In a piston engine, the main bearings are the bearings which hold the crankshaft in place and allow it to rotate within the engine block.
Main bearings are usually plain bearings or journal bearings, held in place by the engine block and bearing caps. The number of main bearings per engine varies between engines, often in accordance with the forces produced by the operation of the engine.
The number of main bearings is primarily determined by the overall load factor and maximum engine speed.Increasing the number of bearings in an engine will generally increase the size and cost of the engine, but also reduces bending stress and deflection caused by the distance from the crank pins to the nearest bearings.
Most engines have at least two main bearings— one at each end of the crankshaft. Additional bearings may be located along the crankshaft, sometimes as many as one bearing per crank pin, as used on many modern diesel engines and petrol engines designed for high RPM.
Some small single-cylinder engines have only one main bearing,[ citation needed ] in which case it must withstand the bending moment created by the offset distance from the connecting rod to the main bearing.
When describing a crankshaft design, the number of main bearings is generally quoted, as the number of crank pins is determined by the cylinder layout. For example, the Toyota VZ V6 engine is described as having a "four bearing crankshaft" and the Jaguar XK6 straight-six engine has a "seven bearing crankshaft".
The lower half of the main bearings are typically held in place by 'bearing caps' which are secured to the engine block using bolts. The basic arrangement is for each bearing cap to have two bolts, but some engines may have four or six bolts per bearing cap (often referred to as "four-bolt mains" or "six-bolt mains" engines). The additional bolts result in increased strength, allowing the engine to withstand higher power output or RPM.
The first car engine to use four-bolt main bearings was the V12 Maybach Zeppelin of 1928, that used them on three of its eight main bearings.
The typical design for a six-bolt main bearing is four vertical bolts (two on each side of the crankshaft) from the bottom extending into the block and two lateral cross-bolts coming from the left and right side pan rails into the side of the main caps to provide additional lateral strength.
A crankshaft is a mechanical component used by in a piston engine to convert the reciprocating motion into rotational motion. The crankshaft is a rotating shaft containing one or more crankpins, that are driven by the pistons via the connecting rods.
The straight-six engine is an internal combustion engine, with six cylinders mounted in a straight line along the crankcase with all the pistons driving a common crankshaft.
The Ford 335 engine family was a group of engines built by the Ford Motor Company between 1969 and 1982. The "335" designation reflected Ford management's decision to produce an engine of that size with room for expansion during its development. This engine family began production in late 1969 with a 351 cu in (5.8 L) engine, commonly called the 351C. It later expanded to include a 400 cu in (6.6 L) engine which used a taller version of the engine block, commonly referred to as a tall deck engine block, a 351 cu in (5.8 L) tall deck variant, called the 351M, and a 302 cu in (4.9 L) engine which was exclusive to Australia.
A connecting rod, also called a 'con rod', is the part of a piston engine which connects the piston to the crankshaft. Together with the crank, the connecting rod converts the reciprocating motion of the piston into the rotation of the crankshaft. The connecting rod is required to transmit the compressive and tensile forces from the piston. In its most common form, in an internal combustion engine, it allows pivoting on the piston end and rotation on the shaft end.
The Ford small-block is a series of 90° overhead valve small block V8 automobile engines manufactured by the Ford Motor Company from July 1961 to December 2000.
The Slant-Six is the popular name for a Chrysler inline-6 internal combustion engine with a overhead valve reverse-flow cylinder head and cylinder bank inclined at a 30-degree angle from vertical. Introduced in 1959, it was known within Chrysler as the G-engine. It was a clean-sheet design that began production in 1959 at 170 cubic inches (2.8 L) and ended in 2000 at 225 cubic inches (3.7 L). It was a direct replacement for the flathead Chrysler straight six that the company started business with in 1925 until the old design was discontinued in the 1960s.
The Chrysler 1.8, 2.0, and 2.4 are inline-4 engines designed originally for the Dodge and Plymouth Neon compact car. These engines were loosely based on their predecessors, the Chrysler 2.2 & 2.5 engine, sharing the same 87.5 mm (3.44 in) bore. The engine was developed by Chrysler with input from the Chrysler-Lamborghini team that developed the Chrysler/Lamborghini Formula 1 V12 engine in the early 1990s.
