The civil air defense project is of great significance to the safety of people's lives and property. The civil air defense emergency command vehicle plays an important role in the entire civil air defense system. In the process of wartime drills, the civil air defense emergency command vehicle plays the role of a mobile command center, not only dispatching and commanding at the scene, but also completing communication and security assurance work. In order to better complete the air defense command work, the Air Defense Emergency Command Center has concentrated on many high-tech applications, mainly including the following.
First, advanced communication system equipment. The civil air defense emergency command vehicle 's communications system integrates the most advanced mobile communications equipment today, comparable to the wartime command vehicle communications system. Such as satellite positioning systems, satellite communications equipment, mobile communications terminals, mobile communications equipment, radio equipment. At the same time, there are devices to combat communication interference, which can ensure the smoothest communication during the war, without interference from other factors. Communication is a very important content in wartime. Only when information is unblocked can people's safety be ensured, and communication can be ensured to be able to form an effective battle plan and defense system.
Second, high-tech defense system devices. Civil defense emergency command vehicle is mainly used to prevent damage to the enemy in time of war, to ensure secure communications. The vehicle itself is not used for combat, but it must have sufficient defensive capabilities to reduce enemy damage to our communications system. For example, vehicles must have bullet-proof and explosion-proof functions, have strong repair capabilities, be able to deal with complex environments in wartime, and be able to ensure the smooth development of communications. With the continuous development of China's communication defense technology, modern civil air defense emergency command vehicles have gradually possessed these powerful functions, ensuring that wartime civil air defense emergency command vehicles can play a good role.
Third, the application of vehicle-mounted ad hoc networks. This is currently the most advanced technology of mobile network technology applied to the command vehicle. It combines the advantages of different communication networks, and it can be well applied to automobiles and become an effective part of the vehicle network system. We must know that modern communication systems must not lack the support of the network. In modern civil defense work, network technology is also one of the commanding heights to win.
Thrust Ball Bearings
Thrust ball bearings are separable and their limit rotational speed is low.
Structures:
1.51000 type single-direction thrust ball bearings, this type of bearing can only accommodate axial load on one direction and can control the axial movement on one direction of the shaft and housing.
2.52000 type double-direction thrust ball bearings, this type of bearings can accommodate axial load on double direction and can control the axial movement on double direction of shaft and housing.
3. 560000 type thrust angular-contact Ball Bearing, as this structure can carry axial load and radial simultaneously.
Cage materials
When the outside diameter is equal or lesser than250mm, thrust ball bearings generally adopt pressed steel sheet cages, when the outside diameter is more than250mm,it will adopt solid cages.
Minimum axial load
When the Thrust Ball Bearing is operating, if the applied axial load is too small, the axial direction is not tightly pressed, then acted by centrifugal force, the steel ball will slip and displace and destroy the normal operation of the bearings. To avoid the occurrence of such case, an axial load, Famin must be applied when the thrust ball bearings is working. The calculating formula is:
In the equation, Famin Minimum axial load (kN)
A Minimum load constant
N Revolution (r/min)
Minimum load constant A is showing in the bearings dimension table. If the applied axial load is small, a spring must be used to preload the bearing.
Permissible tilt angle
The double supporting surface of thrust ball bearings should be parallel. The axis center line should be square with shell supporting surface, if this is not assured, it can compensate by adopting spherical housing washer and self-aligning washer.
Tolerance
The tolerance value of thrust ball bearings is showing in the section [the tolerance of rolling bearing".
Dynamic equivalent axial load
Whenα=90°,thrust ball bearings can only carry axial load and its dynamic equivalent axial load is: Pa=Fa
Whenα≠90, acted by constant and invariable radial and axial loads, the dynamic equivalent axial load is: Pa=XFr+YFa
See Annex Table 1 for the coefficients of X and Y.
Static equivalent axial load
Whenα=90°, the static equivalent axial load is: P0a=Fa;
Whenα≠90°, the static equivalent axial load is: P0a=2.3Frtanα+Fa.
Where: For double-direction bearings, this equation is applicable to the status when the ration of radial load and axial load is an arbitrary value; for single-direction bearings, when Fr/Fa≤0.44ctgα, the equation is reliable; when, the Fr/Fa＞0.67ctgα, the equation can still give satisfactory P0avalue, but not very conservative.
Table 1 Value of X and Y
|
α1) |
Single-direction Bearings2) |
Double-direction Bearings |
e |
||||
|
|
|
|
|||||
|
X |
Y |
X |
Y |
X |
Y |
||
|
45º 3) 50º 55º 60º 65º 70º 75º 80º 85º |
0.66 0.73 0.81 0.92 1.06 1.28 1.66 2.43 4.8 |
1 |
1.18 1.37 1.6 1.9 2.3 2.9 3.89 5.86 11.75 |
0.59 0.57 0.56 0.55 0.54 0.53 0.52 0.52 0.51 |
0.66 0.73 0.81 0.92 1.06 1.28 1.66 2.43 4.8 |
1 |
1.25 1.49 1.79 2.17 2.68 3.43 4.67 7.09 14.29 |
|
α≠90º |
1.25tanα×
(1- |
|
(1- |
(1- |
1.25tanα×
(1- |
|
1.25tanα |
Notes: 1) For α`s medium value, use linear interpolation to calculate the values of X, Y and e.
2) Fa/ Fr≤e is not applicable to single-direction bearings.
3) For thrust bearings withα>45°, use interpolation method to calculate the value of whenα=45°.
Thrust Ball Bearing
One Row Thrust Ball Bearing,Two Row Thrust Ball Bearing,Angular Contact Thrust Ball Bearing,Aligning Housing Ring Thrust Ball Bearing
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