FACTOID # 5: Minnesota and Connecticut are both in the top 5 in saving money and total tax burden per capita.
 
 Home   Encyclopedia   Statistics   States A-Z   Flags   Maps   FAQ   About 
 
WHAT'S NEW
RELATED ARTICLES
People who viewed "Camshaft" also viewed:
 

SEARCH ALL

FACTS & STATISTICS    Advanced view

Search encyclopedia, statistics and forums:

 

 

(* = Graphable)

 

 


Encyclopedia > Camshaft
Computer animation of a camshaft

The camshaft is an apparatus often used in piston engines to operate poppet valves. It consists of a cylindrical rod running the length of the cylinder bank with a number of oblong lobes or cams protruding from it, one for each valve. The cams force the valves open by pressing on the valve, or on some intermediate mechanism, as they rotate. Camshaft is the name of a fictional character in the Transformers universe. ... Image File history File links Nockenwelle_ani. ... Image File history File links Nockenwelle_ani. ... Components of a typical, four stroke cycle, DOHC piston engine. ... A poppet valve is a valve consisting of a hole, usually round or oval, and a tapered plug, usually a disk shape on the end of a shaft also called a valve stem. ... Piston engines are typically arranged with their pistons in rows, moving inside individual cylinders. ... For other uses, see CAM. Animation showing rotating cams and cam followers producing reciprocating motion. ...

Contents

History

The first known cam and camshaft were invented in Iraq (Mesopotamia), described by Al-Jazari in 1206.[1] The cam and camshaft later appeared in European mechanisms from at least the 14th century,[2] or possibly earlier.[3] Mesopotamia was a cradle of civilization geographically located between the Tigris and Euphrates rivers, largely corresponding to modern-day Iraq. ... Diagram from The Book of Knowledge of Ingenious Mechanical Devices by al-Jazari. ...


Timing

A camshaft
A camshaft

The relationship between the rotation of the camshaft and the rotation of the crankshaft is of critical importance. Since the valves control the flow of air/fuel mixture intake and exhaust gases, they must be opened and closed at the appropriate time during the stroke of the piston. For this reason, the camshaft is connected to the crankshaft either directly, via a gear mechanism, or indirectly via a belt or chain called a timing belt or timing chain. In some designs the camshaft also drives the distributor and the oil and fuel pumps. Also on early fuel injection systems, cams on the camshaft would operate the fuel injectors. Image File history File links Download high-resolution version (123x640, 13 KB) This picture may have usage restrictions -- Nockenwelle/Camshaft Source: Own picture File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Camshaft ... Image File history File links Download high-resolution version (123x640, 13 KB) This picture may have usage restrictions -- Nockenwelle/Camshaft Source: Own picture File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Camshaft ... Crankshaft (red), pistons (gray) in their cylinders (blue), and flywheel (black) Continental engine marine crankshafts, 1942 Components of a typical, four stroke cycle, DOHC piston engine. ... Crankshaft (red), pistons (gray) in their cylinders (blue), and flywheel (black) Continental engine marine crankshafts, 1942 Components of a typical, four stroke cycle, DOHC piston engine. ... For other uses, see Gear (disambiguation). ... Timing belt A timing belt, timing chain or cam belt is a part of an internal combustion engine that controls the timing of the engines valves. ... Roller chain and sprocket Roller chain or bush roller chain is the type of chain most commonly used for transmission of mechanical power on bicycles, motorcycles, and in industrial and agricultural machinery. ... Distributor cap. ... A lubricant (colloquially, lube) is a substance (often a liquid) introduced between two moving surfaces to reduce the friction and wear between them. ... mechanical fuel pump, fitted to cylinder head Electric fuel pump Petro-Canada Fuel Pump used to transfer fuel at a gas station. ... // Fuel injection is a means of metering fuel into an internal combustion engine. ...


In a two-stroke engine that uses a camshaft, each valve is opened once for each rotation of the crankshaft; in these engines, the camshaft rotates at the same rate as the crankshaft. In a four-stroke engine, the valves are opened only half as often; thus, two full rotations of the crankshaft occur for each rotation of the camshaft. The two-stroke cycle of an internal combustion engine differs from the more common four-stroke cycle by completing the same four processes (intake, compression, power, exhaust) in only two strokes of the piston rather than four. ... Today Internal combustion engines in cars, trucks, motorcycles, construction machinery and many others, most commonly use a four-stroke cycle. ...


