2.10.12. Conrod and piston group
|Fig. 2.504. Components of the piston and rod: 1 – a bolt of fastening of a cover of a rod – 30 N · + to tighten m on 90 ° (1/4 about.); 2 – rod cover; 3 – bearing insert; 4 – rod; 5 – lock ring; 6 – piston finger; 7 – piston; 8 – piston rings; 9 – piston ring
Check of a thermal gap of piston rings
|Fig. 2.133. Check of a thermal gap of a piston ring
Drive a piston ring from above, at right angle to a cylinder wall, to the lower opening of the cylinder, at distance about 15 mm from its edge (fig. 2.133)
For installation use the piston without rings.
Check of a gap of piston rings on height
Before check clear a ring flute of the piston.
Check of pistons
Measure approximately in 10 mm from bottom edge, at right angle to an axis of a piston finger.
Max. deviation from the nominal size: 0,04 mm
Adjusting situation and compatibility piston/cylinder
|Fig. 2.505. Marking of adjusting provisions of pistons
The arrow indicates the bottom of the piston towards belt pulleys (fig. 2.505)
Check of diameter of the cylinder
|Fig. 2.135. Scheme of check of diameter of the cylinder
Take measurements by means of a nutromer of 50-100 mm in 3 places cross-wise in the cross direction A and in the longitudinal direction B (fig. 2.135)
Max. deviation from the nominal size: 0,10 mm
The adjusting provision of inserts of bearings in rods
|Fig. 2.506. The adjusting provision of inserts of bearings in rods
It is necessary to insert inserts of bearings into a rod or a cover of a rod in the middle.
Distance And = 2,5 mm.
Check of a vystupaniye of pistons in the top dead point
|Fig. 2.507. Check of a vystupaniye of pistons in the top dead point
At installation of new pistons or a new component of the engine check a vystupaniye of all pistons in VMT.
Depending on a vystupaniye of pistons establish the corresponding laying of a head of the cylinder according to the following table.
Marking of laying of a head of the block of cylinders
|Fig. 2.508. Marking of laying of a head of the block of cylinders: 1 – number according to the catalog of spare parts; 2 – code of management; 3 – openings
If at measurement of a vystupaniye of pistons various values were received, for compatibility with consolidation use the largest size.
Sizes of pistons and cylinders
Check of a radial beating of rods
Clear covers of bearings and a neck.
Put Plastigage thread according to bearing width on a radical neck and in inserts of bearings.
Put covers of rods and fasten with the moment 30 N · m, do not turn the crankshaft.
Again uncover rods.
Compare width of a measuring strip of Plastigage to a scale.
Limit admission of 0,08 mm.
Replace bolts of rods.