Abstract:
The thickness of the thin bidirectional ratchet wrench of the present disclosure is preferably less than or equal to 30.0 mm, it can be used in narrow spaces easily, achieves two working modes, and can convert between them conveniently and stably. During use of the thin bidirectional ratchet wrench of the present disclosure, the input torque that the operator exerts is a clockwise torque or a counterclockwise torque, the output torque of the output end of the thin bidirectional ratchet wrench of the present disclosure is a clockwise torque or a counterclockwise torque, alternatively.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation-in-part of PCT/CN2013/070641 filed on Jan. 18, 2013 and PCT/CN2014/080303 filed on Jun. 19, 2014, and all contents of the two prior PCT applications are incorporated herein by reference. 
    
    
     FIELD OF THE DISCLOSURE 
     The present disclosure relates to a hand tool, particularly to a thin bidirectional ratchet wrench. 
     DESCRIPTION OF THE PRIOR ART 
     During use of common hand tools such as screwdrivers and torque wrenches, there is a movement limitation of the human hand when rotating; more specifically, the inability of the human hand to turn continuously in one direction. The operation of such a tool, which a rotation axis of the handle is coaxial with the tool&#39;s main shaft comprises a repetition of the following cycle: first, the hand rotates the handle in the desirable direction (e.g., tightening or loosening a screw); second, the hand rotates in the opposite direction to reposition the tool for the next cycle. During the second portion of the above mentioned cycle, the hand&#39;s reversed rotation can be achieved by re-grasping the handle after releasing it, by the tool if it is equipped with a one-way means such as a ratchet surface to keep the main shaft stationary during the reversed rotation of the handle, or by re-inserting the tool bit to the screw after extracting the bit from engagement with the screw. However, in any case, the hand&#39;s reversed rotation could not bring any effective advance of the fastener, and therefore it becomes a wasted movement. 
     U.S. Pat. No. 5,931,062 discloses a mechanical rectifier having a handle that rotates clockwise or counterclockwise, the shaft rotates in the same direction; therefore, it can improve the efficiency of the hand motion, and save operation time. However, the converting mechanism of the invention can only make the shaft rotate in one direction, which does not allow the rotation of the shaft in two directions. Tightening or loosening a fastener with a torque wrench equipped with the converting mechanism of the invention could only get the result of tightening a fastener (or loosening a fastener) no matter what operation it executes—either tightening or loosening a fastener as the conventional wrenches do. For a torque wrench equipped with the converting mechanism of the invention to execute the operation of tightening and loosening a fastener, the two ends of the shaft of the torque wrench are both engageable with the rotational output, and one end is to execute the operation of tightening a fastener, the other to execute the operation of loosening a fastener. But this design is cumbersome, it is inconvenient to choose the appropriate output end when using the torque wrench. 
     The applicant discloses a bidirectional ratchet wrench in Chinese patent application (CN201320028403.8), which contains a reversing switch and solves the problem of switching the direction of rotation of the main shaft easily. However, a certain torque is needed to tighten fasteners, and is provided by the bidirectional wrench being thick enough to achieve the desired strength. The bidirectional wrench can then be used in spaces large enough to accommodate the thickness of the bidirectional wrench in the main shaft direction to hold the device during use. So this bidirectional wrench cannot be applied in narrow spaces in the main shaft direction, for example, a slit or gap in mechanical components, etc. 
     Therefore, it is desired to develop a thin bidirectional ratchet wrench, which can be used in narrow space easily. 
     SUMMARY OF THE DISCLOSURE 
     In the view of the above, the technical object of the present disclosure is to provide a thin bidirectional ratchet wrench, which can be used in narrow space easily and switch the rotational direction of the main shaft conveniently. 
