Introduction
The weight-type limit switch consists of a weight, lever shaft, return spring, limit switch and mounting bracket, fixed below or on the side of the electric hoist drum via the bracket. During normal operation, the weight hangs down under its own gravity, the lever remains horizontal, and the limit switch is closed; when the hook pulley block rises to the limit position, the top of the pulley frame contacts and lifts the weight, which drives the lever to rotate around the shaft, actuating the limit switch to cut off the hoisting control circuit and stop the hook from rising. After the hook lowers, the weight automatically falls back under gravity and return spring action, and the limit switch recloses. The product has a simple structure, few parts and low failure rate; the limit switch can be selected from domestic or imported high-quality elements with large contact capacity and long mechanical life. As the most basic over-hoisting protection for electric hoists, the weight-type limit switch is widely used in various wire rope electric hoists, usually with bracket-type or multi-function travel limit switches to form two-stage protection.
Our Advantage
Simple structure with low cost: Consisting of a few parts such as weight, lever and switch, with extremely simple structure and easy manufacturing, costing only 1/3~1/5 of electronic limit switches, serving as the most economical and practical over-hoisting protection solution for electric hoists.
Reliable mechanical triggering: Adopting pure mechanical gravity triggering principle, independent of power supply and electronic components, unaffected by voltage fluctuation, electromagnetic interference, sensor failure and other factors; as long as the hook lifts the weight, it operates reliably, serving as the basic safety barrier against over-hoisting.
Easy installation with strong adaptability: Fixed below or on the side of the drum via mounting bracket with bolts, no need to modify the hoist body structure, compatible with 0.5t~100t various electric hoists, convenient for new installation, renovation and replacement, with extremely low maintenance cost.
Automatic reset with simple operation: After the hook lowers, the weight automatically falls back and resets under its own gravity and return spring action, and the limit switch automatically recloses, requiring no manual intervention, with simple operation and no impact on normal hoisting operation cycles.
Double protection enhances safety: Usually used as first-stage limit in conjunction with bracket-type over-hoisting limit switch or multi-function travel limit switch to form two-stage over-hoisting protection; even if the first-stage limit fails due to weight falling off, wire rope slack and other reasons, the second-stage limit still operates reliably, completely eliminating over-hoisting accidents.
Specification
| Parameter | 0.5~5t | 10~20t | 32~50t | 80~100t |
| Applicable Capacity | 0.5/1/2/3/5t | 10/16/20t | 32/50t | 80/100t |
| Weight | 1~3kg | 3~5kg | 5~8kg | 8~12kg |
| Trigger Stroke | 20~50mm | 30~80mm | 50~100mm | 80~150mm |
| Trigger Angle | 15°~30° | 15°~30° | 15°~30° | 15°~30° |
| Response Time | ≤0.1s | ≤0.1s | ≤0.1s | ≤0.1s |
| Reset Mode | gravity + spring auto reset | gravity + spring auto reset | gravity + spring auto reset | gravity + spring auto reset |
| Limit Switch Rating | AC 380V / 5A | AC 380V / 5A | AC 380V / 10A | AC 380V / 10A |
| Contact Form | 1NO+1NC | 1NO+1NC | 1NO+1NC | 1NO+1NC |
| Mechanical Life | ≥ 1M times | ≥ 1M times | ≥ 1M times | ≥ 1M times |
| Weight Material | cast iron | cast iron | cast iron | cast iron |
| Lever Material | steel welded /cast steel | steel welded /cast steel | steel welded /cast steel | steel welded /cast steel |
| Protection Grade | IP54 | IP54 | IP54 | IP54 |
