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How To Overhaul The Camshaft Of A Diesel Generator And Its Bearings

Jan. 21, 2022

The repair of the diesel generator camshaft includes the repair of the camshaft, the repair of the cam, and the repair of other parts. There are three main aspects, as follows:


1. Repair the diesel generator cam.

If there are scratches, roughness and uneven wear on the cam surface, it should be trimmed with a special grinder for camshafts, or carefully repaired according to standard samples. On a special model car or a special camshaft grinder, the thickness of the cam carburized layer is usually 0.50-0.80mm. Therefore, the height of the cam should be carried out on a special model vehicle or a camshaft grinder. If the wear is too large, alloy electrode surfacing can be performed (such as ordinary electrode, carbonization and heat treatment are required after welding), and then the prototype is used for smooth grinding to restore the original geometry. In order to avoid thermal deformation during the surfacing process, the cam can be placed in water, and only the surface welding part is exposed. If the top surface is cone, if the cone disappears or does not meet the requirements, it should be repaired.


2. Repair diesel generator camshaft journal.

There are two ways to repair camshaft journal wear. One of them is a cam bearing that can be pressed into and disassembled into the bearing hole of the cylinder block, and this kind of camshaft is relatively common, and the size of the journal can be reduced and the cam bearing of the corresponding size can be used. Its dressing size is generally divided into four grades, each grade is usually carried out on the grinding machine, and each grade is reduced by 0.25mm (0.25mm.0.50mm.0.75mm.1.00mm). The other is that the camshaft rotates directly at the bearing hole of the cylinder block. When repairing the journal, it is rough machined with chrome plating, and then ground to the standard size or repaired size and then matched.


3. Repair other parts.

If the thread of the camshaft timing gear fixing nut is damaged, it should be repaired by surfacing or replaced with new parts. The synchronous tooth key and the keyway should be matched, and the new key should be replaced if worn. When the gear teeth of the oil pump transmission gear are worn, when the tooth loss exceeds 0.50mm, surfacing repair should be carried out. If the surface of the eccentric is worn more than 0.50mm, it should be repaired. Due to excessive wear or cracks, the wing gear and cam should be replaced.


diesel generator

Diesel generator camshaft bearing repair method:

The matching clearance between the diesel generator camshaft bearing and the journal is usually between 0.03~0.07mm, and the maximum cannot exceed 0.15mm. Those larger than 0.15mm should be repaired or replaced.


When diesel generators are overhauled, the camshaft bearings are usually repaired. The repair method of the bearing bush is the same as that of the crankshaft bearing. The commonly used methods are tearing and scraping. Because the scraper method does not require special equipment, it is adopted by general maintenance units. Its specific preparation steps are as follows.


1. The bearing of the same repair size should be selected according to the repair size of the cam journal.


2. Scrape match. The inner diameter of the bearing after the scraper should be the same as: the journal size + the matching clearance between the bearing and the journal (usually 0.03~0.07mm) + the tolerance between the bearing and the seat hole (usually 0.015-0.02mm).


The scraping thickness of the scraped bearing should be as uniform as possible to ensure that the scraped bearing and the bearing seat hole and the centerlines of each bearing coincide. The bearing that is not pressed into the seat hole should be trial-fitted with the journal, and their fit should be slightly loose. When a thick gauge should be added between the bearing and the journal (its thickness is equal to the clearance between the bearing and the seat hole + the matching clearance between the bearing and the journal), and there should be a little resistance when dragging the bearing. After the bearing is pressed into the seat hole, due to the deformation of the bearing and the reduction of the inner diameter, generally speaking, the reduction of the inner diameter is equal to the interference between the bearing and the seat hole, which can basically meet the required fit clearance.


3. The bearing is pressed into the seat hole, and the pressed bearing should be aligned with the bearing to prevent the bearing from burring.


4. Install the camshaft in the bearing, rotate several pieces, test the contact condition, and grind it properly to ensure a good contact surface. The empirical method to test the tightness of the fit is as follows: when the spur gear is pulled by hand, the camshaft can rotate flexibly, and there will be no obvious gap feeling when the camshaft is moved in the radial direction.


Jiangsu Starlight Electricity Equipments Co.,Ltd. is one of the earliest manufacturers of generators and diesel generator sets in China. The company was established in 1974 and the company occupies an area. With an area of 86,000 square meters and a building area of 45,000 square meters, it has 64 sales and service departments across the country to provide users with one-stop service of design, supply, debugging and maintenance at any time. Welcome customers to come to consult and visit. Looking forward to your inquiry, please send email to us for details sales@dieselgeneratortech.com

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