|
Open type Worm and Worm Wheel arrangement |
Magtorq Crystalliser Drive |
Motor rating |
Generally motor ratings will be from 10 to 30 HP |
Maximum motor rating will be within 7.5 HP |
Efficiency |
Highly inefficient; losses in the gear system are very high and efficiency very poor and going down to 30% |
Efficiency is very high – about 90% |
Labor requirement for operation while the gear unit is running |
As gears are open type and hence one person is always required to attend the oil filling |
As the unit is totally enclosed, no need of frequent oil filling. Oil to be changed only once in a season |
Cleanliness |
The surrounding area is very unclean due to oil overflowing |
As there is no oil overflow; surroundings will remain clean and free of oil spread |
Operation by hand during power failure |
Very difficult to rotate it by hand |
Very low power is required and one person can rotate the shaft easily |
Alignment-related problems |
Due to wear in the bush bearing provided in the crystalliser shaft, the worm wheel tends to bend downward and sit on worm shaft, adding to the load and reducing life of worm and worm wheel. Also, one coupling is required between the motor and worm gear unit, which needs to be aligned properly |
Since the entire gear unit is mounted on the crystalliser shaft (weight of the total gear unit is less than weight of the worm wheel), wear of the bush does not pose any problem. With no couplings and base plates, alignment-related problems are unlikely |
Annual Maintenance |
Generally motors and gear units are dismantled and bearings are changed during off-season. This is a major involving a high cost |
No special annual maintenance is needed. Maintenance is limited to only changing the oil once in a season |
Life of the gear unit |
Since the gears are the open type and the surroundings are dirty due to overflowing of Massecute, life of the gear unit life is short. Higher frictional losses, improper gear meshing, contamination in lubricants etc reduce the gear life |
Totally enclosed construction ensuring continuous lubrication, and there is no scope for entry of foreign material inside the gear unit, which extends the life of the gear unit |