Полное руководство: Поршневой шатун FAW в сборе для трактора CA4251P66K24T1A3E5

Welcome to the complete technical guide for the Поршневой шатун FAW в сборе, the heart of the internal combustion engine for the FAW Jiefang CA4251P66K24T1A3E5 6×4 дизельный полуприцеп тягач. This is the rotating and reciprocating assembly that converts combustion pressure into torque.

This entire rotating and reciprocating group is what defines the engine’s power and durability. The Поршневой шатун FAW в сборе is the complete set of all six matched piston and rod groups. A failure in any part of this system is critical.

This guide is an essential resource for professional engine rebuilders, machine shops, and fleet technicians. Мы разберем всю Поршневой шатун FAW в сборе from top to bottom, breaking down each of the six assemblies into their smallest serviceable units—from the piston rings and pins to the connecting rod bearing shells.

Основной компонент: Поршень (1004011-81Д)

The ‘Piston’ (1004011-81Д) это “crown” принадлежащий Поршневой шатун FAW в сборе. The parts list calls for six, one for each cylinder. This component is responsible for forming the lower half of the combustion chamber and harnessing the immense force of the diesel power stroke. It is cast from a high-strength, low-expansion hypereutectic aluminum alloy, designed to be both lightweight to reduce reciprocating mass and incredibly strong to resist the high temperatures and pressures.

The design of the piston face is critical. In a direct-injection diesel, the top of the piston features a complex “bowl.” The shape of this bowl is not arbitrary; it is precisely engineered to induce “swirl” as the air is compressed, ensuring the injected fuel mixes perfectly with the hot, compressed air for a complete and efficient burn. This material and design choice is critical for the longevity of the Поршневой шатун FAW в сборе.

To survive in this environment, these pistons feature an internal “cooling gallery,” a hollow channel cast into the piston crown, just behind the ring lands. Oil jets in the engine block spray a continuous stream of cool oil into this gallery. This oil absorbs the intense heat from the piston crown and rings, then drains back to the sump. This cooling action is essential for preventing the piston from overheating, expanding, and seizing in the cylinder, and it is a key feature of the modern Поршневой шатун FAW в сборе. A failure in this cooling circuit will quickly destroy the piston, making the integrity of the entire Поршневой шатун FAW в сборе compromised.

The Piston Ring Pack: Sealing Combustion

The piston rings are arguably the most critical sealing components within the entire Поршневой шатун FAW в сборе. This parts list specifies a three-ring pack for each of the six pistons:

• ‘First Compression Ring’ (1004012-81Д) – 6 единицы
• ‘Second Compression Ring’ (1004013-81Д) – 6 единицы
• ‘I-profile Steel Oil Ring Assembly’ (1004030-81Д) – 6 единицы

The ‘First Compression Ring’ is the top ring. Its sole purpose is to seal the cylinder, containing the white-hot, high-pressure combustion gases (which can exceed 2500 пси) within the combustion chamber. It is precision-machined from high-strength ductile iron or steel and often has a “barrel” face and a corrosion-resistant coating (like plasma-moly) to survive the extreme heat and pressure. This is the primary seal for the Поршневой шатун FAW в сборе.

The ‘Second Compression Ring’ has a dual role. It acts as a secondary combustion seal, catching any gases that “blow by” the top ring. Однако, its primary function is oil control. It is often a “taper-faced” или “scraper” дизайн, which effectively scrapes the majority of the lubricating oil off the cylinder wall on the piston’s downstroke, preventing it from being drawn up into the combustion chamber and burned. A worn second ring on the Поршневой шатун FAW в сборе is a very common cause of excessive oil consumption and blue smoke.

The ‘I-profile Steel Oil Ring Assembly’ is the bottom ring and the final line of defense for oil control. This is a modern, complex, three-piece assembly. It consists of two very thin, flexible steel “rails” that ride against the cylinder wall, separated by a central “expander-spacer.” The expander pushes the two rails outward with a precise amount of tension. This design offers superior “conformability” to the cylinder wall, scraping off the final film of oil with minimal friction. This part of the Поршневой шатун FAW в сборе is key to the engine’s long-term efficiency and emissions control.

The health of this ring pack determines the health of the engine. A worn ring pack on any of the six Поршневой шатун FAW в сборе units will result in low compression (hard starting, низкая мощность), high oil consumption, and excessive crankcase “blow-by.” A full rebuild of the Поршневой шатун FAW в сборе always includes a new, complete set of piston rings.

