National Crane Published 10-30-2014 Control # 040-09 5-17
1400H OPERATOR AND SERVICE MANUAL SERVICE
MULTI-STAGE EXTEND CYLINDER DISASSEMBLY AND REPAIR
Cylinder Disassembly
1. After cylinder has been disassembled from boom, place
on supports and place drain pan under holding valve.
2. Using hydraulic power (porta power or crane circuit)
extend cylinder sections approximately 24 in (60 cm). If
stages 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 a special drive tool, drive the packing gland into
the 3rd stage barrel assembly to expose the round cross
section retaining ring. Then use a small needle nose
locking plier to clamp the round cross section retaining
ring to prevent from rotating in the groove. Use two
straight blade screw drivers; one to pry the end of the
ring out of the groove and the other to pry the ring out of
the barrel assembly.
4. Debur ring groove edge. Failure to do so will damage
packing gland and or barrel assembly when packing
gland is removed.
5. 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.
6. Using a special drive tool, drive the packing gland into
the 2nd stage barrel assembly to expose the round
cross section retaining ring. Then use a small needle
nose locking plier to clamp the round cross section
retaining ring to prevent from rotating in the groove. Use
two straight blade screw drivers; one to pry the end of
the ring out of the groove and the other to pry the ring out
of the barrel assembly.
7. Debur ring groove edge. Failure to do so will damage
packing gland and or barrel assembly when packing
gland is removed. Using a 3/16 in hex key wrench,
remove the locking setscrews from the 2nd stage
cylinder shaft piston. Using the proper size spanner
wrench, loosen and completely unscrew piston from the
2nd stage cylinder shaft assembly. Remove nut washer
and piston from 1st stage cylinder shaft assembly.
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 (60°C) oil will allow for easier assembly.
2. Reinstall packing gland retaining ring and stop tube onto
1st stage cylinder shaft assembly.
3. Reinstall piston and related components. Torque
retaining nut to specification.
4. Insert 1st stage into 2nd stage, grease on piston seals
will aid installation, install packing gland and round
retaining ring into 2nd stage.
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, retaining ring 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 counter bore
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 specification.
8. Install setscrew into piston using Loctite Type 243
according to Loctite recommendations and torque.
Loctite and install second setscrew on top of first
setscrew and torque.
9. Reinstall 2nd stage cylinder assembly with piston stop
tube and packing gland into 3rd stage barrel assembly to
within 24 in (60 cm) of fully assembled.
Torque Specifications
5 section 2nd stage piston ____ 600 lb-ft (813 Nm)
1st stage nut________ 300 lb-ft (407 Nm)
4 section 2nd stage piston ____ 200 lb-ft (271 Nm)
1st stage nut________ 300 lb-ft (407 Nm)
Setscrew __________________ 8 lb-ft (11 Nm)
1ST STAGE
2ND STAGE
3RD STAGE
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