Anti-Two Block (ATB) Warning Systems
RaycoWylie’s ATB systems are crucial for preventing crane accidents by avoiding contact between the hook block and boom tip. Our models, both wired (R140) and wireless (R147), offer maximum safety and are easy to install. Ensure the safety of your operations with our reliable solutions that comply with international standards.

R147 (Wireless) - A2B
The R147 Wireless Anti-Two-Block (A2B) system by Rayco-Wylie offers a versatile and reliable solution for crane safety, specifically designed to monitor and prevent over-hoist situations. It features a clear LCD display, internal relay output for motion cut functions, and both audio and visual alerts. This system is ideal for cranes where running cables is impractical.
Available Versions:
R147 – Wireless Anti-Two-Block (A2B) indicator for cranes – 66D0147K1
- RaycoWylie part # 66D0147K1
- Includes 1x switch, 1x weight and chain, 1x display, power cable, and manual.
R147 – Wireless Anti-Two-Block (A2B) indicator for cranes – 66D0147K2
- RaycoWylie part # 66D0147K2
- Includes 2x switches, 2x weights and chains, 1x display (R147 Display), 2x brackets, power cable, and manual.
R147 – Wireless Anti-Two-Block (A2B) indicator for cranes – 66D0147K5
- RaycoWylie part # 66D0147K5
- Single hoist kit for customers with existing weight & chain.
- Includes 1x display, 1x switch, 1x bracket, power cable, and manual.
The R147 system is designed for easy installation, making it a cost-effective choice for various crane applications. Whether you need a single or dual hoist setup, the R147 offers the flexibility and reliability you need to ensure safe crane operations.

R140 (Wired) - A2B
The R140 is a reliable wired ATB warning system that provides both audio and visual alerts when the crane hook approaches the maximum safe height. It connects directly to the tip-mounted ATB switch using a cable, whether on a lattice boom or through a cable reeling drum on a telescopic boom. This system supports the addition of a second switch to monitor both the main and auxiliary hoist using the same display.
Key Features:
- Fail-Safe Operation: Automatically triggers an alarm if the cable is cut.
- Versatile ATB Switch: Rotates 360 degrees and is compatible with all major crane brands.
- Lockout Integration: Equipped with an internal relay for function lockout systems (sold separately).
- Durable Design: Available in both standard aluminum and marine-grade stainless steel, with an IP66 rating for open cab use.
- Proven Reliability: Years of dependable performance in various crane operations.
The R140 is a superior choice for crane safety, offering robust performance and compatibility across major brands.