the technical solution of the present invention is described below in further detail in accompanying with the attached drawings . as shown in fig1 , 3 and 4 , a medical rehabilitation bed includes a bed head , a bed tail and a bed board , wherein a pull rod is arranged at the bottom of the bed board . the pull rod can be arranged at the center of the bottom of the bend board . the pull rod is a rod - like structure or a solid rod - like structure , with one end mechanically connected to a bed head gearbox 101 which is arranged at the bed head , and the other end mechanically connected to a bed tail gear device which is arranged at the bed tail . transmission systems 401 having the same structure and capable of controlling the bed head and the bed tail to ascend and descend are respectively arranged in the bed head and the bed tail . the transmission systems 401 are mechanically connected to the bed head gearbox 101 and the bed tail gear device , respectively . the bed tail gear device is a bed tail gearbox 301 or a handle - containing bed tail gearbox 201 . the bed head includes a bed stand , a bed head board 402 , a bed head frame 403 , roller bayonets 404 , bayonets 405 , connectors 406 , connector dowel pins 407 , lifting racks 408 , roller fixing blocks 409 and rollers 410 . the bed stand is a dual - leg upper - lower framework structure . the bed head frame 403 is processed as a groove - shaped rigid lath structure ( namely a bottom - open groove - shaped structure which is formed by bending two ends at an angle of 90 deg toward the same direction along the same lateral face of the lath ), and is fixed at the upper border of the bed stand through plural bed head frame fixing screws 411 . the upper border of the bed stand is a bottom - open groove - shaped structure ( or the cross section of the upper border is a bottom - open groove - shaped structure ). the lower border of the bed stand is a top - open groove - shaped structure ( or the cross section of the lower border is a top - open groove - shaped structure ). the two ends of the lower border are respectively in fastening connection ( for example , welded connection ) with the two legs of the bed stand . the bed head board 402 is a rigid plate structure , fixed at the upper and lower borders of the bed stand on two sides through plural bed head frame fixing screws 411 . bed legs are hollow cylindrical rigid structures . a long hole is formed on the inner side of each of the bed legs . each of the lifting racks 408 is a hollow cylindrical rigid structure , formed with a long hole on the inner side , and inserted into a corresponding bed leg such that the long hole of the bed leg and the long hole of the lifting rack are positioned on the same side and run through each other . the upper end of each of the lifting racks 408 pins and fixes a corresponding one of the connectors 406 at the end socket through a corresponding one of the connector dowel pins 407 , and the lower end fixes a corresponding one of the roller fixing blocks 409 at the end socket through a corresponding one of the roller bayonets 404 . each of the roller fixing blocks 409 is connected with a corresponding one of the rollers 410 . each of the connectors 406 is provided with a bayonet 405 which supports a corresponding one of the bed legs ( inner side ) and performs a damping role , and the bayonet 405 is a spring . a motor gear connecting box 501 which is mechanically connected to a motor 601 is disposed at the bottom of the bed board . the motor 601 can be fixed at the bottom of the bed board . the motor gear connecting box 501 is provided with a coupling connector 507 . the coupling connector 507 is in a state of being connected or disconnected with the pull rod , which means that , by such configuration , the motor can be used to drive the pull rod to rotate ( namely connected state ), or the motor is not used to drive the pull rod to rotate ( namely the disconnected state ), and the handle is rotated to drive the pull rod to rotate . in the state in which the coupling connector 507 is connected with the pull rod , the motor 601 drives the pull rod to rotate through the motor gear connecting box 501 so that a structure is formed , in which the bed head gearbox 101 and the bed tail gear device which are disposed at the bed head or bed tail drive the bed head or the bed tail to ascend and descend respectively through the transmission systems 401 in mechanical connection . as shown in fig5 a , 5 b and 5 c , each one of the transmission systems 401 includes a support rod 412 , a support rod pin 413 , an internal - thread lifting head limiting pin 414 , a cap 415 , a spiral lifting rod 416 , a screw rod limiting pin 417 , an internal - thread sleeve 418 , an internal - thread lifting head 420 , a steel cable fixing screw 421 , fixed sleeves 422 , a sleeve opening 423 , a steel cable 424 , a steel cable roller dowel pin 425 and steel cable rollers 426 . the spiral lifting rod 416 is positioned between the upper and lower borders of the bed stand in a vertical way , and is formed with an h - shaped cylindrical cap 415 at the end socket of the upper end . the cap 415 supports or supports and fixes the upper border . the lower end of the spiral lifting rod 416 passes through the lower border and is mechanically connected to the bed head gearbox 101 or the bed tail gear device , for example mechanical coupling connection . the internal - thread sleeve 418 is a standing round tube structure , symmetrically formed with two rectangular or square through - holes on the side wall ; the side wall below the through - holes integrally extends outward ; and the extending portion is an overall rectangular plate structure which is vertical to the axis of the internal - thread sleeve 418 . the rectangular plate structure is formed with two through - holes a along one diagonal line ( which means that the rectangular plate structure is provided with two through - holes a which are symmetric to the diagonal line ), and is formed with two screw holes along another diagonal line . a through - hole b is disposed between each one of the through - holes a and each one of the screw holes . in this way , the two symmetric sides of the rectangular plate structure respectively have a through - hole a , a through - hole b and a screw hole . the diameter of each of the through - holes b is smaller than the diameter of the corresponding one of the screw holes , and the through - hole b communicates with the corresponding one of the screw holes . the purpose of such configuration is as follows : the steel cable fixing screw 421 which is fixed at the steel cable 424 passes through the larger screw hole and then enters the smaller through - hole b via a channel which communicates with the screw hole such that the steel cable fixing screw 421 is clamped and fixed at the through - hole b , and then a screw is screwed into the screw hole to fasten the steel cable fixing screw 421 without slipping ; further speaking , such structure firmly fixes the steel cable 424 at the internal - thread sleeve 418 . support rods 412 parallel to the axis of the spiral lifting rod 416 are respectively disposed on two sides of the spiral lifting rod 416 . the support rods 412 pass through the through - holes a . the two ends of each of the support rods 412 are respectively connected with the upper and lower borders of the bed stand in a riveted way . one purpose of configuring the support rods 412 is to strengthen the overall firmness of the spiral lifting rod 416 , and the other purpose is to provide the support rods 412 as guide columns , which facilitates the vertical movement of the internal - thread sleeve 418 on the spiral lifting rod 416 to play a supporting function . the spiral lifting rod 416 is fixed with two screw rod limiting pins 417 . the screw rod limiting pins 417 are respectively positioned between the internal - thread sleeve 418 and the cap 415 and between the internal - thread sleeve 418 and the end socket of the lower end of the spiral lifting rod 416 . actually , the upper and lower two screw rod limiting pins 417 disposed at the spiral lifting rod 416 play the role of limiting the upper dead point position and lower dead point position when the internal - thread sleeve 418 moves on the spiral lifting rod 416 . the internal - thread 420 is a standing round tube structure , respectively provided with screw threads on the inner and outer walls . the internal - thread lifting head 420 is located in the internal - thread sleeve 418 . the internal screw threads are in spiral connection with the spiral lifting rod 416 . internal - thread lifting head limiting pins 414 are respectively disposed at the upper and lower end faces of the internal - thread lifting head 420 . the internal - thread lifting head limiting pins 414 are parallel to the axis of the internal - thread lifting head 420 . the internal - thread lifting head limiting pins 414 are disposed in a way of protruding the upper end face or lower end face of the internal - thread lifting head 420 . when the internal - thread lifting head limiting pin 414 at the upper end face moves to the upper dead point position along with the internal - thread sleeve 418 , the screw rod limiting pin 417 disposed at the upper part stops the rotation of the internal - thread lifting head limiting pin 414 , further stopping the upward movement of the internal - thread sleeve 418 . likewise , when the internal - thread lifting head limiting pin 414 at the lower end face moves to the lower dead point position along with the internal - thread sleeve 418 , the screw rod limiting pin 417 disposed at the lower part stops the rotation of the internal - thread lifting head limiting pin 414 , further stopping the downward movement of the internal - thread sleeve 418 . the sleeve opening 423 is an arc - shaped plate structure , having an inner wall provided with internal screw threads at a screw pitch which is the same as that of the external screw threads of the internal - thread lifting head 420 . the sleeve opening 423 is embedded in the rectangular through - hole of the internal - thread sleeve 418 