Chinese FEDA is a distinguished supplier and manufacturer in the crankshaft industry. We specialize in the production of high-quality, durable, and high-performance crankshafts. With the utilization of advanced technology and superior materials, our products ensure optimum functionality and longevity. Our robust supply chain, combined with our customer-centric approach, enables us to deliver superior products and service worldwide. Trust in Chinese FEDA for all your crankshaft needs – where quality meets excellence.
Table of Contents
What is a Crankshaft？
A crankshaft, integral to an internal combustion engine, converts linear piston motion into rotation. It comprises two primary parts: main bearing journals, forming the rotation axis, and connecting rod journals, fastened to connecting rods attached to pistons. These components, interconnected by webs, ensure efficient engine operation, thus optimizing power output and fuel efficiency.
A crankshaft’s key features include the crank radius (or crank throw), which measures the distance between the main journal center and the crank pin center, determining piston travel range or stroke, which is twice the crank radius.
The crankshaft’s rear end, extending outside the crankcase, ends with a precision-machined flywheel flange. This is bolted to the flywheel, helping to smooth out piston firing pulsations and transmit rotation to the wheels via the transmission and final drive. In automatic vehicles, the crankshaft is bolted to the ring gear, transmitting drive into the automatic transmission, essentially powering various applications.
The crankshaft’s front end, or nose, extends beyond the crankcase, typically locked to a toothed gear that drives the valve train and a pulley powering accessories like the alternator and water pump via a drive belt.
These journals, clamped into the engine block, are the engine’s rotation axis. The journals are machined smooth, often hardened, and secured into saddles with replaceable bearing inserts. The bearings, softer than the journals, absorb contaminants to prevent crankshaft damage. Main bearing caps, bolted over the journals, are tightened to specific torque.
Connecting Rod Journals
Offset from the rotation axis, these journals are attached to the pistons’ connecting rods. Also known as crank pins or rod bearing journals, they receive pressurized oil via an angled oil passage from the main journal.
To prevent metal-to-metal contact and ensure efficient engine operation, both main and rod journals ride on a film of oil on the bearing surface. Oil galleries from the engine block lead to each crankshaft saddle, and a corresponding hole in the bearing shell allows oil to reach the journal.
Rod Journal Bearings and Lubrication
Rod journal bearings require lubrication through oil passageways within the crankshaft. Clearances between journals and bearings are crucial for maintaining oil pressure. During engine rebuilds, these clearances must be measured to prevent oil loss or metal-to-metal contact.
Counterweights and Balancing
Counterweights in crankshafts mitigate rotational forces and enable smooth operation and higher RPMs. Factory-balanced crankshafts undergo a process involving flywheel attachment, spinning, and adjustments using drilled holes and heavy metals to achieve balance.
Crankshaft Thrust Washers and Endplay
Thrust washers prevent excessive crankshaft lengthwise movement and maintain specified endplay. They may be integrated into main bearings or separate in some engines.
Main Oil Seals
Crankshaft ends are sealed with main oil seals (front and rear) to prevent oil leakage. A breach in these seals can cause rapid oil loss and necessitate costly labor for repair. Replacement is recommended during engine dismantling.
Crankshaft designs vary depending on engine layout, such as inline, V-shaped, or W engines. V6 crankshafts, for example, utilize a split-pin design for even firing intervals.
Crankshafts are typically reliable, but faults can occur due to worn journals or fatigue fractures. Worn journals necessitate grinding, and fatigue fractures are inspected via magnafluxing to prevent failures.
Crankshaft Modifications and Upgrades
Grinding and Oversized Bearings
Journals wear and may become rough, out-of-round, or tapered. To restore their surfaces, crankshaft grinding is performed. This process reduces journal diameters, requiring the installation of thicker, oversized bearings.
Stroker and Engine Capacity
A stroker crankshaft, featuring a larger crank radius, increases stroke length and engine capacity. Installing a stroker crankshaft necessitates shorter connecting rods to prevent excessive piston travel and potential cylinder damage. Stroker kits, including shorter connecting rods and pistons, are available for popular engines, such as the Mazda MX5 Miata 1.8L, converting it to a 2L engine at a cost of around $5,500.
Offset Grinding and Stroke Increase
Offset grinding, an alternative to stroker crankshafts, involves grinding rod journals to a smaller size and at an offset, moving the journal center away from the crankshaft centerline. This increases the crank radius and stroke. The achievable stroke increase depends on journal thickness.
Crankshaft Production Methods
Molding: Create a mold for the cast iron crankshaft.
Melting: Pour molten iron into the mold.
Cooling: Cool and remove the cast crankshaft.
Heating: Heat steel billet until red hot.
Pressing: Shape billet with high pressure.
Cooling: Cool the forged crankshaft.
Machining and Finishing
Machining: Smooth journals and bearing surfaces.
Drilling: Create oil passageways.
Hardening: Enhance journal durability.
Billet Crankshaft Production
Material Selection: Choose a solid block of high-grade material.
CNC Machining: Machine material into a custom crankshaft.
Inspection: Check quality and accuracy before use.