     For the above purpose, the present disclosure provides a thin bidirectional ratchet wrench comprising a working part and a handle, the working part comprising a main shaft configured to output torque and having a central axis perpendicular to the handle, a capstan gear mounted on the main shaft, a follower gear mounted on the main shaft, a transmission seat mounted on the main shaft and having a central axis perpendicular to the central axis of the main shaft, and an idle gear mounted on the transmission seat and rotating between the capstan gear and the follower gear. The working part further comprises a first ratchet surface rotating together with the capstan gear, and a second ratchet surface rotating together with the follower gear, a first pawl element and a second pawl element configured to rotate the main shaft. Moreover, the first pawl element has a first pawl and a second pawl that are matched with the first ratchet surface selectively, wherein the first pawl skids on the first ratchet surface in a first direction but engages with the first ratchet surface in a second direction, and the second pawl engages with the first ratchet surface in the first direction but skids on the first ratchet surface in the second direction. In addition, the second pawl element has a third pawl and a fourth pawl that are matched with the second ratchet surface selectively, wherein the third pawl skids on the second ratchet surface in the first direction but engages with the second ratchet surface in the second direction, and the fourth pawl engages with the second ratchet surface in the first direction but skids on the second ratchet surface in the second direction. The working part further comprises a reversing switch configured to set the first pawl element and the second pawl element in a first condition and a second condition, the first pawl and the third pawl are matched with the first ratchet surface and the second ratchet surface, respectively, under the first condition. Further, the second pawl and the fourth pawl are matched with the first ratchet surface and the second ratchet surface, respectively, under the second condition. Moreover, the handle entrains the capstan gear to rotate, and the transmission seat is equipped with a holding device, when holding the holding device and rotating the handle to entrain the capstan gear, the capstan gear entrains the follower gear to rotate reversely via the idle gear. Further, the first direction is clockwise or counterclockwise, the second direction is opposite to the first direction; the thickness of the working part is less than or equal to 30.0 mm. 
     In a further embodiment, the first pawl element and/or the second pawl element are/is made of high strength material, preferably, the material used is injected powder metallurgy. 
     In a further embodiment, thickness of one of the pawl elements is less than or equal to 6.5 mm, the other one is less than or equal to it, thickness of the ratchet surface that engages with the pawl element equal to the thickness of the pawl element, thickness of the transmission seat is less than or equal to 8.0 mm, and modulus of the idle gear is less than or equal to 1.0; preferably, the thickness of the first pawl element is 5.0 mm, the thickness of the second pawl element is less than the thickness of the first pawl element, the thickness of the transmission seat is 6.0 mm, the modulus of the idle gear is 0.6, and the thickness of the working part is 25.0 mm. 
     In a further embodiment, the handle has a ring-shaped head, and the first ratchet surface is disposed on the inner circumference of the ring-shaped head. 
     In a further embodiment, the first ratchet surface is disposed on an inner circumference of the capstan gear. 
     In a further embodiment, the second ratchet surface is disposed on an inner circumference of the follower gear. 
     In a further embodiment, the holding device is a holding ring. 
     In a further embodiment, the first pawl element is fan-shaped and/or the second pawl element is fan-shaped. 
     In a further embodiment, the first pawl element and the second pawl element are mounted on a countershaft having a central axis parallel to but not overlapping in the main shaft, and the countershaft being in engagement with the main shaft and configured to entrain the main shaft to rotate. 
     In a further embodiment, the countershaft drills through the main shaft. 
     In a further embodiment, the reversing switch has spring inside and comprises a newel, a first spring-loaded plunger and a second spring-loaded plunger, the newel is disposed inside the main shaft, the first spring-loaded plunger and the second spring-loaded plunger is fixed on the newel in turn, and the first spring-loaded plunger and the second spring-loaded plunger matches with the first pawl element and the second pawl element, respectively. 
     In a further embodiment, springs are disposed inside the first spring-loaded plunger and the second spring-loaded plunger. 
