a. If rigidly mounted (as on most telescopic machines), the Dynamometer should be positioned so that the hoist
rope is deflected as little as possible. When viewed in plar, i.e., looking down on top of the Dynamometer, it must be
mounted directly on the natural line of the rope when the rope is on the center of the hoist drum. It is recommended that a
string be stretched between the boom head sheave and the center groove of the drum to ascertain the correct mounting
position. The largest sheave on the Dynamometer must be toward the hoist drum.
Long mounting bolts are provided for securing the Dynamometer to the members welded or clamped to the
boom. These long bolts, together with the taper washers provided, allow the Dynamometer to be "jacked up" so that the
rope line is as straight as possible through the unit when viewed from the side. It is essential that the mounting bolts are
fully tightened and that all members are firm and rigid.
b. If the angle of the hoist rope and it's distance from the boom prohibit the use of rigid mountings as described
in section "a", the Dynamometer may be mounted on a "swinging arm" frame specially constructed for the purpose.
Typical mounting arrangements are shown on Sketch 1. Polyurethane bumpers are usually fitted on the boom or
superstructure to support the Dynamometer when the rope is slackened or during transit. The mounting position of this
frame varies for each type of crane and, again, the largest sheave on the Dynamometer must be toward the hoist drum.
REEVING THE HOIST RAPE THROUGH THE DYNAMOMETER.
The rope is passed under the two outer rollers and over the three center rollers. This applies a slight deflection to the rope
causing a load to be imparted to the Load Cell under the middle roller.
If it is not possible to pass the rope through the Dynamometer, proceed as follows:-
a. Remove the cotter pins which lock the shafts of the two outer sheaves in the side plates. With a punch or
drift pin, tap out the shafts making sure that the needle roller bearing in the bores of the sheaves are not damaged in the
process.
The side thrust washers and sheaves can now be lifted out.
b. Remove the bolts or studs retaining the three spacers directly above each of the three center sheaves and
remove the spacers.
2-1-9
