Crane Duty Helical Gear Boxes
SELECTION PROCEDURE
Satisfactory performance of the gearbox is dependent upon correct selection. The selection of a gear unit is definitely influenced by the course of duty of the crane that ought to be determined and specific. Single, Double and Triple stage Horizontal gear models type HA, HB and HC are recommended for Hoist and Long crane duty helical gearbox Travel drive. Three stage vertical gear units type VC are suggested for cross travel drives of the EOT crane. Assembly arrangement must be specified while purchasing 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 based 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 compared to the consumed HP.

EXAMPLE
1. Decide on a unit to transmit 9 HP from 720 rpm 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 end up being 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
· Since the consumed HP is 9, the unit HB-350 will be suitable.

2. Select a unit to transmit 3 HP from 960 rpm electric engine 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 be suitable.
· Start to see the ratio column and in the size VC – 32Q, for insight rpm of 960 in class IV duty the ranked HP is 3