Fig. 2.4. Cranked shaft: 1–gear wreath of the sensor of provision of a cranked shaft; 2–bolt of fastening of a gear wreath of the sensor of provision of a cranked shaft; 3–cranked shaft; 4–the bottom loose leaf of a cranked shaft with a persistent fillet of the radical bearing; 5–cover of the radical bearing; 6–bolt of fastening of a cover of the radical bearing; 7–bottom loose leaf of the radical bearing; 8–top loose leaf of the radical bearing; 9–the top loose leaf of a cranked shaft with a persistent fillet of the radical bearing
The cranked shaft of the engine is shown on
Remove pistons and rods.
Remove the holder of a back epiploon and a back epiploon of a cranked shaft.
Covers of radical bearings should be numbered.
Unscrew cover bolts, remove covers together with loose leaves of bearings.
Take out a cranked shaft from support.
Remove from a cranked shaft a gear wreath of the sensor of provision of a cranked shaft.
Take out loose leaves from the block of cylinders and remove persistent half rings of the central bearing.
When dismantling put on covers of radical bearings of a cranked shaft of a label that at the subsequent assembly to establish them on former places.
Check of a technical condition
Clear a cranked shaft solvent and dry it the compressed air.
Examine radical and shatunny necks of a shaft on existence of damages, non-uniform wear and cracks.
Carry out a copper coin on the bearing. If the bearing erases copper, means, its surface is too rough and it is necessary for processing.
Be convinced of purity of oil channels. Eliminate the found defects or replace defective details.
Check a konusnost and ovality of necks of a shaft.
Nominal diameter of necks of a shaft, mm:
the radical..... 50
Ovality and konusnost of radical and shatunny necks of a shaft no more than 0,005.
Check necks of epiploons of a cranked shaft on existence of wear tracks or damages. If epiploons wiped flutes on necks, new epiploons will pass oil.
Loose leaves of radical and shatunny bearings check external survey on existence of an otslaivaniye, melting traces, прихвата. Defective loose leaves replace.
On loose leaves it is impossible to perform any podgonochny operations. At teases, risks or otsloyeniye replace loose leaves new.
Check of gaps between loose leaves and necks of a cranked shaft
For gap check between loose leaves and necks of a cranked shaft measure diameter of radical and shatunny necks, and also internal diameter of loose leaves. The gap is defined as a difference between diameter of a neck and internal diameter of the loose leaf.
Nominal gaps (engines of 1,3 l), mm:
between loose leaves and radical necks of a cranked shaft No. 1, 2, 4, 5..... 0,028–0,046
between loose leaves and a radical neck No. 3 (the central neck)..... 0,034–0,52
between loose leaves and shatunny necks..... 0,024–0,042
Nominal gaps (engines of 1,1 l), mm:
between loose leaves and radical necks of a cranked shaft No. 1, 2, 3, 4, 5...... 0,020–0,038
between loose leaves and shatunny necks..... 0,012–0,041
Check of gaps by means of the calibrated plastic wire
Gap check between loose leaves and necks of a shaft can be carried out by means of the calibrated plastic wire.
Before check wipe necks of a shaft and loose leaves for removal of oil, greasing and other pollution.
Put on a working surface of a neck a piece of the calibrated plastic wire. The length of a piece of a wire should be equal to width of the corresponding loose leaf. Besides, the wire should not block lubricant openings.
Establish a cranked shaft, loose leaves and covers of bearings.
Tighten bolts of fastening of covers the demanded moment, thus it is necessary to watch, that the shaft did not turn.
Remove covers of bearings. Determine gaps between loose leaves of the bearing and shaft necks by width of the most flattened site of a wire by means of a scale put on packing of a wire.
If gaps exceed maximum permissible, replace loose leaves of bearings. If replacement of loose leaves did not possible to receive normal gaps, прошлифуйте necks of a cranked shaft till next repair size and establish loose leaves of the corresponding repair size.
Check forward and back epiploons of a cranked shaft on existence of damages and wear of condensing edges. Replace defective epiploons.
Installation of a cranked shaft
Establish the top loose leaves of radical bearings of a cranked shaft in support in the block of cylinders.
At a reuse of loose leaves of radical bearings of a cranked shaft establish them on former places according to the labels put at dismantling.
Establish persistent half rings.
Lay a cranked shaft in support, previously having greased necks with engine oil.
Establish covers of radical bearings with the bottom loose leaves and tighten bolts of fastening of covers the demanded moment in the following order:
– cover of the average bearing;
– cover of the 2nd bearing;
– cover of the 4th bearing;
– cover of the forward bearing;
– cover of the back bearing.
