Electric Hoist knowledge of safety precautions 1, stop in addition to the reliable work, must also have the function of the fault phase protection. 2, noise: A) lifting tools working under rated load, the noise is not more than 85 db (a); B) operation under no-load operation, the noise is not more than 80 db (A). 3, temperature monitoring: the action of thermal control component temperature is 160 ℃ plus or minus 10 ℃ or 170 ℃ + 10 ℃. 4, when a second brake, its function should meet the following requirements: normally doesn't work. When the first brake failure, it can reliably support live load. 5, when with overload limiter, its function shall meet the following requirements. Mechanical overload limiter: A) composite error is not more than 8%; B) the action of load is not more than 1.15 times the rated load; C) when to load action can automatically cut off the lifting power circuits. 6, electronic overload limiter: A) composite error is not more than 5%; B) action load with time delay is not greater than 1.1 times the rated load; Action without delay load is 1.25 times the rated load; C) when to load action can automatically cut off the lifting power circuits.