Mainfall Capacity and Main fall Tackle

Homework / test English to French Tech/Engineering Mechanics / Mech Engineering Boom operation

Contexte:
'The Boom Tip Extension Capacity is the lesser of:

1.The maximum rated capacity of the Boom Tip Extension (40,000 pounds)
2.The hoisting drum's maximum rated single line pull multiplied by the allowable parts of line used.
3.The allowable rope load multiplied by the allowable parts of line used (Refer to appropriate rating chart)
4.The MAINFALL CAPACITY at the same working radius less the weight of the MAIN FALL TACKLE. (Refer to appropriate rating chart and to Figure 5.11-15A)

Comment traduire 'mainfall' dans les deux cas?
Avec 'Capacité' et 'Appareil'?
Lumière, s'il vous plait.