Abstract:
Disclosed is a twin-pedal-controlled swivel caster, comprising a caster body frame ( 1 ), a pair of caster assemblies ( 2 ) disposed at two sides of the caster body frame ( 1 ), a swivel assembly ( 5 ) disposed on the caster body frame ( 1 ), and a braking module ( 3 ) capable of braking by stepping on a braking pedal ( 32 ) and a brake release module ( 4 ) capable of resetting the movement of the caster by stepping on a braking release pedal ( 41 ), both of which are disposed in the caster body frame ( 1 ). By means of the pedals, the swivel caster can both lock the rotation of a wheel plate of the caster and lock the direction of rotation of the caster, and can also release the dual-locked state by means of the braking release pedal ( 41 ) located in the same direction as the braking pedal ( 32 ), making the caster return to a state of full freedom again. The braking and braking release actions of the swivel caster are convenient and easy, and the swivel caster is simple to operate.

Description:
TECHNICAL FIELD 
       [0001]    The present application relates to a caster, in particular, it relates to a double-pedal controlled swivel caster. 
       BACKGROUND 
       [0002]    After wheel was invented, it has become easier to move large size item. There was significant deficiency for early wheels, i.e., the wheels could only move along a straight line or they were difficult to brake, as a result the flexibility for movement and the safety for stop were restricted. Then the wheel with all degrees of freedom and brake structure was created, that is what we now call “universal caster”. Nowadays the universal casters are widely used in the fields of medical instrument, office, retailing device, furniture and the like. The appearance of universal caster has brought an Epoch-making revolution for people to move equipment. With the continuous upgrade of the application demand, the caster has gradually become a necessary part of daily work, it can endow more and more devices for working in office and operation with mobile ability. Current universal caster is typically braked with a single pedal, in this case, for shifting between the braking and the releasing of brake, the user should continuously change the force direction of foot so as to perform the operation on the caster, for example, when brake a caster the pedal should be pressed down; when release the brake the pedal should be raised up. The user may feel uncomfortable after a long period of repeated braking operation, therefore the existing caster structure should be improved, and the traditional mode of braking a caster by pressing down and raising up the pedal should be altered by adding auxiliary parts. 
       SUMMARY 
       [0003]    The technical problem to be solved by the present application is to overcome the deficiency in prior art, and provide a double-pedal controlled swivel caster, which comprises two pedals located in the same direction to perform both the operations of universally braking and releasing of brake. 
         [0004]    To solve the above-said technical problem, the present application provides the following technical solution: a double-pedal controlled swivel caster comprising a caster main frame, a pair of caster assemblies disposed at both sides of the caster main frame, a swivel assembly disposed on the caster main frame, and a braking module arranged in the caster main frame for braking after a brake pedal is pressed down, and a brake release module arranged in the caster main frame for restoring the movement of the caster after a braking release pedal is pressed down. 
         [0005]    Further, there are two wheel sheet slots arranged on both sides of the caster main frame for setting the caster assemblies, and a central shaft disposed in the wheel sheet slots, and the caster assembly comprises a wheel sheet sleeved on the central shaft. 
         [0006]    Further, there is a main shaft hole arranged on the caster main frame, and the swivel assembly comprises a spindle cover, bearing and universal brake gear set, wherein the universal brake gear set includes a upper gear and a lower gear engaging with each other, the universal brake gear set is arranged inside the bearing, the universal brake gear set and the bearing are fixed inside the main shaft hole by means of the spindle cover. 
         [0007]    In particular, the caster main frame contains a brake groove therein, the brake module is disposed inside the brake groove, the brake module comprises a brake block arranged inside the brake groove for controlling the rotation of the wheel sheet and a brake pedal arranged inside the brake block with one side extending outside the caster main frame for jacking up the brake block. 
         [0008]    In particular, a first universal engaging tooth is arranged at the bottom of the lower gear of the swivel assembly, a top sheet is arranged on the top of the brake block, and a second universal engaging tooth engagable with the first universal engaging tooth is disposed on the top sheet. 
