2.2.24. Check of conrod necks and conrod bearings

Fig. 2.145. Measurement of ovality and conicity of a conrod neck micrometer

Check conrod necks for existence of signs of uneven wear or damages. Measure ovality and conicity of a conrod neck by a micrometer. If the conrod neck has damages or its ovality or conicity exceed extreme values, replace a bent shaft or a proshlifuyta a conrod neck with reduction of its diameter to the next repair size and use inserts of the reduced size.

Extreme values on ovality and conicity of 0,01 mm.

Fig. 2.146. Scheme of check of a conrod bolt

Deformation of a conrod bolt (a bolt with an inhaling in a zone of plastic deformation).

Measure diameter of a carving of a conrod 1 bolt 2 in points of "A" and "B" by a micrometer 3. Calculate a difference of diameters ("A" - "B"). If the difference exceeds extreme value, replace a rod.

Scheme of measurement of a conrod bolt "a": 32 mm, "b": 40 mm.

Extreme value of a difference of diameters of a conrod bolt ("A" - "B"): 0,1 mm.

For repair conrod bearings of the nominal size and bearings increased are delivered (under necks of a bent shaft of the reduced diameter) on 0,25 mm of thickness, bearings of the nominal size are broken into 5 types differing according to the admission.

Fig. 2.147. Connecting rod: 1 – red paint

For identification of the bearing of the increased thickness, marking of red color which is put, as shown in the figure 2.147 is used, thickness of the bearing of the increased thickness makes 1,605–1,615 mm in the central part.

Check bearing inserts for existence of signs of an oplavleniye, pointed corrosion, a prozhog or stratifying, also examine a contact spot print. Defective inserts of bearings have to be replaced.

Before check of a gap in the bearing clear bearings and conrod necks.

To establish inserts in a rod and a cover of a rod.

Put a piece of the calibrated plastic wire 1 on the surface of a conrod neck (parallel to a bent shaft) so that it did not close the oil channel.

Fig. 2.148. Laying of a piece of a calibration wire

Establish a cover of a rod 1 on a rod.

Fig. 2.149. Installation of a cover of a rod

At installation of a cover you watch that the tag in the form of an arrow 2 on a cover was turned towards a pulley of a bent shaft, as shown in the figure 2.149. Oil engine conrod bolts, gradually tighten deaf nuts 3 as follows.

and. Tighten all nuts the moment of 15 N · m.

b. Repeatedly tighten them on 45 °

c. Repeat operation b) once again.

Deaf nut of the conrod bearing (a): tighten the moment 15 N · m, tighten on 45 ° and 45 °

Uncover and determine gap size by flattening of the calibrated plastic wire 2 in the widest place, using a scale 1 on packing of the calibrated plastic wire.

If the gap exceeds extreme value, use the new bearing of the nominal size. After selection of the new bearing check a gap again.

Nominal rate: 0,029–0,047 mm.

Extreme value: 0,065 mm.

If the gap cannot be normalized by installation of the new bearing of the nominal size, a proshlifuyta a conrod neck to the next repair size and use the bearing of thickness increased by 0,25 mm.

NOTE After check of a gap in the conrod bearing check deformation of conrod bolts.

Fig. 2.151. Marking on a rod and its cover: A – No. of internal diameter of the lower head of a rod; B – tag of the indication of weight

Check No. on a rod and its cover, as shown in the figure 2.151.

NOTE If the bearing is in an unsatisfactory state or the gap in the bearing – differs from norm, pick up and install the new bearing of the nominal size as follows. When replacing for any reason of a bent shaft or a rod with the bearing, pick up new bearings of the nominal size for numbers which are beaten out on a rod and its cover and/or to the letters which are beaten out on a cheek of a bent shaft near the 3rd cylinder.

Three No. ("1", "2" and "3") correspond to the following internal diameters of the lower head of a rod.

For example, No. "1" specifies that the internal diameter of the lower head of a rod makes 45,000–45,006 mm.

Then check diameter of a conrod neck of a bent shaft. On a cheek of a bent shaft No. 3 four letters, as shown in the drawing are beaten out. Three letters ("A", "B" and "C") correspond to the following diameters of conrod necks of a bent shaft. For example, the letter "A" specifies that the corresponding diameter of a conrod neck of a bent shaft makes 41,994–42,000 mm

Fig. 2.152. Marking of outer diameter of conrod necks of a bent shaft: A – diameter of a conrod neck of a bent shaft of the cylinder No. 1; B – diameter of a conrod neck of a bent shaft of the cylinder No. 2; C – diameter of a conrod neck of a bent shaft of the cylinder No. 3; D – diameter of a conrod neck of a bent shaft of the cylinder No. 4

Fig. 2.153. Color marking of inserts of conrod bearings: 1 – color marking

There are five types of bearings of the nominal size differing on thickness. For distinction they have identification tags of the following flowers in the places shown in the figure 2.153.

Every color corresponds to a certain thickness of the central part of the bearing.

Fig. 2.150. Measurement of the flattened piece of a calibration wire

Using a scale 1 on packing with the calibrated plastic wire 2, check a gap in the bearing for the picked-up bearing of the nominal size (fig. 2.150). If gap size still exceeds extreme value, install the bearing of the increased thickness and again check a gap.