Installation Method of 24V 70A Generator for Cummins QSL 9.3 Engine

I. Pre-installation Preparation

Tool and Material Preparation

• Special Tools: Torque wrench (range: 0–200 N·m), socket wrench set, Phillips/flathead screwdriver, belt tension gauge.

• Installation Materials: Generator mounting bolts (Cummins original part number: 3903930), lock washers, generator drive belt (original part number subject to engine configuration), thread locker (Loctite 242, medium strength).

• Protective Equipment: Insulated gloves, safety goggles, anti-slip gloves.

Safety Inspection

1. Ensure the engine is shut down and cooled down. Disconnect the negative battery cable to prevent short circuit during installation.

2. Clean oil stains, dust and rust from the generator mounting bracket and its surrounding areas. Check the bracket for cracks and deformation; replace any damaged bracket before installation.

3. Inspect the appearance of the generator to be installed: the rectifier, stator and rotor shall be free of damage; the terminals shall be free of oxidation; the pulley shall rotate flexibly without jamming.

II. Installation Procedures

Generator Positioning

1. Lift the 24V 70A generator to the engine mounting bracket by hoisting or manual handling, and align the bolt holes on the generator base with those on the bracket.

2. Insert 2 positioning bolts first (do not tighten them) to ensure the generator is properly positioned, avoiding bolt or thread damage caused by forced alignment.

Fastening Generator Mounting Bolts

1. Apply a small amount of medium-strength thread locker (Loctite 242) to the bolt threads, then install all the fixing bolts and lock washers in sequence.

2. Use a torque wrench to tighten the bolts in diagonal sequence in 2–3 steps. The final torque value shall comply with Cummins specifications: 45–50 N·m for M10 bolts, 85–90 N·m for M12 bolts (refer to the generator nameplate for the exact torque value).

Drive Belt Installation

1. Loosen the lock bolt of the engine belt tensioner and adjust the tensioner to the slack position.

2. According to the engine pulley layout drawing, fit the belt over the crankshaft pulley, generator pulley and tensioner in sequence. Ensure the belt is fully seated in the pulley grooves without twisting or deviation.

3. Adjust the belt tension using a belt tension gauge: the standard tension for the 24V 70A generator belt is 80–100 N (or a deflection of 10–15 mm when pressing the midpoint of the belt). After adjustment, tighten the lock bolt of the tensioner.

Electrical Wiring Connection

1. Connect the generator output terminal (B+): Connect the 24V battery positive cable (cross-sectional area: not less than 35 mm²) to the generator B+ terminal. Install a flat washer and lock nut, tighten to a torque of 25–30 N·m, and cover with an insulating protective cap.

2. Connect the excitation circuit: Connect the regulator control wire (thin wire) to the generator D+ terminal, ensuring a secure connection without loosening or short-circuit risks.

3. Connect the grounding circuit: Reliably connect the generator housing grounding terminal to the engine block, with the grounding resistance required to be less than 0.1 Ω.

Reset Inspection

1. Reconnect the negative battery cable and check that no tools or debris are left around the generator.

2. Manually rotate the generator pulley to confirm there is no jamming or abnormal noise, and the belt does not slip.

III. Post-installation Commissioning

1. Start the engine and run it at idle speed for 3–5 minutes. Observe the generator operation status: no abnormal noise, oil leakage or peculiar smell.

2. Measure the generator output voltage with a multimeter: the voltage at idle speed shall be 27–28 V, and not less than 25 V at full load (70A), meeting the 24V system standard.

3. Check the belt tension: shut down the engine and let it cool down after 10 minutes of operation, then measure the belt tension again and readjust if there is any deviation.

Precautions for Installation of 24V 70A Generator for Cummins QSL 9.3 Engine

I. Pre-installation Safety Precautions

Power-off Operation Specifications

1. All operations must be performed after the engine has completely shut down and cooled to room temperature. Disconnect the negative battery cable to prevent short circuits during installation that could damage the generator regulator or engine ECU.