         [0009]    In particular, an annular groove is disposed on one side of the wheel sheet, and a first brake engaging tooth is arranged on the wall surface of the inner ring of the annular groove, the brake block includes a main body, a positioning hole arranged at the center of the main body and movable upwards and downwards along the central shaft of the central shaft of the caster main frame, and a brake pad extending outwards from each side of the bottom of the main body, wherein the brake pad passes through the caster main frame and inserts into the annular groove of the wheel sheet, and a second brake engaging tooth engagable with the first brake engaging tooth is arranged on the surface of the brake pad. 
         [0010]    In particular, a hollow groove is arranged inside the brake block main body, the brake pedal comprises a main body and a pedal connected therewith and extending outwards, a center hole concentrical to the central shaft of the caster main frame is arranged on the main body, a convex surface contactable with the brake block is arranged outside the main body, and the main body is arranged inside the hollow groove of the brake block main body. 
         [0011]    In particular, a slope is arranged on the main body of the brake block, and the brake release module butts against the slope. 
         [0012]    Furthermore, a brake release groove and a restriction rail along the axis thereof are arranged on the caster main frame, the brake release module containing a brake release pedal and a spacing shaft is arranged inside the brake release groove, wherein the brake release pedal contains a pedal and an ejector rod perpendicular thereto, a spacing hole is disposed on the ejector rod for the spacing shaft passing through, the spacing shaft is movable along the restriction rail of the caster main frame, and the ejector rod butts against the brake module. 
         [0013]    In particular, the brake release module further comprises a return spring arranged on the ejector rod. 
         [0014]    The advantageous effect of the present application is as follows: the swivel caster in the double-pedal controlled swivel caster according to the present application can not only rotate in different directions freely, but also lock the wheel sheet and prohibit its rotation by means of the pedal, so the caster is fixed and cannot rotate any more, more important, the double locked status can be released by means of another brake release pedal, therefore the caster resets to universal rotation with full degrees of freedom. The caster contains a brake module which not only controls the lock of wheel sheet of caster automatically to prohibit its rotation, but also capable of locking the universal control direction so as to prevent the random rotation of the whole caster, the caster also contains a brake release module which may release the double locked state by means of the brake release pedal of the same orientation with the brake module. In particular, as the brake release pedal is pressed down, the brake block of the brake module is pushed down simultaneously, so the caster obtains the freedom of moving and the brake release module eliminates the painful lift of the brake pedal for the brake release, therefore both actions of brake and release are easy to perform. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is a perspective view of a double-pedal controlled caster according to an example of the present application. 
           [0016]      FIG. 2  is a sectional view of a double-pedal controlled caster according to an example of the present application. 
           [0017]      FIG. 3  is an exploded perspective view of a double-pedal controlled caster according to an example of the present application. 
           [0018]      FIG. 4-1  is a perspective view of the caster main frame of a double-pedal controlled caster according to an example of the present application. 
           [0019]      FIG. 4-2  is a side view of the caster main frame of a double-pedal controlled caster according to an example of the present application. 
           [0020]      FIG. 5  is a perspective view of the wheel sheet of a double-pedal controlled caster according to an example of the present application. 
           [0021]      FIG. 6  is a perspective view of the brake block of a double-pedal controlled caster according to an example of the present application. 
           [0022]      FIG. 7  is a perspective view of the brake pedal of a double-pedal controlled caster according to an example of the present application. 
           [0023]      FIG. 8  is a perspective view of the brake release pedal of a double-pedal controlled caster according to an example of the present application. 
       
    
    
       [0024]    In the accompanying Figures:  1 : caster main frame,  11 : central shaft;  12 : wheel sheet slot;  13 : brake groove;  131 : hollow groove; 
         [0025]      132 : side groove;  14 : brake release groove;  141 : restriction rail;  15 : main shaft hole; 
         [0026]      2 : caster assembly;  21 : wheel sheet;  211 : sheet shaft hole;  212 : annular groove; 
         [0027]      2121 : first brake engaging tooth;  213 : buckling groove;  22 : caster lid;  221 : clamp clasp; 
         [0028]      23 : caster bearing,  24 : bearing cap; 
         [0029]      3 : brake module,  31 : brake block,  311 : positioning shaft hole,  312 : brake pad, 
         [0030]      3121 : second brake engaging tooth,  313 : positioning shaft,  314 : hollow groove, 
         [0031]      315 : top sheet,  3151 : second universal engaging tooth,  316 : brake release slope, 
         [0032]      32 : brake pedal,  321 : main body,  3211 : center hole,  322 : pedal,  33 : retaining spring; 
         [0033]      4 : brake release module,  41 : brake release pedal,  411 : pedal,  412 : ejector rod,  413 : spacing hole, 
         [0034]      42 : return spring,  43 : spacing shaft; 
         [0035]      5 : swivel assembly,  51 : spindle cover,  52 : universal brake gear,  521 : upper gear, 
         [0036]      522 : lower gear:  5221 : first universal engaging tooth,  53 : bearing. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0037]    Objects, advantages and embodiments of the present application will be explained below in detail with reference to the accompanying drawings and examples. However, it should be appreciated that the following description of the example is merely exemplary in nature and is not intended to limit this application. 