     The thin bidirectional ratchet wrench of the present disclosure reduces the thickness of all the parts in the working part (along the extending direction of the main shaft  100 ) on the basis of satisfying the output torque needed, hence reducing the whole thickness of the working part largely, so it can be used in narrow spaces easily and satisfy the torque needed to tighten fasteners, achieving two working modes and being capable of converting between them conveniently and stably. 
     The present disclosure would be described in detail hereinafter in combination with the attached drawings for better understanding the purpose, features and effects of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view of the thin bidirectional ratchet wrench of the present disclosure in the preferred embodiment; 
         FIG. 2  is a sectional view of the working part of the thin bidirectional ratchet wrench in  FIG. 1 ; 
         FIG. 3  shows an exploded view of the driving mechanism in the thin bidirectional ratchet wrench of the present disclosure in the preferred embodiment; 
         FIG. 4  shows an exploded view of the reversing mechanism in the thin bidirectional ratchet wrench of the present disclosure in the preferred embodiment; 
         FIG. 5  shows the main shaft mounted first pawl element and second pawl element; 
         FIG. 6  is a front view of the first pawl element in  FIGS. 4 and 5 ; 
         FIG. 7  shows cooperation between the first pawl element and the first ratchet surface when the thin bidirectional ratchet wrench of the present disclosure in the preferred embodiment is on the first working mode; 
         FIG. 8  shows the knob for changing working mode of the thin bidirectional ratchet wrench of the present disclosure; 
         FIG. 9  shows the blocking device in the thin bidirectional ratchet wrench of the present disclosure; and 
         FIG. 10  is a side view of the blocking device in  FIG. 9 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As shown in  FIGS. 1 and 2 , the thin bidirectional ratchet wrench, which refers to one detailed embodiment of the present disclosure, comprises a handle  20  and a working part  10 , the handle  20  is socketed to the working part  10  across a ring-shaped head  21  (see  FIG. 3 ) through longitudinal extension. Inside the working part  10  is main shaft  100 , outside is a holding ring  102 . One end of the main shaft is an output end  101 , which extends beyond the working part  10  and the head  21  of the handle  20 . The output end  101  can be a component, which is suitable to operate various fasteners like quoin screws, by mounting different sleeves. 
     The thin bidirectional ratchet wrench of the present disclosure comprises a driving mechanism coupled to a reversing mechanism, the input torque from the handle  20  is transmitted to the main shaft  100  of the working part  10  through the driving mechanism, and the direction of the output torque from the output end  101  is in a first direction or a second direction, wherein the first direction and the second direction are opposite. Such as, when the input torque of the working part  10  is a clockwise torque or a counterclockwise torque, the output torque of the output end  101  is a clockwise torque, or when the input torque of the working part  10  is a clockwise torque or a counterclockwise torque, the output torque of the output end  101  is a counterclockwise torque. 
     The structure of the driving mechanism of the thin bidirectional ratchet wrench of the present disclosure is shown in  FIG. 3 , which comprises a first ratchet surface  311 , a capstan gear  312 , a second ratchet surface  321 , a follower gear  322 , a transmission seat  330 , and idle gears  331 ,  332 . Wherein the first ratchet surface  311  and the capstan gear  312  connect and are coaxial with each other; in this embodiment, the first ratchet surface  311  is disposed in the inner circumference of the ring-shaped head  21  of the handle  20 , the driving engages with the head  21  of the handle  20 , thus the head  21  will drive driving gear to rotate when the handle  20  rotates. In another embodiment, the first ratchet surface  311  can be disposed in the inner circumference of capstan gear  312 ; the second ratchet surface  321  can be disposed in the inner circumference of follower gear  322 . The faces of the first ratchet surface  311  and the second ratchet surface  321  connect with the outer face of the main shaft  100 ; the capstan gear  312  and the follower gear  322  are face-gears, faces of the capstan gear  312  and the follower gear  322  are face-to-face. The first ratchet surface  311 , the second ratchet surface  321 , the capstan gear  312  and the follower gear  322  are coaxial and the central axes thereof overlap in that of the main shaft  100 . 