and is in spiral connection with the external screw threads of the internal - thread lifting head 420 . the fixed sleeves 422 are semi - round plate structures , wrapping the excircles of the internal - thread sleeve 418 and the sleeve opening 423 in pairs and being fastened and connected ( for example through welding ) to form a round tube structure . the plural steel cable rollers 426 are uniformly distributed in the groove - shaped structure of the lower border of the bed stand and are pinned and fixed with the lower groove - shaped border through steel cable roller dowel pins 425 . for example , two steel cable rollers 426 are respectively disposed on each one of the left and right sides of a spiral lifting center 416 which serves as the center , and the external two steel cable rollers 426 are located at positions of the lower border respectively connected with a bed leg , as shown in fig5 b . the steel cable 424 bypasses plural steel cable rollers 426 , gets in via the long holes formed on the inner sides of each bed leg and each corresponding lifting rack 408 ; one end ( getting in the holes ) of the steel cable is connected with the connector dowel pin 407 in a locked way , and the end socket of the other end is connected with the steel cable fixing screw 421 in a fastened way . the steel cable fixing screw 421 passes through the screw hole in the rectangular plate structure and is clamped at the corresponding one of through - holes b . a structure is formed , in which the internal - thread sleeve 418 integrally moves up and down on the spiral lifting rod 416 , driving the extension and withdrawal of the steel cable 424 , and then driving the lifting racks 408 to move up and down through the steel cable 424 . as shown in fig6 , the bed head gearbox 101 includes a female bed head gearbox housing 102 , a male bed head gearbox housing 103 , a large shaft bushing a 104 , a first small shaft bushing a 1051 , a second small shaft bushing a 1052 , a third small shaft bushing a 1053 , a first bearing shim a 1061 , a second bearing shim a 1062 , a third bearing shim a 1063 , a fourth bearing shim a 1064 , a first plane bearing a 1071 , a second plane bearing a 1072 , a first spring shim a 1081 , a second spring shim a 1082 , an open - end short shaft a 109 , a first dowel pin a 1101 , a second dowel pin a 1102 , a first bevel gear a 1111 , a second bevel gear a 1112 , a limiting shim a 112 , a closed - end long shaft a 113 and a split pin a 114 . the female bed head gearbox housing 102 and the male bed head gearbox housing 103 are respectively integrally molded by injection , and after being folded , can enclose components inside to prevent slipping and misalignment . the female bed head gearbox housing 102 and the male bed head gearbox housing 103 are internally provided with first convex and concave spaces which face each other and are used for clamping and fixing components . the convex and concave spaces refer to the interiors of the female bed head gearbox housing 102 and the male bed head gearbox housing 103 which are internally molded by injection according to the external size of each of the components to be limited such that the corresponding components are embedded therein , thus fulfilling the aim of fixing the components ; the second convex and concave spaces and the third convex and concave spaces mentioned later are the same as the first convex and concave spaces and therefore are not further described . the first bevel gear a 1111 and the second bevel gear a 1112 are positioned in the first convex and concave spaces , and are in mutually vertical arrangement and in engaged connection . the so called mutually vertical ( the first bevel gear a 1111 and the second bevel gear a 1112 ) arrangement and engaged connection refers to that the axes of the two bevel gears are vertical to each other and that the teeth of the bevel portions of the two bevel gears are mutually engaged . the mutually vertical arrangement and engaged connection of the first bevel gear b and the second bevel gear b and that of the first bevel gear c and the second bevel gear c are in a similar way . the open - end short shaft a 109 is vertically disposed , with a lower end coupled and fixed with the first bevel gear a 1111 and an upper end formed with an open slot which is mechanically connected with the transmission systems 401 . the open - end short shaft a 109 is provided with the first dowel pin a 1101 which limits and locks the first bevel gear a 1111 . the open - end short shaft a 109 is sequentially annularly sleeved in the large shaft bushing a 104 , the first small shaft bushing a 1051 , the first bearing shim a 1061 , the first plane bearing a 1071 , the second bearing shim a 1062 and the first spring shim a 1081 which are limited by the first convex and concave spaces from the top down . the above top - to - bottom sequential loop overlapping is achieved in this way : the large shaft bushing a 104 is closest to the upper open slot , below followed by the first small shaft bushing a 1051 , the first bearing shim a 1061 , the