5.2.2. Krivoshipno-shatunny mechanism

Fig. 3.5. Details of the block of cylinders and krivoshipno-conrod mechanism: 1 — the top compression ring; 2 — the lower compression ring; 3 — an oil scraper ring; 4 — the piston; 5 — a piston finger; 6 — a lock ring; 7 — a rod; 8 — connecting rods; 9 — a cover of the lower head of a rod; 10 — an arm; 11 — the block of cylinders; 12 — laying; 13 — the holder of a back epiploon of a bent shaft; 14 — a back epiploon; 15 — a flywheel; 16 — a back cover of the block of cylinders; 17 — an opening stopper for discharge of cooling liquid; 18 — the aligning plug; 19 — a bent shaft; 20 — an insert of the third support with persistent fillets; 21 — covers of radical bearings of a bent shaft; 22 — an insert of radical bearings of a bent shaft

Structure of the mechanism (see fig. 3.5) same, as on the petrol engine.

The bent shaft on a design is similar to a shaft of the petrol engine. Dimensional characteristics of a bent shaft are presented in tab. 3.2.

Parameter	Size, mm
Diameter of radical necks:
0th group	52,967-52,975
1 - group	52,959-52,967
2nd group	52,951-52,958
Diameter of conrod necks:
0th group	49,968-49,974
1 - group	49,962-49,968
2nd group	49,954-49,961
Axial gap:
nominal	0,05-0,18
maximum	0,3
Radial gap:
nominal	0,039-0,063
maximum	0,085
Ovality of necks, no more	0,05
Conicity of necks, no more	0,05

An inspection of technical condition of a bent shaft is carried out similar to checks of a bent shaft of the petrol engine.

The flywheel is cast from cast iron, has the gear wreath intended for launch of the engine by a starter, fastens to a flange of a bent shaft bolts. The most admissible beating of a surface under the conducted clutch plate of 0,15 mm.

Pistons are cast from aluminum alloy with high content of silicon. The combustion chamber is executed in the piston bottom. Rods steel, stamped, double-T section, with the direct socket of the lower head. Inserts of radical bearings thin-walled of aluminum alloy on the steel basis. Dimensional groups of inserts differ in paint (tab. 3.3). Width of an insert of the third radical bearing of 27,95 mm.

Color marking	Thickness, mm
Yellow	1,816-1,820
Green	1,820-1,824
Brown	1,824-1,828
Black	1,828-1,832
Blue	1,832-1,836

For replacement of worn-out inserts in spare parts inserts of radical bearings of two repair sizes under necks of a bent shaft, proshlifovanna on 0,25 and 0,50 mm are delivered.

Pistons of the repair sizes are produced with the outer diameter increased by 0,25 — 0,50 mm. On each piston are established two compression and one oil scraper ring. Gaps in piston rings are given in tab. 3.4. Rings are established by a tag of "TORAHS" up. Piston fingers are similar on a design and are established the same as on the petrol engine, but have bigger diameter. Dimensional characteristics of conrod and piston group are presented in tab. 3.5. An inspection of technical condition is carried out similar to check for the petrol engine.

Ring	Gap in the lock, mm	Gap between a ring and a flute of the piston, mm
The top compression	0,12-0,30	0,060-0,095
The lower compression	0,38-0,53	0,040-0,075
Oil scraper	0,30-0,55	0,030-0,070

Parameter	Size, mm
Diameter of the piston:
1 - group	84,465-84,479
2nd group	84,475-84,485
3rd group	84,485-84,495
4th group	84,495-84,505
5th group	84,505-84,519
1 repair size +0,25	84,715-84,765
2 repair size +0,50	84,965-85,015
Gap in interface the piston cylinder	0,025-0,045
Diameter of an opening under a piston finger	24,991-24,999
Axial gap of a rod on a neck of a bent shaft, no more	0,3
Radial gap of the lower head of a rod	0,031-0,051
Diameter of a piston finger	24,994-25,000
Tightness in interface the piston - a piston finger	0,004
Radial gap in interface a piston finger rod:
nominal	0,025
maximum	0,044