Overhaul Method of Camshaft of Cummins Generator Set

Oct. 22, 2021

Common faults of the camshaft of Cummins diesel generator sets include abnormal wear, abnormal noise and fracture. The symptoms of abnormal wear often appear before the occurrence of abnormal noise and fracture.

1. The camshaft of diesel generator set is almost at the end of the engine lubrication system, so the lubrication status is not optimistic. If the oil pump has insufficient oil supply pressure due to excessive use time or other reasons, or the lubricating oil passage is blocked and the lubricating oil cannot reach the camshaft of the diesel generator set, or the tightening torque of the bearing cap fastening bolts is too large, the lubricating oil cannot enter the diesel generator set Camshaft clearance will cause abnormal wear of the camshaft of the diesel generator set.

2. The abnormal wear of the camshaft of the diesel generator set will cause the gap between the camshaft and the bearing seat to increase, and the camshaft of the diesel generator set will move axially, resulting in abnormal noise. Abnormal wear will also cause the gap between the drive cam and the hydraulic tappet to increase. When the cam is combined with the hydraulic tappet, an impact will occur, which will cause abnormal noise.

3. Diesel generator set camshafts sometimes have serious faults such as fractures. Common causes include hydraulic tappet cracking or severe wear, severe lubrication, poor quality of diesel generator set camshafts, and cracked diesel generator set camshaft timing gears, etc. 

Cummins Generator Set

4. In some cases, the malfunction of the camshaft of the diesel generator set is caused by man-made reasons, especially when the camshaft of the diesel generator set is not properly disassembled and assembled when the engine is repaired. For example, when disassembling the camshaft bearing cap of a diesel generator set, use a hammer or a screwdriver to pry pressure, or install the bearing cap in the wrong position, resulting in mismatch between the bearing cap and the bearing seat, or the tightening torque of the fastening bolts of the bearing cap is too large, etc. . When installing the bearing cover, pay attention to the direction arrow and position number on the surface of the bearing cover, and use a torque wrench to tighten the bearing cover fastening bolts in strict accordance with the specified torque.

Technical requirements--camshaft

1)The camshaft must not be bent or cracked; the journal must not be stripped, crushed, or strained. Excessive wear must be repaired; the thread of the shaft end must be good.

2) Allow cold adjustment and straightening.

3)The cam working surface must not have peeling, pits or damage; when the cam profile wear is greater than 0.15mm, it is allowed to form grinding, and the surface hardness after grinding must not be lower than HRC57. The lift crankshaft must meet the original design requirements, but with The base circle radius of the air cam must not be less than 49.5mm, and the base circle radius of the oil supply cam must not be less than 47.0mm.

Gear transmission

1. After inspection, all gears are not allowed to have cracks, breakages, and partial wear. The pitting area of the tooth surface must not exceed 10% of the tooth surface area, and the hard damage must not exceed 5% of the tooth surface area.

2. The brackets must not be cracked or damaged. The verticality of the axis of the bracket shaft to the bracket mounting flange must meet the design requirements.

3. The joint surface of the bracket and the body must be closely attached. After the screws are tightened, a 0.03mm feeler gauge is not allowed to be inserted.

4. After the gear is assembled, it must rotate flexibly, the markings are clear and complete, and the lubricating oil path is clean and unobstructed.

4. Single-section camshafts are allowed to be replaced.

5. The radial runout of each journal of the camshaft to the common axis of journals 1, 5, and 9 is 0.1mm, and the indexing tolerance of each cam relative to the cam of the same name at the first (ninth) position is 0.5 degrees.

Repair method

1. Surface treatment: Use oxygen acetylene to roast the surface of the worn parts of the engine camshaft until no sparks are splashed, and then support the worn parts, and then polish the worn parts of the camshaft of generating sets to expose the original metal color, and then clean and polish the worn parts with absolute ethanol;

2. After the empty test of the bearing, clean the inner surface of the bearing with absolute ethanol and apply Soleil SD7000 release agent after the empty test is correct;

3. Proportionally blend the Soleil carbon nano-polymer materials, blend them to be uniform and without color difference, and then evenly apply the blended materials to the parts to be repaired;

4. Install the bearing and heat the material to solidify;

5. Disassemble the bearing, remove the excess material on the surface, and apply the material twice;

6. Install the cam and ensure the position and direction of the cam to ensure the use effect after the repair, then the repair can be completed.

Pump transmission

1. Clean all and remove the oil stain in the oil circuit.

2. The pump support box shall be free of cracks and damages, and the installation contact surface shall be flat.

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