         [0038]    Referring to  FIGS. 1 to 8 , a double-pedal controlled swivel caster according to the present application is shown. The swivel caster is suitable to install onto all kinds of equipment, so as to make the equipment to rotate, move and brake freely. In particular, the swivel caster can be employed in such equipment as medical device, health care device, mobile retailing equipment, household furniture and the like. Next, for further details please refer to  FIGS. 1 to 3 , the embodiments of the present application provide the structure of a double-pedal controlled swivel caster, which includes a caster main frame  1 , a pair of caster assemblies  2  disposed on both sides of the caster main frame  1 , a swivel assembly  5  disposed on the caster main frame  1 , and a braking module  3  arranged in the caster main frame  1  for braking after stepping on a brake pedal  32 , and a brake release module  4  arranged in the caster main frame  1  for restoring the movement of the caster after stepping on a braking release pedal  41 . There are a set of caster assemblies  2  arranged on each side of the main frame  1 , such that the basic function of moving freely for the swivel caster can be achieved. A swivel assembly  5  is disposed on the caster main frame  1 , when the caster including the caster main frame  1  is installed on equipment, it can endow this caster with rotation function of full freedom degree. Meanwhile, the brake module  3  in the main frame  1  can brake the caster by means of stepping on the brake pedal  32 . The brake module  3  can control the two caster assemblies  2  on both sides, so as to stop the caster assembly  2  and control the movement of the caster; meanwhile the brake module  3  can also control the swivel assembly  5 , as a result the caster cannot rotate, therefore after preforming the brake the caster is totally kept in the status of “double locked”, i.e., stop moving and rotating. With respect to the release of the brake to the brake module  1 , there is no need to raise the brake pedal up. The release of brake can be carried out directly by employing the brake release module  4  of the same direction with the brake module  3  of the present application. By means of stepping on the brake release pedal  41  of the brake release module  4 , the components of “double locked” status in the brake module  3  is reset, thereby the brake state is released, and the swivel caster restores to the capability of moving and rotating with full freedom degree. Both the brake pedal  32  of the brake module  3  and the brake pedal  32  of the brake release module  4  of the present application employ the brake mode of receiving force in the same direction, therefore the operations of brake and release can be carried out easily, and the equidirection control of double pedals can be achieved. 
         [0039]    In particular, please refer to  FIGS. 4-1  to  5 , there are two wheel sheet slots  12  for receiving corresponding caster assemblies  2  arranged on both sides of the caster main frame  1 , and a central shaft  11  is arranged inside the wheel sheet slot  12 . The caster assembly  2  contains a wheel sheet  21  disposed on the central shaft  11  and a caster lid  22  arranged outside of the wheel sheet  21 . In particular, there is a shaft hole  211  arranged at the center of the wheel sheet  21 . A bearing  23  is installed in the shaft hole  211  of wheel sheet  21 , and the wheel sheet  21  containing bearing  23  is fixed onto the central shaft  11  of the caster main frame  1 . A bearing cap  24  is disposed between the wheel sheet  21  and the caster lid  22 , the bearing cap  24  is used for pressing against the inner ring of the bearing  23 , so as to fix the wheel sheet  21  onto the central shaft  11  of the caster main frame  1  meanwhile the wheel sheet  21  remains rotatable around the central shaft  11 . And the bearing cap  24  can be pressed onto the wheel sheet  21  tightly by means of caster lid  24 . The caster lid  22  is buckled outside the wheel sheet  21 . There are four evenly spaced clamp clasps  221  perpendicular to caster lid  22  arranged on one side along the circumference of the caster lid  22 , and there are four buckling groove  213  corresponding to and engagable with the clamp clasps  221  arranged along the circumference of the wheel sheet  22 . The clamp clasp  221  of the caster lid  22  is buckled into the buckling groove  213  of wheel sheet  21 , so as to press the bearing cap  24  against the inner ring of the bearing  23 . 
