Installation Method for Yuchai 28V Generator

I. Pre-installation Preparation (Mandatory Safety and Compatibility Checks)

1. Safety Operations (Mandatory Implementation)Stop the engine, disconnect the negative battery terminal and wait for 3 minutes to discharge residual power. Post a "Under Maintenance - No Starting" warning sign, and wear insulated gloves and safety goggles.
   Clean the work area of oil stains and metal debris to avoid conductive impurities causing short circuits; use insulated tools to operate electrical terminals.
2. Tools and Consumables List| Category | Details | Purpose ||----------|---------|---------|| Special Tools | Torque wrench (accuracy ±3%), socket set (8–16mm), dial indicator, level, belt tension gauge | Precise bolt tightening, coaxiality detection, transmission tension calibration || Consumables | Original factory elastic coupling/flange gasket, new mounting bolts (Grade 10.9), terminal cleaner, insulating sleeve, conductive paste | Sealing and leak prevention, preventing bolt fatigue fracture, improving conductivity |
3. Compatibility and Pre-inspection Requirements

• Verify that the generator model matches the engine (e.g., suitable for Yuchai YC4F/YC6J series engines). Check for no housing cracks, no terminal oxidation, and ensure the rotor rotates smoothly without jamming.

• Inspect the drive-end bearing for no looseness or abnormal noise; ensure the voltage regulator (e.g., built-in IC regulator) wiring is intact, and the excitation winding insulation resistance is ≥1MΩ (tested with a 500V megohmmeter).

• The flatness of the flywheel housing mounting surface shall be ≤0.1mm. Check studs for no deformation or corrosion; replace them if necessary and pre-install according to specified torque.

II. Core Mechanical Installation Steps (Alignment and Tightening are Critical)

1. Positioning and Coaxiality Calibration

• Single-support generator: Align the front cover spigot with the flywheel housing spigot, connect to the flywheel via elastic steel plates, ensuring coaxiality error ≤0.1mm and parallelism ≤0.05mm.

• Dual-support generator: Install the elastic coupling, use a dial indicator to detect that the radial runout of the two couplings is ≤0.08mm and the end face runout is ≤0.05mm. Adjust the bracket if the deviation exceeds the limit.

• Belt-driven models: The generator and engine pulleys must be coplanar (deviation ≤0.5mm). Adjust the belt tension according to model specifications (deflection of B-type belt: 10–15mm under 10kg force).

2. Mounting Bolt Torque Tightening (By Specification)| Bolt Specification | Installation Position | Torque Value | Tightening Sequence ||--------------------|-----------------------|--------------|---------------------|| M10 | Generator mounting bolt | 45–50N·m | Tighten diagonally and crosswise step by step to avoid uneven loading || M12 | Generator mounting bolt | 75–80N·m | Same as above || M8 | Coupling/flange bolt | 22–25N·m | Tighten symmetrically and evenly |
3. Sealing and Protection Treatment

• Apply a thin, uniform layer of sealant (e.g., Yuchai-specified silicone sealant) on the mounting surface, avoiding blockage of bolt holes; add a metal gasket for flange connections to ensure no leakage.

• Route the wiring harness away from high-temperature components (e.g., exhaust manifold), with fixed points spaced ≤300mm apart. Protect easily worn parts with corrugated pipes.

III. Electrical Wiring Connection Specifications (Reverse Polarity Prevention and Insulation are Key)

1. Wiring Sequence and Torque (Irreversible)

• Connect the ground wire: Reliably connect the generator housing ground point to the engine/frame, tighten the bolt to 18–20N·m, and apply conductive paste to reduce contact resistance.

• Connect the main power supply (B+): Connect a thick cable (cross-sectional area ≥16mm²) to the generator B+ terminal, tighten the nut to 12–15N·m, and install an insulating sleeve to prevent short circuits.

• Connect the excitation wire (F): Connect to the regulator excitation terminal according to the circuit diagram, ensure the plug locks in place to avoid excitation instability caused by loosening.

• Connect the charging indicator wire (L): Connect to the corresponding regulator terminal, ensuring the indicator light turns on/off normally (extinguishes after startup is normal).

2. Wiring Inspection Key Points

• Ensure all wiring terminals are free of looseness and exposure, and the wiring harness has no interference or abrasion. Connect the battery positive and negative terminals correctly; reverse connection is strictly prohibited (it will burn out the regulator and rectifier).

• Check that the ground resistance is ≤4Ω; add a ground electrode if necessary to ensure effective leakage protection.

IV. Function Testing and Acceptance (Mandatory Items)

1. Static Testing

• Reconnect the negative battery terminal (torque: 5N·m), check that the wiring harness has no looseness, transmission components have no interference, and the coaxiality error between the generator and flywheel housing is ≤0.3mm.

• Use a multimeter to measure the resistance between the B+ terminal and ground: forward conduction and reverse cutoff indicate a normal rectifier; the excitation circuit resistance shall comply with the manufacturer's specifications (usually 2–5Ω).

2. Dynamic Power Generation Testing

• Start the engine at idle speed and observe the charging indicator: it should extinguish after startup. At idle speed (750–850rpm), the charging voltage shall be 27–29V (28V system); when the speed rises to the rated value (e.g., 1500rpm), the voltage shall stabilize at 28±0.5V.

• Load test: With 50% rated load, the voltage fluctuation shall be ≤±0.2V, the frequency shall be stable (49.5–50.5Hz for 50Hz models), and there shall be no abnormal noise or vibration.

• Temperature rise and insulation inspection: Operate continuously for 1 hour; the generator housing temperature shall be ≤80℃, and the excitation winding temperature shall be ≤105℃. Re-test the insulation resistance after shutdown, which shall be ≥1MΩ.

3. Acceptance Criteria

• All fastening bolts shall be free of looseness, sealing points shall have no leakage, and the transmission belt shall have no slipping or abnormal noise.

• The power generation parameters shall comply with Yuchai original factory specifications, the charging curve shall be stable, and there shall be no false triggering of overvoltage or undervoltage protection.

V. Key Precautions (Core of Fault Prevention)

References：

Core Technical Sources (Authoritative Basis)