Tools Measurement

# Tools Measurement - A EN 201 Agricultural Power Units Using...

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A EN 201 – Agricultural Power Units Using the Micrometer, Other Measuring Devices, & Small Engine Specialty Tools Objectives: The Student Will Be Able To: 1. Summarize use of the micrometer , (parts, reading, operation, handling, and care); 2. Identify and describe the uses of the flat feeler gauge; 3. Identify and describe the torque wrench and discuss the measures of torque; 4. Identify and describe various spark plug adjustment tools; 5. Describe the use of plastigage; 6. Describe the compression gauge and list the potential causes for a loss of compression; 7. Identify and describe each specialty tool; and 8. Operate each of the specialty tools discussed. Required Reading For Quiz : 1. Chapter 12, Engines, Fundamentals of Service ; John Deere 2. This laboratory chapter I. The Micrometer : One of the more common measuring devices used on engines is the micrometer, shown in Figure, 2.1. Since it is designed to measure machine work where tolerances are quite close, it is essential that the micrometer be very accurate. In most cases, the micrometer is an expensive but very useful instrument, which is quite easy to use once the main working parts and a few basic operating principals are understood. Fig. 2.1, An Outside One-Inch Micrometer It is important to first understand the marks that are on the sleeve and the thimble. If you turn the thimble until the “0” marks on the thimble and the sleeve come together, the micrometer is at its smallest measurement possible. On the one- inch (1”) micrometer, shown in Figure 2.2, the measurement is exactly 1.000”. A micrometer should occasionally be checked for accuracy. Micrometer manufacturers will usually provide information on proper adjusting methods.

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Fig. 2.2, Checking the Accuracy of a One-Inch Micrometer The marks on the thimble represent .001 inch, (one thousandth of an inch), each. If you turn the thimble away from you to the very next mark on the thimble, as in Figure, 2.3, and if this is a one-inch micrometer, the spindle will be exactly .001 inch from the anvil. Fig. 2.3, One Thousandths of an Inch (.001”) One complete revolution of the thimble is equal to .025 inch, (twenty five thousandths of an inch), because each complete revolution of the thimble moves it one full mark on the sleeve. In other words, each mark on the sleeve is equal to .025 inches of movement for the spindle. Every fourth line on the sleeve is a little longer than the other lines. These longer marks stand for .1 inch, (one tenth of an inch), each. To find out how much the micrometer is open, (the distance between the measuring surfaces), the marks on the sleeve may read like an ordinary rule. Remember that the numbers 1, 2, and 3 mean .100 inch each, or .100 inch, .200 inch, and
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Tools Measurement - A EN 201 Agricultural Power Units Using...

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