Manitowoc National Crane NBT40 Series, Service Manual

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BOOM MAINTENANCE NBT40 SERVICE MANUAL
4-44
Published 8-01-2017 Control # 287-11
do not move equally, retain the moving stage to allow for
equal extension of cylinder. Remove the holding valve
from the 1st stage butt plate and drain oil.
3. Using the proper size spanner wrench (listed on the
cylinder parts page break down), loosen the packing
gland and completely unscrew from the 3rd stage barrel
assembly.
4. Remove the 2nd/1st stage cylinder assembly from the
3rd stage barrel assembly and place on supports.
Caution must be exercised in the support and removal of
2nd/1st stage cylinder assembly as damage to the
chrome surface will necessitate replacement.
5. Using the proper size spanner wrench (listed on the
cylinder parts page break down), loosen the packing
gland and completely unscrew from the 2nd stage
cylinder assembly.
6. Remove the 1st stage cylinder assembly from the 2nd
stage cylinder assembly and place on supports. Caution
must be exercised in the support and removal of the 1st
stage cylinder assembly as damage to the chrome
surfaces will necessitate replacement.
7. Using a 3/16 in alien wrench, remove the locking
setscrews from the 1st stage cylinder shaft piston and
from the 2nd stage cylinder shaft piston. Using the
proper size spanner wrench, loosen and completely
unscrew pistons from the 1st and 2nd stage cylinder
shaft assemblies. Remove stop tubes from the 1st and
2nd stage cylinder shaft assemblies.
8. Wipe and inspect all cylinder internal and external
surfaces for damage. Wipe and inspect all threaded
components for damage to threads.
9. Inspect wear pads on the 3rd stage barrel sheave case
assembly. Replace as required.
10. Ensure that the O'ring seal area of the packing gland
bores on both the 2nd stage cylinder assembly and the
3rd stage barrel assembly are smooth and free of nicks
and lubricate to eliminate damage to the packing gland
O'ring during reassembly.
Cylinder Reassembly
1. Replace cylinder packing parts as required on 1st stage
cylinder assembly. Refer to parts pages for replacement
packing kit part number. Warming the U-cup seals in
140°F oil will allow for easier assembly.
2. Reinstall packing gland and stop tube onto 1st stage
cylinder shaft assembly.
3. Install O'ring and backup rings on inner diameter of 1st
stage piston and thread onto 1st stage cylinder shaft
assembly until snug making certain piston counterbore
is seated over shaft assembly properly. Take care not to
damage the O'ring while installing piston. Using the
proper size spanner wrench tighten piston onto 1st stage
cylinder shaft assembly to 600 lb-ft.
4. Install setscrew into piston using Loctite Type 243
according to Loctite recommendations and torque to
8 lb-ft. Loctite and install second set-screw on top of first
setscrew and torque to 8 lb-ft.
5. Replace cylinder packing parts as required on 2nd stage
cylinder assembly. Refer to parts pages for replacement
packing kit part number.
6. Reinstall packing gland and stop tube onto 2nd stage
cylinder shaft assembly.
7. Install O'ring and backup rings on inner diameter of 2nd
stage piston and thread onto 2nd stage cylinder shaft
assembly until snug making certain piston counterbore
is seated over shaft assembly properly. Take care not to
damage the O'ring while installing piston. Using the
proper size spanner wrench, tighten piston onto 2nd
stage cylinder shaft assembly to 600 lb-ft.
8. Install setscrew into piston using Loctite Type 243
according to Loctite recommendations and torque to
8 lb-ft. Loctite and install second set-screw on top of first
setscrew and torque to 8 lb-ft.
9. Reinstall 2nd stage cylinder assembly with piston stop
tube and packing gland into 3rd stage barrel assembly to
within 24 in of fully assembled. Carefully start packing
gland into 3rd stage barrel and tighten to within 1/4 in of
snug. Using the proper size spanner wrench, torque the
packing gland to 600 lb-ft.
10. Apply a 3/16 in wide band of Loctite 518 to outer threads
of packing gland and complete installation.
11. Reinstall 1st stage shaft assembly with piston, stop tube
and packing gland into 2nd stage cylinder assembly to
within 24 in of fully assembled Carefully start packing
gland into 2nd stage and tighten to within 1/4 in of snug.
12. Apply a 3/16 in wide band of Loctite 518 to outer threads
of packing gland and complete installation. Using the
proper size spanner wrench, torque the packing gland to
600 lb-ft.
13. Install holding valve onto 1st stage shaft butt plate. Cycle
test cylinder to ensure leak proof operation. Apply oil to
the 1st stage shaft assembly through the holding valve.
Support the 2nd and the 3rd stages as they extend and
retract.
JIB BOOM
Jib Stowage Bracket Adjustment
It is extremely important for the safety of the crane operator
and all others working near the crane that the jib boom
extension be properly secured to the jib stowage bracket
(Figure 4-27) and to the boom nose of the main boom.
Reference Only