The purifier bowl is mounted upon the vertical shaft. The most important point is that the bowl is driven on a keyless taper secured by a lock nut on the vertical shaft. The vertical shaft is supported on the upper part by a bearing with six springs located in the radial direction that function to take up vibration in the horizontal direction. The lower end of the vertical shaft is supported by a self aligning rollar ball bearing to take up the vertical thrust. The ball bearing on the lower end is usually of a double row angular contact type. Between the upper bearing and the lower bearing is the air deflector and spindle pulley where the belt engage.The horizontal shaft is supported on both the ends by simple ball bearings just to support and allow rotation. As the motor rotates it transfers its rotation through the centrifugal clutch to belt. The belt then transfer the vertical movement from motor to horizontal movement to the spindle pulley of the driving device. The driving device then rotates the bowl body vertically.
There will be two reason of providing the clutch in purifier they are as follows;
1. Clutch is provided so that gradual load shoul come on the motor because at the time of staerting very high torque is required to rotate the bowl.
2. Some time bowl is heavily loaded and to prevent the motor from burning clutch slips and prevent the motor to trip on overload.
NOW LET US OVERHAUL THE DRIVING DEVICE U WILL UNDERSTAND BETTER;
Friction Clutch Arrangement
The purifier bowl and its associated bowl parts are really heavy when assembled together. Thus the inertia is huge enough that the machine cannot be started in the same manner like other pumps or blowers. If such heavy machinery is started with direct coupling, the motor will trip on overload or may cause severe damage to the worm gear arrangement due to sudden load on the gears. In order to avoid such disaster, a friction clutch is mounted on the horizontal shaft. The motor shaft which is connected to coupling hub ,has two or more friction pads mounted on coupling hub, which is contained within the friction drum. Thus as the motor starts, the friction pads move out due to centrifugal force, thus causing a friction on the internal surface of the friction drum. This friction starts to drive the belt pulley, gradually increasing its speed. As the motor speed reaches maximum, the centrifugal force on the pads reach a maximum value, creating maximum friction which gradually brings the belt pulley in horizontal shaft to the rated speed. Thus the motor does not get overloaded and the high inertia machine is brought to rated speed gradually without any damage.As the motor rotates it transfers its rotation through the centrifugal clutch to belt. The belt then transfer the vertical movement from motor to horizontal movement to the spindle pulley of the driving device. The driving device then rotates the bowl body vertically.
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