is provided used for taking in the flywheel lock (Fig. 28); twelve holes are used for cranking the shaft by hand.Piston (Fig. 29) is made of high silicon-alumi¬nium alloy. The piston head has a non-split toroidal combustion chamber; besides, an insert made of heat- resistant cast iron is moulded under the upper comp-ression ring in the grove.Piston pin 5 is a hollow floating-type pin. The pin is locked with two spring locking rings against axial shifting in the piston.-Each piston mounts two compression rings 2 and 3 of one-lateral trapezoid section and one oil control ring 1 composed of a cast iron box-section ring and spring-coiled expander 8. Connecting rods 6 made of steel are of double T-section. The connecting rod big end is splittable. The connecting rod is machined finally in assembly with its cap; therefore, the caps could not be interchanged. In the engine the connecting rods are fitted only in assembly with their caps. Each set «cap — connecting rod» has the same marks of three-digit numerals. Besides, the connecting rod cap has the cylinder ordinal number.The connecting rod big end bearing has replaceable shells, that of the small end is made as a bimetal bushing having a bronze-made carrying layer. The connecting rod cap is fastened with two bolts press-fitted in the rod.For disassembling the «piston — connecting rod» set, remove the locking rings off the bosses and, after heating the piston in an oil bath up to 80 °C, pick out the piston pin. For taking out the piston rings, apply a special remover.Before re-assembling, wash all the parts, blow through the oil ducts with compressed air, coat the friction surfaces with diesel oil. Check that the piston pin fits easily the pre-heated piston.Do not fit the pin in a cold piston.For fitting the compression and oil control rings on the piston, use a fixture. When fitting, place the compression rings with skewed side marked BEPX (Top) facing the piston head. The composite oil control ring should be placed part by part: first insert the spring-coiled expander in the groove, then place the oil control ring so that the expander joint is diametrically opposed to the ring lock. Spread apart the compression ring locks.Recesses for valves in the piston head are located at one side with the slots for tabs of the connecting rod shells and displaced towards the Vee of the engine. The connecting rod cap bolts should be tighte-
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