The Chevrolet small-block engine is a series of gasoline-powered, V-8 automobile engines, produced by the Chevrolet division of General Motors between 1954 and 2003, using the same basic engine block. Referred to as a "small-block" for its size relative to the physically much larger Chevrolet big-block engines, the small block family spanned from 262 cu in (4.3 L) to 400 cu in (6.6 L) in displacement. Engineer Ed Cole is credited with leading the design for this engine. The engine block and cylinder heads were cast at Saginaw Metal Casting Operations in Saginaw, Michigan.
The KA engines were a series of four-stroke inline-four gasoline piston engines manufactured by Nissan, which were offered in 2.0 and 2.4 L. The engines blocks were made of cast-iron, while the cylinder heads were made of aluminum.
The powerplant used in Saturn S-Series automobiles was a straight-4 aluminum piston engine produced by Saturn, a subsidiary of General Motors. The engine was only used in the Saturn S-series line of vehicles from 1991 through 2002. It was available in chain-driven SOHC or DOHC variants.
The Toyota VZ engine family is a series of V6 gasoline piston engines ranging from 2.0 to 3.4 L in displacement and both SOHC and DOHC configurations, and was Toyota's first V6 engine. The family introduced many changes for Toyota, including various EFI, ECU, and engine improvements from generation to generation. The VZ was Toyota's response to the Nissan VG engine. The low angle DOHC cylinder heads excel in low-mid torque and power, making the VZ well-suited for various uses in cars, trucks, and SUVs. The blocks are all strongly made using cast iron with large interconnected main bearing cradles and two bolt main bearing caps. Forged steel crankshafts, and cast iron main bearing support girdles became standard with the 3VZ-FE. Piston and ring construction are typical parts, with rods varying between large and very large for stock V6 production engines.
A crankpin, also known as a rod bearing journal, is a mechanical device in an engine which connects the crankshaft to the connecting rod for each cylinder. It has a cylindrical surface, to allow the crankpin to rotate relative to the "big end" of the connecting rod.
The Lotus-Ford Twin Cam is an inline-four petrol engine developed by Lotus for the 1962 Lotus Elan. A few early examples displaced 1.5 litres, but the majority were 1.55-litre (1557ml) engines. It used a Ford 116E iron cylinder block and a new aluminium cylinder head with dual overhead camshafts. The Twin Cam was used in a variety of vehicles until Lotus stopped production in 1973. It was succeeded by the Lotus 907 engine.
A long-bolt or through-bolt engine is an internal combustion piston engine where, following usual practice, the cylinder head is held down by bolts or studs. Conventionally the cylinder head is bolted to the cylinder block and the crankshaft main bearings are in turn bolted to the crankcase by separate bolts. In the long-bolt engine however, a single set of long bolts is used, spanning from the cylinder head right through to the crankshaft bearing caps.
High-speed steam engines were one of the final developments of the stationary steam engine. They ran at a high speed, of several hundred rpm, which was needed by tasks such as electricity generation.
The Mercedes-Benz OM 138 is a diesel engine manufactured by Daimler-Benz. In total, 5,719 units were produced between 1935 and 1940. It was the first diesel engine especially developed and made for a passenger car. The first vehicle powered by the OM 138 was the Mercedes-Benz W 138. The light Mercedes-Benz trucks L 1100 and L 1500 as well as the bus O 1500 were also offered with the OM 138 as an alternative to the standard Otto engine.
The De Dion-Bouton 130 hp aircraft engine, also referred to as De Dion-Bouton 12B, was a twelve-cylinder, air cooled vee aircraft engine that has been built by De Dion-Bouton.
The Volkswagen-Audi V8 engine family is a series of mechanically similar, gasoline-powered and diesel-powered, V-8, internal combustion piston engines, developed and produced by the Volkswagen Group, in partnership with Audi, since 1988. They have been used in various Volkswagen Group models, and by numerous Volkswagen-owned companies. The first spark-ignition gasoline V-8 engine configuration was used in the 1988 Audi V8 model; and the first compression-ignition diesel V8 engine configuration was used in the 1999 Audi A8 3.3 TDI Quattro. The V8 gasoline and diesel engines have been used in most Audi, Volkswagen, Porsche, Bentley, and Lamborghini models ever since. The larger-displacement diesel V8 engine configuration has also been used in various Scania commercial vehicles; such as in trucks, buses, and marine (boat) applications.