Pulling tower structure

Pulling tower structure comprising:

• a vertically elongated, upright support having a pair of parallel side walls spaced apart transversely of the height of the support and rigidly cross-connected in such manner as to leave the support open at its front, a top sheave vertically alined with the interior of the support and journaled on the support adjacent to its upper end on an axis normal to the planes of the side walls, a pair of vertically elongated upright members disposed within the support and secured respectively to the side walls in transversely spaced apart relation, said members respectively having rear edge portions and each edge portion having a plurality of vertically spaced apart notches opening to the rear of the support and the notches in each member being respectively transversely alined with those in the other member, a cross shaft disposed within the support and having opposite end portions selectively receivable by any selected pair of transversely alined notches, a second sheave carried by the cross shaft between the members and below the top sheave, a flexible tensionable element trained over the top sheave and extending downwardly to and under the second sheave and thence forwardly through the open front of the support for connection to a load, a second pair of vertically elongated upright members secured respectively to the interiors of the side walls and spaced rearwardly from the respective notched members by a distance at least equal to the diameter of the shaft end portions, said second members and notched members combining to provide a pair of vertical tracks for guiding the shaft end portions during vertical movement of the shaft and second sheave to new positions, and positioning means connected to the cross shaft for manually moving the cross shaft rearwardly out of such selected pair of notches for vertical re-positioning thereof in another pair of alined notches after the forces of the element are removed.