2. It is prohibited to connect or disconnect generator circuits while the engine is running to avoid electric shock or mechanical injury.

Component Inspection Requirements

1. Inspect the generator mounting bracket: it shall be free of cracks, deformation and rust; the bracket bolts shall not be stripped. Damaged components must be replaced with original Cummins parts, and welded repairs are strictly forbidden for continued use.

2. Verify generator parameters: the nameplate must indicate a voltage of 24V and a current of 70A, which must be compatible with the Cummins QSL 9.3 engine to prevent power generation system malfunctions caused by mismatched installation.

3. Inspect the generator appearance: the rectifier and stator windings shall be free of damage and burn marks; the pulley shall rotate flexibly without jamming; the terminals shall be free of oxidation and looseness.

Tool and Material Specifications

1. A torque wrench must be used to control bolt tightening torque. Do not use an adjustable wrench for forced tightening, as this may cause bolt thread damage or generator housing deformation.

2. Bolts shall be original Cummins parts (Part Number: 3903930), equipped with lock washers. Medium-strength thread locker (Loctite 242) is recommended; high-strength thread locker is prohibited to avoid difficulties in subsequent disassembly.

3. Cable specifications must match requirements: the cross-sectional area of the B+ terminal cable shall be not less than 35 mm²; the excitation circuit shall use high-temperature resistant and flame-retardant wires to prevent overheating due to overload.

II. Prohibited Operations During Installation

Prohibitions for Bolt Fastening

1. When fastening generator mounting bolts, tighten them in diagonal sequence in 2–3 stages. Do not tighten bolts on one side in a single pass to prevent base cracking caused by uneven stress.

2. Strictly comply with torque standards: 45–50 N·m for M10 bolts, 85–90 N·m for M12 bolts. Excessive torque may damage threads, while insufficient torque will cause loosening and abnormal noise during operation.

Prohibitions for Belt Installation and Adjustment

1. Belt tension must be adjusted only via the tensioner. Do not pry the generator housing to adjust its position, as this may damage generator bearings or end caps.

   
   

References：

I. Details of the Core Source

1. Pre-installation Preparation: Corresponding to the chapter "Generator Installation - Pre-installation Inspection" in the manual, covering tool selection, safety specifications and component inspection requirements.

2. Installation Procedures: Corresponding to the chapter "Generator Mounting and Belt Installation", specifying the bolt tightening sequence, torque standards, and methods for belt installation and tension adjustment.

3. Electrical Connection: Corresponding to the chapter "Electrical System - Generator Wiring", regulating the connection requirements for the B+ terminal, excitation circuit and grounding circuit.

4. Post-installation Commissioning and Precautions: Corresponding to the chapter "Post-installation Testing and Maintenance Precautions", including voltage testing, maintenance cycles and other related content.

II. Supplementary Authoritative Sources

1. Cummins QuickServe Online (QSOL) Platform: The electronic version of the above manual can be retrieved and obtained through Cummins' official QSOL platform. This platform is a globally authorized technical document and parts inquiry database of Cummins, providing services for downloading and online viewing of the latest version of the manual.

2. Original Parts and Technical Bulletins

• The specifications of accessories such as generator mounting bolts (Part Number: 3903930) and belts are derived from the Cummins QSL9.3 Engine Parts Catalog, which is used in conjunction with the maintenance manual.

• Details such as thread locker selection and grounding resistance standards are referenced from the supplementary specifications for power generation system installation in Cummins Technical Bulletins.

III. Source Retrieval and Verification Methods

1. Visit the Cummins QuickServe Online platform (https://quickserve.cummins.com). After registering an account, enter the engine model QSL9.3 and manual number 4021488 to retrieve and download the complete manual.

2. Contact authorized Cummins dealers and apply for a copy of the exclusive maintenance manual for this engine model by providing the engine serial number to verify the authority of the installation specifications.

3. The copyright of the manual belongs to Cummins Inc. All technical parameters and operation specifications shall be subject to the latest version of this manual. If the manual is updated, the installation procedures shall be adjusted according to the content of the new version.