Acceptance Standard Of Gearbox

Acceptance standard of gearbox:
Appearance inspection;
No-load, temperature rise test;
Bearing clearance test;
Measurement test of cabinet vibration;
Measurement test of shaft vibration displacement;
Installation and adjustment requirements;
Daily inspection and maintenance of the gearbox.

Visual inspection

1. Check by visual inspection, the appearance should be glossy, the spray paint should be evenly closed, whether the end caps, upper and lower covers and other studs are complete; whether the nameplates are clearly and correct;

2. It is not allowed to fill any gasket between the split surfaces of the box, but sealant or water glass can be applied to ensure sealing; 　

3. When assembling, before tightening the box bolts, a 0.05mm feeler gauge should be used to check the tightness between the joint surface of the box cover and the box seat; 　

4. The seal of the shaft extension should be coated with grease. The sealing devices of the reducer should be installed strictly according to the requirements.

No-load, temperature rise test

Add enough clean lubricating oil according to the specified amount of oil, and carry out forward and reverse no-load test runs at the rated speed. The trial run time should be more than half an hour, and should meet the following requirements:

1. The connecting parts and fasteners must not be loose.

2. There should be no oil leakage or oil leakage at each sealing place and joint.

3. The reducer should be balanced and normal, and there should be no shock, vibration and abnormal noise.

4. The oil pump works normally and the oil path is unimpeded.

After the reducer has passed the no-load test run, it should be subjected to a load test run. The load should be slowly loaded in four stages at the rated speed in the test according to 25%, 50%, 75%, and 100% of the rated load of the reducer. The operating time of each stage is subject to the stable lubricating oil temperature rise, and the oil temperature should not exceed 100°C after continuous operation for 3 hours. If the gearbox itself has a cooling system, the oil temperature should not exceed 90°C.

Bearing clearance test

When adjusting the bearing clearance of the differential, the axial momentum of the differential can be measured with a detection meter, and the amount of clearance left can refer to the ministry standard or national standard issued by the Ministry of Communications in recent years. If there is no testing conditions and no reference data, the following methods can be used to adjust the bearing clearance:

Tighten the differential bearing adjusting nut in the opposite direction first, until the differential bearing cannot rotate, or add a sufficient washer to the bottom of the bearing thrust surface of the semi-floating rear axle case differential to prevent the differential from pulling Until the bearing rotates. Then gradually remove the pad or loosen the nut with a 0.05-0.08 mm thick washer, so that the differential can rotate freely in its position, so that it can be turned 1-2 revolutions once by hand. However, it must be noted that the bearing clearance after the differential bearing cover or semi-floating rear axle housing is tightened shall prevail. If the bearing clearance is adjusted by adjusting the nut, the bearing clearance will change after the differential bearing cover is tightened, and the bearing cannot rotate. This is the reason why the bearing housing is under pressure from the bearing cover.

The main reasons for the wear of the differential bearings are the serious lack of lubricating oil, the deformation of the differential housing, and the misalignment of the bearing necks, as well as the improper adjustment of the bearing clearance. When the bearing clearance is adjusted too large, the bearing clearance will become larger and larger, resulting in accelerated wear of the transmission joints. If the bearing clearance is adjusted too small, the frictional resistance of the bearing will be large. The bearing seat is filled with the bearing cover, that is, the bearing cover cannot shrink and deform after the bearing cover bolts are tightened, and the bearing cover cannot move in the bearing cover. High temperature is generated during transmission. In the case of poor lubrication and heat dissipation conditions, the bearing will be ablated. When the lubrication and heat dissipation are adequate, the surface of the roller rod will also be damaged (commonly known as bearing damage).

In short, adjusting the differential bearing clearance during the warranty period is the key to prolonging the service life of the bearing, so be careful when adjusting the bearing clearance and timely maintenance.

Measurement test of cabinet vibration

The vibration intensity value at the measuring point can be obtained by measuring the vibration at the bearing seat. Since the measured vibration value is an absolute quantity, the supporting structure of the test should be regarded as a fixed basic structure. During the test, at least within the speed range of the test, the resonance of the supporting structure must be avoided. The measured vibration intensity is a function of the dynamic coupling between the rotating part of the gear unit and the supporting box. The coupling is very direct when using rolling bearings. When using sliding bearings, the vibration of the shaft is more or less suppressed due to the damping effect of the oil film. Sliding bearings are greatly affected by speed, torque, load and lubricating oil. When evaluating the vibration intensity of the bearing seat, the influence of these changing factors must be considered. (Generally caused by imbalance and eccentricity) may not be strongly transmitted to the bearing seat of the gear device, but under heavy load conditions, the transmission intensity of these vibrations may be high. In addition, the high-frequency vibration caused by gear meshing will also be strongly transmitted to the bearing housing and dominate the measured box vibration signal.

When measuring box vibration, you can use a speed sensor or accelerometer. The linear range of the speed sensor measurement depends on its type, generally 10～2500Hz. When it is lower than the gear tooth meshing frequency of the high-speed gear device, the measurement range should be not low. For the accelerometer of 10kHz, the instrument must be adjusted during use. When converting the signal into a speed signal, special attention must be paid to eliminate the influence of low-frequency noise. At the same time, attention must be paid to the installation method of the sensor to ensure the linear measurement range of the instrument .