Duration

Duration can often be confusing because manufacturers may select any lift point to advertise a camshaft's duration and sometimes will manipulate these numbers. The power and idle charateristics of a camshaft rated at .006" will be much different than one rated the same at .002". Whenever duration is quoted, be sure to note the lift at which it is given.


Many performance engine builders have learned to gauge a race profile's aggressiveness by looking at the duration at .020", .050" and .200". The .020" number determines how responsive the motor will be and how much low end torque the motor will make. The .050" number is used to estimate where peak power will occur, and the .200" number gives them an estimate of the power potential. For other senses of this word, see torque (disambiguation). ...


In general, duration determines how many crankshaft degrees a camshaft maintains more than a given tappet lift. Crankshaft (red), pistons (gray) in their cylinders (blue), and flywheel (black) Continental engine marine crankshafts, 1942 Components of a typical, four stroke cycle, DOHC piston engine. ... In mechanical engineering, a tappet is a projection which imparts a linear motion to some other component within an assembly. ...


Camshaft position

Depending on the location of the camshaft, the cams operate the valves either directly or through a linkage of pushrods and rockers. Direct operation involves a simpler mechanism and leads to fewer failures, but requires the camshaft to be positioned at the top of the cylinders. In the past when engines were not as reliable as today this was seen as too much bother, but in modern gasoline engines the overhead cam system, where the camshaft is on top of the cylinder head, is quite common. Some engines use two camshafts each for the intake and exhaust valves; such an arrangement is known as a double or dual overhead cam (DOHC), thus, a V engine may have four camshafts. The cylinder head from a GMC van. ... A cylinder head sliced in half shows two overhead camshafts—one above each of the two valves. ... A V engine is a common configuration for an internal combustion engine. ...


Maintenance

The rockers or cam followers sometimes incorporate a mechanism to adjust and set the valve play through manual adjustment, but most modern auto engines have hydraulic lifters, eliminating the need to adjust the valve lash at regular intervals as the valvetrain wears. A hydraulic lifter, also known as a hydraulic tappet or a hydraulic lash adjuster, is a device for maintaining zero valve clearance in an internal combustion engine. ...


Sliding friction between the surface of the cam and the cam follower which rides upon it is considerable. In order to reduce wear at this point, the cam and follower are both surface hardened, and modern lubricant motor oils contain additives specifically to reduce sliding friction. The lobes of the camshaft are usually slightly tapered, causing the cam followers or valve lifters to rotate slightly with each depression, and helping to distribute wear on the parts. The surfaces of the cam and follower are designed to "wear in" together, and therefore when either is replaced, the other should be as well to prevent excessive rapid wear. In some engines, the flat contact surfaces are replaced with rollers, which eliminate the sliding friction and wear but adds mass to the valvetrain. Sliding friction is when two objects are rubbing against each other. ... Surface hardening processes are used to improve the wear resistance of machine parts without affecting the tough interior of the parts. ... A lubricant (colloquially, lube) is a substance (often a liquid) introduced between two moving surfaces to reduce the friction and wear between them. ... // A typical container of motor oil, with some in a glass. ...


Alternatives

In addition to mechanical friction, considerable force is required to overcome the valve springs used to close the engine's valves. This can amount to an estimated 25% of an engine's total output at idle, reducing overall efficiency. Two approaches have been tried to reclaim this "wasted" energy but have proven difficult to implement:

Desmodromic valves are those which are positively closed by a leverage system, rather than relying on the more conventional springs to close the valves. ... Ducati Motor Holding is an Italian motorcycle manufacturer. ... Most piston engines today employ a camshaft to operate poppet valves. ... For other uses, see Solenoid (disambiguation). ... For other uses, see BMW (disambiguation). ... Fiat S.p. ... VALEO is a French automotive components manufacturer. ... Ricardo Engineering Consultants, or Ricardo as it is often more simply known, is a publicly listed company named after its founder Sir Harry Ricardo, that creates designs for specialist or advanced combustion engines used particularly in the automotive and aerospace industries. ...

See also

Look up Camshaft in
Wiktionary, the free dictionary.

Wikipedia does not have an article with this exact name. ... Wiktionary (a portmanteau of wiki and dictionary) is a multilingual, Web-based project to create a free content dictionary, available in over 150 languages. ... piston engine Bristol Perseus The sleeve valve is a type of valve mechanism for piston engines which have traditionally relied on the more common poppet valve. ... To meet Wikipedias quality standards, this article or section may require cleanup. ...

