Terms Starting with M

 
MacPherson strut suspension-An independent suspension system consisting of a coil spring, shock absorber, and upper bearing and support.

Magnetic pickup-A sensor that will produce a charge of electricity as a magnet passes by.  This sensor is usually used to measure crankshaft rotation or position.

Magnetic pickup sensor-A sensor that uses magnetism to generate a small electrical signal every time a rotating shaft turns past a specific point.  This type of sensor is often used to sense or signal the rotational speed or rpm of a shaft or gear.

Mag wheel-A type of wheel that uses magnesium metal for the rim. 

Main bearing clearance-The clearance between the engine main bearing journal and the main bearings.

Major thrust-The thrust forces applied to a piston on the power stroke.

Manual shift valve-A valve in the automatic transmission that is controlled by the position of the gearshift lever.

Master cylinder-The unit used for displacing brake fluid under pressure in a hydraulic brake system.  The master cylinder can be either single or dual design.

Mechanical advantage-A linkage or lever able to gain either distance or force.  The rocker arm on an engine valve system uses mechanical advantage to gain distance to open the valve farther.

Mechanical efficiency-A measure of the mechanical operation of a machine.

Meter-A device used to measure or control the flow of a liquid such as fuel.  To control the amount of fuel passing into an injector.  Fuel is metered to obtain the correct measured quantity.

Methanol-An alcohol product made from coal, wood, grain, or other biomass fuel, used to increase oxygen when mixed with certain fuels.

Metric system-A system of measurement based on the meter.  All units of length and volume are derived from the meter.  These include centimeter, kilometer, millimeter, liter, cubic centimeter, and so on.

Metric thread-The thread on a bolt measured by indicating the number of millimeters between each thread.

Micrometer-A measuring tool used to accurately measure length to 0.001 of an inch.  

Microprocessor-A series of circuits using semiconductors and integrated circuits for computer applications.  Microprocessors can accept electrical inputs, store them, and feed them out to other circuits and systems on the automobile.

Minor thrust-The thrust forces applied to an engine piston on the compression stroke.

Motor-Any power device that imparts motion to an object.  A gasoline engine is considered a motor because it causes the vehicle to move forward.  An electric motor also causes rotational motion to occur, such as the motor that rotates gears to move the electric car seat forward and backward.

MSDS-An abbreviation from the words Material Safety Data Sheet.   MSDS sheets contain information about hazardous ingredients, physical and chemical properties, fire and explosion data, reactivity data, health hazards, control measures, and precautions for using various chemical in the automotive shop.

Multiple-disc clutch-A hydraulic clutch used in the automatic transmission.  The clutch uses a series of discs, both friction and smooth metal to lock up two rotating shafts.

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