Pistons.

Pistons are cast from высококремнистого an aluminium alloy and thermally processed. A head of the piston the cylindrical. The piston bottom — flat, with four цековками under valves which prevent a contact (blows) about the bottom of the piston of plates of valves at infringement of phases газораспределения, caused, for example, breakage of a chain of a drive of camshafts.

In the top part of a cylindrical surface of pistons three flutes are pierced: in two top are established компрессионные rings, and in bottom — маслосъемное.

In the top part of a skirt of the piston are executed on two apertures from both parties with an exit in a flute under маслосъемное a ring which serve for tap of the oil accumulating under маслосъемным by a ring.

Piston skirt oval in cross-section section and бочкообразная — in longitudinal. The big axis of an oval is located in a plane, a perpendicular axis of a piston finger. The size of ovality of the piston makes 0,514 0,554 mm. The greatest diameter of a skirt of the piston in longitudinal section settles down below an axis of a piston finger on 8 mm.

Diameter of a skirt in longitudinal section smoothly decreases and in a direction to the bottom, and in an opposite direction. The maximum reduction of diameter by a facet edge under the bottom flute makes 0,047—0,056 mm. On the bottom edge of a directing part of a skirt the maximum reduction of diameter makes 0,009—0,018 mm.

In a piston body between the bottom flute and an aperture under a piston finger the steel thermoregulating insert serving for reduction of deformation of the piston at heating to working temperature and reduction of initial assembly backlashes at assemblage is filled in. Pistons are established in cylinders of the same dimensional group with a backlash of 0,036-0,060 mm. For maintenance of a demanded backlash pistons and block cylinders are divided (on diameter) into five groups, designated by the corresponding letter (And, In, Г,) which is beaten out on the bottom of the piston and is put by a paint on an external surface in the top part of the block, on the right side.

For improvement extra earnings the working surface of pistons has a special microrelief.

That pistons worked correctly, they should be established in cylinders in strictly certain position. For this purpose on a lateral wall one of lugs under a piston finger has a cast inscription "BEFORE". According to this inscription the piston the specified party should be turned to a forward part of the engine.

Piston rings.

Fig. 4.114. Piston rings: 1 — top компрессионное a ring; 2 — bottom компрессионное a ring; 3 — a ring disk; 4 — a dilator

Kompressionnye rings are cast from pig-iron. The top ring 1 (fig. 4.114) has бочкообразную a working surface for improvement extra earnings and is covered by a layer of porous chrome; the working surface of the bottom ring 2 is covered by a layer of tin in the thickness of 0,006-0,012 mm or has a phosphatic covering which is put on all surface, thickness of 0,002-0,006 mm. On an internal surface bottom компрессионного rings there is a bore. This ring should be established on the piston bore upwards, to the piston bottom. Infringement of this condition causes sharp increase of the expense of oil and дымление the engine.

The maslosemnoe ring — modular, three-element, consists of two steel ring disks 3 and one two-functional dilator 4 which are carrying out functions of radial and axial dilators. The working surface of ring disks is covered by a chrome layer.

Piston fingers.

Piston fingers — floating type (they are not fixed neither in the piston, nor in a rod), became made from низколегированной хромоникелевой, the external surface of a finger is subjected углеродонасыщению on depth of 1,0-1,5 mm and is tempered by heating ТВЧ to hardness НRСэ 59—66. External diameter of a finger — 22 mm.

Axial moving of a finger is limited to the lock rings established in flutes of lugs of the piston. Lock rings are made of a round spring wire in diameter of 1,6 mm.

To warn knock of fingers, them select to pistons with the minimum backlash, admissible for greasing conditions.

Rods.

Rods — steel, shod with a core двутаврового sections. In a piston head of a rod запрессована the thin-walled plug from оловянистой bronze. A krivoshipnaja head of a rod the demountable.

The cover кривошипной heads fastens to a rod two bolts with шлифованной a landing part. Bolts of fastening of covers and a nut шатунных bolts are made of the alloyed steel and thermally processed. Nuts шатунных bolts have a self-stopped carving and consequently in addition are not stopped.

Covers of rods cannot be rearranged from one rod on another. For prevention of a possible error on a rod and on a cover (on a lug under a bolt) serial numbers of cylinders are beaten out. They should be located on the one hand. Besides, grooves for fixing ledges of loose leaves also should be in a rod and a cover on the one hand.

For cooling of the bottom of the piston by oil in a rod apertures are executed: in a core — diameter 5 mm, in the top head — 3,5 mm.

For maintenance of dynamic steadiness of the engine the total weight of the piston, a piston finger, rings and a rod, established in the engine, can have a difference on cylinders no more than 10 г that is provided with selection of details of the corresponding weight.

Cranked shaft.

