Alignment Check and Correction of Yuchai Diesel Generator Set

If the centerlines of the Yuchai diesel engine and generator are misaligned during operation, it will cause severe vibration, which can easily damage instruments, oil pipes and water tanks; rubber hinges will wear quickly. At the same time, the crankshaft bearing and generator bearing wear will be aggravated, and even breakage accidents may occur. Therefore, after the generator is assembled, the centerline must be checked and corrected.

(1) Manifestations and causes of centerline misalignment

① Manifestations of centerline misalignment

Centerline misalignment mainly manifests in two aspects: offset and stagger.

② Causes of centerline misalignment

The main causes of centerline misalignment are: the base nuts of the generator are not tightened, causing offset during operation; the generator is not installed correctly after disassembly and maintenance; the centerline is not carefully corrected after replacing the rubber hinge.

(2) Inspection and correction of centerline

Taking Yuchai diesel generator set as an example, the method for checking and correcting the centerline between the diesel engine and the generator is described here.

①Install special tools. Fix the special tool on the vertical surfaces of the hinge plate and the flywheel, and turn it to the vertical upward position.

② Adjust the parallel screw and vertical screw to maintain a 0.50mm gap with the round iron, then fix the screws. Then rotate the flywheel 180 degrees, measure and record the gaps between the parallel screw, vertical screw and the round iron respectively, so as to calculate the stagger amount and offset amount of the two shafts in the vertical direction.

Stagger amount = large gap - small gap

Offset amount = (large gap - small gap)/2, offset amount ≤ 0.1mm

Here is an example: Suppose the measured gaps between the parallel screw, vertical screw and the round iron are 0.65mm and 0.20mm respectively. Then: Stagger amount = 0.65−0.50/0.532 = 0.28mm/m—the generator tail is too high, Offset amount = 0.50−0.20/2 = 0.15mm—the generator is too high.

a. Stagger amount. The correction method is: loosen the four base screws of the generator, slightly jack up the base of the generator, appropriately reduce the base shim, then level the generator, and tighten the four base screws. Finally, recheck and correct if it does not meet the requirements.

b. Offset. For offset correction, loosen the four screws of the generator base and appropriately adjust the thickness of the shim at the front and rear of the base.

④ Rotate the flywheel so that the special tool is on the left and right sides of the horizontal direction. Use the above method to check the stagger amount and offset amount of the two shaft centers. If the stagger amount and offset amount of the two shaft centerlines in the left-right (front-rear) direction exceed the allowable limits, correct them.

⑤ Recheck. After correcting the misalignment and offset between the generator centerline and the diesel engine crankshaft, recheck until the offset and stagger amount of the two centerlines meet the requirements.

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