National Crane Published 10-30-2014 Control # 040-09 5-15
1400H OPERATOR AND SERVICE MANUAL SERVICE
SINGLE STAGE CYLINDER DISASSEMBLY AND REPAIR
1. Retract cylinder shaft with oil from the hydraulic system
until about 12 in (30 cm) of shaft is extended. The barrel
must be filled with oil to prevent a compressed air
chamber being formed which could result in injury at
disassembly.
2. Disconnect cylinder from machine. Cap all hydraulic
connections.
3. Remove the cylinder from the machine and place on
supports with an oil pan directly beneath the cylinder
head area.
4. Using the proper size spanner wrench (listed on the
cylinder parts page breakdown), loosen packing gland
and completely unscrew from barrel assembly.
5. Remove the shaft and piston assembly by hand.
6. Using a hex key wrench remove one or two set-screws
in the piston.
7. Using the proper size spanner wrench (listed on the
parts page breakdown), loosen and completely unthread
piston from rod assembly.
8. Wipe and inspect cylinder barrel for internal damage.
9. Wipe and inspect cylinder rod assembly for damage.
10. Inspect all threaded components for damage to threads.
11. Replace cylinder packing parts as required. Soaking the
U-cups in warm oil [140°F (60°C)] will aid installation.
Refer to parts pages for replacement packing kit part
number.
12. Reinstall packing gland onto rod assembly.
13. Install O-rings and backups on inner diameter of piston
and thread onto rod assembly until snug. Using spanner,
tighten piston.
14. On most threaded pistons, two setscrews are utilized to
lock each other in place. Apply Loctite 243 to setscrews
and torque each setscrew.
15. Reinstall rod assembly with packing gland into barrel
assembly and tighten packing gland until within 0.25 in
(0,63 cm) of engaged.
16. Apply a band of Loctite 518 to outer threads on packing
gland and complete installation.
17. Using a spanner wrench, torque packing gland.
18. If cylinder utilizes an external setscrew to lock the
packing gland in place, apply Loctite 243 and torque.
CYLINDER
BARREL
THREADED PACKING
GLAND
CYLINDER
ROD
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