JLG sky trak mmv Service Manual page 461

2
2
11. Apply Loctite Primer "T" and Threadlocker #271
(red), to a new locknut (7) in accordance with Loctite
instructions. Install the nut onto the threaded end of
the rod (6). Torque the nut to 1100-1250 lb/ft (1492-
1695 Nm).
IMPORTANT: Avoid using excess force when clamping
the cylinder in a vise. Apply only enough force to hold the
cylinder securely. Excessive force can damage the cylin-
der tube (5).
12. Fasten the tube (5) in a soft-jawed vise or other
suitable holding device.
13. To aid in installation, lubricate the o-rings and the
inside of the tube, piston and head gland with clean,
filtered hydraulic oil.
IMPORTANT: Use a suitable installation tool or com-
pression sleeve to help prevent twisting or damaging the
seals and o-rings when installing the piston (8) and head
gland (4) into the cylinder. When sliding the rod and pis-
ton assembly in the tube, DO NOT damage the piston by
scraping it against the threads in the tube. Keep the rod
in line with the tube to prevent binding.
14. Keep the rod (6) straight and carefully insert the rod
into the tube (5). Avoid scratching, nicking or
damaging the tube while installing the rod.
Model MMV Rev. 12/04
1
11
8
7
5
4
14
13
12
17
16
9
20
10
15. Begin threading the head gland (4) into the tube (5).
Place the locking insert (3) in its hole in the head
gland threads just before the hole is threaded into
the tube. Use a suitable pin spanner wrench to
thread the head gland (4) completely into the tube
(5). Torque the head gland to 300-400 lb/ft (407-542
Nm).
16. Lubricate the pilot-operated check valves (2) with
clean, filtered hydraulic oil. Using new oiled o-rings,
thread the pilot-operated check valves into tube (5).
Torque valves to 35-40 lb/ft (47,2-54,2 Nm).
17. Test the cylinder at low operating pressure
(100 psi or 6,9 bar) to verify that the piston and rod
move freely in both directions.
18. Increase the operating pressure to the maximum for
the cylinder (4000 psi or 275 bar) and check for external
leakage and for free movement in both directions.
19. Retract the piston fully.
Hydraulic System
6
15
19
3
18
MT1900
9.163