The camshaft of a diesel generator is a component in a diesel engine that controls the opening and closing of valves. The appearance of early wear on the surface of the valve cam is basically the same, mainly concentrated near the tip, especially the highest part. Cam wear will reduce the height of the cam, resulting in insufficient valve opening.
The main cause of early wear is poor lubrication. This is because there are two lubrication methods for the cam and the bottom surface of the camshaft of diesel generators: one is splash lubrication; Another type is the oil that enters the oil passage, passes through the oil passage on the camshaft bearing seat, flows into the rocker arm through the rocker arm shaft seat, lubricates the rocker arm shaft, rocker arm, and push rod ball head, then flows into the tappet through the push rod, and then flows out through the lower oil hole to lubricate the cam and the bottom surface of the tappet. If the oil level in the oil pan is too low or the clearance between the tappet and cylinder block bearing holes is too small, the oil cannot flow into the tappet, which will cause poor lubrication and severe wear between the cam and the bottom surface of the tappet.
In addition, the abnormal operation of the valve tappets is also a reason for early wear on the surface of the valve cam. During normal operation, the tappet should have rotational motion to ensure even wear and prevent biting. If there is glue between the tappet and the shaft hole, bending of the push rod, and mismatch between the spherical surface at the bottom of the tappet and the cam slope, the tappet cannot rotate during operation, which will cause increased wear.
The inspection of cam wear can be judged by measuring the distance (i.e. cam lift) between the centerline of the cam tip and the base circle with a micrometer. For example, the intake cam lift of the Iveco 8140 diesel engine is 9.5mm, and the exhaust cam lift is 10.5mm. If the change in cam lift exceeds 0.5mm, it must be ground or replaced with a new part.
Inspection and adjustment of axial clearance
If the axial clearance of the camshaft exceeds the allowable value, it will cause a significant change in the valve timing, resulting in insufficient intake and poor exhaust of the diesel generator. A common method for detecting the axial clearance of camshafts is to pry the camshaft forward and insert a feeler gauge between the timing gear and the thrust flange to check. The general requirement for this gap is 0.07-0.25mm. The limit device of the camshaft of WD615 diesel engine is different from other diesel engines. During inspection, the camshaft can be pried forward and measured with a feeler gauge between the first journal groove and the camshaft limit plate. The standard value should be 0.1-0.4mm. When changing the gap, it can be adjusted by using different thicknesses of thrust plates, limit plates, or adjustment rings.
Maintenance of bending deformation
The inspection method for camshaft bending is similar to the crankshaft inspection method. First, place the camshaft on two parallel V-frames with the two end journals as the reference, or fix the camshaft between the two top pins of the lathe, and measure the runout of the middle journals with a dial gauge. 1/2 of the dial gauge reading is the straightness of the camshaft. If half of the journal runout exceeds 0.025mm, it should be corrected or replaced with a new part using cold pressing method. The roundness and cylindricity of the worn camshaft journal should generally be less than 0.15mm. When measuring the degree of wear with a micrometer and exceeding the specified value, the journal should be worn or the bearing replaced.
Dingbo Power was founded in 1974 and is one of the earliest manufacturers of generators and diesel generator sets in China. If you want get more information, please feel free to send email to sales@dieselgeneratortech.com we will pay highly attention on your question.
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