Mechanical Chain Wear Indicator

grabcad

This mechanical device could be integrated into a hoist to serve as an early indicator of increasing chain length, hence providing a chain wear warning. The four gears function similarly to a differential, with the two smaller ones moving within an arc due to phase differences between the larger gears. A friction clutch links these small gears, allowing adjustment of the pointer's zero position after loading a new chain. As the chain lengthens, it effectively causes the big gears to turn in opposite directions, leading to the swinging arm and pointer moving downwards. In practice, one could replace the pointer with a switch activated when the chain has extended by 2%. Alternatively, rotary encoders can be used instead of gears, detecting phase differences electronically, with an alarm triggered upon reaching a 2% length increase threshold. The pointer arm is spring-loaded to offset backlash and gear mesh issues, ensuring accurate readings even beyond the initial 2% length increase.