What problems should be paid attention to in the disassembly and assembly of the toggle arm connecti

The function of the crank connecting rod mechanism is to provide a combustion place, and convert the expansion pressure of the gas acting on the top of the piston after fuel combustion into the torque of the crankshaft rotation, and continuously output power. The crank linkage mechanism is the main moving part of the engine to realize the working cycle and complete the energy conversion.

Before disassembly, the external dust should be removed, and the position and mark of the disassembled parts should be carefully observed and remembered.

Before the piston linkage set is withdrawn, the cement step in the upper part of the liner cover town must be scraped off to avoid damage to the piston and piston ring.

When taking the piston connecting rod set, it can be pushed out directly with a wooden stick.

After the piston connecting rod group is withdrawn, the connecting rod cover, tile and connecting rod bolts should be installed in situ immediately.

When disassembling the cylinder liner, a cylinder liner puller or a wooden rod should be used. The cylinder liner cannot be directly struck with a metal rod.

The removed piston ring should be placed in order. Cylinder gaskets and gaskets should be properly kept.

If you need to disassemble the flywheel, you should use the flywheel puller, and the two bolts that are screwed into and out of the puller should be alternated, and it is strictly forbidden to hit hard with a hammer. When removing the flywheel, in order to prevent the flywheel from falling loose and hurting people, do not rush to remove the bolt after it is loosened.

Remove the oil pan, oil strainer, float and oil pump, and remove the crankshaft pulley. Unscrew the fixing bolt of the F crankshaft timing toothed pulley, remove the crankshaft timing toothed pulley, unscrew the fixing bolt of the intermediate shaft toothed pulley, and remove the intermediate toothed pulley.

Disassemble the sealing flange, take out the intermediate shaft, disassemble the front oil seal and the front oil seal flange, disassemble the clutch pressure plate assembly and the flywheel assembly, in order to ensure its dynamic balance, the assembly mark should be made on the flywheel and the platform leaving the shell.

Before removing the piston connecting rod assembly, the axial clearance of the large end of the connecting rod should be checked, and the ultimate clearance value of the car is, and the connecting rod should be replaced if it is greater than this value. Remove the connecting rod bearing cover and pull the piston connecting rod set out of the cylinder.

After removing the piston connecting rod group, pay attention to the mark on the connecting rod and the connecting rod cap and piston should be consistent with the serial number of the cylinder, if there is no mark, it should be reprinted. Check the axial clearance of the crankshaft, the limit axial clearance is, if it exceeds this value, the thrust washer should be replaced, the bolt of the main bearing cover should be loosened in the prescribed order, the main bearing cover should be removed, and the crankshaft should be removed.

The crank connecting mechanism is the core mechanism of the engine to realize the conversion of thermal energy and mechanical energy, and its function is to convert the heat energy released by fuel combustion into mechanical energy that can drive the car through pistons, connecting rods, crankshafts, etc. The crank connecting rod mechanism is mainly composed of cylinder block, cylinder head, piston, connecting rod, crankshaft and flywheel and other parts, and the crank connecting rod mechanism is the core mechanism of the engine to realize the mutual conversion of thermal energy and mechanical energy, and its function is to convert the heat energy released by fuel combustion into mechanical energy that can drive the car through pistons, connecting rods, crankshafts, etc. The crank connecting rod mechanism is mainly composed of cylinder block, cylinder head, piston, connecting rod, crankshaft and flywheel and other parts.

1.Valve chamber cover 2Belt tensioner 3

Remove the belt 4Remove timing gears, sprockets, pulleys 5Remove the cylinder head assembly 6

Dismantle the flywheel 7The engine is turned upside down, the oil pan fixing bolt is removed, and the oil pan 8Remove the piston connecting rod set (note the order) 9

Remove the crankshaft (note the order).

The crank connecting rod mechanism is composed of three parts: the body group, the piston connecting rod group, and the crankshaft flywheel group.

Crank linkage mechanism.

1) Machine body group: cylinder block, cylinder gasket, cylinder head, crankcase, cylinder liner and oil pan.

2) Piston connecting rod group: piston, piston ring, piston pin, connecting rod.

3) Crankshaft flywheel group: crankshaft, flywheel, torsional shock absorber, balance shaft.

The body of the fuselage group is the skeleton that constitutes the engine, and is the installation foundation of the various mechanisms and systems of the engine, and all the main parts and accessories of the engine are installed inside and outside to bear various loads. Therefore, the body must have sufficient strength and rigidity.

Cylinder blockThe cylinder block is the assembly base of each mechanism and system of the engine, and is the most important component of the engine. There are water-cooled cylinder blocks and air-cooled cylinder blocks.

The water-cooled cylinder block is generally cast into one piece with the upper crankcase. The upper part of the cylinder block shoots out all the cylinders, and the cavities around the cylinders are connected to each other to form a water jacket. The lower part is the crankcase that supports the crankshaft.

There are three forms of cylinder block: in-line, V-shaped and horizontally opposed, and two types are commonly used in automobiles. The structure of the lower part of the cylinder block has three forms: general, gantry, and tunnel, and the air-cooled cylinder block and crankcase adopt a split structure, and the cylinder block and crankcase are cast separately and then assembled together. There are many heat sinks cast on the outer surface of the cylinder block and cylinder head to ensure full heat dissipation, the material of the cylinder block is generally gray cast iron, in order to improve the wear resistance of the cylinder, sometimes a small amount of alloying elements such as nickel, molybdenum, chromium, phosphorus, etc. are added to the cast iron.

However, in fact, except for the cylinder wall surface mated with the piston, the other parts do not have high requirements for wear resistance. For the sake of material economy, cylinder liners are widely embedded in the cylinder body to form the cylinder working surface. In this way, the cylinder liner can be made of alloy cast iron or alloy steel with good wear resistance to prolong the service life of the cylinder, while the cylinder block can be made of ordinary cast iron or aluminum alloy materials with low wear resistance.

There are two types of cylinder liners: dry and wet.

The outer surface of the dry cylinder liner is not in direct contact with cold water, and its wall thickness is generally 1 3mm. The outer surface of the cylinder liner and the inner surface of the assembled cylinder adopt an interference fit.

The outer surface of the wet cylinder liner is in direct contact with the cooling water, and the cooling effect is good. Its wall thickness is thicker than that of dry cylinder liners, generally 5 9mm.

The main function of the cylinder head of the cylinder head is to close the upper part of the cylinder, which, together with the top of the piston and the cylinder wall, constitutes the combustion chamber.

Generally, a cooling water jacket is cast in the cylinder head of a water-cooled engine, and the lower end face of the cylinder head is connected with the water jacket corresponding to the upper end of the cylinder block, and the circulation of water is used to cool the high-temperature parts such as the combustion chamber wall; The cylinder head of an air-cooled engine has a number of fins cast on it, which reduces the temperature of the combustion chamber by increasing the heat dissipation area.

The cylinder head of the engine should have intake and exhaust valve seats, duct holes and intake and exhaust channels, etc. The cylinder head of a gasoline engine should also have a spark plug hole, while the diesel engine should have a hole for installing an injector.

The cylinder gasket is equipped between the cylinder head and the cylinder block, and its function is to ensure the sealing between the cylinder head and the cylinder block, and prevent the combustion chamber from leaking and the water jacket from leaking.

The main function of the oil pan is to store the oil and close the crankcase. The oil pan is stressed very little and is generally thin.