Blocks with rolling elements are an engineering development of the plain bearing block.
Roller Bearing Blocks are the 'Rolls Royce' premium choice for high load bearing capability and low resistance under dynamic load. Go for roller bearings if you want exceptional performance for Racing, Regatta or Performance Cruising, especially for applications where it may be necessary to release or adjust a control line when under extreme tension. Prompt, safe and uncomplicated manoeuvre can be more easily achieved if the control line can be fine tuned or released under pressure e.g. your running backstay/vang/kicker purchase, main sheet or spinnaker halyard.
Roller Bearings are a succession of small diameter tubes or cylinders fitted into a roller 'race or cage' between the sheave and the axle. Roller bearings have more surface area contact than ball bearings. The increased surface area increases the load capacity and distributes it more evenly so that roller bearing blocks, generally have a much higher resistance to distortion under load than ball bearing blocks. Roller bearings don't run quite as freely as ball bearings but they are exceptionally low friction.
The picture shows a roller bearing on a sheave, an exploded diagram of a Harken roller bearing block and another design of roller bearing.
Roller bearing block features:
- Ultimate dynamic load capacity
- Premium Choice for severe conditions
- Excellent effectiveness under extreme static loads
- Outstanding response under acute dynamic loads
- Ultimate all round, multi-purpose high performance functionality for Regatta sailing
- Excellent durability with Torlon roller bearings
Parts of a Yacht Rigging Block, traditional and modern