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