Crane Duty Helical Gear Boxes
SELECTION PROCEDURE
Satisfactory performance of the gearbox depends upon correct selection. Selecting a gear unit is usually influenced by the class of duty of the crane that ought to be determined and specified. Single, Double and Triple stage Horizontal gear units type HA, HB and HC are suggested for Hoist and Long Travel drive. Three stage vertical equipment units type VC are suggested for cross travel drives of the EOT crane. Assembly arrangement should be specified while ordering the gear units.
1. Compute the required reduction ratio.
2. Determine the horsepower required for the prime mover.
3. Refer to the rating table, discover in the ratio column and based on input rpm verify the gear box ranking horizontally for various class of duty of the crane.
4. The size should be selected in a way that the rated HP is equal or more compared to the consumed HP.
EXAMPLE
1. Decide on a unit to transmit 9 HP from 720 rpm electric engine for hoist 
drive in a course II duty crane, the reduction ratio required is 31.50.
· For hoist drive a two stage horizontal gearbox type HB will be suitable.
· See the ratio column and in the size HB-350, for input rpm of 720 in class II duty the rated HP is 9.5
· Because the consumed HP can be 9, the machine HB-350 will become suitable.
2. Decide on a unit to transmit 3 HP from 960 rpm electric motor for cross travel drive in a class IV duty crane, the decrease ratio required is 14.26.
· For cross travel drive, a vertical gearbox type VC will end up being suitable.
· See the ratio column and in the size VC – 32Q, for input rpm of 960 in class IV duty the ranked HP is 3
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