         [0040]    Next, please refer to  FIG. 4-1 , there is a main shaft hole  15  arranged on the caster main frame  1 , and the swivel assembly  5  comprises a spindle cover  51 , a bearing  53  and a universal brake gear set  52 , wherein the universal brake gear set  52  includes an upper gear  521  and a lower gear engaging with the upper gear  521 , the universal brake gear set  52  is arranged inside the bearing  53 , the universal brake gear set  52  and the bearing  53  are fixed inside the main shaft hole  15  by means of the spindle cover  51 . Specifically, the device employing the swivel caster can be fixed onto the swivel assembly  5  by means of an axis body. And the swivel caster controls the free movement of the whole caster by means of the swivel assembly  5  as it contains a universal brake gear set  52 . The upper gear  521  has a through hole for an axis body passing through, the upper gear  521  contains an upper cylinder and an upper retainer ring connected thereto, the through hole runs through both the upper cylinder and the upper retainer ring, and there is a first meshing tooth engagable with the lower gear  522  disposed on the bottom side of the upper cylinder. The upper cylinder of the upper gear  521  is arranged inside the bearing  53 , and the upper retainer ring presses against the inner ring of the bearing  53 . The lower gear  522  also contains a through hole for an axis body passing through, the lower gear  522  contains a lower cylinder and a lower retainer ring connected thereto, the through hole runs through both the lower cylinder and the lower retainer ring, and there is a second meshing tooth engagable with the first meshing tooth of the upper gear  521  disposed on the upper side of the lower cylinder. The lower cylinder of the lower gear  522  is arranged inside the bearing  53 , and the lower retainer ring presses against the outer ring of the bearing  53 . The lower retainer ring of the lower gear  522  is arranged on the bottom of the main shaft hole  15  of the caster main frame  1 , the upper gear  521  is locked into the main shaft hole  15  by means of the spindle cover  51 , and the upper gear  521  presses against the bearing  53 . As the swivel caster is in a state of free rotation, there is a certain distance between the upper cylinder of upper gear  521  and the lower cylinder of lower gear  522  although they both are arranged inside the bearing  53 , as a result the first and second meshing teeth cannot contact with each other. 
         [0041]    Next, please refer to  FIGS. 3 and 6 , a brake groove  13  is arranged inside the caster main frame  1 , a brake module  3  is disposed inside the brake groove  13 , the brake module  3  contains a brake block  31  arranged inside the brake groove  13  and a brake pedal  32  arranged inside the brake block  31  with one side thereof extending to the outside of the caster main frame  1  and jacking up the brake block  31 . In particular, a hollow groove  131  is arranged inside the caster main frame  1 , a through hole (not shown) connects the hollow groove  131  with the main shaft hole  15 . A first universal engaging tooth  5221  is arranged on the bottom of the lower gear  522  of the swivel assembly  5 , a top sheet  315  is arranged on the top of the brake block  31 , and a second universal engaging tooth  3151  engagable with the first universal engaging tooth  5221  is disposed on the top sheet  315 . The top sheet  315  of the brake block  31  can contact with the swivel assembly  5  inside the main shaft hole  15  through the through hole (not shown) connecting the hollow groove  131  with the main shaft hole  15 . When the brake pedal  32  is pressed down, the brake pedal  32  jacks the brake block  31  up, therefore the top sheet  315  of the brake block moves upwards to contact with the lower gear  522  of the swivel assembly  5 , meanwhile, the first universal engaging tooth  5221  is engaged with the second universal engaging tooth  3151 , as a result the lower gear  522  cannot rotate. At the same time, as the brake block  31  moves upwards, the lower gear  522  is forced to move upwards, therefore the upper gear  521  of the universal brake gear set  52  contacts with the lower gear  522 , as a result the first meshing tooth of the universal brake gear set  52  is engaged with the second meshing tooth, and the upper gear  521  cannot rotate, meanwhile the universal brake gear set  52  presses downwards against the bearing  53 , so the inner and outer rings of the bearing  53  cannot rotate, so as to control the swivel caster and make it cannot rotate relative to the axis body of the connection device. That is to say, when the brake block  31  jacks up, the universal brake gear set is locked by the top sheet  315 , therefore the whole swivel caster is controlled and cannot rotate relative to the connected device, so the rotation direction of the swivel caster is locked. 
