Crane Duty Helical Gear Boxes
SELECTION PROCEDURE
Satisfactory performance of the gearbox is dependent upon correct selection. The selection of a gear unit can be influenced by the class of duty of the crane which should be determined and specified. Single, Dual and Triple stage Horizontal gear products type HA, HB and HC are recommended for Hoist and Long Travel drive. Three stage vertical equipment products 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. Make reference to the rating desk, see in the ratio column and predicated on input rpm check 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 than the consumed HP.
EXAMPLE
1. Decide on a unit to transmit 9 HP from 720 rpm crane duty helical gearbox electric engine 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 become suitable.
· Start to see the ratio column and in the size HB-350, for input rpm of 720 in course II duty the ranked HP is 9.5
· Because the consumed HP is usually 9, the machine HB-350 will be suitable.
2. Decide on 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 be suitable.
· Start to see the ratio column and in the size VC – 32Q, for input rpm of 960 in course IV duty the ranked HP is 3