first plane bearing a 1071 , the second bearing shim a 1062 and the first spring shim a 1081 in turn . the first bearing shim a 1061 and the first plane bearing a 1071 and the second bearing shim a 1062 and the first spring shim a 1081 and the first bevel gear a 1111 are in compact compression and connection , representing that the five components can rotate synchronously ( along with the open - end short shaft a 109 ), which means that the first convex and concave spaces respectively independently limit the large shaft bushing a 104 and the first small shaft bushing a 1051 , as shown in fig6 . the closed - end long shaft a 113 is horizontally arranged , coupled and fixed with the second bevel gear a 1112 . the closed - end long shaft a 113 is provided with the second dowel pin a 1102 which limits and locks the second bevel gear a 1112 . one end ( for example , left end ) of the closed - end long shaft a 113 passes through the limiting shim a 112 and the second small shaft bushing a 1052 which are limited by the first convex and concave spaces , and extends out , and the end socket is provided with the split pin a 114 for being connected with the pull rod . the other end ( for example , right end ) of the closed - end long shaft a 113 is sequentially annularly sleeved in the third small shaft bushing a 1053 ( the third small shaft bushing a 1053 is positioned at the most right end ), the fourth bearing shim a 1064 , the second plane bearing a 1072 , the third bearing shim a 1063 and the second spring shim a 1082 which are limited by the first convex and concave spaces from the right to the left . the fourth bearing shim a 1064 and the second plane bearing a 1072 and the third bearing shim a 1063 and the second spring shim a 1082 and the second bevel gear a 1112 are in compact compression and connection , which means that the five components can synchronize with the closed - end long shaft a 1113 during rotation . the first convex and concave spaces independently limit the third small shaft bushing a 1053 , as shown in fig6 . the small shaft bushing independently limited in the corresponding convex and concave spaces as shown in fig7 and 9 can be explained and understood in a similar way . the corresponding large shaft bushing is also independently limited . as shown in fig7 and fig7 a , the handle - containing bed tail gearbox 201 includes a female bed tail gearbox housing 202 , a male bed tail gearbox housing 203 , a large shaft bushing b 204 , a first small shaft bushing b 2051 , a second small shaft bushing b 2052 , a third small shaft bushing b 2053 , a first bearing shim b 2061 , a second bearing shim b 2062 , a third bearing shim b 2063 , a fourth bearing shim b 2064 , a first plane bearing b 2071 , a second plane bearing b 2072 , a first spring shim b 2081 , a second spring shim b 2082 , an open - end short shaft b 209 , a first dowel pin b 2101 , a second dowel pin b 2102 , a first bevel gear b 2111 , a second bevel gear b 2112 , a long shaft b 212 , a split pin b 213 and a handle 224 . the female bed tail gearbox housing 202 and the male bed tail gearbox housing 203 are respectively integrally molded by injection . the female bed tail gearbox housing 202 and the male bed tail gearbox housing 203 are internally provided with second convex and concave spaces which face each other and are used for clamping and fixing components . the first bevel gear b 2111 and the second bevel gear b 2112 are positioned in the second convex and concave spaces , and are in mutually vertical arrangement and in engaged connection . the open - end short shaft b 209 is vertically arranged , with a lower end coupled and fixed ( for example by means of interference fixing , others concerning coupling and fixing can be explained in this way ) with the first bevel gear b 2111 and an upper end formed with an open slot which is mechanically connected with the transmission system 401 . the open - end short shaft b 209 is provided with the first dowel pin b 2101 which limits and locks the first bevel gear b 2111 . the open - end short shaft b 209 is sequentially annularly sleeved in the large shaft bushing b 204 , the first small shaft bushing b 2051 , the first bearing shim b 2061 , the first plane bearing b 2071 , the second bearing shim b 2062 and the first spring shim b 2081 which are limited by the second convex and concave spaces from the top down ( the large shaft bushing b 204 is on the top , and the large shaft bushing b 204 and the first small shaft bushing b 2051 are respectively independently limited by the second convex and concave spaces . the so called limiting can be explained as position limiting ). the first bearing shim b 2061 and the first plane bearing b 2071 and the second bearing shim b 2062 and the first spring shim b 2081 and the first bevel gear b 2111 are in compact compression and connection , which means that the five components ( including the first bevel gear b 2111 ) synchronize with the open - end short shaft b 209 during rotation . the long shaft b 212 is horizontally arranged , coupled and fixed with