BASIC BLOCK - TM-5-3805-263-14P-2

ELECTRICAL SYSTEM - TM-5-3805-263-14P-2_31

TM-5-3805-263-14P-2 Grader Heavy Road Motorized Type I Nonsectionalized Type II Sectionalized Manual
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BASIC BLOCK SYSTEMS OPERATION TM 5-3805-263-14&P-2 BASIC BLOCK CYLINDER BLOCK The cylinder block has four cylinders arranged in- line. There are five main bearings that support the crankshaft. Thrust bearings installed on the rear main bearing web control the end play of the crank- shaft. The cylinder block has cylinder liners that can be replaced. The top surface (deck) of the cylinder block is the support for the liners. A spacer plate, that goes between the cylinder block and the head, is used to eliminate the need to counterbore the block for the liner flange. PISTONS, RINGS AND CONNECTING RODS The cast aluminum piston has three rings; two compression rings and one oil ring. All rings are located above the piston pin bore. The two compres- sion rings are of the KEYSTONE type and seat in an iron band that is cast into the piston. KEYSTONE rings have a tapered shape and the movement of the rings in the piston groove (also of tapered shape) results in a constantly changing clearance (scrubbing action) between the ring and the groove. This action results in a reduction of carbon deposit and possible sticking of rings. The oil ring is a standard (conventional) type and is spring loaded. Holes in the oil ring groove provide for the return of oil to the crankcase. The piston pin bore in the piston is offset (moved away) from the center of the piston 0.76 mm (.030 in.). The full floating piston pin is held in the piston by two snap rings which fit into grooves in the piston pin bore. The piston pin end of the connecting rod is tapered to give more bearing surface at the area of highest load. The connecting rod is installed on the piston with the bearing tab slots on the same side as the “V” mark on the piston. CRANKSHAFT The crankshaft changes the combustion forces in thecylinder into usable rotating torque which powers the machine. There is a gear at the front of the crankshaft that drives the timing gears and the en- gine oil pump. The connecting rod bearing surfaces get oil for lubrication through passages drilled in the crankshaft. Lip seals and wear sleeves are used at both ends of the crankshaft to control oil leakage. 1-20

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