Care must be taken to ensure this assembly does not foul any part of the boom or boom foot when the boom is raised or
At the extreme end of the lever arm, which is bolted to the pulley, is a turnbuckle which terminates in a small angle
bracket. This bracket is welded or clamped to the boom, the turnbuckle being at right angles to the lever arm. Spacers
may be needed when mounting this bracket to ensure that there is no strain on the arm during its operation. The
turnbuckle is desired for adjustment purposes at a later stage.
The pulley contains alternative tapped holes, allowing the lever arm to be mounted at the required angle. Additionally, the
cast bracket, when removed from the shaft, can be replaced the reverse way. Thus the assembly may be used at either
the left or right hand boom foot with the cable exit either to the rear or downwards. It is most essential to ensure that
during the total boom movement, the cable remains on the opposite side of the pulley, away from the bracket. As a guide,
the cable should be directly opposite the bracket when the boom is at 45° to the horizontal.
Should it not be suitable to mount this assembly directly on the center line of the boom foot pin, it is possible to position it
so that the level arm is parallel to but some distance away from, the boom. In this case the turnbuckle must be replaced
by an arm, of adjustable length, set to the same dimension as the distance between the center of the boom foot pin and
the center of the pulley. The dimension between the boom foot pin and the mounting position of this new arm on the boom
must be identical with the operating length of the existing lever arm. In this way, a parallelogram is formed ensuring that
the movement of the lever arm is identical to that of the boom.
On some machines, where the boom foot pin is securely fastened to the boom (and hence rotates with the boom), the
pulley may be attached directly to the boom foot pin.
INSTALLING THE FLEXIBLE DRIVE CABLES.
Position the boom so that it is truly horizontal. Rotate the pulley at the rear of the Control Box until the actuating arm within
the box is also truly horizontal. A setting hole is provided in the actuating arm which lines up with a hole in the back face of
the Control Box. A 3/16" diameter rod of suitable length may now be used to lock this arm in position while the drive cable