the second bevel gear b 2112 . the long shaft b 212 is provided with the second dowel pin b 2102 which limits and locks the second bevel gear b 2112 . one end ( or right end ) of the long shaft b 212 passes through the third small shaft bushing b 2053 which is limited by the second convex and concave spaces , and extends out , and the end socket is provided with an open slot and is fixedly connected with the handle 224 through the open slot . the other end ( left end ) of the long shaft b 212 is sequentially annularly sleeved in the second spring shim b 2082 , the fourth bearing shim b 2064 , the second plane bearing b 2072 , the third bearing shim b 2063 and the second small shaft bushing b 2052 which are limited by the second convex and concave spaces from the right to the left , and extends out of the second convex and concave spaces , which means that the second small shaft bushing b 2052 is positioned at the most left end of the five components . the end socket of the other end ( left end ) of the long shaft b 212 is provided with the split pin b 213 for being connected with the pull rod . the second spring shim b 2082 and the fourth bearing shim b 2064 and the second plane bearing b 2072 and the third bearing shim b 2063 and the second bevel gear b 2112 are in compact compression and connection , which means that the five components ( the second spring shim b 2082 , the fourth bearing shim b 2064 , the second plane bearing b 2072 , the third bearing shim b 2063 and the second bevel gear b 2112 ) can synchronize with the long shaft b 212 during rotation . the second small shaft bushing b 2052 is independently limited by the second convex and concave spaces . as shown in fig7 a , the handle 224 includes a handle fixing screw 223 , a grip dowel pin 225 , grip shims 226 , a grip spring 227 , a grip bolt 228 , a grip 229 and a grip connector 230 . the handle wall of the handle 224 is a cylindrical rigid structure ; the end socket of one end of the handle wall is provided with an annular connecting portion in an integrated or fastened way . the grip connector 230 is sunk in the annular connecting portion and is connected with the annular connecting portion in a fastened way through the handle fixing screw 223 . the end socket of the other end of the handle wall of the handle 224 is formed with a groove or a recessed portion . the grip connector 230 is an integrally cylindrical or solid column ; one end is provided with a projecting portion ; and the projecting portion is inserted in the open slot formed on the long shaft b 212 and forms an interlocking structure . the grip 229 is a hollow cylindrical structure , internally inserted with the grip bolt 228 . the grip bolt 228 is annularly sleeved with the grip spring 227 which is held by two grip shims 226 . the end socket of one end of the grip bolt 228 is inserted into the groove or recession portion which is formed at the end socket of the other end of the handle wall of the handle 224 and is connected in a riveted way through the grip dowel pin 225 . the end socket of the other end of the grip bolt 228 is provided with a limiting portion which limits the slide - out of the grip 229 . in this way , when the grip 229 is rocked , the projecting portion formed on the grip connector 230 is inserted into the open slot of the long shaft b 212 and forms an interlocking to drive the long shaft b 212 to rotate , thus driving the transmission system 401 to ascend and descend the bed head or bed tail through the bevel gear . as shown in fig8 , the bed tail gearbox 301 includes a female bed tail gearbox housing 202 , a male bed tail gearbox housing 203 , a large shaft bushing c 304 , a first small shaft bushing c 3051 , a second small shaft bushing c 3052 , a third small shaft bushing c 3053 , a first bearing shim c 3061 , a second bearing shim c 3062 , a third bearing shim c 3063 , a fourth bearing shim c 3064 , a first plane bearing c 3071 , a second plane bearing c 3072 , a first spring shim c 3081 , a second spring shim c 3082 , an open - end short shaft c 309 , a first dowel pin c 3101 , a second dowel pin c 3102 , a first bevel gear c 3111 , a second bevel gear c 3112 , a long shaft c 312 , a split pin c 313 and a limiting shim c 314 . the female bed tail gearbox housing 202 and the male bed tail gearbox housing 203 are respectively integrally molded by injection . the female bed tail gearbox housing 202 and the male bed tail gearbox housing 203 are internally provided with second convex and concave spaces which face each other and are used for clamping and fixing components . the structure of the bed tail gearbox is identical with the structure of the handle - containing bed tail gearbox . the first bevel gear c 3111 and the second bevel gear c 3112 are positioned in the second convex and concave spaces , and are in mutually vertical arrangement and in engaged connection . the open - end short shaft c 309 is vertically arranged , with a lower end coupled and fixed with the first bevel gear c 3111 and an upper end formed with an open slot which is mechanically connected