Tighten bolts of fastening of covers evenly in two-three receptions before receiving the demanded moment of an inhaling.
Covers of bearings establish an arrow towards a pulley of a cranked shaft, considering numbers of covers.
Moments of an inhaling of bolts of fastening of covers of radical bearings of engines, N · м:
1,1 l...... 50–55
1,3; 1,5; 1,6 l..... 55–60
Moments of an inhaling of bolts of fastening of covers of rods of engines, N · м:
1,1 l...... 20–23
1,3; 1,5; 1,6 l...... 32–35
Be convinced of ease of rotation of a cranked shaft and compliance with norm of an axial gap of a shaft (a gap between a persistent fillet of loose leaves of the average radical bearing and cheeks of a cranked shaft).
Nominal rate of an axial gap of a cranked shaft of engines, mm:
1,1 l...... 0,05–0,25
1,3; 1,5; 1,6 l..... 0,005–0,175
Establish an epiploon in an opening in the holder of a back epiploon of a cranked shaft and press it an opravka against the stop, trying not to allow a distortion.
Establish the holder of a back epiploon and sealing laying and tighten five bolts of its fastening.
Before installation put engine oil on a working edge of an epiploon and an interfaced surface of a cranked shaft.
Establish a back cover of the block of cylinders and tighten bolts of fastening of a cover.
Establish covers of rods.
Tighten bolts of fastening of covers.
Fig. 2.5. A flywheel of the engine of cars with a mechanical transmission: 1–gear wreath of a flywheel; 2–flywheel; 3–a bolt of fastening of a flywheel to a flange of a cranked shaft
The flywheel of the engine of cars with a mechanical transmission is shown on
Fig. 2.6. A flywheel of the engine of cars with an automatic transmission: 1, 3 – connecting flanges of a flywheel; 2–leading flange of a flywheel; 4–a bolt of fastening of a flywheel to a flange of a cranked shaft
The flywheel of the engine of cars with an automatic transmission is shown on
Check a condition of a gear rim of a flywheel and in case of damage of teeths replace a flywheel. If on a flywheel from a conducted disk of coupling cracks owing to an overheat are found, it is necessary to replace a flywheel. The gear wreath of a flywheel should not be turned at a torque of 590 N · by m (60 kgfs · м) or to move in the axial direction at effort of 3,9 kN (400 kgfs).
Before removal of a flywheel from a cranked shaft put the labels defining their mutual situation in a collected condition. At engine assembly industrially the flywheel is balanced assembled with cranked shaft. Thus, their mutual situation at repair of the engine should not be broken.
On the surface of a flywheel adjacent to a flange of a cranked shaft, and a basic surface of a conducted disk of coupling scratches and teases are not allowed. The admission of not planeness of a basic surface of a conducted disk of coupling makes 0,06 mm.
Scratches and teases on a basic surface of a conducted disk of coupling remove with a pro-point, removing a metal layer in thickness no more than 1 mm. Pierce as well a surface adjacent to a flange of a cranked shaft. At a pro-point it is necessary to provide parallelism of these surfaces. Admissible not parallelism makes 0, 1 mm.
Moment of an inhaling of bolts of fastening of a flywheel of engines, N · м:
1,1 l..... 70–80
1,3 l..... 130–140
1,5; 1,6 l...... 120–130
Useful data and councils
Bearings of engines
What bearings are established in your engine? Not all motorists can answer such question intelligibly.
Nevertheless bearings there are. And not any, but quite certain. They are durable, but are not eternal, and when fail, without understanding of the main point not to manage. Well and for professional repairmen it is the most usual matter.
As the bearing works
Sliding bearings serve in modern automobile engines as support for cranked and camshafts practically in all cases. Kacheniye bearings (ball, roller, needle) apply to the similar purposes only in small motorcycle motors.
Necessary operability of bearings of sliding is reached by use of effect of a so-called oil wedge. At rotation of a smooth shaft in a gap between shaft and an opening oil moves. As the loading operating on a shaft, causes its excentric shift, oil is as though tightened in a being narrowed part of a gap and forms the oil wedge interfering contact of a shaft with walls of an opening. The more pressure and viscosity of oil in a gap, the big loading (before contact of surfaces) maintains the sliding bearing.
The actual pressure of oil in a zone of a wedge reaches 50–80 MPas (500–800 kg/cm
), and in some designs and it is more. It in hundreds times is higher, than in submitting system (system of greasing of the engine). However it is not necessary to think that pressure of giving influences operation of the bearing a little. The it is higher, the there is an oil pumping via the bearing more intensively and better it is cooled with that.
