Crane Duty Helical Equipment Boxes
SELECTION PROCEDURE
Satisfactory performance of the gearbox depends upon correct selection. The selection of a gear unit is influenced by the class 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 suggested for Hoist and Long Travel drive. Three stage crane duty helical gearbox vertical equipment models type VC are recommended for cross travel drives of the EOT crane. Assembly arrangement should be specified while buying the gear units.

1. Compute the required reduction ratio.
2. Determine the horsepower necessary for the prime mover.
3. Make reference to the rating desk, see in the ratio column and based on input rpm examine the gear box rating horizontally for various class of duty of the crane.
4. The size should be selected such that the ranked HP is equal or even 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 course 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 course II duty the ranked HP is 9.5
· Because the consumed HP is usually 9, the unit 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 class IV duty crane, the decrease ratio required is 14.26.
· For cross travel drive, a vertical gearbox type VC will become 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