castellated retention nuts which screw on studs projecting from the camshaft flange end. The smaller gears, such as the magneto drive and pump drive are usually held by a key which is set into a taper shaft and the gears are tightly clamped on the taper by substantial clamping nuts. Fig. 93.-End Sectional View of Lewis Six Cylinder Motor Showing Unconventional Construction in Which Cylinders and Crank Case are Formed Integral. Attention has been previously called to the necessity of marking the timing gears. The manner in which this can be done is clearly indicated at Fig. 95, B. It will be seen that the crankshaft gear is provided with two figures, "1" and "1," opposite cer Fig. 95.-Showing Method of Marking Timing Gears and Group of Miscellaneous Motor Parts. tain teeth. The camshaft drive gear is provided with a numeral 1 to indicate the space that the tooth marked 1 on the crankshaft gear should occupy. Similarly the intermediate gear which transmits motion to the magneto drive gear is marked with a 2 and 3 which should correspond to the corresponding numerals on the crankshaft gear and member driving the magneto armature. At C, Fig. 95, is shown a group of the important internal parts of the engine. These are plainly marked and should be readily recognized by even the novice. At Fig. 95, D, a typical piston and connecting rod assembly is depicted. In this view, the parts are also identified and further description is unnecessary. Fig. 96.-Lower Portion of Engine Base Removed to Show Crankshaft and Accessibility of Main Bearings. The illustration at Fig. 96, is that of the crankcase shown at Fig. 92, as it looks when viewed from the bottom after the lower portion of the crankcase has been removed. As will be apparent, the main bearing caps that hold the crankshaft in place may be released by taking off the retention nuts and the connecting rod bearing caps which keep these members attached to the crank pins are also exposed for inspection. In some multiple cylinder engines the cylinders are cast individually and instead of the crankshaft having three main bearings, as in the engine shown at Fig. 96, it has five main bearings as indicated in the sectional view of the Overland engine shown at Fig. 97. When the cylinders are cast individually it is possible to replace a defective cylinder without sacrificing the remainder ast is imperative if the cylinders are cast in block. Individual cylinders Fig. 97.-Longitudinal Sectional View of Overland Four Cylinder Motor, a Type Having Individual Cylinder Castings and a Five Bearing Crankshaft. are more easily handled, but where these are used it is absolutely necessary to mark them so that they will always be replaced in proper position. In most cases, the cylinders are duplicates of each other and if they were not marked it would not be difficult to transpose them on the engine base, an undesirable proceeding. In order to familiarize the motorist or novice repairman with engine construction a side sectional view of a typical power plant |