Valve gear

The valve mechanism consists of the following elements:

- Valves;

- Valve guides;

- The valve seats;

- Valve springs;

- Plates and crackers fixing the valve assembly with a spring;

- Pushers;

- Two camshafts.

Valves

Valves (Fig. 3.7) are made of heat-resistant alloy steel. Working facet of the exhaust valves are covered with stellite. Basic parameters of valves are shown in Table. 3.3.

Valve seats

Saddles (Fig. 3.8) valves are pressed into the combustion chambers of the cylinder head. Main valve seats parameters given in Table. 3.4.

Guides

sleeve valves

Valve guides pressed into the lower section of the cylinder head and the parameters are specified in the Table. 3.5.

The maximum clearance between the guide and operating the inlet (outlet) valves - 0.15 mm.

Valve spring

The outer diameter of the valve springs (Fig. 3.9) - 27,7-28,1 mm internal diameter - 20,08-20,12 mm.

The valve spring is checked by inspection and measurement of the height in the free state and under load. The values of load and the corresponding elevation values shall conform to Table. 3.6.

Hydraulic

valve tappets

Pushers (Fig. 3.10), hydraulic, self-adjusting, filled with oil. A spring disposed in the cylinder follower, keeps it in contact with the camshaft; the force of the spring below the spring force of the valve, which provides linear movement of the latter.

The check valve prevents the squeezing of oil when exposed to a cam follower on the camshaft and excess oil pressure in the cylinder pushrod over the oil pressure in the engine lubrication system.

Hydraulic pusher has three modes of operation.

Mode 1 (fig. 3.11) - when the plunger is in contact with the base circle of the cam of the camshaft, oil from the bearing channel of the camshaft via tappet enters the groove and a hole in the side surface. The oil passes through a slot located in the upper part of the pusher, and supplied to the cylinder pushrod. When the pusher does not affect the contour of the cam, engine oil pressure is higher than the oil pressure in the cylinder and a pusher of the oil passes through the check valve of the cylinder pushrod.

Mode 2 (fig. 3.12) - when the plunger is pressed down, the oil pressure in the cylinder becomes higher than its oil pressure in the engine, the check valve closes and the plunger acts as a rigid body.

Mode 3 (Fig. 3.13) - when returning to the pusher contact with the base circle of the cam camshaft engine oil pressure above the oil pressure in the cylinder pushrod. The check valve is opened by passing the oil that provides the pressing pusher camshaft.

The main parameters of hydraulic pushers are shown in Fig. 3.14, and are shown in Table. 3.7.