JACK

An appliance which is placed under a load to raise or lower it.

JIB

A member attached to the crane structure from which the load is suspended. It can not be luffed while the crane is under load. Please note: In the past, ‘jib’ was often used to mean the same thing as ‘boom’.

JIB TROLLEY

A crab or saddle from which the load is suspended and which can traverse along the jib.

JOCKEY SHEAVE

A diverting sheave which can freely run along the length of an axle to reduce the fleet angle of the lead rope.