Under certain conditions the operating mode with the minimum friction (it also call liquid) can be broken. It happens at fall of viscosity of oil, for example because of its overheat owing to insufficient giving, and decrease in frequency of rotation of a cranked shaft at loading increase.
Quite often, especially after engine repair, not optimum geometry of knot affects also. At an insignificant deviation of a form of surfaces from cylindrical, at a distortion of axes and other defects of details probably local increase of specific loading (i.e. the loading carried to the area of a surface) above an admissible limit. Then the oil film in these parts becomes thin, and surfaces of a shaft and the bearing start to adjoin on microroughnesses. There is a mode of the semi-liquid greasing, being characterized increase of a friction and a gradual warming up of the bearing. Further it can lead to a so-called boundary friction with complete contact of the rubbing surfaces the overheat, skhvatyvany (teases), jamming, fusion and bearing destruction will be which consequence.
It is clear that in operation the mode of a boundary friction is unacceptable. Nevertheless it takes place at violation of supply of oil, and it occurs because of its shortage in a case more often: or owing to oversight of the driver, or at damage of the pallet of a case as a result of arrival on an obstacle.
The mode of semi-liquid greasing is admissible only for short time when he does not manage to affect wear of the bearing. An example – start-up of the cold engine. However, there is other danger: at very low temperature oil can become too viscous and its normal giving is restored too long (20–30 with and more). In this case and semi-liquid greasing is capable to affect wear of details considerably.
Improvement of a design of automobile engines is connected with continuous increase of frequency of rotation of a cranked shaft and increase in engine capacity. The tendency to increase in compactness of designs, including reduction of width and diameter of bearings is at the same time observed. It means that specific tension grows in knot of a friction. And as load of the bearing at operation of the engine cyclically changes on size and the direction, the probability of so-called fatigue failure of details increases. To provide operability of bearings in such conditions, special designs, materials and technologies are required.
As the sliding bearing is arranged
Usually bearings of cranked shaft in modern engines are carried out in the form of thin-walled loose leaves or plugs in thickness from 1,0 to 2,5 mm (it is rare more). Loose leaves of radical bearings of a cranked shaft do to thickness because of need to place in them a circular flute for supply of oil to shatunny bearings. The general tendency – reduction of thickness of loose leaves which now averages 1,8–2,0 mm at radical and 1,4–1,5 mm at shatunny bearings. The loose leaves are thinner, the better they adjoin to a surface of the case of the bearing (bed), heat from the bearing is better allocated for that, the geometry, less admissible gap and noise at work is more exact, it is more knot resource.
That at installation in a bed the loose leaf precisely accepted its form, in a free condition it should have a tightness on diameter of a bed (so-called straightening) and not cylindrical form of variable radius. Besides, the tightness is necessary for a good prileganiye to a surface and keeping from a provorachivaniye and on length of the loose leaf – it call a vystupaniye. All these parameters depend on thickness, width and diameter of loose leaves, straightening averages 0,5–1,0 mm, and a vystupaniye – 0,04–0,08 mm. However for reliable operation of the bearing of it still it is not enough. About the socket line thickness of loose leaves reduce by 0,010–0,015 mm to avoid задиров in these parts. Teases can appear owing to opening deformation in the bearing case in the block of cylinders under the influence of working loading when the working gap in the bearing is small.
Materials for loose leaves can be different. Their choice depends on a choice of a material of a cranked shaft and its heat treatment, extent of speeding up of the engine and the set resource. To a certain extent affect here and traditions of automobile firm.
Loose leaves always become the multilayered. A loose leaf basis – a steel tape which provides durability and reliability of landing in the bearing case. On a basis with various ways put a layer (or some layers) the special antifrictional material which thickness makes 0,3–0,5 mm. The main requirements to an antifrictional material are a low friction on a shaft, high durability and heat conductivity (i.e. heat from a shaft surface to the bearing case is good to take away ability). The first requirement soft metals, for example alloys with the big content of tin and lead (in particular best of all provide, widely known babbits).
In the past babbits were widely applied on the low-forced low-turnaround engines. With growth of loadings durability of such loose leaves with a thick layer of babbit appeared insufficient. The problem was solved by replacement of all this layer by peculiar "sandwich" – the lead-tin bronze covered thin (0,03–0,05 mm) a layer of the same babbit. The loose leaf became multilayered.
