Due to the size of the diameter of axle and bearing hole measurement inaccuracy or cooperate with surface roughness, do not meet the standard requirements to cause excessive interference fit, make the NSK bearing race is being squeezed from a large, resulting in the radial clearance of bearing itself is reduced, the bearing rotating difficulties, fever, wear or jammed, caused serious bearing inner and outer race in cracking during installation.
Not rotating seat clearance or interference is often used not to cooperate, so not rotating seat is likely to produce tiny creep, and make the seat and the contact surface of roller changing, seat ring raceway wear uniform.
At the same time can also eliminate the shaft in the bearing due to thermal elongation roller axial stuck phenomenon.
Clearance fit, but too much will make not rotating seat with roller rotation, the axis (
Or bearing hole)
And the inner race (
Or the seat)
Serious wear and friction bearing heating, vibration occurs.
B。
NSK bearings and trunnion or improper assembly method of the bearing holes are smaller, more assembly pressure into the method.
The simplest method is to use copper bar and hammer, according to certain order way symmetry on bearing seat with interference fit, the bearing pressure into the smoothly.
In addition, also can use soft metal casing borrowed hammer into or press press.
If improper operation, it will make the seat deformation craze, or a hammer hit the interference fit in the seat, will make the raceway and rolling body produces indirect indentation or bearing was damaged.
C。
NSK bearing assembly time, improper control of temperature in the assembly, if its interference with diameter of axle is bigger, generally USES the hot pack assembly.
The bearing in cans containing oil, engine oil barrels outside with hot water or flame heating, heating process requirement of the oil temperature control at 80 ℃ ~ 90 ℃, generally will not exceed 100 ℃, most will not exceed 120 ℃.
Bearing heated rapidly remove the suit on the journal.
If improper temperature control heating temperature is too high, the bearing causes tempering hardness due to lower, in the operation of the bearing is easy to wear and spalling, and even cracking.
D。
Improper assembly clearance adjustment of rolling bearing clearance is divided into radial clearance and axial clearance, its function is to guarantee the normal operation of the rolling body and lubrication and compensating thermal elongation.
For bearing clearance can be adjusted, because of its axial gap and radial gap there is a direct proportion relationship between, so the installation is adjust axial clearance can be obtained as long as the radial clearance, but they are usually in pairs (
In the ends of the shaft or end)
And, therefore, only need to adjust a bearing axial clearance.
Generally, gasket, is used to adjust axial clearance, some screw or thrust ring adjustment is also available.
For NSK bearing clearance shall not adjust, because of the radial clearance as defined by the standard in manufacturing has been good, can't adjust, such loading on the diameter of axle bearing or bearing hole, after the actual radial clearance is called assembly radial clearance, assembly time to assemble the size of the radial clearance just can make the necessary work in the operation of radial clearance, to ensure the flexible bearing rotation.
Such bearings at work, because the axial thermal elongation during temperature rise and make them seat relative displacement, so as to reduce the bearing radial clearance, even make the roller stuck between the inner and outer race.
If one of the two bearing roller bearing bearing (
Another bearing fixed on the shaft and bearing seat)
Set aside axial clearance between and side cover, can avoid the above phenomenon.
Phenomenon: 1)
In general engine running stability and no sound, when the engine speed changes suddenly a depressing 'boring boring' tapping, at the same time accompanied by vibration phenomenon.
2)
Change the engine load, and the noise.
The higher the speed, the greater the noise.
3)
Single cylinder 'fire' feel change, and in the adjacent two cylinder sound fire at the same time will be significantly weakened.
Reasons: 1)
Crank shaft and the shaft neck fit clearance is too large.
2)
The crankshaft and the axial clearance is too large.
3)
The crankshaft bearing cap is loose.
4)
Crankshaft bearing and cause poor lubrication journal bearing alloy ablation falls off and ring.
5)
Crankshaft bending deformation, the crankshaft journal circles.
6)
The crankshaft bearing and bearing relative rotation.
Diagnosis: 1)
The noise from the lower cylinder body near the crankcase.
Oil pressure decreases obviously.
Engine in the condition of low and medium speed jitter throttle, a clear and depressing continuous beat accompanied by engine vibration phenomenon.
2)
High-speed engine, the body vibration is larger, a significant reduction in the oil pressure at the same time, for the NSK bearings and shaft neck clearance is too large or bearing alloy ablation fall off.
3)
Single cylinder fire test sound a little change, and the adjacent two cylinder break fire sound significantly diminished or disappeared, it is between the two cylinder crankshaft bearing ring.
4)
Speed is not high but the body vibration is larger, a swing shaking phenomenon, at the same time issued a heavy and large 'boom boom' tapping is a fracture.
5)
Increases with temperature rise and noise to the sound become cluttered, may be the crankshaft bending.
