Trolley Vehicle Track Limit Switch

The core working principle of limit switch for gantry crane:
     Position detection: When the moving parts of the crane (large, small or lifting mechanism) reach the preset position, triggering devices such as collision rulers, rollers or heavy hammers contact the limit switch operating head, or metal objects approach non-contact sensors.
     Signal conversion: Mechanical displacement drives the internal lever/push rod, causing the moving contact to separate from the normally closed contact (NC) and close with the normally open contact (NO), completing the circuit state switching; Non contact type directly outputs electrical signals through inductance/photoelectric/Hall effect.
     Execution control: The signal is transmitted to the control system, immediately cutting off the power supply of the forward direction motor (limit) or triggering deceleration before stopping (working limit), to prevent overtravel, impact or collision. Some designs allow reverse operation for reset.

Key operation and maintenance specifications for limit switches of gantry cranes:
     Installation and debugging: Professional personnel set the trigger position according to the working conditions to ensure that the working limit is activated before the ultimate limit, and verify the reliability of the "trigger stop" logic.
     Daily inspection: Before each shift, visually inspect whether the collision block is loose, whether the switch is firmly fixed, and whether the contacts are burned; It is strictly prohibited to short-circuit or bypass the limit circuit.
     Functional testing: Conduct weekly no-load trial runs to test whether the limit switches in each direction accurately trigger the stop; Conduct monthly ultimate limit failure protection testing.
     Fault handling: If the limit is misoperated or does not operate, the machine must be stopped and powered off for troubleshooting. Common causes include block displacement, mechanical jamming, contact oxidation, or circuit breakage. After repair, it needs to be rechecked.
     Reset requirement: After the ultimate limit is triggered, the operating handle must be reset to zero, and the reset button or manual reset switch must be pressed before it can be operated in the safe direction again. ‌ ‌‌