Связующий шаг (1004020A81D): Forging Strength

The ‘Connecting Rod Assembly’ (1004020A81D) это “рука” that connects the piston (via the piston pin) to the crankshaft. It is the namesake component of the Поршневой шатун FAW в сборе. This component must withstand incredible, reversing stresses: it is violently pushed down by the combustion stroke and just as violently pulled back up by the exhaust stroke.

To handle this, these rods are not cast; they are drop-forged from a single billet of high-strength steel. The forging process aligns the steel’s grain structure, giving it immense fatigue resistance. They are typically an “I-beam” cross-section, which provides the maximum possible strength and rigidity for the lowest weight. This is the standard for any heavy-duty Поршневой шатун FAW в сборе.

A key feature of this modern ‘Connecting Rod Assembly’ is its “fracture-split” big-end cap. The rod and its bearing cap are forged as a single piece. The main bolt holes are drilled and tapped, and then the cap is literally “треснутый” или “snapped” off the rod using a hydraulic press. This creates a perfectly matched, irregular, interlocking surface that is far stronger and more resistant to shifting under load than any machined flat surface could ever be. This strength is vital to the entire Поршневой шатун FAW в сборе.

Because they are a matched set, a connecting rod cap can *never* be interchanged with another rod, not even one from the same engine. The entire `Connecting Rod Assembly` is a balanced and matched unit, and its integrity is fundamental to the proper operation of the Поршневой шатун FAW в сборе.

Поршневая булавка (1004018-81Д) and Circlips (1004019-81Д)

The ‘Piston Pin’ (1004018-81Д), часто называемый “wrist pin,” is the component that forms the pivot between the piston and the “small end” of the connecting rod. It’s a hollow, thick-walled tube made of extremely hard, case-hardened steel, polished to a mirror finish. This pin links the two main parts of the Поршневой шатун FAW в сборе.

This system uses a “full-floating” дизайн. This means the pin is not pressed into either the rod or the piston. It is free to rotate, или “float,” in both the connecting rod’s small-end bushing and the piston’s pin boss. This design allows for better load distribution and reduced wear, and it is superior for the longevity of the Поршневой шатун FAW в сборе.

To prevent this floating pin from sliding sideways and gouging the cylinder wall, it is secured by two ‘Piston Pin Circlips’ (1004019-81Д). The parts list calls for 12 clips, which is two per piston (one on each side). These small spring-steel clips snap into grooves inside the piston’s pin boss. These small clips are a critical, non-reusable part of the Поршневой шатун FAW в сборе.

Connecting Rod Bearings (1004026-81Д / 1004028-81Д)

The ‘Connecting Rod Upper Bearing Shell’ (1004026-81Д) and ‘Connecting Rod Lower Bearing Shell’ (1004028-81Д) are the final components of the Поршневой шатун FAW в сборе. These two “half-shells” come together to form the “big end” bearing that rides on the crankshaft’s rod journal.

They are not identical. The “upper” оболочка, which sits in the connecting rod itself, is the one that endures the colossal force of the combustion stroke. Как таковой, it is often made of a more robust, harder material than the lower shell, which only carries the “inertial” load of the Поршневой шатун FAW в сборе on the upstroke.

These are precision, multi-layer components with a steel backing for strength and a thin, мягкий, “babbitt” (tin-alloy) or similar overlay. The crankshaft does not ride on the metal; it rides on a hydrodynamic film of oil, just thousandths of an inch thick. This oil is supplied by a hole in the crankshaft. A worn bearing in the Поршневой шатун FAW в сборе will cause this oil clearance to become too large, resulting in a “rod knock” sound.

Measuring the oil clearance of the Поршневой шатун FAW в сборе with Plastigage during assembly is one of the most critical steps in an engine rebuild. The precision of these shells, along with the rod and cap, is what ensures a quiet, long-lasting engine.

FAW Piston Connecting Rod Assembly Parts List

В следующей таблице представлена ​​полная, detailed breakdown of all components identified in the ‘Piston Connecting Rod Assembly’ схема трактора FAW CA4251P66K24T1A3E5. Использование оригинальных запчастей для вашего Поршневой шатун FAW в сборе is crucial for ensuring proper balance, fit, and engine longevity.

Технические характеристики и контекст сборки

Технические характеристики Поршневой шатун FAW в сборе are defined by its matched, balanced design for a 6-cylinder diesel engine. Each Поршневой шатун FAW в сборе is a precision-matched set.