How To Overhaul The Camshafts And Timing Gears Of Diesel Generators

Common failure forms and inspections of diesel generator camshafts and timing gears. The repair method is as follows:

1. Common abnormal forms of camshafts.

(1) Cam wear.

(2) The journals and bearings are worn.

(3) The shaft is bent.

2. Common abnormal forms of timing gears.

(1) Tooth wear.

(2) Broken teeth.

Why do diesel generator camshafts and timing gears fail?

The structural characteristics (long and thin) and working characteristics of the camshaft of the internal combustion engine (periodically bearing uneven loads) cause the wear of journals and bearings during operation. Loss of roundness and bending of the entire axis. Cam and cylinder relative movement of the parts, causing wear on the cam shape and height. The bending of the shaft will increase due to excessive bearing wear. The bending of the shaft will push the oil pump gear. Timing gears, journals, bearings, etc. wear, and even cause the gear running noise, which will break the teeth and make the spherical surface of the valve tappet rotate inflexibly, tolerances, etc., thereby accelerating wear.

However, in general, due to the small force on the camshaft, its wear rate is very slow, and it generally takes two or three overhaul cycles (or even longer) for the internal combustion engine to reach the allowable limit of use. However, these wear will affect the accuracy of the valve train operation and cause difficulties in the adjustment between the valve stem end and the tappet. Therefore, when the internal combustion engine is overhauled, the camshaft, cam, cam bearing, timing gear, etc. should be carefully inspected.

How to check diesel generator camshaft?

Diesel generator camshaft overhaul includes camshaft bending overhaul. It includes three aspects: camshaft bending inspection, cam inspection, and cam journal inspection. Details as follows:

1. Diesel generator camshaft bending test.

The detection method is: install the camshaft on the lathe or on the V-shaped iron block, take the journals at both ends as the fulcrum, and use a dial indicator to check the swing difference of each intermediate journal. If the maximum value of bending exceeds 0.025mm (that is, the total value of the dial indicator reading is 0.05mm), a cold pressing correction should be performed. Measure the journal supported by one or more (such as 3), when the shaft has two (such as 4) supporting the journal, measure the middle two journals.

2. Overhaul the diesel generator cam.

To test the cam, it can be measured with a standard sample or an outer diameter micrometer. If the top of the cam is worn more than 1mm, it should be repaired by surfacing. In addition, the wear of the cam tip arc should not exceed the allowable range.

3. Overhaul the cam journal of the diesel generator.

The out-of-roundness and taper error of the cam journal should not exceed 0.03mm, and the journal wear should not exceed 1mm.

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