BearingsWritten by Seamus Dolly
Since Murphy or whoever it was, took credit for round wheel, rolling technology has changed somewhat.
Today, friction whether static or dynamic, is reliant on bearings to reduce motor or engine load. What is sometimes overlooked is inherent features and design of a bearings to reduce temperature where it is not necessary. The basic requirement is to reduce contacting surface areas. More extreme requirements are to reduce vibration, reduce allotted space required to house such a bearing, and extend their life.
Needle roller bearings are used where load is spread length ways, and a typical or common application would be “big end” bearings of motorcycles. Plain bearings are still used in big ends, of cars and most other crankshaft scenarios. The principle behind a plain bearing is that thinner a material is, harder it is to compress or displace it. Plain bearings, often called bushings, can be “steel backed” with a relatively thin coating of white metal applied to bearing contact surface. This would be common type in automotive big end applications, and should a piece of offensive hard material contaminate oil, it can be safely embedded within white metal. Should it be small enough then it is not an issue.
More plain bearings can be of a bronze base with impurities cast or sintered into them. The purpose is to absorb oil or lubricant before application, and become “self-lubricating, for a limited time anyway.
Many years before industrial revolution, bearings were made from anything available that was considered appropriate. Timber, sometimes from apple trees but not in any way exclusive to them, have been used in windmills and water mills.
Indeed, stone bushings were not unusual. You’ve heard of more expensive watches been said to contain “X number of Jewels”? The purpose of such jewels was to reduce friction and associated loads. This would be a loose example of metal to stone contact.
Thrust bearings are designed to work through a different axis, and may be ball-type, cylindrical roller type or a combination of both. Taper roller bearings are an example.
High temperature bearings have in-built allowance for expansion, or to put it another way; they have more clearance. High-speed bearings often have “cages” made from non-metallic materials. Typically, this material is tufnol or plastic.
Improve Gas Mileage Without Damaging Your CarWritten by Marilyn Pokorney
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Words: 622 including resource box Copyright: 2004 Marilyn Pokorney
Please leave resource box intact with an active link, and send a courtesy copy of publication in which article appears to: firstname.lastname@example.org --------------------------------------------------------- Many of gas saving devices being advertised do not work and can actually damage your vehicle.
After evaluating and testing more than 100 alleged gas- saving devices, Environmental Protection Agency has found only a few that improve mileage and none that do so significantly.
The gas-saving products on market seem to fall into clearly defined categories. These include, but are not limited to: air-bleed devices, vapor-bleed devices, liquid injection devices, ignition devices, fuel line devices, mixture enhancers, internal engine modification devices, fuels and fuel additives, oils and oil additives, and driving habit modifiers.
The EPA evaluates or tests products to determine whether their use will result in any measurable improvement to fuel economy. However, EPA cannot say what effect gas-saving products will have on a vehicle over a long period of time. It is possible that some products may harm car or adversely affect its performance.
For example, if an "air bleed" device actually adds significant amounts of air to air-and-fuel mixture, it may cause an engine to misfire, a condition which greatly increases potential engine damage or mechanical failure. This is especially likely to happen on cars manufactured between 1974 and 1982, because their carburetors are pre-set for a maximum amount of air to be burned with fuel. "Air-bleed" devices will not work at all on many cars manufactured after 1982, because these cars have "feedback" carburetors that automatically adjust air-and-fuel mixture rendering device useless.