1D Auto Parts sells various auto engine parts at retail or wholesale prices, such as engine pistons, cylinder liners, valves, cylinder gaskets and piston rings, and provides a 12 month warranty. The country of origin is Taiwan, China.

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A piston acts as a movable end of the combustion chamber. The conversion of thermal energy into mechanical work and vice versa is facilitated by a piston. Pistons are hence an essential part of heat engines. Due to its good and lightweight thermal conductivity, cast aluminum alloy is frequently used to make pistons.

Some of the main features of the piston include the piston head, piston pin bore, piston pin, skirt, ring grooves, ring lands, and piston rings.

Piston's head

This is the top surface of the piston and during typical engine operation, it is subjected to extreme stresses and heat.

Piston pin bore

It is a through hole that is located in the piston's side and is parallel to the piston's direction of travel. The connecting rod's tiny end is joined to the piston via a hollow shaft called a piston pin. The part of a piston closest to the crankshaft, called the skirt, aids in keeping the piston straight as it passes through the cylinder bore. For the purpose of reducing piston mass and allowing room for the revolving crankshaft counterweights, certain skirts have profiles carved into them.


A piston ring is held in place by a recessed region called a ring groove that surrounds the piston's outer edge. The two parallel sides of the ring groove known as the "ring lands" serve as the piston ring's sealing surface. An inflatable split ring known as a piston ring is used to provide a seal between the piston and the cylinder wall. Cast iron is frequently used to make piston rings. Under the heat, stress, and other dynamic forces, cast iron maintains the integrity of its initial shape. Piston rings return oil to the crankcase, transfer heat from the piston to the cylinder wall, and seal the combustion chamber. Engine design and cylinder material have an impact on the size and layout of the piston rings.

Piston Rings

The compression ring, wiper ring, and oil ring are three types of piston rings frequently utilized in small engines. The piston ring in the ring groove closest to the piston head is known as a compression ring. The compression ring prevents any leaks from occurring in the combustion chamber. The piston is forced toward the crankshaft when the air-fuel combination ignites due to pressure from the combustion gases being applied to the piston head. The pressurized gases pass into the groove of the piston ring after passing through the space between the cylinder wall and the piston. The piston ring is forced against the cylinder wall by the pressure of the combustion gas to create a seal. The piston ring pressure is roughly inversely proportional to the pressure of the combustion gas.

The piston ring with a tapered face that is situated in the ring groove between the compression ring and the oil ring is known as a wiper ring. The wiper ring is employed to better seal the combustion chamber and to remove extra oil from the cylinder wall. The wiper ring stops combustion gases from passing by the compression ring.


The piston ring in the ring groove nearest to the crankcase is known as an oil ring. During piston movement, the oil ring is utilized to remove extra oil from the cylinder wall. Through ring apertures, extra oil is returned to the engine block's oil reservoir. Due to the fact that lubrication is provided by combining oil and gasoline, two-stroke cycle engines do not require oil rings. The combustion chamber is sealed by piston rings, which also transfer heat to the cylinder wall and manage oil consumption. The combustion chamber is sealed by a piston ring under both natural and applied pressure. Based on the layout and physical characteristics of the material employed, inherent pressure is the internal spring force that causes a piston ring to expand. To reduce the diameter of a piston ring due to inherent pressure, considerable power is needed. The space between the free or uncompressed piston rings determines the inherent pressure. The free piston ring gap is the separation between a piston ring's two ends when it is not squeezed. Generally speaking, the more force the piston ring exerts when squeezed in the cylinder bore, the larger the free piston ring gap.

For an effective seal, a piston ring has to offer a consistent and positive radial fit between the cylinder wall and its running surface. The piston ring's intrinsic pressure is what creates the radial fit. Additionally, the piston ring needs to keep the piston ring lands sealed.

A piston ring closes the combustion chamber with applied pressure in addition to the pressure that is already there. The piston ring expands as a result of applied pressure, which is the pressure that combustion gases apply to it. A chamfered edge opposing the running surface can be seen on some piston rings. When the combustion gas pressures are not there, this chamfered edge causes the piston ring to rotate.

Cylinder wall contact pressure is another aspect of piston ring design to take into account. This pressure is typically influenced by the combustion gas exposure, free piston ring gap, and flexibility of the piston ring material. Cast iron is the only material utilized for piston rings in Briggs & Stratton engines. Cast iron adapts to the cylinder wall with ease. Cast iron may also readily have additional materials coated on it to increase its longevity. Cast iron is readily deformed, thus caution must be used while handling piston rings. The compression ring, wiper ring, and oil ring are three types of piston rings frequently utilized in small engines.

Compression Ring

As the top or ring closest to the combustion gases, the compression ring experiences the most chemical corrosion and operates at the highest temperature. 70% of the heat from the combustion chamber is transferred from the piston to the cylinder wall through the compression ring. Compression rings on Briggs & Stratton engines are typically barrel- or taper-faced. A piston ring with a running surface that has a roughly 1° taper angle is known as a taper-faced compression ring. For the purpose of preventing any extra oil from entering the combustion chamber, this taper offers a gentle wiping motion.

A piston ring with a barrel-faced compression ring has a curved running surface to consistently lubricate the piston ring and cylinder wall. Additionally, it creates a wedge effect to improve oil distribution throughout the whole piston stroke. The curved running surface also lessened the chance of an oil film breakdown brought on by too much pressure at the ring edge or too much piston tilt during operation.

Wiper Ring

The piston's next ring from the cylinder head is the wiper ring, also known as the scraper ring, Napier ring, or backup compression ring. The compression ring's running surface is lubricated by an oil layer that has a constant thickness thanks to the wiper ring. In Briggs & Stratton engines, wiper rings typically feature a face with a taper angle. As the piston travels toward the crankshaft, the tapered angle, which is positioned toward the oil reservoir, wipes the surface. The oil ring and the taper angle make contact, directing any extra oil on the cylinder wall back to the oil reservoir. Excessive oil consumption happens when a wiper ring is placed improperly, with the tapered angle closest to the compression ring. Excess oil is wiped toward the combustion chamber by the wiper ring, which is the source of this.

Oil Ring

Two thin rails or running surfaces make up an oil ring. The radial center of the ring has holes or slots that let the flow of extra oil back into the oil reservoir. All of these characteristics are often included in one-piece oil rings. A spring expander is used by certain on-piece oil rings to exert more radial pressure on the piston ring. This raises the pressure exerted on the cylinder wall's unit (measured amount of force and running surface area). Of the three piston rings, the oil ring has the highest inherent pressure. In certain Briggs & Stratton engines, an expander, two rails, and a three-piece oil ring are used. On each side of the expander are the oil rings. The expander often has several holes or windows that allow oil to be returned to the groove of the piston ring. Inherent piston ring pressure, expander pressure, and the high unit pressure made possible by the narrow running surface of the thin rails are all used by the oil ring. Since the piston serves as the combustion chamber's moveable end, it must tolerate pressure changes, temperature stress, and mechanical strain. The longevity and performance of an engine are influenced by the material and design of the pistons. Aluminum alloy is typically used to die-cast or gravity-cast pistons. Cast aluminum alloy is inexpensive to produce, lightweight, and has outstanding structural integrity. Due to aluminum's small weight, less mass and force are needed to start and maintain the piston's acceleration. As a result, the piston is able to use more of the power generated by combustion to drive the application. Piston designs are built on advantages and trade-offs to get the best possible engine performance.



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