SWING
NBT40 SERVICE MANUAL
6-4
Published 8-01-2017 Control # 287-11
SWING GEARBOX AND BRAKE
The rotation drive is a double planetary gear reducer with an
integral brake. The gear reducer is designed to give long life in
heavy duty applications such as crane rotation. The gearbox
incorporates tapered roller bearings on the output shaft and
heavy duty bearings in the planet gears.
NOTE:
Motor and cartridge valves are not serviceable in
the field. Return them to an authorized distributor
for service.
Removal and Installation
Removal
1.
Tag all hydraulic hose and gearbox ports Figure 6-1.
Remove all hoses from the gearbox and plug open
ports.
2.
Attach a lifting device to the gearbox (11, Figure 6-11)
capable of lifting approximately 275 lbs. Apply tension to
the lifting cable.
3.
Remove six screws and six flatwasher (14, Figure 6-11)
securing the gearbox to the turret. Lift the gearbox from
the turret.
4.
Remove two screws and two lock washers (15,
Figure 6-11) securing the hydraulic motor (1) to the
gearbox (11), remove the motor.
Installation
1.
Secure the hydraulic motor (1, Figure 6-11) to the
gearbox (11) with two screws and two lock washers (15).
2.
Using a capable lifting devise, position the gearbox (11)
onto the turret. Secure the gearbox (11) to the turret with
six screws and six flatwasher (14).
3.
Connect hydraulic hoses to the gearbox and hydraulic
motor.
Disassembly & Assembly Instructions
If the rotation drive needs to be repaired, use the following
procedure for disassembly.
NOTE:
The weight of the rotation gearbox with integral
brake and a hydraulic motor bolted on the input end
of the assembly is approximately 275 lbs (124 kg).
Tools Required
•
Scribe or small punch
•
Oil drain pan
•
Eye bolts 1/4”
•
Retaining ring pliers
•
Gear puller
•
Ratchet wrench (1/2” drive)
•
9/16” socket (1/2” drive)
•
Socket for pinion nut (Whittet-Higgins P/N BAS-14)
•
Soft hammer (brass or plastic)
•
Press
•
Drift rod (1/4” to 3/8” diameter)
•
Torque wrench [1/2” drive - approximately 100 ft-lb
(135 N·m)]
Parts Required to Rebuild
•
Seals
•
O-rings
•
Back-up rings
•
Parts to replace damaged or worn parts
•
Locknut (9) and lockwasher (8)
Disassembly
(See Figure 6-2 for reference (#) numbers.)
1.
With a scribe or small punch make a set of marks on the
brake assembly flange (15) and the top edge of the gear
housing (1) to aid in reassembly.
2.
Remove both drain plugs (17) and drain the oil from the
unit. Drainage is facilitated when the oil is warm.
3.
Remove the eight capscrews (16) holding the brake
assembly (15) onto the gear housing (1).
4.
Lift the brake assembly (15) off of the gearbox. If
necessary, screw the hydraulic motor bolts into the
brake assembly for use as handles.
5.
Remove the thrust washer (11) and input sun gear (14)
from the input planetary assembly (13).
6.
Install three 1/4” eyebolts into the three planet pins of the
input planetary assembly (13) and with a small chain pull
the planet set (13) from the gear housing.
7.
Remove the output sun gear (12) and thrust washer (11)
from the output planetary assembly (10).
8.
Using the eyebolt/chain method outlined in step 6,
remove the output planetary assembly (10) from the
gear housing.
9.
To remove the output shaft (2) from the gear housing (1),
bend the tab on the lockwasher (8) out of the slot in the
locknut (9). Loosen and remove the locknut (9) from the
output shaft (2).
Reference Only
Summary of Contents for National Crane NBT40 Series
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