     The transmission seat  330  and the holding ring  102  are fixed together. The idle gears  331 ,  332  are mounted on the transmission seat  330 , which is perpendicular to the main shaft  100 . The idle gears  331 ,  332  are matched between the capstan gear  312  and the follower gear  322 , their teeth engage with the teeth of the capstan gear  312  and the follower gear  322 , respectively. When the holding ring  102  is fixed or the transmission seat  330  is fixed, the capstan gear  312  will drive the follower gear  322  to rotate via the idle gears  331 ,  332 . In this embodiment, the idle gears  331 ,  332  are angle gears. 
     The structure of the reversing mechanism of the thin bidirectional ratchet wrench of the present disclosure is shown in  FIG. 4 , comprises a newel  220 , a reversing switch comprising a first spring-loaded plunger  221 , a second spring-loaded plunger  222 , a first pawl element  211 , and a second pawl element  212 . The newel  220  is fixed in the main shaft  100 , spring  224  is arranged on the newel  220 , which is between the first end  2201  of the newel  220  and the main shaft  100 . The first spring-loaded plunger  221  and the second spring-loaded plunger  222  are fixed on the newel  220  and the first spring-loaded plunger  221  and the second spring-loaded plunger  222  are perpendicular to the main shaft  100  along the active direction. Preferably, the first spring-loaded plunger  221  and the second spring-loaded plunger  222  have elastic elements such as a spring. The first pawl element  211  and second pawl element  212  are fixed on the main shaft  100  across a countershaft  210 , as shown in  FIG. 5 . The countershaft  210  is parallel to the central axis of the main shaft  100  but does not overlap it, the first pawl element  211  and the second pawl element  212  can rotate around the countershaft  210 . 
     The first pawl element  211  and the second pawl element  212  have a similar structure, namely a first fan-shaped pawl, a second fan-shaped pawl and a fan-shaped space between them. Take the first pawl element  211  for example,  FIG. 6  shows the top view of the first pawl element  211  (direction towards the output end  101  along the main shaft  100 ), as can be seen from  FIG. 6 , the first pawl element  211  comprises the first fan-shaped pawl  2111 , the second fan-shaped pawl  2112 , and the fan-shaped space  2110  between them. The fan-shaped face of the first fan-shaped pawl  2111 , the fan-shaped space center section  2110  and the fan-shaped face of the second fan-shaped pawl  2112  constitute the first surface of the first pawl element  211 . The first pawl element  211  also has a second surface which is a special shaped surface and contains a concave section  2113 , which has a first side wall  2114  and a second side wall  2115  in this embodiment. The first side wall  2114  and the second side wall  2115  extend along the main shaft  100 . The first pawl element  211  has a hole  2101 , which is matched with the countershaft  210 , the countershaft  210  fixes the first pawl element  211  on the main shaft across the hole  2101  (see  FIG. 5 ). In this embodiment, the hole  2101  is arranged on the fan-shaped center section  2110  of the first pawl element  211 , preferably, on the center of gravity of the first pawl element  211 . The structure of the second pawl element  212  is similar to the first pawl element  211  with a thickness less than that of the first pawl element  211  in this embodiment, but in other embodiments, the thickness of the second pawl element  212  can be equal to or more than that of the first pawl element  211 . 
