Slewing Ring Installation and Maintenance
1. The requirement of installing frame
1.1 The installing surface of the slewing ring shall be flat and free of grease. Weld bumps, burrs, paint or other uneven contaminants shall be removed. The installing surfaces of inner ring and outer ring shall be in full contact with the connection structure. The flatness of the installing surface (including horizontal angular deviation) shall be checked before installing (as shown in Figure 1 and Table 2 ).
1.2 The installing frame shall have enough rigidity, for which the maximum deflection under extreme loads shall accord to Table 3.
Table 3: Maximum allowable deflection
2. Installation requirements
2.1 Horizontally put the slewing ring on the installing frame. The soft zone and the loading plug shall be located in the non-loading, infrequently loading or lightly loading zone.
2.2 Slewing rings shall adopt high-strength bolts, and select the appropriate strength according to the load case. Installing bolts and nuts of slewing rings shall comply with GB/T 3098.1 and GB/T 3098.2
a. For general construction machinery, Grade 10.9 bolts are recommended.
b. If there are critical requirements on bolt static strength under rated load and bolt yield strength under maximum load while no emphasis on fatigue strength, Grade 12.9 bolts are recommended.
c. For occasions with frequently changing loads which requires critical fatigue strength, Grade 8.8 bolts are recommended.
2.3 It is recommended to use tempered flat washers. The spring washer is not allowed.
2.4 Bolts installation requires adequate pre-tightening force, which shall be ≥0.7 times of bolts yield limit. The pre-tightening force shall conform to value in Table 4.
2.5 When tightening the bolts, it shall use torque wrench to tighten bolts symmetrically several times along the 180°direction (The threads shall be lightly oiled). See Figure 2.
2.6 It shall check the pre-tightening force of bolts after first 100 hours operation, then check it every 500 hours, and shall always maintain adequate pre-tightening force.Table 4: The pre-tightening torque and force of bolts
Figure 2: Sequence of tightening bolts
3. Adjusting the meshing backlash between gear and pinion
Before pre-tightening installing bolts, it is necessary to test the meshing backlash between gear and pinion (see Figure 3), especially for gear hardened products, it shall be ensured that the backlash between maximum runout point of slewing ring (marked with green paint) and the pinion meet the following requirements:
a. Meshing of soft teeth surface: the backlash shall not be less than 0.03*m (m is the gear module).
b. Meshing of hard teeth surface: the backlash shall not be less than 0.06*m (m is the gear module).
Figure 3: Backlash inspection diagram
4. Adjustment after installation
4.1 After pre-tightening all the bolts, clear debris between gears and those around slewing ring away in time. Ensure there is no interference during working.
4.2 Slowly rotate the slewing ring for more than 3 rounds, and carefully check whether it operates smoothly, whether there is abnormal noise, stagnant phenomenon, and whether the gear and pinion mesh well.
4.3 Welding operation is not allowed on or near the equipment which have already installed with slewing ring.
5. Lubrication
The slewing ring raceway has been lubricated with a small amount of EP2 grease before delivery. Consumers shall re-lubricate with suitable grease according to actual working condition. When filling the grease, the slewing ring shall be rotated slowly, and be injected grease while rotating, so that the grease can be filled evenly until a small amount of grease is extruded from the sealing, which indicates that it has been fully filled while the lubrication shall be stopped. The frequency of lubrication is as follow:
a. Generally, it is necessary to fill in grease once every 100 operating hours for ball slewing ring, and once every 50 operating hours for roller type.
b. The filling period shall be shortened to at least once a week if there is special working condition such as in the tropics, high humidity, severe dust, large temperature difference and long continuous working.
c. The slewing ring shall be re-lubricated before and after long time shutdown.
d. The gear shall be cleaned and lubricated every 8-10 working days, while no contaminants are allowed.
6. Other instructions
6.1 Cleaning
It is forbidden to flush the slewing ring directly with water during use to prevent water from entering the raceway. It shall critically prevent hard contaminants from approaching or entering the meshing area.
6.2 Checking of the seal
It shall check seals at least every 6 months, replace the seal if it is damaged.
6.3 Inspecting the gear
Gear may be worn at the meshing area. A permissible wear limit depends on the application. The wear limit at each flank of the gear shall not exceed 0.15 times of module.
6.4 Storage
The slewing ring shall be stored in roofed area with specific features: dry, flat and no corrosive medium; no immersing, drenching or vertical placing allowed.
Maanshan Tongli Slewing ring Co., Ltd. Copyright Anhui ICP Preparation No. 15004889-1 disclaimer Business License