with the transmission system 401 . the open - end short shaft c 309 is provided with the first dowel pin c 3101 which limits and locks the first bevel gear c 3111 . the open - end short shaft c 309 is sequentially annularly sleeved in the large shaft bushing c 304 , the first small shaft bushing c 3051 , the first bearing shim c 3061 , the first plane bearing c 3071 , the second bearing shim c 3062 and the first spring shim c 3081 which are limited by the second convex and concave spaces from the top down . the large shaft bushing c 304 is positioned on the top of the open - end short shaft c 309 . the large shaft bushing c 304 and the first small shaft bushing c 3051 are respectively independently limited by the second convex and concave spaces . the first bearing shim c 3061 and the first plane bearing c 3071 and the second bearing shim c 3062 and the first spring shim c 3081 and the first bevel gear c 3111 are in compact compression and connection , which means that the five components ( the first bearing shim c 3061 , the first plane bearing c 3071 , the second bearing shim c 3062 , the first spring shim c 3081 and the first bevel gear c 3111 ) synchronize with the open - end short shaft c 309 during rotation . the long shaft c 312 is horizontally arranged , coupled and fixed with the second bevel gear c 3112 . the long shaft c 312 is provided with the second dowel pin c 3102 which limits and locks the second bevel gear c 3112 . one end ( right end ) of the long shaft c 312 passes through the limiting shim c 314 and the third small shaft bushing c 3053 which are limited by the second convex and concave spaces , and the end socket is provided with an open slot . the other end ( left end ) of the long shaft c 312 is sequentially annularly sleeved in the second spring shim c 3082 , the fourth bearing shim c 3064 , the second plane bearing c 3072 , the third bearing shim c 3063 and the second small shaft bushing c 3052 which are limited by the second convex and concave spaces from the right to the left , and extends out of the second convex and concave spaces , which means that the second small shaft bushing c 3052 is positioned at the most left end . the end socket of the other end ( left end ) of the long shaft c 312 is provided with the split pin c 313 for being connected with the pull rod . the second spring shim c 3082 and the fourth bearing shim c 3064 and the second plane bearing c 3072 and the third bearing shim c 3063 and the second bevel gear c 3112 are in compact compression and connection , which means that the five components ( the second spring shim c 3082 , the fourth bearing shim c 3064 , the second plane bearing c 3072 , the third bearing shim c 3063 and the second bevel gear c 3112 ) can synchronize with the long shaft c 312 during rotation . the second small shaft bushing c 3052 is independently limited by the second convex and concave spaces . as shown in fig9 , the motor gear connecting box 501 includes a female connecting box housing 502 , a male connecting box housing 503 , a short motor shaft 504 , a coupling long shaft e 505 , a first small shaft bushing e 5041 , a third small shaft bushing e 5051 , a first limiting shim e 5042 , a second limiting shim e 5052 , a first bevel gear e 5043 , a second bevel gear e 5053 , a first split pin e 5044 , a second split pin e 5054 , a first dowel pin e 5045 , a second dowel pin e 5055 , a first spring shim e 5046 , a third split pin e 5056 , a first bearing shim e 5047 , a second spring shim e 5057 , a first plane bearing e 5048 , a third bearing shim e 5058 , a second bearing shim e 5049 , a second plane bearing e 5059 , a second small shaft bushing e 50410 , a fourth bearing shim e 50510 , a fourth small shaft bushing e 5051 , a coupling connector spring 506 and a coupling connector 507 . the female connecting box housing 502 and the male connecting box housing 503 are respectively molded by injection . the female connecting box housing 502 and the male connecting box housing 503 are internally provided with third convex and convex spaces which face each other and are used for clamping and fixing components . here , the so called convex and concave spaces ( or the third convex and concave spaces ) refer to the interiors of the female connecting box housing 502 and the male connecting box housing 503 which are internally molded by injection with molds according to external sizes or partial external sizes of components to be limited such that the corresponding components can be embedded therein , thus fulfilling the aim of fixing or limiting the components when the female connecting box housing 502 and the male connecting box housing 503 are folded . the first bevel gear e 5043 and the second bevel gear e 5053 are positioned in the third convex and concave spaces , and are in mutually parallel arrangement and in engaged connection . the so called ( the first bevel gear e 5043 and the second bevel gear e 5053 ) mutually parallel arrangement and engaged connection is that the axes of the two bevel gears are parallel ( for example , the directions of