A piston is a component of reciprocating engines, reciprocating pumps, gas compressors and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod. In a pump, the function is reversed and force is transferred from the crankshaft to the piston for the purpose of compressing or ejecting the fluid in the cylinder. In some engines, the piston also acts as a valve by covering and uncovering ports in the cylinder.
The rotary engine is an early type of internal combustion engine, usually designed with an odd number of cylinders per row in a radial configuration, in which the crankshaft remained stationary in operation, with the entire crankcase and its attached cylinders rotating around it as a unit. Its main application was in aviation, although it also saw use before its primary aviation role, in a few early motorcycles and automobiles.
Internal combustion piston engines are usually arranged so that the cylinders are in lines parallel to the crankshaft. Where they are in a single line, this is referred to as an inline or straight engine.
A V engine, or Vee engine is a common configuration for an internal combustion engine. The cylinders and pistons are aligned, in two separate planes or 'banks', so that they appear to be in a "V" when viewed along the axis of the crankshaft. The Vee configuration generally reduces the overall engine length, height and weight compared with an equivalent inline configuration.
Engine configuration is an engineering term for the layout of the major components of a reciprocating piston internal combustion engine. These components are the cylinders and crankshafts in particular but also, sometimes, the camshaft(s).
A W engine is a type of reciprocating engine arranged with its cylinders in a configuration in which the cylinder banks resemble the letter W, in the same way those of a V engine resemble the letter V.
A connecting rod is a rigid member which connects a piston to a crank or crankshaft in a reciprocating engine. Together with the crank, it forms a simple mechanism that converts reciprocating motion into rotating motion.
Engine balance refers to those factors in the design, production, engine tuning, maintenance and the operation of an engine that benefit from being balanced. Major considerations are:
The crossplane or cross-plane is a crankshaft design for piston engines with a 90° angle between the crank throws. The crossplane crankshaft is the most popular configuration used in V8 road cars.
In aviation, an inline engine is a reciprocating engine with banks of cylinders, one behind another, rather than rows of cylinders, with each bank having any number of cylinders, but rarely more than six.
Musgrave's non-dead-centre engine was a stationary steam engine of unusual design, intended to solve the problem of stopping on dead centre. It was designed in 1887 to serve as a marine engine. It used a pair of linked cylinders to prevent the engine from stopping in a position where no turning force can be applied. At least one engine is known to survive.
A monobloc or en bloc engine is an internal-combustion piston engine where some of the major components are formed, usually by casting, as a single integral unit, rather than being assembled later. This has the advantages of improving mechanical stiffness, and also improving the reliability of the sealing between them.
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.
A tunnel crankcase, tunnel crankshaft or disc-webbed crankshaft engine is a diesel engine where the crankshaft is designed so that the main bearings are enlarged in diameter, such that they are now larger than the crank webs. They thus form the largest diameter of any part of the crankshaft. Rather than a conventional crankcase that has webs across it to support the narrow bearings of a conventional crankcase, the crankcase now has a large tunnel through it, hence the name.
An undercut crankshaft is a form of crankshaft for piston engines, where the overall length of the crankshaft is shortened by overlapping the main bearings of the crankshaft with the big end bearings of the connecting rods.
An internal combustion engine (ICE) is a heat engine where the combustion of a fuel occurs with an oxidizer in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combustion engine, the expansion of the high-temperature and high-pressure gases produced by combustion applies direct force to some component of the engine. The force is applied typically to pistons, turbine blades, rotor or a nozzle. This force moves the component over a distance, transforming chemical energy into useful mechanical energy.
