Admin: 1 revision imported: Mitul Imported from Wikipedia

2021-04-11T19:42:22Z

1 revision imported: Mitul Imported from Wikipedia

setup>Cewbot: Fix broken anchor: Wrong capitalization / spaced section title #6.8_L_V10→Ford Modular engine#6.8 L V10

2021-02-27T10:46:14Z

Fix broken anchor: Wrong capitalization / spaced section title #6.8_L_V10→Ford Modular engine#6.8 L V10

New page

[[File:Napier Deltic Diesel Engine Barrowhill.jpg|thumb|[[Napier Deltic]] diesel locomotive engine]]

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 bearing]]s or [[journal bearing]]s, 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.

== Number of main bearings ==
The number of main bearings is primarily determined by the overall load factor and maximum engine speed.<ref name="Bosch Auto Handbook">{{cite book |title=Bosch Automotive Handbook |date=2004 |publisher=Robert Bosch GmbH |isbn=978-0-7680-1513-3 |pages=465 |url=https://books.google.com/books?id=uKoeAQAAIAAJ |language=en}}</ref> 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 bearing 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.<ref name="Bosch Auto Handbook" />

Some small single-cylinder engines have only one main bearing,{{citation needed|date=November 2019}} 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 engine|Toyota VZ]] V6 engine is described as having a "four bearing crankshaft" and the [[Jaguar XK6 engine|Jaguar XK6]] straight-six engine has a "seven bearing crankshaft".<ref>{{cite web |title=Toyota 5VZ-FE (3.4 L, V6, DOCH) engine: review and specs, service data |url=https://www.engine-specs.net/toyota/5vz-fe.html |website=www.engine-specs.net |access-date=29 November 2019 |date=15 March 2019}}</ref><ref>{{cite web |title=Best Inline Six Engines |url=https://www.hagerty.com/articles-videos/articles/2018/01/02/best-inline-six-engines |website=www.hagerty.com |access-date=29 November 2019}}</ref>

== Bearing caps ==
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.<ref>{{cite web |title=Are 4 bolt main blocks stronger than 2 bolt main blocks? |url=https://www.badasscars.com/index.cfm/page/ptype=product/product_id=83/prd83.htm |website=www.badasscars.com |access-date=1 December 2019}}</ref>

=== {{anchor|4-bolt}} 4 bolt main ===

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.<ref name="Ludvigsen">{{Cite book |title=The V12 Engine |chapter=Chapter 7: Teutonic Twelves |last=Ludvigsen |first=Karl |author-link=Karl Ludvigsen |publisher=Haynes Publishing |location=Sparkford, Yeovil |year=2005 |isbn=1-84425-004-0 |ref={{harvid|Ludvigsen|V12 Engine}} |pages=160}}</ref>

==== Engine examples with 4 bolt main bearings ====

{{Expand section|date=November 2020}}

*[[International Harvester IDI]]
*[[Ford Modular engine|Ford Modular V8 engines]]
*[[Chevrolet big-block engine]]
*[[Chevrolet_big-block_engine#L18|8.1 Vortec]]
*[[Navistar_VT_engine#MaxxForce_7|Navistar VT engine (Maxxforce 7)]]/[[Ford_Power_Stroke_engine#6.4_Power_Stroke|6.4 Ford Power Stroke engine]]
*[[Navistar_VT_engine#VT365|Navistar VT 365 engine]]/[[Ford_Power_Stroke_engine#6.0_Power_Stroke|6.0 Ford Power Stroke engine]]
*[[Navistar T444E engine]]/[[Ford_Power_Stroke_engine#7.3_Power_Stroke|7.3 Ford Power Stroke engine]]

=== 6 bolt main ===

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-bolted bearing|cross-bolts]] coming from the left and right side pan rails into the side of the main caps to provide additional lateral strength.

==== Engine examples with 6 bolt main bearings ====

{{Expand section|date=November 2020}}
*[[Ford EcoBoost engine]]
*[[Ford Godzilla engine]]
*[[Ford Boss engine]]
*[[Ford_Power_Stroke_engine#6.7_Power_Stroke|Ford Scorpion diesel engine]]
*[[Ford_Modular_engine#6.8 L V10|Ford Modular 6.8 v10]]
*[[General Motors LS engine]]
*[[Chrysler Hemi engine#Third Generation: trademarked|3rd Gen Hemi]]
*[[Viper engine]]

== See also ==
* [[Crankcase]]
* [[Crankshaft]]

== References ==
{{reflist|colwidth=30em}}

{{Automotive engine |state=expanded}}
[[Category:Engine technology]]
[[Category:Bearings (mechanical)]]

← Older revision	Revision as of 19:42, 11 April 2021
(No difference)

Main bearing - Revision history

Admin: 1 revision imported: Mitul Imported from Wikipedia

setup>Cewbot: Fix broken anchor: Wrong capitalization / spaced section title #6.8_L_V10→Ford Modular engine#6.8 L V10