     The first surface of the first pawl element  211  and the second pawl element  212  face the first ratchet surface  311  and the second ratchet surface  321 , respectively. Specifically, the teeth of the fan-shaped pawl (which contains the first fan-shaped pawl  2111  and the second fan-shaped pawl  2112 ) of the first pawl element  211  face the teeth of the first ratchet surface  311 , the teeth of the fan-shaped pawl (contains the first fan-shaped pawl and the second fan-shaped pawl) of the second pawl element  212  face the teeth of the second ratchet surface  321 . The second surface of the first pawl element  211  and the second pawl element  212  face the surface of the newel  220 ; specifically, the second surface of the first pawl element  211  faces the ball-head section of the first spring-loaded plunger  221  and the second surface of the second pawl element  212  faces the ball-head section of the second spring-loaded plunger  222 . When the thin bidirectional ratchet wrench of the present disclosure is in the first working mode, the ball-head section of the first spring-loaded plunger  221  connects with the first side wall  2114  of the concave section  2113  of the first pawl element  211 , and the ball-head section of the second spring-loaded plunger  222  connects with the first side wall of the concave section of the second pawl element  212 . When the thin bidirectional ratchet wrench of the present disclosure is in the second working mode, the ball-head section of the first spring-loaded plunger  221  connects with the second side wall  2115  of the concave section  2113  of the first pawl element  211 , and the ball-head section of the second spring-loaded plunger  222  connects with the second side wall of the concave section of the second pawl element  212 . 
     When the thin bidirectional ratchet wrench of the present disclosure is in the first working mode, see  FIG. 7 , the teeth of the first fan-shaped pawl  2111  of the first pawl element  211  connect with the teeth of the first ratchet surface  311 ; similarly, the teeth of the first fan-shaped pawl of the second pawl element  212  connect with the teeth of the second ratchet surface  321 . When the head  21  of the handle  20  drives the first ratchet surface  311  to rotate such that the moving direction of the first ratchet surface  311  beside the first fan-shaped pawl  2111  is from the first fan-shaped section  2111  to the second fan-shaped section  2112 , the first ratchet surface  311  rotates clockwise seen in the  FIG. 7 . With the clockwise moving direction, the ball-head section of the first spring-loaded plunger  221  connects with the first side wall  2114  of the concave section  2113  of the first pawl element  211 , and the first ratchet surface  311  can drive the first pawl element  211  to rotate because the teeth of the first fan-shaped pawl  2111  engage with the teeth of the first ratchet surface  311 , and rotation of the first pawl element  211  is transferred to the countershaft  210  through the main shaft  100 ; thus, driving the main shaft  100  to rotate. However, when the moving direction of the first ratchet surface  311  beside the first fan-shaped pawl  2111  is from the second fan-shaped section  2112  to the first fan-shaped section  2111 , the first ratchet surface  311  rotates counterclockwise seen in the  FIG. 7 . With the counterclockwise moving direction, the ball-head section of the first spring-loaded plunger  221  connects with the first side wall  2114  of the concave section  2113  of the first pawl element  211  and the first ratchet surface  311  cannot drive the first pawl element  211  to rotate because the teeth of the first fan-shaped pawl  2111  do not engage with the teeth of the first ratchet surface  311 . 
     Meanwhile, when the moving direction of the second ratchet surface  321  beside the first fan-shaped pawl of the second pawl element  212  is from the first fan-shaped section to the second fan-shaped section in the second pawl element  212 , the second ratchet surface  321  rotates clockwise. With the clockwise moving direction, the ball-head section of the second spring-loaded plunger  222  connects with the first side wall of the concave section of the second pawl element  212 , and the second ratchet surface  321  can drive the second pawl element  212  to rotate because the teeth of the first fan-shaped pawl of the second pawl element  212  engage with the teeth of the second ratchet surface  321 , and rotation of the second pawl element  212  is transferred to the countershaft  210  through the main shaft  100 , thus driving the main shaft  100  to rotate. However, when the moving direction of the second ratchet surface  321  beside the first fan-shaped pawl of the second pawl element  212  is from the second fan-shaped section to the first fan-shaped section in the second pawl element  212 , the second ratchet surface  321  rotates counterclockwise. With the counterclockwise moving direction, the ball-head section of the second spring-loaded plunger  222  connects with the first side wall of the concave section of the second pawl element  212  and the second ratchet surface  321  cannot drive the second pawl element  212  to rotate because the teeth of the first fan-shaped pawl of the second pawl element  212  do not engage with the teeth of the second ratchet surface  321 . 
