Manitowoc National Crane NBT30H-2, Service Manual

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HOIST NBT30H-2 SERVICE MANUAL
5-4
03-20-19 Control # 613-06
14. Position the side plate (1) over cable drum on rods (43).
Secure the side plate with the three capscrews (2).
Tighten capscrews to 80 to 90 lb-ft (109 to 122 Nm).
15. Install the brake sub-assembly into the side plate (1).
Make sure that the pilot of the brake housing aligns with
the bore in the bearing and that the bolt holes for the
motor and vent are oriented properly. Install the eight
capscrews (2). Tighten the capscrews evenly to 80 to
90 lb-ft (109 to 122 Nm).
16. Install a new O-ring (305) onto the face of the motor and
reinstall the motor/counterbalance valve assembly.
Reconnect the hose (70).
17. Fill both the gearbox and the brake section with the
proper amount and type of lubricants. See
Lubrication ,
page 8-1.
HOIST SERVICE
Brake
NOTE: See Figure 5-4 for item number identification.
1. Evenly remove the four capscrews (11) holding the
brake cover (20) in place. Spring pressure will raise the
cover up as the capscrews are loosened. Remove the
cover from the brake housing.
2. Remove the springs (24) from the piston and check the
springs for free height. Each spring should measure at
least 1.20 in (30.5 mm) with no force.
3. To remove the brake piston (10), install two pieces of all-
thread (3/8-16NC) in the bottom of two spring pockets.
4. Using jam nuts, screw the all-thread pieces in evenly
until the piston is clear of the housing. An alternate way
of removing the piston is to use shop air to slowly
pressurize the brake cavity until the piston is out of the
bore.
5. Grasp the brake driver/clutch assembly (Items 38, 13,
23, 14, 15 & 17) and remove it from the brake housing.
6. Remove the stator plates (19) and friction discs (18)
from the brake housing and check for excessive wear.
Be sure to check the top stator plate for scoring caused
by the removal tools and polish if necessary. Friction
discs should measure no less than 0.055 in (1.397 mm)
thickness and stator plates should measure no less than
0.068 in (1.727 mm) thickness.
7. With a hook wire or pry bar, remove the seal.
8. Examine the bushing (39) in the brake housing for wear
and replace if necessary.
9. If brake housing (21) is removed from the hoist, examine
the journal on the brake housing, where the seal (304)
fits, for wear. If severely worn, replace the brake
housing.
10. Carefully disassemble the brake driver/clutch assembly
noting the direction of lockup for the clutch (34). The
clutch assembly must be re-assembled with the arrow
pointing in the proper direction for the hoist to function
properly. Inspect the outside diameter on the input driver
(38) and inside diameter of the brake driver (13) where
the clutch (34) runs. If there is any pitting or spalling
(flakes of a material that are broken off) on the driver
then it and the clutch must be replaced.
11. Re-assemble the driver/clutch assembly, making sure
that the clutch is installed properly.
12. Install a new seal into the brake housing. If the brake
housing is removed from the hoist temporarily install the
input sun gear into the brake housing, and slide the
driver/clutch assembly onto the sun gear spline.
13. Install the stator plates (19) and friction discs (18) into
the brake housing starting with a stator and alternating
friction discs and stator plates. There is one more stator
plate than friction disc so the last item installed is a stator
plate.
14. After installation, check the brake stackup to make sure
that the dimensions are within the tolerance shown in
Figure 5-3. If your measurement is greater than shown,
either some friction discs and stator plates have been
left out, or the friction discs are worn beyond acceptable
tolerances. If your measurement is less than shown, too
many plates or discs have been inserted or they are not
seated properly.
15. Coat the new backup rings and O-rings with light oil and
install onto the piston (10) with the backup rings toward
the outside of the piston. See Figure 5-3 for proper O-
ring and backup ring installation.
16. Carefully install the piston into the brake housing and
gently tap it down until it is seated.
17. Install the springs (24) into the spring pockets of the
piston. If working in a horizontal position, coat the
bottom of each spring with chassis lube to keep it in
position.
0.400 in ±0.050
(10.16 mm ±1.27)
FIGURE 5-3