Causes of actual operation failures:
Fan impeller output speed is 127 / min, the load is relatively large, is a typical low-speed heavy load equipment. When the fan is running, the various parts in the system will bear the load, especially motor and reducer, bearing large load winter fan brought torque transmission outages, affected by damp and hot steam and external wind driven, positive rotation sometimes produces high speed, high up to 50-60r / min, on human can't stop then, open suddenly reverse, because it is the prime mover, the fan component has inertia, motor, transmission shaft, gear and vane operation are not synchronized, in turn lag, when the motor reversal moment, moment of inertia due to the rotation of the drive shaft is still running in original mode, when the drive shaft into the gear rotation moment. Because of inertia rotation is still running, according to the original way by analogy, this is the force coupling bolts will be between the four of them are equal and opposite The moment, thus forming the bolt torque suffered by the force moment from large to small, then from the vector change, have a strong impact on the bolt load so as to form larger changes, the friction between the screw and the bearing surface of the flange between the instantaneous failure may disappear, self-locking, failure.
Another characteristic of winter fan reversal is a short operation time, the number of starts, according to the need of ice per day, running 6 times, each time lower than the winter down, a fan about starting nearly 600 times, so the frequent start will make the bolt under the instantaneous variable load frequency increases, a smooth start, great to reduce the harm of excess torque.
Cooling tower operating environment, the temperature difference between winter and summer up to about 60 degrees, in the case of large changes in temperature, because of the threaded joints and the joint was found in time, the fault will soon be in depth. In the same conditions, the connection position, it's easy to bear alternating load and combined effects of damage and other factors, make the winter fan running fan fault bolt, bolt by the rotation of the drive shaft bolts due to the tensile stress of bolt and bolt holes produced by horizontal circumferential force squeeze and properly handle, avoid the failure to expand and spread, diaphragm, drive shaft, impeller and other components, cause greater harm.