MACHINE RIGGING
SECTION IV
VIEW "A"
Figure 4-1. Attaching Tip Section
8. Install the boom backstops. Refer to the topic Boom
Backstops.
Never allow a loaded boom to compress the
backstop springs. If this minimum clearance is
BOOM BACKSTOPS. Boom backstops are used as a safety
not maintained, tension within the boom hoist
and warning device. They are not intended to stop the boom
lines may collapse the boom over the back-
during operation. The primary purpose of the backstops is to
stops.
give the operator a means of judging when to stop raising
the boom.
To install the boom backstops on the boom, proceed as fol-
lows:
One point should be kept in mind by the operator when
using the boom backstops. If a load IS picked up at a time
1. Lay the backstop assembly on the boom base. Start the
when the boom backstops are nearly bottomed, the weight
backstop pin through the lug on the boom base, the spacers
of the load will stretch the boom hoist cables, causing the
and the backstop pipe. Lock the backstop pin with the cotter
backstops to extend, thus giving the impression that the
pins (see Figure 4-2).
backstop clearance has been increased If the operator
should then raise the boom still further, in line with the ap-
2. Lift the machine end of the backstop assembly into posi-
parent increased backstop clearance. releasing the load will
tion against the revolving frame. Install the backstops with
allow the stretched boom hoist lines to contract .This con-
the gantry compression member base pin. Secure them
traction will force the boom against the backstops and
with cotter pins.
major damage can result.
4-2
