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Install and Remove Piston Connecting Rod of Diesel Generator

Nov. 13, 2018

Basic structural principle of piston connecting rod of diesel generator set


The piston connecting rod is one of the main moving parts in the diesel generator set. Care must be taken when disassembling the piston connecting rod. When changing parts, pay attention to the structural differences of each model, otherwise it will cause adverse consequences.

Install and Remove Piston Connecting Rod of Diesel Generator.jpg


The piston is made of eutectic silicon aluminum alloy. The basic diesel generator sets have different piston structure differences. When changing the piston, pay special attention to the valve pocket depth dimension and the piston pin hole to the piston top surface distance dimension. Otherwise, the piston may be related to the cylinder head or The valve collides, causing a serious accident, or causing the compression ratio to drop and fail to work properly.


The piston skirt is a finished surface that prevents knocking when disassembling. There are 4 small holes of 5mm on the piston pin seat for lubricating oil splashing. The inner pin of the piston can be reused to adjust the weight of the piston set. Marked for use by the user when installing or replacing a new piston. The difference in weight of each piston in the same diesel generator set should be no more than 10g.


Reminder: During maintenance, a small area of scratches on the top of the piston, burn marks or slight damage to the skirt, can be used after repairing with a scraper and oil stone, otherwise it should be replaced.


Diesel generator piston rod self-assembly points


Some customers will choose to assemble themselves after the diesel generators are purchased. So today, Starlight will talk about the assembly of the piston rods in detail. The following are some of the points listed by the staff for your reference.


1. Press-fit connecting rod copper sleeve. It is best to use a press when installing the connecting rod copper sleeve, or by means of a vise. Do not use a hammer to strike; the oil hole or oil groove on the copper sleeve should be aligned with the oil hole on the connecting rod to ensure lubrication.


2. Assemble the piston and connecting rod. When assembling pistons and connecting rods, pay attention to their relative position and orientation.


3. Cleverly loaded with piston pins. The piston pin and the pin hole are in an interference fit. When installing, the piston should be evenly heated to 90 °C ~ 100 °C in water or oil. After taking out, put the tie rod in the proper position between the piston pin hole, and then install the piston pin coated with organic oil in the given direction. Into the piston pin hole and the connecting rod copper sleeve.


4. Piston ring installation. When installing the piston ring, pay attention to the position and sequence of each ring.


5. Loading the link set.


Under normal circumstances, regardless of the distance, diesel generator manufacturers will be responsible for the assembly work of everyone, manufacturers who are unable to provide this service need more careful contact and inspection, so as to avoid cooperation errors.


Assembly method of diesel generator set piston connecting rod set



The piston connecting rod group is mainly composed of a piston, a piston ring, a piston pin and a connecting rod. Its assembly is an important part of the assembly process of diesel generator sets, so what is its assembly method?


1. 1. When replacing the connecting rod, measure the weight of each connecting rod of the same diesel generator set. On the basic diesel generator set, the weight tolerance of the connecting rod components is 30g (the tolerance for the diesel generator set used for the calibration speed >1500r/min is 20g).

2. The piston of the diesel generator set is heated to 100-120 ° C in the oil, and the piston is taken out, and the piston pin coated with the oil on the outer surface is loaded into the small hole of the piston and the connecting rod in time. At this point, attention must be paid to the relative position of the valve pocket at the top of the piston and the large head cutout of the connecting rod. The 4-6 cylinder in-line diesel generator set is shown in Figure 1; the 12-cylinder V-type diesel generator set is shown in Figure 2. After the piston is installed, install the piston pin lock spring with a pointed clamp (as shown in Figure 3).



3. Install the piston ring, you can use the wire ring sleeve (as shown in Figure 4), the piston ring is expanded to just pass the top of the piston, but it should not be too large to prevent the piston ring from breaking. When installing the screw spring oil ring assembly parts, first install the spring sleeve ring groove and then install the oil ring ring so that the spring is fully embedded in the inner groove of the oil ring ring, and the spring interface is placed opposite the oil ring ring opening. After the position is installed, the openings of the piston rings should be shifted by about 120° in sequence, and there should be no jamming in the ring groove.



4. Apply sufficient cleaning oil to the matching surfaces of the piston rod connecting rod, cylinder liner and crankshaft of the generator set, then place special tools for the piston on the cylinder liner, turn the crankshaft, and connect the connecting rod journal of the piston connecting rod. Turn to the 70 ° or so after the top dead center, and then carefully insert the piston rod into the cylinder liner (as shown in Figure 5). When installing, pay attention to the large cut surface of the connecting rod (with the pairing mark) should face the lower window of the body on the same side. Finally, the genset piston is pressed by hand, so that the inner circle of the connecting rod big head bearing and the connecting rod journal fit.



5. Rotate the crankshaft, turn the crank of the piston connecting rod to the position where the screw of the connecting rod is easy to fit, install the paired connecting rod cover, and evenly tighten the connecting rod screw two to three times with a torque wrench until the specified torque is 255- 274N.m (26-28kgf.m) is shown in Figure 6. After the cylinders are assembled, check the connecting rod screws again, otherwise it will cause serious accidents.



6. According to the method shown in Figure 7, the interference gap between the connecting rod head and the crankshaft connecting rod journal opening is measured by a thousand-piece piece. If there is no gap or the crankshaft is not flexible, it may be caused by improper assembly or other reasons. Should be promptly checked and excluded. After the piston rods of each cylinder of the generator set are assembled, the crankshaft should be flexible and free from blockage.



Correct disassembly method of generator set piston connecting rod set


The piston connecting rod is made of eutectic silicon aluminum alloy and is one of the main moving parts in the Yuchai generator set. When disassembling and installing the piston rod of the generator set, it must be careful and correct, and change the structural difference of each model, otherwise it will cause adverse consequences. The following describes the correct disassembly method of the piston rod set of the Yuchai generator set.


1. Remove the cylinder head and scrape off the char and oil on the upper part of the cylinder liner.

2. Remove the lower window cover of the body, turn the crankshaft, and turn the piston to be removed to a position later than the top dead center.

3. When removing the connecting rod screw, pay attention to the connecting rod cover by hand to prevent it from falling into the oil sump and prevent the bearing from being damaged.

4. Pull the piston rod of the Yuchai generator set up from the lower end of the connecting rod, take out the piston connecting rod from the upper end of the cylinder sleeve along the center line of the cylinder, and strictly prevent the connecting rod from injuring the inner wall of the cylinder sleeve.

5. Heat the piston to 100-120 ° C in the oil and take out the piston pin. After removing the piston, attach the connecting rod bushing, connecting rod cover and connecting rod screw to the corresponding connecting rod body, and clean and check the wear of the mating surface or replace the damaged parts.


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