Gallery

Components of a typical, four stroke cycle, DOHC piston engine. (E) Exhaust camshaft, (I) Intake camshaft, (S) Spark plug, (V) Valves, (P) Piston, (R) Connecting rod, (C) Crankshaft, (W) Water jacket for coolant flow.
Double overhead cams control the opening and closing of a cylinder's valves.
Valve timing gears on a Ford Taunus V4 engine — the small gear is on the crankshaft, the larger gear is on the camshaft. The gear ratio causes the camshaft to run at half the RPM of the crankshaft.

Labeled diagram of a four-stroke engine, created by Wapcaplet in Blender. ... The four-stroke cycle of an internal combustion engine is the cycle most commonly used for automotive and industrial purposes today (cars and trucks, generators, etc). ... This article or section should include material from Spark gap A spark plug is an electrical device that fits into the cylinder head of some internal combustion engines and ignites compressed aerosol gasoline by means of an electric spark. ... A poppet valve is a valve consisting of a hole, usually round or oval, and a tapered plug, usually a disk shape on the end of a shaft also called a valve stem. ... For the American composer, see Walter Piston. ... piston (top) and connecting rod from typical automotive engine (scale is in centimetres) Components of a typical, four stroke cycle, DOHC piston engine. ... Crankshaft (red), pistons (gray) in their cylinders (blue), and flywheel (black) Continental engine marine crankshafts, 1942 Components of a typical, four stroke cycle, DOHC piston engine. ... Image File history File links animated scheme of a four stroke internal combustion engine, Otto principle Source: self-made: UtzOnBike (3D-model & animation: Autodesk Inventor) File links The following pages link to this file: Four-stroke cycle ... A cylinder head sliced in half shows two overhead camshafts—one above each of the two valves. ... Image File history File links Front view of distribution gear in a Ford Taunus V4 engine. ... A poppet valve is a valve consisting of a hole, usually round or oval, and a tapered plug, usually a disk shape on the end of a shaft also called a valve stem. ... For other uses, see Gear (disambiguation). ... Ford Taunus was a large family car sold by Ford in Germany. ... 1700 cc High Compression Ford Taunus V4 V4 and V-4 redirect here. ... Crankshaft (red), pistons (gray) in their cylinders (blue), and flywheel (black) Continental engine marine crankshafts, 1942 Components of a typical, four stroke cycle, DOHC piston engine. ... Gears on a piece of farm equipment, gear ratio 1:1. ...

Footnotes

  1. ^ Georges Ifrah (2001). The Universal History of Computing: From the Abacus to the Quatum Computer, p. 171, Trans. E.F. Harding, John Wiley & Sons, Inc. (See [1])
  2. ^ A. Lehr (1981), De Geschiedenis van het Astronomisch Kunstuurwerk, p. 227, Den Haag. (See [2])
  3. ^ http://emp.byui.edu/DavisR/202/202C16.html retrieved June 21, 2007
Wikimedia Commons has media related to:
camshafts

  Results from FactBites:
 
RPM-camshaft (483 words)
Cams range in lift and duration (the amount of time the valve is open) to degrees of overlap, and centerline.
Lift is the amount of rise on the camshaft lobe, and must be taken into consideration if a higher lift than stock is going to be your choice.
But the easiest way to degree in a camshaft, is by the centerline process off of the intake valve centerline.
Camshaft Variables Basics - Tech Article - Chevy High Performance Magazine (1884 words)
The camshaft's function is to time each valve opening and closing point in relation to the piston and the combustion process to every degree of the engine's 360-degree rotation.
During the camshaft's installation, it is extremely important to make sure the crankshaft and camshaft's timing gears are properly aligned by placing the dimple on the crankshaft timing gear in the 12 o'clock position while the dimple on the camshaft timing gear is positioned at 6 o'clock.
Camshafts that typically measure less than 0.550-inch lift and 220 degrees of duration (at 0.050-inch lift) are usually safe with flat-top pistons, but even then they should be checked for acceptable clearance.
  More results at FactBites »

 
 

COMMENTARY     

Liz34Leon
19th July 2010
Every body acknowledges that our life seems to be not cheap, however some people require cash for various things and not every one earns enough cash. Therefore to receive fast credit loans or just short term loan would be a right solution.
There are 1 more (non-authoritative) comments on this page

Share your thoughts, questions and commentary here
Your name
Your comments

Want to know more?
Search encyclopedia, statistics and forums:

 


Press Releases |  Feeds | Contact
The Wikipedia article included on this page is licensed under the GFDL.
Images may be subject to relevant owners' copyright.
All other elements are (c) copyright NationMaster.com 2003-5. All Rights Reserved.
Usage implies agreement with terms, 1022, m