teeth of the bevel portions of the two bevel gears are the same , as shown in fig9 ) and that the teeth of the non - bevel portions of the two bevel gears are mutually engaged . the short motor shaft 504 is horizontally arranged , coupled and fixed with the first bevel gear e 5043 . the short motor shaft 504 is provided with the first dowel pin e 5045 which limits and locks the first bevel gear e 5043 . one end ( or left end ) of the short motor shaft 504 passes through the first limiting shim e 5042 and the first small shaft bushing e 5041 which are limited by the third convex and concave spaces , and extends out of the third convex and concave spaces , and the end socket is formed with a pin hole in which the first split pin e 5044 is inserted . the other end ( or right end ) of the short motor shaft 504 is sequentially annularly sleeved in the first spring shim e 5046 , the first bearing shim e 5047 , the first plane bearing e 5048 , the second bearing shim e 5049 and the second small shaft bushing e 50410 which are limited by the third convex and concave spaces from the left to the right ( which means that the second small shaft bushing e 50410 is positioned at the most right end or outer end ). the first bevel gear e 5043 and the first spring shim e 5046 and the first bearing shim e 5047 and the first plane bearing e 5048 and the second bearing shim e 5049 are in compact compression and connection , which means that the five components ( the first bevel gear e 5043 , the first spring shim e 5046 , the first bearing shim e 5047 , the first plane bearing e 5048 and the second bearing shim e 5049 ) synchronize with the short motor shaft e 504 during rotation . the second small shaft bushing e 50410 is independently limited by the third convex and concave spaces without projection . the coupling long shaft e 505 is horizontally arranged , coupled and fixed with the second bevel gear e 5053 . the coupling long shaft e 505 is provided with the second dowel pin e 5055 which limits and locks the second bevel gear e 5053 . one end ( left end ) of the coupling long shaft e 505 passes through the second limiting shim e 5052 and the third small shaft bushing e 5051 which are limited by the third convex and concave spaces , and extends out of the third convex and concave spaces , and the end socket is formed with a pin hole in which the second split pin e 5054 is inserted . the other end ( right end ) of the coupling long shaft e 505 is sequentially annularly sleeved in the second spring shim e 5057 , the third bearing shim e 5058 , the second plane bearing e 5059 , the fourth bearing shim e 50510 and the fourth small shaft bushing e 50511 which are limited by the third convex and concave spaces from the left to the right . the fourth small shaft bushing e 50511 is positioned at the most right end or outer end of the five components , and is independently limited by the third convex and concave spaces . the second bevel gear e 5053 and the second spring shim e 5057 and the third bearing shim e 5058 and the second plane bearing e 5059 and the fourth bearing shim e 50510 are in compact compression and connection , which means that the five components ( the second bevel gear e 5053 and the second spring shim e 5057 and the third bearing shim e 5058 and the second plane bearing e 5059 and the fourth bearing shim e 50510 ) synchronize with the coupling long shaft e 505 during rotation . the other end ( right end ) of the coupling long shaft e 505 extends and gets out of the third convex and concave spaces , and the end socket is formed with a pin hole in which the third split pin e 5056 is inserted . the coupling connector 507 is an integrally hollow cylindrical structure which is square outside and round inside , having slot holes on the lateral side ; one end of the coupling connector is inserted into the coupling long shaft e 505 , and the other end is formed with a pin slot opening at the end socket . the coupling connector 507 is in pin connection with the other end or right end of the coupling long shaft e 505 through the third split pin e 5056 . the coupling connector 507 is internally provided with the coupling connector spring 506 .
a medical rehabilitation bed is disclosed , relating to the technical field of self - help rehabilitation bed structures in medical instrument products . the medical rehabilitation bed comprises a bed head , a bed tail and a bed board . a pull rod is arranged at the bottom of the bed board ; one end of the pull rod is mechanically connected to a bed head gearbox arranged at the bed head , and the other end of the pull rod is mechanically connected to a bed tail gear device arranged at the bed tail . transmission systems having the same structure and capable of controlling the bed head and the bed tail to ascend and descend are arranged in the bed head and the bed tail , respectively . the transmission systems are mechanically connected to the bed head gearbox and the bed tail gear device , respectively . the medical rehabilitation bed has a compact structure and comprehensive functions .