     Because the drive among the idle gears  331 ,  332 , the capstan gear  312  and the follower gear  322  when the holding ring  102  is fixed, the rotation direction of the second ratchet surface  321  is opposite to the first ratchet surface  311 . It can be seen from this, when the thin bidirectional ratchet wrench of the present disclosure is in the first working mode, the input torque from the working part  10  is a clockwise torque, the first ratchet surface  311  rotates clockwise and the second ratchet surface  321  rotates counterclockwise. The first pawl element  211  engages with the first ratchet surface  311  and the second pawl element  212  does not engage with the second ratchet surface  321 ; thus, the first pawl element  211  drives the main shaft  100  to rotate clockwise and the output torque is a clockwise torque. When the input torque from the working part  10  is a counterclockwise torque, the first ratchet surface  311  rotates counterclockwise and the second ratchet surface  321  rotates clockwise. The first pawl element  211  does not engage with the first ratchet surface  311  and the second pawl element  212  engages with the second ratchet surface  321 ; thus, the second pawl element  212  drives the main shaft  100  to rotate clockwise and the output torque is a clockwise torque. 
     When the thin bidirectional ratchet wrench of the present disclosure is in the second working mode, the teeth of the second fan-shaped pawl  2112  of the first pawl element  211  connect with the teeth of the first ratchet surface  311 ; similarly, the teeth of the second fan-shaped pawl of the second pawl element  212  connect with the teeth of the second ratchet surface  321 . When the head  21  of the handle  20  drives the first ratchet surface  311  to rotate such that the moving direction of the first ratchet surface  311  beside the second fan-shaped pawl  2112  is from the first fan-shaped section  2111  to the second fan-shaped section  2112 , the first ratchet surface  311  rotates clockwise. Because the ball-head section of the first spring-loaded plunger  221  connects with the second side wall  2115  of the concave section  2113  of the first pawl element  211 , the first ratchet surface  311  cannot drive the first pawl element  211  to rotate. The teeth of the second fan-shaped pawl  2112  do not engage with the teeth of the first ratchet surface  311 . However, when the moving direction of the first ratchet surface  311  beside the second fan-shaped pawl  2112  is from the second fan-shaped section  2112  to the first fan-shaped section  2111 , the first ratchet surface  311  rotates counterclockwise. Because the ball-head section of the first spring-loaded plunger  221  connects with the second side wall  2115  of the concave section  2113  of the first pawl element  211 , the first ratchet surface  311  can drive the first pawl element  211  to rotate. The teeth of the second fan-shaped pawl  2112  engage with the teeth of the first ratchet surface  311  and the rotation of the first pawl element  211  is transferred to the main shaft  100  through the countershaft  210 , thus driving the main shaft  100  to rotate. 
     Meanwhile, when the moving direction of the second ratchet surface  321  beside the second fan-shaped pawl of the second pawl element  212  is from the first fan-shaped section to the second fan-shaped section in the second pawl element  212 , the second ratchet surface  321  rotates clockwise. Because the ball-head section of the second spring-loaded plunger  222  connects with the second side wall of the concave section of the second pawl element  212 , the second ratchet surface  321  cannot drive the second pawl element  212  to rotate. Specifically, the teeth of the second fan-shaped pawl of the second pawl element  212  do not engage with the teeth of the second ratchet surface  321 . However, when the moving direction of the second ratchet surface  321  beside the second fan-shaped pawl of the second pawl element  212  is from the second fan-shaped section to the first fan-shaped section in the second pawl element  212 , the second ratchet surface  321  rotates counterclockwise. Because the ball-head section of the second spring-loaded plunger  222  connects with the second side wall of the concave section of the second pawl element  212 , the second ratchet surface  321  can drive the second pawl element  212  to rotate, and the teeth of the second fan-shaped pawl of the second pawl element  212  engage with the teeth of the second ratchet surface  321 , and the rotation of the second pawl element  212  is transferred to the main shaft  100  through the countershaft  210 , thus driving the main shaft  100  to rotate. 
