I. Main Components of Diesel Generator Sets:

1. Crankshaft and Main Bearings

The crankshaft is a long shaft fitted into the lower part of the cylinder block. Offset connecting rod journals, i.e., crankshaft crankpins, are mounted on the shaft. These are used to convert the reciprocating motion of the piston connecting rod into rotary motion. Oil passages are drilled inside the crankshaft to supply lubricating oil to the main bearings and connecting rod bearings. The main bearings supporting the crankshaft in the cylinder block are sliding bearings.

2. Cylinder Block

The cylinder block is the framework of an internal combustion engine. All other components of the diesel engine are mounted on the cylinder block using screws or other connecting methods. The cylinder block has many threaded holes for connection to other components using bolts. There are also holes or supports in the cylinder block for supporting the crankshaft; holes for supporting the camshaft; and cylinder bores into which cylinder liners can be fitted.

3. Piston, Piston Rings, and Connecting Rod

The piston and piston rings fitted in its ring grooves serve to transmit the pressure from the combustion of fuel and air to the connecting rod connected to the crankshaft. The connecting rod connects the piston to the crankshaft. The piston pin, which is usually fully floating (the piston pin floats relative to both the piston and the connecting rod), connects the piston and connecting rod.

4. Camshaft and Timing Gear

In a diesel engine, the camshaft operates the intake and exhaust valves; in some diesel engines, it can also drive the lubricating oil pump or fuel injection pump. The camshaft is timed by the crankshaft through a timing gear or camshaft gear that meshes with the gear at the front end of the crankshaft. This drives the camshaft and ensures that the diesel engine valves are in the correct position relative to the crankshaft and piston.

5. Cylinder Head and Valves

The main function of the cylinder head is to provide a cover for the cylinder. In addition, the cylinder head has intake and exhaust ports to allow air to enter the cylinder and exhaust gases to exit. These ports are opened and closed by driven valves located in valve guides on the cylinder head.

6. Fuel System

The fuel system injects the correct amount of fuel into the diesel engine cylinders at the precise time, depending on the load and speed of the diesel engine.

7. Turbocharger

A turbocharger is an exhaust gas-driven air pump that supplies pressurized air to the diesel engine. This increase in pressure, called boosting, increases the power of the diesel engine.

II. Overhaul of Main Components of Cummins Diesel Generator Sets

1. Stator Inspection

When inspecting the stator windings, use a multimeter to measure the resistance between the various stator winding terminals. The resistance between the three terminals should be consistent, and the resistance between the windings and the core should be infinitely large. If there is a short circuit, open circuit, or ground fault in the stator windings, the stator assembly should be rewound or replaced.

2. Rotor Inspection

When inspecting the rotor, use a multimeter to measure the resistance between the two slip rings. This resistance should be between 18-20 ohms. If the measured resistance is too high or too low, it indicates a fault in the rotor windings. The rotor assembly should be disassembled for repair or directly replaced. The area between the two slip rings should be clean, and the surface of the slip rings should be smooth, without burning or uneven wear. Dirt on the rotor surface can be wiped clean with cotton gauze dipped in a small amount of gasoline or alcohol; if there is slight burning or wear, it can be smoothed with fine sandpaper; if there is serious burning, it can be repaired by machining and then polished with fine sandpaper.

3. Inspection of Silicon Rectifier Components

The silicon diodes used in silicon rectifier generators come in two types. The lead with a red symbol is the positive lead, and the lead with a black symbol is the negative lead. Before determining whether a diode is good or bad, it is generally necessary to use a soldering iron to solder open one end of the positive or negative lead, and then use a multimeter for testing. The testing method is: set the multimeter switch to the R*1 resistance range (digital multimeter to the diode range). When measuring, place the red probe on the diode with the red symbol and the black probe on the metal panel. When testing with a general multimeter, the pointer should indicate around 10 ohms; when testing with a digital multimeter, the multimeter will emit a beep. Then, place the black probe on the diode with the red symbol and the red probe on the metal panel. If the multimeter reading is above 10 kiloohms, the silicon diode is normal. If the measured forward and reverse resistance values are both large, it usually indicates poor internal contact or an open circuit in the diode; if the measured forward and reverse resistance values are both small, it usually indicates an internal short circuit in the diode. Whether the diode has a short circuit or an open circuit, a new diode should be replaced. During installation, the diode should be pressed into the hole and not hammered to avoid internal damage to the diode.

4. Inspection of Brush Equipment

The brush holder should be free of deformation and cracks, the pressure of the brush spring should meet the technical requirements, and the contact area between the brush and the commutator should be more than 85%.

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