Patent Publication Number: US-6339977-B1

Title: Reversible ratchet wrench

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to wrenches and, more particularly, to a reversible ratchet wrench, which has a simple structure, and is easy to operate. 
     Various reversible ratchet wrenches have been disclosed, and have appeared on the market. Conventional reversible ratchet wrenches are commonly complicated, and therefore their manufacturing cost is high. FIG. 8 shows a reversible ratchet wrench according to the prior art. This structure of reversible ratchet wrench comprises a casing, a ratchet wheel, two movable stop members, a spring, and a control wheel. The casing is a hollow cylindrical member, comprising a receiving chamber, which holds the ratchet wheel, enabling the ratchet wheel to be rotated with the tool bit holder shank attached thereto, and a side opening, which receives the stop members at two sides of the ratchet wheel. The spring forces the stop members into engagement with the ratchet wheel to stop the ratchet wheel from rotary motion relative to the casing. The control wheel is revolvably mounted on the casing, having a protruded block. By means of rotating the control wheel leftwards or rightwards, the protruded block is alternatively pressed on the stop members to control the direction of rotation of the ratchet wheel relative to the casing. Because this structure of reversible ratchet wheel is complicated, its manufacturing cost is high. 
     SUMMARY OF THE INVENTION 
     The present invention has been accomplished under the circumstances in view. It is the main object of the present invention to provide a simple structure of reversible ratchet wheel, which is inexpensive to manufacture. It is another object of the present invention to provide a simple structure ot reversible ratchet wheel, which is easy to operate. The reversible ratchet wheel of the present invention comprises a casing fastened to a tool handle to hold a tool bit holder shank and a tool bit at the shank, a forward control ratchet wheel and a backward control ratchet wheel concentrically mounted in the casing, first and second springs respectively mounted in the casing to support the forward control ratchet wheel and the backward control ratchet wheel respectively, a stop control ratchet wheel coupled to the tool bit holder shank tor synchronous motion, a third spring adapted to force the stop control ratchet wheel into engagement with the forward control ratchet wheel and the backward control ratchet wheel, and a rotary control knob mounted on the casing and turned between a first position where the stop control ratchet wheel is maintained meshed with the forward control ratchet wheel and the backward control ratchet wheel, a second position where the forward control ratchet wheel is disengaged from the stop control ratchet wheel tor enabling the tool bit holder shank to be rotated with the stop control ratchet wheel in one direction, and a third position where the backward control ratchet is disengaged from the stop control ratchet wheel for enabling the tool bit holder shank to be rotated with the stop control ratchet wheel in the reversed direction. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded view of a reversible ratchet wrench according to the present invention. 
     FIG. 2 is a sectional assembly view of the present invention, showing the stop control ratchet wheel meshed with the forward control ratchet wheel and the backward control ratchet wheel. 
     FIG. 3 is similar to FIG. 2 but showing the forward control ratchet wheel disengaged from the stop control ratchet wheel, the backward control ratchet wheel meshed with the stop control ratchet wheel. 
     FIG. 4 is similar to FIG. 2 but showing the backward control ratchet wheel disengaged from the stop control ratchet wheel, the forward control ratchet wheel meshed with the stop control ratchet wheel. 
     FIG. 5A is top view of the stop control ratchet wheel according to the present invention. 
     FIG. 5B is a sectional view of FIG.  5 A. 
     FIG. 6A is a top view of the forward control ratchet wheel according to the present invention. 
     FIG. 6B is a sectional view of FIG.  6 A. 
     FIG. 7A is a top view of the backward control ratchet wheel according to the present invention. 
     FIG. 7B is a sectional view of FIG.  7 A. 
     FIG. 8 is an exploded view of a reversible ratchet wrench according to the prior art. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, a reversible ratchet wrench in accordance with the present invention is generally comprised of a casing  1 , a first spring member  11 , a second spring member  12 , a backward control ratchet wheel  2 , a forward control ratchet wheel  3 , a stop control ratchet wheel  4 , a third spring member  42 , and a rotary control knob  5 . The casing  1  is adapted for coupling to a tool handle, comprising a receiving chamber  10 , and an upright coupling tube  101  axially disposed in the receiving chamber  10 . The first spring member  11  and the second spring member  12  are conical type compression springs. The outer diameter of the second spring member  12  is smaller than the inner diameter of the first spring member  11 , so that the second spring member  12  can be received within the first spring member  11 . 
     Referring to FIG.  7  and FIG. 1 again, the backward control ratchet wheel  2  is barrel-like disk comprising a center through hole  20 , a series of teeth  21  sloping leftwards around the center through hole  20 , a plurality of radial ribs  22  equiangularly spaced around the periphery, each radial rib  22  having an upwardly protruded block  23  of a predetermined height. 