     Because the drive among the idle gears  331 ,  332 , the capstan gear  312  and the follower gear  322  when the holding ring  102  is fixed, the rotation direction of the second ratchet surface  321  is opposite to the first ratchet surface  311 . It can be seen from this, when the thin bidirectional ratchet wrench of the present disclosure is in the second working mode, the input torque from the working part  10  is a clockwise torque, the first ratchet surface  311  rotates clockwise and the second ratchet surface  321  rotates counterclockwise. The first pawl element  211  does not engage with the first ratchet surface  311  and the second pawl element  212  engages with the second ratchet surface  321 ; thus, the first pawl element  211  drives the main shaft  100  to rotate counterclockwise and the output torque is an anticlockwise torque. When the input torque from the working part  10  is a counterclockwise torque, the first ratchet surface  311  rotates counterclockwise and the second ratchet surface  321  rotates clockwise. The first pawl element  211  engages with the first ratchet surface  311  and the second pawl element  212  does not engage with the second ratchet surface  321 ; thus, the second pawl element  212  drives the main shaft  100  to rotate anticlockwise and the output torque is an anticlockwise torque. 
     As previously mentioned, the first working mode and the second working mode of the thin bidirectional ratchet wrench of the present disclosure can be switched and selected via the newel  220 . To be convenient, in this embodiment, as shown in  FIG. 8 , a first end of the newel  220  has a knob  223 , which would be coupled to the newel  220  by embedding two ears (ear  2201  in  FIG. 8 ) of the newel  220  into the knob  223 . In this way, the newel  220  will rotate when turning the knob  223 . In this embodiment, two spines protrude out of the surface of the knob  223 , such as spine  2231 , such that turning the knob  223  can be achieved by putting rotating torque on the two spines, including the spine  2231 . 
     The thin bidirectional ratchet wrench of the present disclosure also contains a blocking device, which keeps the thin bidirectional ratchet wrench of the present disclosure on the selected working mode until the operator switches it to the other mode. In  FIGS. 9 and 10 , the blocking device in this embodiment comprises of a spring  224  arranged on the newel  220 , a ball  400  disposed between the output end  101  and the second end of the newel  220  in a recess matched with the ball  400  on the second end of the newel  220 ; more specifically, a first recess  410  and a second recess  420 . The first recess  410  and the second recess  420  are parallel to each other and are separated by the smooth spine; directions between the spine and the newel have an angle. 
     The spring  224  keeps a force, which is from a second end  2202  of the newel  220  to a first end  2201 . On the newel  220  and the main shaft  100 , the ball  400  is in the first recess  410  or in the second recess  421  beside the second end  2202 . When turning the knob  223 , the spring  224  is compressed, the ball  400  is beside one end of the first recess  410  or in the second recess  420 . The ball  400  can move into the second recess  420  from the first recess  410  or vice versa, and reset the ball  400  back to the first recess  410  or the second recess  420  beside the second end  2202 . 
     When the ball  400  is in the first recess  410 , the ball-head sections of the first spring-loaded plunger  221  and the second spring-loaded plunger  222  maintain contact with the first side wall of the concave section of the first pawl element  211  and the second pawl element  222 , respectively, and the thin bidirectional ratchet wrench of the present disclosure is in the first working mode. When the ball  400  is in the second recess  420 , the ball-head sections of the first spring-loaded plunger  221  and the second spring-loaded plunger  222  maintain contact with the second side wall of the concave section of the first pawl element  211  and the second pawl element  222 , respectively, and the bidirectional wrench of the present disclosure is in the second working mode. When turning the knob  223  to rotate the newel  220  to let the ball  400  move from the first recess  410  to the second recess  420 , the thin bidirectional ratchet wrench of the present disclosure turns from the first working mode to the second working mode. When turning the knob  223  to rotate the newel  220  to let the ball  400  move from the second recess  420  to the first recess  410 , the bidirectional wrench of the present disclosure turns from the second working mode to the first working mode. 