The cranked shaft is cast from high-strength pig-iron, five-basic, has for the best unloading of support eight counterbalances. The shaft is dynamically balanced: an admissible disbalance — no more than 18 г·см on each end of a shaft. Diameter of radical necks — 62 mm, шатунных — 56 mm. Radical and шатунные necks are connected by apertures in shaft cheeks. Cavities in шатунных necks are closed by carving stoppers and intended for additional clearing of the oil arriving on шатунные of a neck.

Oil to radical necks is spent on channels in partitions of the block from an oil highway, to cavities шатунных necks — on apertures in cheeks of a shaft from flutes in the top loose leaves of radical necks of a cranked shaft.

Fig. 4.115. The average (persistent) radical bearing of a cranked shaft: 1 — the block of cylinders; 2 — bearing loose leaves; 3 — persistent semiwashers; 4 — a bearing cover; 5 — a cranked shaft

Axial moving of a cranked shaft is limited to persistent steel-aluminium semiwashers 3 (fig. 4.115), located on either side of the average (persistent) radical bearing.

Semiwashers are turned by an antifrictional layer to cheeks of a cranked shaft 5. Semiwashers are kept from rotation at the expense of ledges on the bottom semiwashers entering into grooves at end faces of a cover of 4 radical bearings. The size of an axial backlash makes 0,06—0,162 mm.

Fig. 4.116. The forward end of a cranked shaft: 1 — a bolt (or a ratchet); 2 — a pulley-dempfer with a synchronisation disk; 3 — an epiploon; 4 — a chain cover; 5 — the plug; 6 — an asterisk; 7 — the block of cylinders; 8 — bearing loose leaves; 9 — a cranked shaft; 10 — a bearing cover; 11 — oil картер; 12 — a rubber sealing ring; 13 — a lock washer

On the forward end of a cranked shaft on шпонках are established a leading asterisk 6 (fig. 4.116.) a drive of camshafts, the plug 5 and a pulley-dempfer 2. All these details are pulled together by a bolt 1 screwed in a forward end face of a cranked shaft. Between an asterisk and the plug it is established rubber sealing by a ring of roundish section.

On a cylindrical surface of a pulley-dempfera of a cranked shaft it is executed risk for definition ВМТ of the first cylinder at installation of a drive of camshafts. At label combination on a pulley-dempfere with an edge-index on a cover of a chain the piston of the first cylinder is in ВМТ. Besides, on a pulley-dempfere the special gear disk (a synchronisation disk) with number of teeths 60 minus 2 teeth which ensures functioning of the gauge of position of a cranked shaft is executed. The forward end of a cranked shaft is condensed by a rubber epiploon 3, запрессованным in a chain cover. Reliable work of an epiploon is provided with centering of a cover of a chain on two pins-plugs, запрессованных in a forward end face of the block of cylinders.

Fig. 4.117. The back end of a cranked shaft: 1 — a cranked shaft; 2 — bearing loose leaves; 3 — the block of cylinders; 4 — a cover; 5 — an epiploon; 6 — a flywheel; 7 — a bolt of fastening of a flywheel; 8 — the bearing; 9 — распорная the plug; 10 — a washer of bolts of a flywheel; 11 — oil картер; 12 — a bearing cover

The back end of a cranked shaft also is condensed by a rubber epiploon 5 (fig. 4.117), запрессованным in a cover 4 which fastens to a back end face of the block of cylinders.

Flywheel.

The flywheel is cast from grey pig-iron, established on a landing ledge and a pin of a flange of a cranked shaft and fastens to it six bolts М8 having самоконтрящуюся a carving. For reliability of fastening of a head of bolts nestle on the steel thermoprocessed washer. On a flywheel напрессован a gear rim for start-up of the engine by a starter. To a back end face of a flywheel six bolts М8 attach coupling. In the central aperture of a flywheel 8 primary shaft of a transmission are established распорная the plug 9 and the bearing.

Loose leaves.

Radical and шатунные bearings of a cranked shaft consist of the thin-walled loose leaves made from малоуглеродистой of a steel tape, filled in with a thin layer antifrictional высокооловянистого an aluminium alloy. A thickness of the radical loose leaf — 2,5—2,508 mm, шатунного — 2,0—2,008 mm. In each bearing it is established on two loose leaves. Axial moving and проворачиванию loose leaves in beds of the block and in rods is interfered by fixing ledges on the loose leaves entering into corresponding grooves in beds of the block or in rods.

The top loose leaves of radical bearings with flutes and apertures, bottom — without flutes and apertures. Through an aperture of the top loose leaf oil arrives to bearings from the channel in block bed, and through apertures in cranked to a shaft — to шатунным to bearings. The aperture in шатунных loose leaves coincides with an aperture in a rod. Width of radical loose leaves of 28,0 mm, шатунных — 20,5 mm. The diametrical backlash between a neck and loose leaves makes 0,019—0,073 mm for radical and 0,009—0,063 mm for шатунных bearings.