∮20×∮8×49 (sandblasted)

The piston pin is a cylindrical pin fitted into the piston skirt. Its middle section passes through the small end bore of the connecting rod, serving to connect the piston and the connecting rod. Its function is to transmit the gas‑force acting on the piston to the connecting rod, or to enable the connecting‑rod small end to drive the piston in motion. To reduce weight, piston pins are typically manufactured from high‑quality alloy steel and are made hollow.

∮20×∮8×49

Under high-temperature conditions, the piston pin is subjected to significant cyclic impact loads. Moreover, because the piston pin swings only through a small angle within the pin bore, it is difficult to form a stable lubricating oil film, resulting in poor lubrication. Consequently, the piston pin must possess adequate stiffness, strength, and wear resistance. Its mass should be kept as low as possible, and the fit between the pin and the pin bore should provide an appropriate clearance while ensuring excellent surface quality. In general, the stiffness of the piston pin is particularly critical; if the pin bends or deforms, it may lead to damage to the piston pin seat.

∮23.1×39 (Type 70)

The crank pin consists of a dowel and a countersunk screw. Its distinguishing feature is that the dowel comprises two wedge-shaped elements, 1 and 2; the inner surfaces of these two wedges are inclined planes, while the outer surface of wedge 2 is a flat plane that closely mates with the bicycle’s bottom bracket spindle. The outer surface of wedge 1 is an arcuate surface that fits snugly against the arcuate surface of the crank pin hole in the bicycle frame. At each end of wedges 1 and 2, a countersunk screw 3 is fastened, so that under the action of these two screws, the inclined surfaces of the two wedges come into close contact and slide axially until the crank is locked in place.

∮25.1×39 (Type 100)

In small- and medium-displacement motorcycle engines, a split-type crankshaft–connecting‑rod assembly is typically formed by press‑fitting the left and right crankpins to the crankshaft journal; the connecting‑rod big end employs a needle roller bearing with a cage. Using a modular crank design eliminates the need for large forging equipment during blank production and facilitates various heat‑treatment and machining operations, thereby effectively shortening the production cycle.

∮25.1×39 single-sided circular marking

The piston pin is a cylindrical pin fitted into the piston skirt. Its middle section passes through the small end bore of the connecting rod, serving to connect the piston and the connecting rod. Its function is to transmit the gas‑force acting on the piston to the connecting rod, or to enable the connecting‑rod small end to drive the piston in motion. To reduce weight, piston pins are typically manufactured from high‑quality alloy steel and are made hollow.

∮26×42

Under high-temperature conditions, the piston pin is subjected to significant cyclic impact loads. Moreover, because the piston pin swings only through a small angle within the pin bore, it is difficult to form a stable lubricating oil film, resulting in poor lubrication. Consequently, the piston pin must possess adequate stiffness, strength, and wear resistance. Its mass should be kept as low as possible, and the fit between the pin and the pin bore should provide an appropriate clearance while ensuring excellent surface quality. In general, the stiffness of the piston pin is particularly critical; if the pin bends or deforms, it may lead to damage to the piston pin seat.

∮29×46 single oil hole

The crank pin consists of a dowel and a countersunk screw. Its distinguishing feature is that the dowel comprises two wedge-shaped elements, 1 and 2; the inner surfaces of these two wedges are inclined planes, while the outer surface of wedge 2 is a flat plane that closely mates with the bicycle’s bottom bracket spindle. The outer surface of wedge 1 is an arcuate surface that fits snugly against the arcuate surface of the crank pin hole in the bicycle frame. At each end of wedges 1 and 2, a countersunk screw 3 is fastened, so that under the action of these two screws, the inclined surfaces of the two wedges come into close contact and slide axially until the crank is locked in place.

∮30×54 (Type 125)

In small- and medium-displacement motorcycle engines, a split-type crankshaft–connecting‑rod assembly is typically formed by press‑fitting the left and right crankpins to the crankshaft journal; the connecting‑rod big end employs a needle roller bearing with a cage. Using a modular crank design eliminates the need for large forging equipment during blank production and facilitates various heat‑treatment and machining operations, thereby effectively shortening the production cycle.

∮32×54 double oil holes

The crankshaft is a critical component of the engine. It receives forces transmitted from the connecting rods and converts them into torque, which it delivers to drive the engine’s auxiliary components. Subjected to the combined effects of centrifugal forces from rotating masses, cyclic gas‑induced inertial forces, and reciprocating inertial forces, the crankshaft experiences bending and torsional loads.

∮32×59 blind hole

The function of crankshaft counterweights (also called balancing weights) is to balance the rotational centrifugal forces and their moments; in some cases, they can also counteract the reciprocating inertial forces and their moments. When these forces and moments are themselves balanced, the counterweights can further reduce the load on the main bearings. The number, size, and placement of the counterweights must be determined based on factors such as the engine’s cylinder count, cylinder arrangement, and crankshaft geometry.
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Our company was established in 2002 and primarily manufactures and sells a wide range of motorcycle crankpins and automotive piston pins. We have over ten years of specialized experience in producing motorcycle crankpins.

A long history of production

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A full range of products is available.

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The factory is equipped with advanced machinery.

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Strong technical capabilities

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