TM-9-2815-220-34 Direct Support Manual for AVDS-1790-2C and AVDS-1790-2D Engines Download
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g parts replacement. all applicable components of the kit or set should be installed. c. When to1·que tightening nuts, bolts, and screws, and a torque specification is not noted in the text or illustration covering the installation, it is understood that the standard torque values in paragraph 3-41 prevail. Whenever a nut, bolt or screw requires that special attention be given, the torque value will be noted in the text or illus- ration pertaining to that operation. Torque wrench readings are of no value, unless properly used. It must be understood that it is not the force necessary to turn the nut, bolt, or screw that is important, but the resultant pull on the part that completes the union. Therefore, resist- ance of the nut to turning must be kept to a minimum. Threads must be clean and undam- aged, and lubricated with OE30 engine oil or GAA grease to reduce the friction. NOTE When using a torque wrench, the final reading must be taken while the nut, capscrew, or bolt is turning. When torque reading is close to that specified when wrench is at the end of its swing, back off the nut slightly and change TM 9-2615-220·34 wrench position; then pull to the desired reading while the nut is turning. To start a partially tightened nut will re- qui1·e a much higher torque than that required to keep a nut turning. The ratio of pounds-torque to pounds-pull on a bolt is not an even ratio and excess torque may easily overstress the bolt. Under-torquing bolts and studs subject to cyclic loads such as cylinder base studs and connecting rod bolts will re- sult in fatigue failures. It is therefore important that the torque values specified in this manual be followed to avoid failures of fasteners. . All bolts and nuts should be secured with lock nuts, tab washers, locking wire, lock washer, or cotter pins, as specified. Many engine failures have been traced to neglect of this simple pre- caution. 3-158. Installation Instructions The same illustrations support both removal and installation procedures, references to illustra- tions contained in Chapter JI and II I are used throughout this section. Section XXVlll. ASSEMBLY OF ENGINE FROM SUBASSEMBLIES 3-159. General This section covers instructions for complete as- sembly of the engine from subassemblies, and installation of engine accessories. Components are grouped together in proper assembly order. The crankcase assembly was partially assembled during repair of engine components. Normally the crankcase assembly will be on the overhaul stand after it has been inspected and the main bearing bores have been checked. If the crank- case is not on the stand, install on maintenance and overhaul stand, part number 10912260, (fig. 3-14 7) and rota le stand so that oil pan nangcs ;ire up. 3-160. Starter Drive Gearshaf1 Install new preformed packing on starter driven gearshaft bearing cage and install bearing cage in crankcase assembly (fig. 3-140). Secure bear- ing cage to crankcase assembly with six slotted nuts (fig. 3-139) and secure slotted nuts with lock· ing wire. 3-161. Generator and Idler Gears, Piston Oller Nozzle, and Crankshaft and Connecting Rod Assembly a. Install new preformed packing (fig. 3-308) on starter idler gearshaft and install idler gear and aline with idler gearshaft bore in crankcase. Se- cure starter idler earshaft to crankcase with Figure 3·308. /11atalli11g atarter idler gear. Change? 3·221