The ZOOMLION Height Limit Switch 1020500721, also called the Hoisting Limit Switch or Anti-Two-Block (A2B) Switch, is an important safety protection device installed on crane boom systems. Its primary function is to prevent the hook block from colliding with the boom head during lifting operations.
When the hook approaches the upper limit position, the switch sends a signal to the crane control system or LMI system, automatically stopping dangerous hoisting movement and protecting the crane structure, wire rope, sheaves, and lifting components.
Compatible ZOOMLION Crane Models
Commonly Compatible Models
The ZOOMLION Height Limit Switch 1020500721 is widely used on multiple ZOOMLION crane series, including but not limited to:
ZTC Truck Crane Series
ZTC250
ZTC300
ZTC350
ZTC500
ZTC550
QY Truck Crane Series
QY25V
QY30V
QY50V
QY70V
RT Rough Terrain Crane Series
RT55
RT60
RT75
Other Zoomlion Crane Platforms
Mobile hydraulic cranes
Heavy lifting crane systems
Boom crane applications equipped with A2B safety systems
Compatibility may vary depending on crane configuration, production year, and LMI system version. Please confirm with the crane nameplate and original part number before ordering.
Main Functions of the A2B Switch
Anti-Two-Block Protection
The A2B limit switch is designed to prevent the hook block from contacting the boom tip or upper sheave assembly. This greatly reduces the risk of:
Crane Damage
Wire rope damage
Boom head impact
Sheave assembly failure
Hoisting system overload
Safety Risks
Unexpected lifting accidents
Mechanical failure
Load handling hazards
System Protection
Automatic hoisting cut-off
Alarm signal transmission
LMI system integration
Industry crane systems widely use A2B protection devices as an essential operational safety component.
Advantages of Genuine ZOOMLION Spare Parts
Quality Assurance
Using original ZOOMLION spare parts ensures:
Stable Performance
Reliable signal transmission
Accurate limit protection
Strong environmental adaptability
Perfect Compatibility
Direct replacement
Easy installation
Suitable connector matching
Longer Service Life
Durable housing structure
High reliability under harsh working conditions
Excellent vibration resistance
.
Why Choose Our ZOOMLION Crane Spare Parts?
Professional Export Service
We specialize in construction machinery spare parts for global customers.
Our Advantages
Genuine OEM spare parts
Large inventory available
Fast international shipping
Professional technical support
Export experience for worldwide markets
Available Supply
Original ZOOMLION parts
Electrical spare parts
Hydraulic spare parts
LMI system components
Sensors and switches
Inquiry and Purchase Information
Contact Us for a Fast Quotation
To provide the correct ZOOMLION Height Limit Switch 1020500721 and avoid compatibility issues, please send the following information when making an inquiry:
Required Information
Crane model
Crane serial number
Machine nameplate photos
Original part number
Required quantity
Destination country
Detailed shipping address
Postal code
Our sales team will quickly confirm compatibility, stock availability, shipping cost, and delivery time for your order.
