The hovercaft usually uses rolling bearing as supporting bearing for the shaft system. However, the operation condition of the rolling bearing in the shaft system on a hovercraft is very severe.Therefore, the proper selection of the rolling bearing type, the comprehensive consideration of the lubrication and sealing should be taken into account by the designers.It is also one of the key problems to the reliable operation of the propulsion and lifting system on the hovercraft.Industrial Bearings Solutions introduces and analyzes the service conditions, type selection,installation requirements, lubrication and sealing of the rolling bearing on the hovercraft.and presents an example of the application of the rolling bearing in the shaft system on a hovercraf.
Rolling Bearing Type:
According to the role of rolling bearings in the hovercraft's shafting, it can be divided into two categories: rolling support bearing and rolling thrust bearing. According to the configuration of rolling bearing in the hovercraft's shafting, it can also be divided into two types: locating bearing and floating bearing. In the hovercraft's shafting, axially bidirectional bearings are called fixed bearings, and all types of bearings that are capable of bearing axial thrust except radial load are suitable for locating bearings. X or O type diagonal contact ball bearings (general type) and pair tapered roller bearings can also be used as locating bearings. The thrust bearing is the bearing bearing floating bearing in the shaft system to compensate for axial thermal expansion. Almost all bearings without axial guidance can be used as floating bearings. Socket movement. In the small and medium sized all hovercraft hovercraft shafting, the aligning bearing (ball or roller) and the centripetal ball bearing are often used as floating bearings. In the combination of the locating bearing and the floating bearing, the bearing can axially guide the axle in two directions, and the floating bearing compensates for the thermal expansion difference between the shaft and the bearing block. When two sets of bearings are used to support the shaft, there is only one axial bearing, and the other bearings are floating bearings.
High Temperature Adaptability Of Rolling Bearings:
The working temperature of rolling bearings in the hovercraft shafting is generally not higher than 120 degrees. If the cage made of glass fiber reinforced polyamide 66 is used, it can even endure higher temperature in a short time. However, when the bearing is lubricated with oil, if the oil contains additives, it may affect the service life of the cage.
High Speed Adaptability Of Rolling Bearings:
In the bearing sample,the "limit speed" data are usually given. When the speed of the rolling bearing rises to a certain limit, it can no longer guarantee normal and uniform operation. At this time, the inertia force and minimal shape deviation of the rolling body and cage can lead to the change of operation and the deterioration of the lubrication state, which will increase the friction and wear of the working face.The "limit speed" given by the general bearing company sample is based on engineering practice,and has considered some additional conditions, such as smooth operation, effective seal and suitable lubrication.When the speed and high speed increase, the bearing load should not be too small, and it should not be lower than P/C =0.02. The working speed of bearings should never exceed the limit speed, even if the bearing working conditions and cooling conditions are better.
Rolling Bearing Coordination:
Fit tolerance between the inner ring and the rolling axis,the outer ring and housing is standardized in ANSI / ABMA in.With parts of the bearing characteristics required for reliable operation,depending on the operating conditions of applications.Hovercraft shaft having good flexibility,to adapt to the deformation of the hull in the storm,so that the respective floating bearing having axial mobility.Since the shaft hovercraft typically exposed to the weather deck, which is far less than the life of the bearing fatigue life,in addition to considering the reliable fixation of the bearing ring and uniformly support,installation and removal is also easy to fit when selected,so that the field of emergency replacement.By an interference fit bearing ring is easiest and most reliable way to achieve a circumferential direction of the fixing.This mounting can be prevented since the fretting between the bearing bore and the shaft outer diameter or the outside diameter relative movement between the bearing and the bearing seat produced.Interference fit uniformly supporting collar,but also achieve the purpose of full use of the bearing load capacity.The larger the load, the more interference fit should be tight,especially on the impact load.For the fit between the bearing inner ring and the shaft,while the outer ring and housing have adopted a tight fit,but the actual design tolerance fit or differentiated,generally tight fit of the bearing inner ring is greater than the outer bearing with circles.Take into consideration the difference in temperature between the fitting member and the bearing rings,the bearing also taking into account the choice of type and size fit.
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