Series 75



  •  Class leading performance and sleek, contemporary styling
  •  Excellent dynamic and high static load performance
  •  Less than half the friction of the nearest competitor

  Product No. Desc. Sheave ØMax. Rope ØMax. Cable ØPin ØM.W.L.B. L.Weight
 RF74100 RF74100 Single, universal head 7514-815003000354
 RF74100AW RF74100AW Single, aluminium rope/wire sheave 75148815003000432
 RF74108 RF74108 Halyard, screw pin with roller head 7514-815003000234
 RF74108A RF74108A Mast base block 7514-81500*3000*230
 RF74110 RF74110 Single, becket, universal head 7514-815003000428
 RF74140 RF74140 Stand-up, swivel 7514--15003000468
 RF74142 RF74142 Series 75 Core Block stand-up kit 751415003000434
 RF74151 RF74151 Foot, single 7514--15003000259
 RF74202 RF74202 Double, non-swivel head 7514--15003000506
 RF74251 RF74251 Foot block, double 75-1500**3000**530

* Full block rated load can only be achieved with uniformly distributed load across full length of clevis pin. ie. 14mm (9/16”) diameter mast collar post or 14mm (9/16”) wide mast collar plate/tang.
Blocks supplied with 8mm clevis pin & split pin to suit a 14mm post (not supplied)
** Total block load. Maximum load on top sheave not to exceed 50% of total block load.


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.

Universal Bearing -

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 optimisation and the cut-away design minimises 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, minimising rope wear.