Measurement test of shaft vibration displacement

It is recommended to use a non-contact sensor to measure shaft displacement.
There are many forms of non-contact vibration sensors, and their measuring working principles are different. The main forms are: capacitive, inductive and eddy current sensors. Because the eddy current sensor has the advantages of wide frequency range, small size and insensitive to changes in working environment conditions, it is more commonly used in the measurement of gear devices.

Non-contact sensors are generally used to measure the relative movement between the gear shaft and the bearing housing. Place the two probes perpendicular to each other on the specified measurement surface, and the movement track of the gear shaft can be displayed by an oscilloscope. Most flying contact sensors (mainly referring to eddy current sensors) can be used to determine the position of the shaft in the bearing gap.

Although the eddy current sensor has a wide frequency response range (0～10kHz), generally only a small amount of shaft vibration signal can be measured when the frequency exceeds 500Hz. Therefore, non-contact sensors are not suitable for vibration evaluation above 500 Hz.
When the non-contact sensor works in the low frequency range, it can be used to distinguish the vibration influence factors related to shaft imbalance and mechanical error, such as gear radial runout, roundness, etc. It can also distinguish gear force, torque and misalignment force. The size of the additional load caused on the shaft can identify the related problems of the bearing and the possible instability.

When installing a non-contact sensor, ensure that there is no large relative movement between the sensor and the bearing or the box. It is best to use a rigid component to insert the sensor into the box, and the sensor can be contacted from the outside, and the sensor can be calibrated without opening the box cover And maintenance.
The measuring surface should be concentric with the journal and be compatible with the evaluation grade.

Installation and adjustment requirements

1. Installation of rolling bearings.
When the rolling bearing is installed, the inner ring of the bearing should be close to the shaft shoulder, and the gap should not pass through a 0.05mm thick feeler gauge.
2. Bearing axial clearance.
For bearings with non-adjustable clearance (such as deep groove ball bearings), the axial clearance is 0.25~0.4mm; for bearings with adjustable clearance, the axial clearance value is adjustable. Click to view the axial clearance of tapered roller bearings; the axial clearance of angular contact ball bearings.　
3. Tooth side clearance of gear (worm gear) meshing.
Feeler gauge or lead pressing method can be used. That is, the lead wire is placed on the tooth slot, and then the gear is turned to squash the lead wire. The sum of the thickness of the squashed lead wire on the two tooth sides is the size of the tooth side.
4. Tooth surface contact spots Cylindrical gear tooth surface contact spots 2-10-4; bevel gear tooth surface contact spots 2-11-4; worm drive contact spots 2-12-4.

Daily inspection and maintenance of gearbox

Check whether the oil level, oil temperature and oil pressure are normal every day, check whether the output, input and piping joints of the reducer are leaking, check whether the temperature of each bearing is normal, listen to whether the running sound is normal, etc., and find abnormalities immediately exclude.

1. Check the contents every day:

Whether the oil temperature (temperature rise) of the reducer is normal.
Observe whether the oil pump and cooler are turned on, whether the lubricating oil circuit is unblocked, and whether the current and pressure of the roller press are normal.
Check whether the sound of the reducer is normal and whether there is any abnormal sound.

2. Weekly inspection content:

Use kerosene or gasoline to clean the filter screen, the magnetic rod and the inner cavity of the filter housing and wipe them clean. The foreign matter from the filter needs to be precipitated, stored and analyzed. When copper scraps appear, they need to be cleaned regularly every two days. Observe the changes of the copper scraps. If the situation does not decrease, it should be shut down immediately and unpacked for inspection. This is a precursor to abnormal wear of the bearing cage.
After cleaning the reducer filter, add the lost lubricating oil. Pay attention to the grade and quality of the lubricating oil added to be consistent with the one used.
Check whether the bolts are loose, and tighten them immediately if they are loose.
Check the input shaft and output shaft of the reducer for oil leakage, noise and temperature abnormalities.
Check whether the connecting bolts between the motor and the reducer are tight every month, and check whether the connecting bolts between the reducer and the mounting base are tight every week.

3. Monthly inspection content:

Tighten the bolts connecting the reducer and the torque plate and the bolts of the locking plate. Pay attention to the tightening method according to the specifications.
Check whether the heat exchange of the cooler is normal, whether the water pressure and flow have changed, and whether cleaning measures are needed.
Check the last oil change time and make sure to change the oil every 6 months (change it immediately if it is found to be deteriorated, emulsified, etc.).

4. Annual inspection content:

Stop the machine for maintenance, remove the dust on the input and output ends of the reducer, clean the vent cap, and repaint the appearance of the paint.
Replace damaged components and replace vulnerable and consumable parts according to the problems that occur during normal use of the equipment.
Recheck whether the bolts of the shrink disk are tightened, and tighten them again with the rated torque.
Clean the cooler and the scale of the circulation system pipeline. Note that when disassembling the pipeline, it is necessary to wrap the joints with a clean cloth to prevent dust from entering the reducer.
Every three years, it needs to be returned to the factory for overhaul, replacement of damaged parts such as bearings and oil seals, and repair or replacement of individual wearing parts.

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