Manitowoc National Crane 800D, Operator'S And Service Manual

Page: 139 / 256

National Crane
Published 5-27-2018 Control # 039-06 5-33
800D SERVICE
ANTI-TWO-BLOCK INTERNAL WIRE
SYSTEM/FOUR SECTION BOOM (CABLE
ON TOP OF SECTIONS)
Operation
The internal anti-two-block wire system is routed through the
boom in two stages. The first stage, 1/2, runs between the
top plates of the first and second sections on a traveling
block. The 1/2 and 2/3/4 sections are joined with a Weather-
Pack connector. The second stage, 2/3/4, is anchored at the
back of the second section, passes over the sheave at the
end of the telescoping cylinder and is then anchored at the
hoist end of the fourth section. After running the length of the
boom inside of the fourth section, it is connected to the anti-
two-block switch mounted on the side of the sheave case.
Maintenance
In the event of a break in continuity of the anti-two-block wire,
the hydraulic portion of the system will be disabled and make
certain crane functions inoperative. Before repair or
replacement of either of the two stages, check for continuity
loss at the anti-two-block switch, connector damage or
corrosion, and overall system condition. Due to the
environmental exposure of the system, a thorough check of
the circuit should be performed.
If the internal wire has lost continuity it will probably be
necessary to replace only one of the two stages in the circuit,
the 1/2 or the 2/3/4 stage. A simple continuity test of both
stages should identify which one contains the failure.
1. Unplug the Weather-Pack connector linking the two
stages together at the hoist end of the second boom
section.
2. With the anti-two-block switch in its closed position
(weight suspended from switch or overridden with the
red flag), check continuity across the Weather-Pack
terminals on the 2/3/4 stage. If there is no continuity in
the 2/3/4 stage, recheck continuity of the anti-two-block
switch on its own and recheck continuity of the 2/3/4 wire
to ensure the wire is the problem. If continuity exists, the
problem is in the 1/2 stage.
3. If the fault is suspected in the 1/2 stage, unplug the
connector at the turret. Install a jumper wire across the
terminals of one of the connectors and check for
continuity at the opposite connector.
After determining which wire stage contains the fault, refer to
the following procedures for replacement.
1/2 STAGE ANTI-TWO BLOCK WIRE
REPLACEMENT
The 1/2 stage anti-two-block wire is located between the top
plates of the 1st and 2nd boom sections, riding on a traveling
block. The maintenance of this wire can be accomplished
with the boom fully assembled but would be simplified if the
2/3/4 boom assembly was removed from the first section.
Do not, under any circumstances, work at an elevated
height without using proper fall protection as required
by local, state, or federal regulations.
Disassembly Of 1/2 Stage
Alternative No. 1
This procedure pulls the replacement wire through the boom
following the path of the defective wire.
Special tools or equipment:
•Two end-to-end electrical butt connectors
•Shrink tube or electrical tape
1. Retract boom completely.
2. Unplug Weather-Pack connector between 1/2 and 2/3/4
stage, located at rear of second boom section.
3. Unplug connector in turret and disconnect wire from
cushion clamp on bottom of first boom section.
4. Measure the amount of wire from the retaining plates to
the connectors on both ends of the 1/2 wire. Record
these numbers for later use.
5. Remove capscrews and retaining plates from the top
backs of the first and second sections.
6. Attach replacement anti-two-block wire to damaged wire
with a “temporary splice”, securing the conductors with
end-to-end butt connectors and shrink tube or electrical
tape. This connection must be secured well enough to
pull the new wire through the boom.
7. Slowly pull the new wire into the boom by pulling on the
opposite end of the damaged wire. If this method fails,
Alternative No. 2 should be used.
8. Once enough new wire has been pulled past the
retaining plate location, remove temporary splice,
reattach the retaining plate and install the connector on
that end of the wire. The connectors on this cable are
two separate styles. Make sure the Weather-Pack
connector is on the end that will attach to the 2/3/4 wire.
9. Loosely attach the retaining plate on the other end of the
new wire.
10. While pulling on the new wire with a tension of about 15-
25 lb (7-11 kg), tighten the capscrews on the retaining
plate.
11. Using the length recorded earlier, measure the cord and
attach the connector. The connectors on this cable are
two separate styles. Make sure the Weather-Pack
connector is on the end that will attach to the 2/3/4 wire.
Fo
r
Reference
Only