In modern engines stalebronzobabbitovy loose leaves usually carry out chetyrekhkhsloyny (under babbit there is still very thin layer of nickel) or even five-layer when for improvement extra earnings from above the thinnest layer of tin is put on a working surface. Exactly bearings on many foreign engines so look.
Along with it the wide circulation was received also by steel-aluminum loose leaves. As an antifrictional material aluminum alloys with tin, lead, silicon, zinc or cadmium both with coverings, and without them here serve. Most often in world practice the aluminum alloy from 20 % of tin without a covering is used. It well resists to high loadings and speeds of rotation of modern engines, including
diesel engines, and at the same time possesses satisfactory "softness". Nevertheless steel-aluminum loose leaves are more rigid, than babbitovy (or with a babbitovy covering) therefore are more inclined to teases in the conditions of insufficient greasing.
Auxiliary and camshafts of engines rotate, as a rule, with smaller frequency, than cranked, and test much smaller loadings therefore it is easier than a condition of their work. Loose leaves and plugs of these shaft usually do of the materials similar described. Besides, here sometimes apply babbit or bronze without a covering. Often these bearings at all have no plugs or loose leaves and are formed directly rastachivaniy openings in a head of the block of cylinders. In such designs the head is executed from an aluminum alloy with silicon which possesses quite good antifrictional properties.
The general for bearings of modern engines, especially if it is a question of support of cranked shaft, compliance of a material and a design of loose leaves to a material and operating conditions of a shaft (frequency of rotation, loading, a greasing condition etc.) is. Therefore any replacement of details when, for example, at repair put loose leaves from other engine, cannot be recommended. Otherwise the durability of the repaired unit can appear very small. to decide on such step, it is necessary to have the relevant information.
Loose leaves of bearings of sliding represent very exact (precision) details. to guarantee small, but quite certain (on the average 0,03–0,06 mm) working gaps in bearings, when manufacturing maintain thickness of the loose leaf with accuracy about 5-8 microns, and length – 10–20 microns. Violation of these requirements can lead to change of a working gap in the bearing or density of landing of the loose leaf in the case that is inadmissible as can lead to decrease in reliability and a resource of all engine as a whole.
Who makes sliding bearings
Complexity of all circle of the problems connected with creation of high-quality automobile bearings of sliding, led to that their production gradually passed to specialized firms. Abroad many of such firms at the same time let out also other details for engines, and deliveries go both on conveyors of automobile plants, and in sale – in the form of spare parts. Some firms such are a part of known multinational production and commercial and industrial corporations. From world manufacturers of bearings of sliding for engines it should be noted firms Kolbenschmidt (KS), Glyco, TRW, Sealed Power, Glacier, Clevite, Bimet first of all. In recent years bearings started to do and such firms "korifei", as Mahle and Goetze. Among "young" it is necessary to mention the specialized firm King (Israel) which has begun release of bearings in the early eighties of the last century. The majority of the listed producers issues the huge nomenclature of bearings and delivers the production in spare parts everywhere, including on our market (through dealers or the wholesale trading companies). Generally certainly, it is bearings for engines of foreign cars – European, Japanese and American.
It is possible to find loose leaves in sale both standard, and the various repair sizes (differing from standard, as a rule, no more than on 0,75 mm) for the majority of widespread models. On less widespread models, and also in need of purchase of loose leaves of the bigger repair size usually it is necessary to make out the order and to wait on the average for 5-10 days (at different trading companies these terms are various).
Quality of such production usually does not cause doubts neither on geometry, nor on materials. Though, if there is a choice and doubts in what firm manufacturer to prefer, it is necessary to mean the following. Such firms as Kolbenschmidt, Glyco, Glacier are one of main suppliers for mass production. Upon purchase of their products it is possible even to receive the same loose leaves that put on engines «at the birth». The difference consists only in absence on new details of an emblem of firm – the manufacturer of the car. By the way, search "native" (or so-called original) loose leaves of the repair sizes can appear problematic. Not all automobile firms deliver repair loose leaves in the spare part and the price of loose leaves in "original" packing is, as a rule, much higher, than directly from their producer.
Loose leaves of production of other, less eminent firms are usually cheaper, though will find differences as manufacturing difficultly. Moreover, if there is a choice, here it is possible to try to consider and car service conditions. So, rather cheap loose leaves, strangely enough, resist to bad quality oils and маслофильтрам, "walking" on our shops and the markets, than more expensive stalebronzobabbitovy slightly better. It practice of use under repair steel-aluminum loose leaves of King firm instead of the regular bronzobabbitovy, in particular, showed: such replacement does not put a damage of reliability of engines, but allows to save considerably.