The structure of the crankshaft

The crankshaft is a core component in the engine, and its structure is complex and functionally critical. Here are the main components of the crankshaft and its functions:

‌Spindle Neck

The main shaft journal is the support part of the crankshaft, which is installed in the main bearing seat of the crankcase through the main bearing, and the support crankshaft rotates about its center line. The number and arrangement of the main shaft journal depends on the number of cylinders of the engine and the support method of the crankshaft (full support or non-full support).

‌Connecting rod neck

The connecting rod journal is used to connect the connecting rod head, converting the reciprocating motion of the piston into the rotational motion of the crankshaft. The number of connecting rod journals of inline engines is equal to the number of cylinders, while the number of connecting rod journals of V-type engines is half of the number of cylinders. The connecting rod journal is usually made hollow to reduce the mass and centrifugal force of the rotating part.

‌Crank arm

The crank arm connects the main journal and the connecting rod journal. Some engines also have balance blocks on the crank arm to balance the unbalanced centrifugal force and centrifugal moment of the crank shaft to reduce vibration.

‌Balance Block

The balance block is installed on the crank arm to balance the centrifugal force and centrifugal moment generated when the engine rotates, and sometimes it can balance part of the reciprocating inertia force to ensure stable rotation of the crankshaft.

Front and rear axle ends

Front axle end: Usually equipped with timing gears, pulleys, torsional shock absorbers and starter claws. The front end is also equipped with an oil-swinging pan and an oil seal to prevent oil leakage.

Rear axle end: used to install the flywheel and output power through the flywheel. The rear end is also equipped with an oil barrier flange and oil return thread to prevent the engine oil from leaking backwards.

Quguai

A connecting rod journal and its crank arms at both ends and two adjacent main journals form a curved crank. The number of curved turns is related to the number of cylinders of the engine. The number of curved turns of the inline engine is equal to the number of cylinders, and the number of curved turns of the V-type engine is half of the number of cylinders.

Materials and Process

Crankshafts are usually made of high-strength materials such as ductile iron or alloy steel and are precision-processed and heat-treated to improve their strength, stiffness and wear resistance.

‌Summary‌: The structural design of the crankshaft is designed to convert the reciprocating movement of the piston into a rotating movement, while bearing complex forces and torques to ensure the smooth operation of the engine. Its structure includes key components such as main shaft journal, connecting rod journal, crank arm, balance block, front axle end and rear axle end, and its performance is ensured through precision materials and processes.