Assembly instructions planetary gearboxes
A planetary gearbox works by using a sun gear, planet gears, a carrier, and a ring gear to transmit torque, with the sun gear receiving input and driving the planet gears, which are held in place by the carrier and mesh with the stationary ring gear.
I. Pre-Assembly Preparation
Dimensional Accuracy: Measure tooth thickness deviation of planet gears, sun gear, and ring gear (controlled within ±0.01mm), check bearing clearance (radial 0.02-0.05mm), and verify housing flatness (≤0.03mm/m).
Surface Quality: Ensure no burrs, deformation, or corrosion; contact surfaces must be clean, free of dust and oil.
Model Matching: Confirm that part specifications align with design requirements.
Working Environment: Clean, constant temperature (23±2℃), and constant humidity (45-65%).
Calibrated torque wrench and torque multiplier.
Hydraulic press (20-50T) or bearing heater.
Precision measuring tools (micrometer, dial indicator, laser alignment tool).
Special assembly platform (flatness ≤0.02mm).
II. Core Assembly Process
1. Planet Carrier Assembly
Step 1: Install Planet Gear Bearings
Adopt hot fitting method: Heat bearings to 80-120℃ and evenly fit them into planet carrier holes.
Or cold pressing method: Use a hydraulic press for slow pressing to avoid skewing.
Step 2: Mount Planet Gears
Install planet gears onto shafts and pre-tighten with a torque wrench per DIN 6892 standard.
Ensure uniform distribution of planet gears on the carrier with positional deviation ≤0.02mm.
Step 3: Inspection and Adjustment
Measure axial clearance of planet gears (recommended 0.03-0.08mm).
For multi-planet gear configurations, align marks (e.g., stagger dual planet gears by specific tooth counts).
2. Transmission System Integration
Adopt transition fit (H7/k6) with the input shaft to ensure coaxiality.
Connection Between Planet Carrier and Output Shaft
Common methods: Key connection + hydraulic locking structure.
Ensure clean keyways and tight, non-loose fits.
Insert into the housing and check coaxiality with a laser interferometer (≤0.02mm).
Tighten fixing bolts evenly in a cross-symmetrical sequence.
Install the planet carrier assembly into the housing and align with the sun gear.
Mount the end cover and tighten bolts to the specified torque.
3. Lubrication and Sealing System
Grease Lubrication: Filling volume V = 0.3 × bearing chamber volume.
Oil Lubrication: Equip with three-stage filtration (5μm precision).
Control O-ring compression ratio between 15-25%.
Apply sealant (0.1mm thickness) on mating surfaces and allow curing for ≥24h.
Coat labyrinth seals with molybdenum disulfide grease (0.1-0.3mm thickness).
III. Precision Debugging and Performance Verification
1. Backlash Detection and Adjustment
Measure with a torque tester (target ≤3arcmin).
Correct using shims (each 0.05mm shim affects backlash by approximately 1arcmin).
Execute ISO 1940 G2.5 standard.
Unbalance calculation: U = 9549×G×n/(π×r).
No-Load Operation: 4 hours with oil temperature ≤75℃.
Load Testing: Step loading (25%-50%-75%-100%) to detect temperature rise (≤15℃).
Noise Detection: Noise ≤ design value during stable operation.
IV. Motor Connection and Installation
1. Docking Motor with Gearbox
Clean shaft ends and mating surfaces to remove rust-preventive oil.
Ensure the motor shaft keyway is perpendicular to the gearbox input hole clamping screws.
Insert naturally to guarantee coaxiality (radial deviation ≤0.05mm).
2. Fastening Installation
Tighten mounting bolts in a diagonal sequence (preliminary fixation first, then gradual tightening).
Fasten to the specified torque with a torque wrench.
Install anti-torsion brackets (if required).
V. Common Issues and Prevention
1. Abnormal Noise Caused by Assembly Errors
Causes: Poor tooth contact, improper bearing preload, or planet gear positional deviation.
Check tooth contact pattern (required ≥70%).
Recheck bearing preload (axial preload = 10-15% of radial load).
Control planet gear shaft positional accuracy (≤0.02mm).
Causes: Poor sealing, housing deformation, or excessive oil level.
Use correctly sized O-rings with standard compression ratio.
Inspect mating surface flatness (blueing method).
Maintain oil level within standard range.
3. Low Transmission Efficiency
Causes: Improper gear meshing clearance, over-tight bearings, or insufficient lubrication.
Strictly control meshing clearance (spur gears: 0.08-0.15mm; helical gears: 0.10-0.18mm).
Ensure bearing clearance meets standards (0.02-0.05mm).
Use the correct type and amount of lubricant.
VI. Assembly Key Points for Different Gearbox Types
1. Parallel Shaft vs. Right-Angle Planetary Gearboxes
Input and output shafts are parallel with a relatively simple structure.
Focus on ensuring shaft parallelism (≤0.05mm) during assembly.
Incorporates a bevel gear steering mechanism requiring precise alignment.
Ensure proper meshing and uniform clearance of the steering mechanism.
2. Spur Gear vs. Helical Gear Planetary Gearboxes
Planet carriers can use single or double support structures.
Must adopt double support structures (to counter axial forces).
Precisely control bearing preload (prevent axial movement).
3. Modular Planetary Gearboxes (e.g., REV Robotics Series)
Pre-assembled gear cartridges for stackable configuration.
Simplified assembly steps:
Fix the motor with the input shaft facing upward.
Stack gear modules and align with the input shaft.
Ensure proper meshing of input splines.
Tighten housing bolts evenly in a star pattern.
VII. Summary and Safety Notes
Cleanliness First: All parts, tools, and the environment must be clean.
Planet gear axial clearance: 0.03-0.08mm.
Coaxiality ≤0.02mm; parallelism ≤0.05mm.
Torque Compliance: Tighten bolts per standards in a cross-symmetrical sequence.
Proper Lubrication: Use the correct type and amount of lubricant; ensure reliable sealing.
Use appropriate lifting equipment and avoid working under suspended components.
Prevent scalds when handling heated parts (bearing heating temperature: 80-120℃).
Follow operating procedures for hydraulic equipment to avoid high-pressure hazards.
Ensure adequate protection during rotating component testing.
After Assembly: Conduct a comprehensive inspection. The gearbox should rotate smoothly by hand and operate without abnormal noise during no-load running before official commissioning.
