reference will now be made in detail to the present embodiments of the present invention , examples of which are illustrated in the accompanying drawings , wherein like reference numerals refer to the like elements throughout . the embodiments are described below in order to explain the present invention by referring to the figures . however , the present application is not limited to the embodiments . fig1 and 2 show side and plan views of a bogie apparatus according to the present application , respectively . the bogie apparatus according to the present application is composed of front and back rotation bogie parts respectively disposed at both ends of a chassis and a composite motion bogie part located at a middle portion of the chassis , wherein the front and the back rotation bogie parts are identical in structure to each other , and thus only one rotation bogie part will be described for purpose of brevity . the rotation bogie parts comprises : an upper inner ring permanent magnet 1 , an upper outer ring permanent magnet 2 , a shaft 4 , a lower inner ring permanent magnet 5 , and a lower outer ring permanent magnet 6 . the upper inner ring permanent magnet 1 is a continuous circular ring and is fixed on a lower surface or a bottom surface of the chassis 15 . the upper outer ring permanent magnet 2 is an discontinuous circular ring and fixed on the lower surface or the bottom surface of the chassis 15 while being located outside the upper inner ring permanent magnet 1 . the upper inner ring permanent magnet 1 and the upper outer ring permanent magnet 2 are arranged concentrically . that is , they have an identical central rotation axis . an upper sleeve 3 is disposed to the chassis 15 at the central rotation axis . the lower inner ring permanent magnet 5 is a continuous circular ring and is fixed on an upper surface or a top surface of a bogie body 16 of a bogie . the lower outer ring permanent magnet 6 is a discontinuous circular ring and fixed on the upper surface or the top surface of the bogie body 16 while being located outside the lower inner ring permanent magnet 5 . the lower inner ring permanent magnet 5 and the lower outer ring permanent magnet 6 are arranged concentrically , that is , they have an identical central rotation axis . a lower sleeve 7 is disposed to the bogie body 16 at the central rotation axis . a shaft 4 has one end fixed in the lower sleeve 7 of the bogie body 16 and the other end fitted in the upper sleeve 3 of the chassis 15 , so that the chassis 15 located above and the bogie body 16 located below are rotatably connected to each other via the shaft 4 . in addition , a position limiting cover 17 is disposed above a top of the upper sleeve 3 of the chassis 15 and fixed to the shaft 4 to restrict the shaft so that the shaft 4 can only rotate and slide up and down in the upper sleeve 3 and can not be drawn out of the upper sleeve 3 . after the chassis 15 and the bogie body 16 are connected via the shaft 4 , the upper inner ring permanent magnet 1 and the upper outer ring permanent magnet 2 fixed on the chassis 15 are aligned with the lower inner ring permanent magnet 5 and the lower outer ring permanent magnet 6 fixed on the bogie body 16 , and identical poles of the upper inner ring permanent magnet 1 and the upper outer ring permanent magnet 2 fixed on the chassis 15 and the lower inner ring permanent magnet 5 and the lower outer ring permanent magnet 6 fixed on the bogie body 16 face one another . as show in fig1 b , in an assembled state , the upper inner ring permanent magnet 1 is superposed on or coincided with the lower inner ring permanent magnet 5 in the plan view , and the upper outer ring permanent magnet 2 is superposed on or coincided with the lower outer ring permanent magnet 6 in the plan view . an air gap of 3 - 100 mm is formed between the upper inner ring permanent magnet 1 and the upper outer ring permanent magnet 2 fixed on the chassis 15 and the lower inner ring permanent magnet 5 and the lower outer ring permanent magnet 6 fixed on the bogie body 16 . with the above configuration , the shaft 4 assures that the upper inner ring permanent magnet 1 and the upper outer ring permanent magnet 2 fixed on the chassis 15 and the lower inner ring permanent magnet 5 and the lower outer ring permanent magnet 6 fixed on the bogie body 16 strictly correspond to one another , so that they cannot be horizontally displaced relative to one another when the chassis 15 and the bogie body 16 rotate horizontally and incline backward and forward at a small angle . since the same poles face each other , a repulsion levitation force for levitating a car is generated . a net magnetic energy of the repulsion levitation force decreases with an increase of the air gap according to the law of a power function . this magnetic field of a circular ring arrangement increases an area of the chassis on which the force acts , so that a load acting on the chassis is dispersed and thus life of the bogie apparatus can be prolonged . in order to increase the rotary performance of the shaft 4 , a bush 22 is provided between the shaft 4 and the upper sleeve 3 . a magnetic levitation force and power chamber 19 is disposed under the