Requirements for parts of the gas distribution mechanism ZIL-5301
The gas distribution mechanism consists of a camshaft, intake and exhaust valves, as well as parts for their installation and drive: pushers, rods, rocker arms, adjusting screws with nuts, plates with crackers, springs, struts and rocker arm axles
Pushers are steel, have spherical bottoms.
As a result of the fact that the camshaft cams are made with a slight inclination, the pushers perform a rotational movement during operation.
Push rods are made of steel rod. The spherical part that goes inside the pusher and the rod cup are hardened.
The valve rocker arms are made of steel and swing on an axis mounted on four racks. The outer pillars are of increased rigidity.
The rocker axis is hollow; has eight radial holes for lubrication of rocker arms. The movement of the rocker arms along the axis is limited by spacer springs.
Inlet and exhaust valves are made of heat-resistant steel. They move in guide bushings pressed into the cylinder head.
Each valve closes under the action of two springs, external and internal, which act on the valve through a plate and crackers.
The sealing collars installed on the valve guides prevent oil from entering the diesel cylinders through the gaps between the valve stems and the valve guides.
The working surfaces of the camshaft bearing journals and cams must be clean, without nicks or marks.
The height of the camshaft cams should be 41.32 ± 0.05 mm.
The surfaces of the cams must be machined to a cone (Fig. 2).
The larger base of the cone should be on the side of the camshaft gear.
The diameters of the camshaft journals must be at least 49.88 mm (for a new shaft - 50-0.050 mm).
The non-roundness and tolerance of the longitudinal section profile of each camshaft journal is 0.01 mm.
The camshaft oil passages must be clean, without traces of tar deposits.
The channels must be thoroughly washed and blown with compressed air.
The gear must be pressed onto the camshaft until it stops.
The bolt securing the gear to the camshaft must be tightened to a torque of 110…160 Nm.
The gap between the end of the journal of the assembled camshaft and the thrust flange (axial play of the shaft) is allowed within 0.3-1.04 mm (see Fig. 2).
The bushing must be pressed into the intermediate gear flush with the ends.
The surfaces of the ends of the gear and bushing must be clean and free of dents. Roughness of processed surfaces - Ra≤2.5 microns.
The inner surface of the intermediate gear bushing must be clean, without marks or burrs. The roughness of the processed surface is Ra≤2.5 microns.
The non-roundness and tolerance of the longitudinal section profile of the inner surface of the intermediate gear bushing is 0.008 mm.
The splined flange of the fuel pump drive gear must fit freely into the splines of the pump shaft bushing without jamming.
The replacement fuel pump drive gear bushing should be pressed in from the side of the short hub until the bushing stops at the end of the gear hub.
When adjusting the gap between the end of the adjusting bolt and the surface of the bar, the adjusting bolt should be screwed all the way into the bar, then unscrewed ⅓... ½ turn and secured with a nut.