Ronstan Series 40 Ball Bearing Orbit Block™ – Quin, Becket (RF48510)
Lightweight Upper Block for High Purchase Systems
The Ronstan Series 40 Quin Orbit Block™ with Becket is designed as the primary upper block in high-performance mainsheet systems, delivering an optimal balance of strength, low friction performance, and weight efficiency.
Featuring a quintuple (five-sheave) configuration, this block enables very high purchase ratios in compact cascading systems. Built on Ronstan’s proven Series 40 Orbit Block™ platform, it incorporates a 2-stage ball bearing system that ensures smooth, low-friction operation across the full working load range—from light trimming to heavily loaded conditions.
The lightweight construction uses toughened, glass fibre reinforced nylon cheeks, reducing weight compared to traditional metal strap designs while maintaining excellent strength and durability. This makes it particularly well suited to performance applications where weight aloft and system efficiency are critical.
A swivel shackle head allows unrestricted rotation or can be locked at 0° or 90°, providing flexibility depending on installation. The integrated becket offers a clean and efficient anchor point for cascading systems, while removable becket pins allow lines to be spliced prior to fitting for a neat, secure setup.
Performance Meets Reliability
Series 40 Orbit Blocks™ are engineered to deliver class-leading dynamic and static load ratings within their size category. The large bearing race and efficient load distribution ensure reliable performance under demanding conditions, while the 2-stage bearing system combines ball bearings for low friction with a secondary full-contact bearing for consistent performance at higher loads.
The result is a highly versatile and dependable block suitable for a wide range of high-load control applications.
Key Features
- Quin (five-sheave) configuration for high purchase systems
- Integrated becket for cascading system anchoring
- 2-stage ball bearing system for low friction across all loads
- Lightweight, high-strength composite construction
- Swivel head with 0° and 90° locking positions
- Removable becket pins for clean spliced rigging
- Compact Orbit Block™ design for efficient line handling
Key Specifications
- Sheave diameter: 40mm
- Maximum rope diameter: 10mm
- Breaking load: 1200kg
- Safe working load: 600kg
- Weight: 246g
Notes:
- MWL refers to total block load
- Becket MWL: 400kg (BL: 800kg)
Applications & System Integration
The RF48510 is designed to act as the upper block in compact, high-efficiency cascading mainsheet systems, forming the primary load-bearing connection at the boom.
When paired with the RF46530 quin ratchet lower block and additional cascade components, it enables the creation of a powerful 12:1 mainsheet system optimised for performance dinghies and off-the-beach catamarans.
A typical 12:1 system is configured as follows:
- Upper block: RF48510 – Quin Orbit Block™ with Becket (this product)
- Lower block: RF46530 – Quin Ratchet Orbit Block™ with Adjustable Cleat
- Cascade blocks: 2 × RF35101 – Series 30 Single Blocks
- Connectors: 2 × RF9003-07 Dyneema® Link connectors
In this configuration:
- One RF35101 is attached to the becket of the upper block (RF48510)
- One RF35101 is attached to the becket of the lower block (RF46530)
- Each is connected using RF9003-07 Dyneema® Links, creating a cascading purchase stage between the two primary blocks
This arrangement delivers a compact and highly efficient 12:1 purchase, allowing sailors to manage high mainsheet loads with significantly reduced effort while maintaining precise control.
Within the system, the RF48510:
- Acts as the primary upper load-bearing block
- Distributes load efficiently across five sheaves
- Provides the becket anchor point for the upper cascade stage
This setup is particularly suited to:
- Off-the-beach catamarans requiring high purchase mainsheet systems
- Performance dinghies with high sheet loads
- Sailors seeking maximum mechanical advantage without increasing system size
By combining RF48510 with RF46530, RF35101 blocks, and RF9003-07 Dyneema® Links, sailors can build a complete, optimised 12:1 mainsheet system using fully compatible Ronstan components.
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