Symptoms Possible Causes Remedies
1. No rotation and –
a. Pressure at swing motor inlet Swing brake not releasing Check brake engagement
increases and disengagement,
check release pressure Internal damage to gearbox Replace broken gears, drive train drive train assemblies Overload Reduce load weight b. Pressure at swing motor inlet Swing motor drive shaft damage Replace swing motor
shows no increase, and the swing
motor is making irregular noises Internal damage to gearbox Repair/replace broken or drive train faulty assemblies
c. Pressure at swing motor inlet shows Hydraulic pump or valve broken Troubleshoot hydraulic no increase, but without irregular system
noises from the swing motor 2. Oil leakage
a. From drive shaft Oil seal damaged Replace oil seal
b. From bolted connections or other Assembly compound (joint sealer) Disassemble and check assembled surfaces old and not sealing, bolt not tight mating surfaces. Reapply
or flange warped Loctite, torque bolts to specifications
3. Excess heat
Gearbox casing becomes excessively Low oil level Replace oil, refill to hot, with or without irregular noise(s) specified level during operation
Bearings or gear worn but not Repair or replace completely inoperative gearbox
REMOVAL
1. Lower bucket to ground.
2. Shut engine down and remove key from starter switch.
3. Fully stroke work levers (joysticks) in all directions to relieve pressure from accumulators.
4. Set safety lever on "LOCK" position. 5. Hang maintenance warning tag on
controls.
6. Disconnect negative (-) battery cable leading to frame from battery.
7. Tag and disconnect hoses from swing motor (1, Figure 6). Plug and cap hoses and port to prevent contamination from entering hydraulic system or component. 8. Disconnect tube (2) from drain valve (3) 9. Remove eleven bolts and washers (4,
Figure 6) holding swing reduction gearbox (5) to frame.
10. Using a suitable lifting device, sling swing motor (1, Figure 6) and remove swing motor and reduction gearbox (5) as an assembly from unit.
NOTE: A drain valve (3, Figure 6) and tube are located on side of gearbox. Be careful not to damage valve or tube.
NOTE: There is one alignment pin (6, Figure 6), located on side of reduction gearbox flange.
WARNING!
If engine must be run while performing maintenance, use extreme care. Always have one person in the cab at all times. Never leave the cab with the engine
DISASSEMBLY
NOTE: Reassembly of the gearbox is easier and more likely to be trouble-free — or cause damage to surfaces or components — if special tools shown on the preceding page are used. These can be ordered through Daewoo After Sales Service, or individual jigs can be fabricated at a local machine shop to the specifications shown.
1. Drain gear oil from the swing motor final drive prior to removal of the gearbox.
2. Loosen and remove the retaining bolts from around the rim of the gearbox. Separate the gearbox and swing motor from the excavator.
3. Remove the No. 1 sun gear as shown.
IMPORTANT
Use a clean, dry container (with at least 8 liters, or 2 gallons capacity) to catch gear oil. A clean container allows an evaluation to be made of the used oil. The presence or relative lack of metal wear shavings in the used oil or obvious deterioration or contamination of the oil can provide a useful indicator of the motor’s general condition.
Figure 7
Figure 8
4. Tighten 10 mm ring bolts into the rim of the carrier, 180 degrees apart. Use a hoist or other lifting assist to separate the No. 1 carrier assembly from the gearbox, with the No. 1 differential gear still attached.
5. Begin disassembly of the No. 1 carrier by using a snap ring pliers to remove the stop ring. Make reference marks showing assembly positions of the differential gears and pins, prior to disassembly. Use a permanent marking pen, removable paint, or another available marking tool that will not cause any surface damage. Remove the side plate (19), the No. 1 differential gears (7), the needle cage bearing (24) and the remaining side plate (18).
NOTE: Use additional locating marks, for reassembly reference, on the side plates or other parts of the assembly. Do not disassemble the No. 1 pin, the No. 1 carrier (10) and the spring pin (31), unless there is evidence of abnormal damage or excessive wear.
6. Remove the No. 1 sun gears.
Figure 10
Figure 11
7. Install 10 mm ring bolts and use them to lift out and separate the No. 2 carrier assembly.
8. Remove the thrust ring, in order to begin disassembly of the No. 2 carrier. Position the carrier vertically, as shown in the photograph. Insert an appropriate tool through the hole in the back side of the carrier. Hammer out the spring pin (31), so that pin No. 2 (14) can be withdrawn. Remove the upper and lower (18, 19) side plates of the differential gears.
9. Disassemble the ring gear. Tighten two 16 mm bolts into the holes shown in the photograph. Separate the ring gear using even force.
10. Before turning the gearbox end for end (180°, so that the drive shaft is facing up, as shown in the photograph) remove the 4 pipes and lock pins (21). Lock pins (21) should not require further disassembly. Loosen the mounting bolts (26) and detach the front cover plate (1).
IMPORTANT
Pin No. 2 should not be reused. Replace it with a new component. Further disassembly of the carrier is generally not required, unless there is evidence of unusual damage or excessive wear.
Figure 14
Figure 15
11. Pry away the front cover plate oil seal and the O-ring (29). The oil seal should normally be replaced each time the cover plate is removed. Inspect the O-ring carefully for any evidence of distortion, hardening or other damage.
12. Tighten ring bolts into the end of the drive shaft. Attach evenly balanced slings to a hoist or other lifting assist and carefully withdraw the drive shaft. Tap the housing with a plastic or other soft-faced hammer if there is any sticking or resistance.
13. Remove the thrust plate.
14. Further disassembly of the drive shaft requires the use of a hydraulic press. Use the drive shaft front bearing jig to separate the bearing and front seal (11). Remove the stop ring (34) on the opposite end of the drive shaft in order to remove the smaller bearing (23) on the inner end of the drive shaft. Make an index reference mark - a dot, or an arrow - on bearings to indicate which end of the bearing faces up, toward the output end of the drive shaft.
Figure 18
Figure 19
15. Carefully inspect the drive shaft for any evidence of abnormal or excessive wear on remaining surfaces or components. No further tear down of the assembly is normally required, unless exceptional damage has occurred.