Fire shutter doors from the practice that, in the helical gear transmission, usually to ensure that the main tooth contact fatigue strength. But for the tooth surface hardness is very high, the core strength and low gear (such as with 20,20 Cr steel after carburizing quenching gear) or more brittle gear, usually to ensure that the root bending fatigue strength of the main. If the two gears are hard and hard tooth surface hardness as high, depending on the circumstances.

Large power transmission, such as the input power of more than 75kW closed gear drive, heat, easy to lead to poor lubrication and gear tooth bonding damage, in order to control temperature, should also be calculated for cooling capacity. Hebei fire doors _