     In this embodiment, the transmission seat  330  is in constant engagement with the holding ring  102 . The transmission seat  330  is fixed with respect to the holding ring  102 , thus when the working part  10  rotates with respect to the holding ring  102 , the idle gears  331 ,  332  make the follower gear  322  and the capstan gear  312  rotate in opposite directions. In use, to keep the idle gears  331 ,  332  working and ensure the second ratchet surface  321  and the first ratchet surface  311  rotate in opposite directions, the operator can orientate the transmission seat  330  by holding the holding ring  102 , thus the capstan gear  312  drives the idle gears  331 ,  331  to rotate, and then drives the follower gear  322  to rotate, thereby making the second ratchet surface  321  and first ratchet surface  311  rotate in opposite directions. It should be noted that in other embodiments of the present disclosure, other methods can also be taken to position the transmission seat  330  and thus drive the idle gears  331 ,  332  to work. 
     In addition, as described previously, the output end  101  of the thin bidirectional ratchet wrench of the present disclosure can be a component, which is suitable to operate various fasteners such as quoin screws, by mounting various sleeves, and the ball  400  in the blocking device can also be used to block the various sleeves, which are mounted on the output end  101  at this moment. 
     In this embodiment, the first pawl element  211  is made of high strength material (such as injected powder metallurgy or NO. 45 steel, etc.) whose strength is 30-40% higher than that of the conventional powder metallurgy material. Thickness (along the extended direction of the main shaft  100 ) of the first pawl element  211  is preferably less than or equal to 6.5 mm. The thickness of the first ratchet surface  311  that engages with the first pawl element  211  is preferably equal to the thickness of the first pawl element  211 . Thickness of the second pawl element  212  is preferably less than or equal to that of the first pawl element  211 . Further, the thickness between a front surface  3301  and a back surface  3302  of the transmission seat is preferably less than or equals to 8.0 mm; the modulus of the idle gears  331 ,  332  is less than or equal to 1. Teeth of the capstan gear  312  and the follower gear  322  engage with the teeth of the idle gears  331 ,  332 . Therefore, thickness (namely the distance between the front surface  103  of the holding ring  102  and the back surface  104  of the main shaft  100  along the extended direction of the main shaft  100 ) of the working part is preferably less than or equal to 30.0 mm. 
     This embodiment reduces the thickness of all the parts in the working part (along the extending direction of the main shaft  100 ) on the basis of satisfying the output torque needed, thereby reducing the whole thickness of the working part; thus, it can be used in narrow spaces easily and still satisfy the torque needed to tighten fasteners. 
     In another embodiment, the first pawl element  211  is made of injected powder metallurgy, the thickness of the first pawl element  211  is preferably less than or equal to 5.0 mm, the thickness of the second pawl element  212  is preferably less than or equal to that of the first pawl element  211 . Further, the thickness of the transmission seat is preferably less than or equal to 6.0 mm; the modulus of the idle gears  331 ,  332  is less than or equal to 0.6. Teeth of the capstan gear  312  and the follower gear  322  engage with the teeth of the idle gears  331 ,  332 . Thickness of the working part is preferably 25.0 mm. 
     In other embodiments, materials of pawl elements do not have to be high strength materials, by disposing the third and fourth pawl elements on the symmetrical position of the first pawl element and the second pawl element related to the main shaft, enough torque can be supplied at the same time reducing the thickness of the pawl element; thus, achieving the purpose of reducing the thickness of the wrench. 
     What stated above described the preferred embodiment in detail. It should be understood that one with ordinary skill in the art can make many modifications and variations according to the present disclosure without any creative work. Therefore, any modification, equivalent replacement and improvement made to the present disclosure without going beyond the spirit and principle of the present disclosure shall be within the scope of the appended claims