1. Regulatory Basis for Dual-Limit Devices

According to the Notice on the Investigation and Management of Potential Risks in Lifting Equipment (SAMR Notice No. 16 [2021]) issued by the State Administration for Market Regulation (SAMR) in 2021, all overhead and gantry cranes must be equipped with (or retrofitted with) dual-limit height safety devices. The key requirements are as follows:

(1) Newly Manufactured Overhead & Gantry Cranes

• Effective May 1, 2021, manufacturers must install two different types of height limiters (e.g., weight-type, circuit-breaker-type, pressure-plate-type, etc.).

(2) Existing Overhead & Gantry Cranes

• Before March 31, 2022, users must retrofit existing cranes with an additional height limiter of a different type than the original.

(3) Exceptions

• Cranes already equipped with mechanical transmission-type limiters (e.g., gear-driven, worm-gear-driven) are exempt from dual-limit requirements.

2. How Height Limiters Work

A height limiter prevents over-hoisting by cutting off power when the hook or lifting attachment reaches the upper limit position. This:

• Stops the hoisting mechanism automatically.

• Prevents wire rope breakage caused by excessive lifting.

• Reduces the risk of load drops and equipment damage.

3. Common Types of Height Limiters

(1) Mechanical Transmission-Type Limiters

• Operates via mechanical shaft rotation to trigger a safety switch.

• Examples:

• Worm-gear-driven limiters

• Gear/cam-driven limiters

(2) Weight-Type Limiters

• Uses a hanging weight to trigger a switch, cutting off the hoist circuit.

(3) Circuit-Breaker-Type Limiters

• Directly interrupts the main power circuit by breaking the electrical connection.

(4) Pressure-Plate-Type Limiters

• Relies on a weight and pressure plate to activate a switch, stopping the hoist.

4. Why Dual-Limit Devices Matter

• Redundancy improves safety – If one limiter fails, the backup ensures protection.

• Compliance with regulations – Avoids penalties and ensures workplace safety.

• Prevents costly accidents – Reduces the risk of crane failure and load drops.

5. Conclusion

The dual-limit requirement for overhead and gantry cranes is a critical safety upgrade mandated by Chinese regulations. By using two independent limiters, crane operators can enhance operational safety and comply with legal standards.

For further guidance on crane safety upgrades, consult a qualified lifting equipment provider.

Need compliant crane solutions? Contact us for expert advice on height limiters and safety retrofits!