bogie body 16 as a magnetic levitation force and power device of the vehicle . since the magnetic levitation force and power chamber 19 is well known and is not a key point of the present application , the detailed description thereof is omitted . referring to fig1 , and 4 , a composite motion bogie part is disposed at a middle position of the chassis 15 . the composite bogie part comprises a plurality of upper strap permanent magnets 8 arranged parallel to one another across the chassis 15 and fixed on the lower surface of the chassis 15 . a plurality of lower strap permanent magnets 11 corresponding to the plurality upper strap permanent magnets 8 in a one - to - one manner are fixed on an upper surface of a bogie body 16 of a further bogie . identical poles of the upper strap permanent magnets 8 and the lower strap permanent magnets 11 face each other , and there is an air gap of 3 - 100 mm between the upper strap permanent magnets 8 and the lower strap permanent magnets 11 . as show in fig1 b , in an assembled state , the upper strap permanent magnets 8 is superposed on or coincided with the lower strap permanent magnets 11 in the plan view . each of the upper strap permanent magnets 8 and the lower strap permanent magnets 11 may be formed by a one - piece strap permanent magnet , or a plurality of short strap permanent magnets arranged across the chassis 15 at an interval equal to or greater than 50 mm . that is , there is a gap of ≧ 50 mm between two adjacent short strap permanent magnets . in an embodiment as shown in fig1 b , four rows of the upper strap permanent magnets 8 and the lower strap permanent magnets 11 are provided , and each row of the four rows of the strap permanent magnets is composed by two short strap permanent magnets . however , the present application is not limited to the above embodiment , the arrangement of the upper strap permanent magnets 8 and the lower strap permanent magnets 11 may be varied as desired . a translation track base 9 is mounted at a shaft hole position on the chassis 15 at a center of the plurality of the upper strap permanent magnets 8 . a translation sleeve 10 is disposed in the translation track base 9 . a lower sleeve 12 of the composite motion bogie part is disposed on the bogie body 16 at a center of the plurality of the lower strap permanent magnets 11 . a shaft 13 of the composite motion bogie part has one end fixed in the lower sleeve 12 of the composite motion bogie part , and the other end fitted in the translation sleeve 10 of the chassis 15 , so that the chassis 15 located above and the bogie body 16 located below are rotatably connected to each other through the shaft 13 . in addition , a position limiting cover 17 is disposed above a top of the translation sleeve 10 and connected to the shaft 13 to limit the shaft 13 so that the shaft 13 cannot be drawn out of the translation sleeve 10 . with the above configurations , the shaft 13 of the composite motion bogie part can rotate and slide up and down in the translation sleeve 10 , and can horizontally slide transversely along with the translation sleeve , thereby achieving a composite motion . among the three motions , the horizontal motion and the up and down sliding motion are primary ones , while the rotation is a minor secondary one , so that the magnetic levitation force is not adversely affected . with the above configurations , a problem in turning of a long car is solved by coupling of the road and the vehicle . the operation principle of the bogie apparatus according to the present application is as follows : the rotation bogie parts disposed at both front and back ends of the chassis only rotate horizontally , while the composite motion bogie part located at the middle portion of the chassis horizontally translates in a left and right direction and rotates . a distance of the translation is inversely proportional to a radius of curvature of the swerving vehicle , but the rotation is minor . therefore , the present application solves the problem in the scenario that the long car swerves on a road of a small radius of curvature . the bogie apparatus according to the present application may be applied to magnetic levitation trains , wheel - rail trains , and long cars . the bogie apparatus according to the present application has the following advantages . 1 . the bogie apparatus according to the present invention is simple in structure , small in friction , flexible in turning , and long in life . 2 . the area on which the force acts between the chassis and the bogie bodies is enlarged , and the load is dispersed . in addition , the air gap does not transfer vibration between lower and upper structures of the vehicle and thus resonance cannot occur . as a result , the vehicle is safe and comfortable . 3 . the bogie apparatus is simple in manufacturing process and itsmanufacturing cost is low . 4 . a length of the vehicle can be increased and the load of the vehicle on the road can be distributed uniformly . although a few embodiments of the present invention have been shown and described , it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention , the scope of which is defined in the claims and their equivalents .