Piston and connecting rod from an automobile engine, showing the big end bearing at the bottom.

In a reciprocating engine, the crank pins are the bearing journals of the big end bearings, at the opposite ends of the connecting rods to the pistons. If the engine has a crankshaft, then the crank pins are the journals of the off-centre bearings of the crankshaft. In a beam engine the single crank pin is mounted on the flywheel; In a steam locomotive the crank pins are often mounted directly on the driving wheels. piston + connecting rod © scan, upload by MH 22:11, 2004 Aug 23 (UTC) This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... piston + connecting rod © scan, upload by MH 22:11, 2004 Aug 23 (UTC) This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... Components of a typical, four stroke cycle, DOHC piston engine. ... A bearing is a component used to reduce friction in a machine. ... In publishing, the term journal means a scientific journal or literary periodical devoted to a specific subject (such as a literary journal) In mining, a journal is a record describing the various strata passed through in sinking a shaft. ... piston + connecting rod In a reciprocating piston engine, the connecting rod or con rod connects the piston to the crank or crankshaft. ... piston + connecting rod In general, a piston is a sliding plug that fits closely inside the bore of a cylinder. ... Crankshaft Continental engine marine crankshafts, 1942 Crankshaft is also the name of a comic strip about an old, curmudgeonly bus driver. ... A beam engine is a design of stationary steam engine. ... Spoked flywheel A flywheel is a heavy rotating disk used as a repository for angular momentum. ... Great Western Railway No. ...

Big end bearings are commonly plain bearings, but less commonly may be roller bearings, see crankshaft. Crankshaft, babbitt metal, plain bearing shells A plain bearing is a bearing which carries load by sliding. ... A rolling-element bearing is a bearing which carries a load by placing round elements between the two pieces. ... Crankshaft Continental engine marine crankshafts, 1942 Crankshaft is also the name of a comic strip about an old, curmudgeonly bus driver. ...

In a multi-cylinder engine, a crank pin can serve one or many cylinders, for example: A piston and cylinder from a steam engine A cylinder in an internal combustion engine is the space within which a piston travels. ...

• In a straight engine each crank pin normally serves only one cylinder.

• In a V engine each crank pin serves two cylinders, one in each cylinder bank.

• In a radial engine each crank pin serves an entire row of cylinders.

Usually found in 4 and 6 cylinder configurations, the straight engine (often designed as inline engine) is an internal-combustion engine with all cylinders aligned in one row, with no or only minimal offset. ... A V engine is a common configuration for an internal combustion engine in which the pistons are aligned so that, if viewed along the line of the crankshaft, they appear to be in a V. Usually, two opposing pistons share one crank on the crankshaft. ... Radial engine of a biplane. ...

Big end design

There are three common configurations of big end bearing:

• If a crank pin serves only one cylinder, then the big end is a relatively simple design, accommodating only one connecting rod. This design is the cheapest to produce, and is used in:
  • All single cylinder engines.
  • Most straight engines.
  • All boxer engines.
  • Some V-twin engines.
• If a crank pin serves more than one cylinder, then the corresponding cylinders may have an offset, to simplify the design of the big end bearing. This design is used in:
  • Most V engines.
  • Multiple row radial engines.
• If more than one cylinder is served by a single crank pin but there is no offset, then some or all of the connecting rods must be forked at the big end. This design in theory provides better engine balance than designs with an offset, but at the cost of considerable extra complexity and cost in both design and manufacture, and either more weight or closer manufacturing tolerances or both to achieve the same strength and reliability. Any extra weight added to the big end itself also carries a penalty of adding vibration and reducing balance. As the number of cylinders grows, the effect of the offset on balance becomes less important, and forked connecting rods become less common. They are mainly used in:
  • Single-row radial engines.
  • Some V-twin engines, notably including motorcycle engines.

Usually found in 4 and 6 cylinder configurations, the straight engine (often designed as inline engine) is an internal-combustion engine with all cylinders aligned in one row, with no or only minimal offset. ... Diagram of the opposing pistons in a boxer engine A flat engine or boxer engine or horizontally opposed engine is a type of engine where the pistons lie horizontally opposed, with pairs of cylinders on the left and the right, as opposed to most modern engines where all pistons are... Honda 90° transverse V-twin A V-twin is a two cylinder internal combustion engine where the cylinders are arranged in a V configuration. ... A V engine is a common configuration for an internal combustion engine in which the pistons are aligned so that, if viewed along the line of the crankshaft, they appear to be in a V. Usually, two opposing pistons share one crank on the crankshaft. ... Radial engine of a biplane. ... Engine balance is the design, construction and tuning of an engine to run smoothly. ... Imme R 100,Germany, 1948/1949 A 125 cc motorcycle, the Italian-manufactured Cagiva Planet. ...

See also

• Connecting rod.

• Crankshaft.