3.3. Gas-distributing mechanism


Fig. 2.4. Drive of valves: 1 – camshaft; 2 – pusher;
3 – bar; 4 – valve saddle; 5 – valve; 6 – the directing valve plug;
7 – lock ring;
8 – washer; 9 – spring;
10 – the cap is maslootrazhatelny; 11 – cap spring; 12 – plate of a spring; 13 – croutons; 14 – yoke; 15 – adjusting screw; 16 – lock-nut; 17 – axis of yokes; 18 – rack; 19 – head of the block of cylinders


The drive of valves is carried out from the camshaft through pushers, a bar of pushers and a yoke (fig. 2.4).
The camshaft steel, shod, has five basic necks, cams of the drive of valves, a gear wheel of the drive of the oil pump and the clown of the drive of the fuel pump. Basic necks of a shaft in the block of cylinders on bearings of sliding represent the steel plugs which are filled in with antifrictional alloy (on model 4178 engines since December, 1995 and model 4218 of the plug are not established).
The drive of the camshaft is carried out from a bent shaft by couple of gear wheels with slanting teeths. A gear wheel on cranked to a shaft pig-iron, and on distributive to a shaft – a plastic wreath with a pig-iron nave. Both gear wheels have two carving openings for a stripper.

Fig. 2.5. Adjusting tags on distributive gear wheels: and – tags


Correctness of phases of distribution is provided with installation of gear wheels on tags (fig. 2.5). "About" on a gear wheel of a bent shaft the tooth hollow has to have a tag against risks on a camshaft gear wheel.

Fig. 2.6. Persistent flange of the camshaft: 1 – gear wheel; 2 – persistent flange;
3 – expansion ring; 4 – camshaft


Axial movement of the camshaft is limited to the steel persistent flange of 2 (fig. 2.6) which is between an end face of a neck of the camshaft and a nave of a gear wheel. The working gap of 0,1-0,2 mm between a nave of a gear wheel and a persistent flange is provided that the expansion ring 3 clamped between a gear wheel and a neck of the camshaft is thicker than a persistent flange.
The gas-distributing mechanism needs periodic adjustment of gaps between yokes and valves which should be carried out on the cold engine after the run 16 000 km or at emergence of signs of violation of gaps (knock of valves, reduction of engine capacity, flash in the carburetor, "shots" in the muffler) in the following order:
– pick up the vacuum regulator phone;
– carefully uncover yokes, avoiding damage of its laying;

Fig. 2.7. Adjusting tags on a pulley damper of a bent shaft: 1 – a pin on a cover of distributive gear wheels; 2 – a tag for the VMT installation; 3 – a tag for installation of the moment of ignition


Fig. 2.8. Adjustment of a gap between a yoke and the valve: 1 – plate of a spring;
2 – valve; 3 – yoke; 4 – adjusting screw; 5 – lock-nut


– install the piston of the first cylinder on a tag of 2 (fig. 2.7) on a pulley of a bent shaft in в.м.т. at a step of compression and the probe check a gap between yokes and valves of the first cylinder. At the wrong gap turn off a lock-nut of 5 (fig. 2.8) of the adjusting screw 4 and, turning the screw-driver the adjusting screw, establish a gap on the probe then, holding the screw-driver the adjusting screw, tighten a lock-nut and double-check correctness of the established gaps;
– after adjustment of gaps of the next cylinder turn a bent shaft half way and adjust gaps for other cylinders according to an order of their work: 1–2–4–3.