MATac: Chapter 6 Automotive Measurement & Math

Terms in this set (32)

specifications / "specs"
...maximum wear limits and dimensions of important parts determined by the manufacturers
customary measuring system / U.S. Customary / English
...used mostly in the United States; unit names originated from sizes of human body parts; units include feet, inches, pounds, etc.
metric measuring system / SI
...uses a power of 10 for all base units; used worldwide for science and math
conversion chart
...consulted when there is a need to convert from one measuring system to another
decimal conversion chart
...commonly used to find equivalent values for fractions, decimals, and millimeters; decimals and millimeters can be more accurate than fractions
steel rule / scale
...frequently used to make low-precision linear measurements; accurate to about 1/64" or 0.4 mm
customary rule
...has number labels that represent full inches, with graduated unnumbered lines representing fractions of an inch
metric rule
...has lines or divisions representing millimeters, with numbered lines usually equaling 10mm or 1cm
pocket rule / pocket scale
..typically 6" long; small enough to fit in a shirt pocket
combination square
...a sliding square that is mounted on a steel rule; needed when the rule must be held perfectly square against the part being measured
tape measure / tape rule
...extends to several feet or meters in length; needed for large distance measurements during body, suspension, and exhaust systems\ repairs
yardstick / meterstick
...a rigid measuring device used for large lineal measurements up to one yard or one meter
dividers
...commonly used for layout work on sheet metal parts; look like a drafting compass, but have straight, sharply pointed tips for scribing circles and lines
outside caliper
...used to make external measurements when 1/64" accuracy is sufficient
inside caliper
...designed for internal measurements in holes and other openings
vernier caliper
...a sliding measuring device that can make inside, outside, and depth measurements with considerable accuracy; some have a dial gauge to make the thousandths part easier to reat
micrometer / mike
...a precision measuring tool; can measure to one ten-thousandths of an inch, or one thousandth of a millimeter
outside micrometer
...used for measuring more accurate external dimensions, diameters, or thicknesses
internal micrometer
...used for measuring more accurate internal dimensions of holes or cylinders
depth micrometer
...helpful for precisely measuring the depth of an opening
telescoping gauge
...used to measure internal part bores or openings
hole gauge
...used for measuring very small holes in parts
micrometer rules
...never drop or over-tighten a micrometer;
store micrometers where that cannot be damaged;
grasp the micrometer frame in your palm and turn the thimble with your thumb and finger;
hold the micrometer squarely with the work;
rock or swivel the micrometer as it is touched on round parts;
place a thin film of oil on the micrometer during storage;
always check the accuracy of a micrometer if it is dropped or struck, or after a long period of use
feeler gauge
...used to measure small clearances or gaps between parts; two types are available in both customary and metric versions
flat feeler gauge
...has precision-ground steel blades of various thicknesses; used to measure distances between parallel surfaces
wire feeler gauge
... has precise-size wires labeled by diameter or thickness; used to measure slightly larger spaces or gaps
dial indicator
...used to measure part movement in thousandths of an inch or hundredths of a millimeter
angle measurement
...specifications for angle are given in degrees; a circle is divided into 360 equal parts called degrees
temperature gauges / thermometers
...used to measure temperature; available in customary Fahrenheit (F) or metric Celsius (C)
torque wrench
...not for measurement, but used to apply a specific amount of turning force to a fastener; usually read in foot-pounds and Newton-meters; three types are:
flex bar
dial indicator
ratcheting
pressure gauge
...used to measure air and fluid pressure in various systems and components; reads in pounds per square inch (psi), kilograms per square centimeter (kg/cm²), or kilopascals (kPa)
vacuum gauge
...used to measure negative pressure or vacuum; reading in inches of mercury (in/hg), or metric kilograms per square centimeter (kg/cm²)
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