Chapter 2 Measuring and Repair Instruments

Engineman 2 - Intermediate engine mechanics training manual
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CHAPTER 2 MEASURING AND REPAIR INSTRUMENTS You, as an Engineman, must he able to identify the basic measuring and repair instruments and the basic components of these instruments. This chapter will help you to recognize the how and when to use and maintain basic measuring and repair instruments and engine test equipment. Measuring instruments are used to check tolerances and specifications during inspections and repairs of internal combustion engines and auxiliary equipment. You, as an Engineman, need measuring instruments to determine what parts are worn and need to be repaired or replaced. The following measuring and repair instruments are discussed in this chapter: dial indicator, dial/vernier caliper, micrometer, snap gauge, bore gauge, strain gauge, borescope, stroboscope, torque wrench, multiplier, adapter, ridge reamer, cylinder hone, and dynamometer. SENSITIVE MEASURING TOOLS Sensitive measuring tools are measuring devices that provide measurement readings to a thousandth of an inch or less. The more common sensitive measuring tools you will use are the dial indicator, dial/vernier caliper, micrometer, snap gauge, bore gauge, and strain gauge. DIAL INDICATOR A dial indicator is used to measure shaft runout, shaft thrust, gear backlash, flywheel face runout, flywheel housing concentricity, and valve seat concentricity. You can mount a dial indicator on a test stand or, with clamps and a magnetic base, directly on the equipment to be measured. Figure 2-1 shows a typical dial indicator with mounting accessories, Most dial indicators have components such as a bezel, indicator pointer, tool post and clamp, magnetic toolholder, and sensor button that are used in taking measurements. The following procedures explain how to use the indicator to take shaft runout and crankshaft end play measurements. Procedures for taking other measurements are similar. Figure 2-1.—Typical dial indicator wlth mounting accessories. Shaft Runout When you need to measure a shaft’s runout, select a suitable position on the shaft, free of keyways, corrosion, or other damage. Clean the surface and remove any burrs around scratches or dents. To take the runout measurement, use the following procedure: 1. Place the shaft in well-oiled V-blocks. If the shaft is a crankshaft, place the bearing journals in the V-blocks. 2. Attach the magnetic base to a machined surface. Mount the dial indicator on a tool mounting holder and attach the holder to the base. 3. Adjust the mounting post so you can easily read the face of the dial. 2-l

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