Abstract: The hoisting assembly comprises a boom, a counterweight support extending in a direction opposite to the boom in the same vertical plane as the boom, and interconnecting device therebetween for selectively adjusting the angular relationship between the boom and the counterweight support, said different elements forming a pendular assembly idly swinging about a horizontal swing shaft to assume a steady, balanced position. The boom is further hingedly connected at a hinge point remote from the swing axis to an intermediary structure pivotingly connected to said swing axis and further connected to the counterweight support by adjustable connecting member. A second adjustable connecting member interconnects the boom and the support of the pendular assembly to selectively vary the span of the boom.