     Referring to FIG.  6  and FIG. 1 again, the forward control ratchet wheel  3  is a barrel-like disk comprising a center through hole  30 , a series of teeth  31  sloping rightwards around the center through hole  30 , a plurality of radial blocks  33  equiangularly spaced around the periphery, and a plurality of bottom grooves  32  disposed at the bottom side wall thereof corresponding to the radial ribs  22  of backward control ratchet wheel  2 . The inner diameter of the center through hole  30  of the forward control ratchet wheel  3  is greater than the outer diameter of the backward control ratchet wheel  2 . The backward control ratchet wheel  2  is put in the center through hole  30  of the forward control ratchet wheel  3  concentrically to force the radial ribs  22  into engagement with the bottom grooves  32  respectively, keeping the radial blocks  33  in alignment with the protruded blocks  23  respectively radially. After the backward control ratchet wheel  2  and the forward control ratchet wheel  3  have been assembled, they are put with the first spring member  11  and the second sprinig member  12  in the receiving chamber  10  of the casing  1  around the upright coupling tube  101 , keeping the forward control ratchet wheel  3  and the backward control ratchet wheel  2  supported on the first spring member  11  and the second spring member  12  respectively. 
     Referring to FIG.  5  and FIG. 1 again, the stop control ratchet wheel  4  comprises a center through hole  40 , which has a cross section fitting the cross section of the tool bit holder shank  6 , a series of first teeth  411  disposed at one side, namely, the bottom side thereof and sloping leftwards around the center through hole  40 , and a series of second teeth  41  disposed at the bottom side and sloping rightwards around the series of first teeth  411 . The tool bit holder shank  6  is inserted through the center through hole  40  of the stop control ratchet wheel  4  into the upright coupling tube  101  of the casing  1 , and adapted to hold a tool bit. Further, retainer rings  61  are fastened to respectively outside annular grooves around the periphery of the tool bit holder shank  6  to secure the tool bit holder shank  6  to the casing  1 , enabling the tool bit holder shank  6  to be rotated in the upright coupling tube  101 . The stop control ratchet wheel  4  is inserted into the receiving chamber  10  of the casing  1 , keeping the series of first teeth  411  and the series of second teeth  41  respectively meshed with the series of teeth  21  of the backward control ratchet wheel  2  and the series of teeth  31  of the forward control ratchet wheel  3 . The third spring member  42  is mounted on the top of the stop control ratchet wheel  4 . The rotary control knob  5  is covered on the receiving chamber  10  of the casing  1 , comprising an annular coupling groove  51  disposed at the bottom side thereof and coupled to the peripheral wall of the casing  1 , a center through hole  50  for the passing of the tool bit holder shank  6 , and a plurality of downwardly extended protruded blocks  52 . 
     When assembled, as shown in FIG. 2, the rotary control knob  5  can be rotated to control the working direction of the tool bit holder shank  6 . FIG. 2 shows the downwardly extended protruded blocks  52  of the rotary control knob  5  do no action to the radial blocks  33  of the forward control ratchet wheel  3  and the protruded blocks  23  of the backward control ratchet wheel  2 , the forward control ratchet wheel  3  and the backward control ratchet wheel  2  are respectively pushed outwards by the spring members  12  and  13  to force the respective series of teeth  31  and  21  into engagement with the first and second series of teeth  41  and  411  of the stop control ratchet wheel  4 , and therefore the tool bit holder shank  6  is stopped from rotary motion relative to the casing  1 . Referring to FIG. 3, when rotating the rotary control knob  5  in one direction, the downwardly extended protruded blocks  52  of the rotary control knob  5  force the radial blocks  33  of the forward control ratchet wheel  3  downwards to disengage the forward control ratchet wheel  3  from the stop control ratchet wheel  4 . At this time, the backward control ratchet wheel  2  is still maintained meshed with the stop control ratchet wheel  4 , and therefore the tool bit holder shank  6  can be rotated in one direction relative to the casing  1 . Referring to FIG. 4 when rotating the rotary control knob  5  in the reversed direction, the downwardly extended protruded blocks  52  of the rotary control knob  5  force the protruded blocks  23  of the backward control ratchet wheel  2  downwards to disengage the backward control ratchet wheel  2  from the stop control ratchet wheel  4 . At this time, the forward control ratchet wheel  3  is still maintained meshed with the stop control ratchet wheel  4 , and therefore the tool bit holder shank  6  can be rotated in the reversed direction relative to the casing  1 . 
     While only one embodiment of the present invention has been shown and described, it will be understood that various modifications and changes could be made thereunto without departing from the spirit and scope of the invention disclosed.