cheeks and stainless fixings complete the durable package. For reliability and a long service life, these blocks are the right choice for sheets, halyards and control line applications for cruising and racing.
Dynamic and high static load performance
The Ronstan Universal Bearing incorporates our proven 2-stage bearing system
Stage 1 - Under moderate loads, Acetal ball bearings ensure minimum friction.
Stage 2 - Under heavy loads, where deformation of ball bearings alone would result in increased friction, a sliding Acetal bearing on a polished stainless steel race takes over, maintaining low friction performance.
Additionally the ball bearings are configured to act as a thrust bearing between the sheave and cheeks, preventing the sheave from rubbing on the cheeks and causing friction when the line lead in and out of the block isn’t perfect. Particularly important for cheek blocks.
Alloy cheek plates
Block cheeks are manufactured from the highest quality alloy for maximum strength. Material optimization and the cut-away design minimizes weight and allows easy fresh water rinsing of salt and debris from the bearings. Cheek design has been further styled with flaring at the block throat and reduced gap between the cheek and sheave, minimizing rope wear.
Ideal for use on mainsheet, spinnaker sheet, vang, halyard and backstay applications on boats up to 14m (46ft).
General applications on larger yachts.
Alloy sheave models are available for use with wire.
Sheave: U.V. stabilized acetal or anodized aluminum (AW models).
Cheek plates: Aluminum alloy
Ball Bearings: High compression strength carbon black acetal.
Pin: 2205 stainless steel