         [0042]    In particular, please refer to  FIG. 5 , an annular groove  212  is disposed on one side of the wheel sheet  21 , and a first brake engaging tooth  2121  is arranged on the wall surface of the inner ring of the annular groove  212 . The brake block  31  includes a main body  31 , a positioning hole  311  arranged at the center of the main body  31  and movable upwards and downwards along the central shaft  11  of the central shaft  11  of the caster main frame  1  and a brake pad  312  extending outwards from each side of the bottom of the main body  31 , wherein the brake pad  312  passes through the caster main frame  1  and inserts into the annular groove  212  of the wheel sheet  21 , and a second brake engaging tooth  3121  engagable with the first brake engaging tooth  2121  is arranged on the surface of the brake pad  312 . A side groove  132  is disposed on the bottom of the caster main frame  1  so as to connect the hollow groove  131  with the wheel sheet slot  12 . And the brake pad  312  is just arranged inside the side groove  132  of the caster main frame  1 . When the wheel sheet  21  of the swivel caster rotates normally, the brake pad  312  is only inserted into the annular groove  212  of the wheel sheet  21  through the side groove  132 , at this time, the first brake engaging tooth  2121  does not contact with the second brake engaging tooth  3121 , therefore the brake block  31  has no effect on the rotation of the wheel sheet  21 . When the brake pedal  32  is pressed down, the brake pedal  32  props up the brake block  31  and forces the brake pad  312  of the brake block  31  to move upwards, then the first brake engaging tooth  2121  is engaged with the second brake engaging tooth  3121 , and the brake pad  312  controls the wheel sheet  21  and prohibits its rotation, so as to perform a brake to the swivel caster, so the swivel caster cannot move and the wheel sheet  21  of the swivel caster is locked. 
         [0043]    Accordingly, when the brake pedal  32  is pressed down, the brake pedal  32  props up the brake block  31 , then the top sheet  315  at the top of the brake block  31  is connected with the swivel assembly  5 , therefore the rotation direction of the swivel caster can be controlled; meanwhile the brake pads  312  on both sides of the brake block  31  are forced to move upwards and connect with the wheel sheets  21  on both sides of the caster main frame  1 , so as to control the rotation of the wheel sheet of the swivel caster, and the lock of the rotation direction of the swivel caster and brake are performed. 
         [0044]    In particular, a hollow groove  314  is arranged inside the brake block main body  31 , the brake pedal  32  contains a main body  321  and a pedal  322  connected with the main body  321  and extending outwards. A center hole  3211  concentrical to the central shaft  11  of the caster main frame  1  is arranged on the main body  321 , a convex surface  3212  contactable with the brake block  31  is arranged on the outer side of the main body  321 , and the main body  321  is arranged inside the hollow groove  314  of the brake block main body  31 . According to the embodiments of the present application, when the brake pedal  32  is pressed down, the main body  321  of the brake pedal rotates around the center hole  3211 , and the convex surface  3212  butts against the inner part of the brake block  31 . When the pedal  322  of the brake pedal  322  is pressed down, the convex surface  3212  butts against the brake block  31  and moves upwards so as to carry out the process of braking of swivel caster and stopping the rotation of the caster. A positioning column  313  is disposed on the brake block main body  31 , and a positioning hole (not shown) corresponding to the positioning column  313  is arranged inside the caster main frame  1 , a retaining spring  33  is arranged on the positioning column  313 . As the brake pedal  32  rotates along the convex surface  3212  when the brake pedal is pressed down to prop up the brake block  31 , when the top sheet  315  of the brake block  31  butts against the lower gear  522  of the swivel assembly  5  and reaches the peak point of the brake block  31 , the retaining spring  33  on the positioning column  313  reaches its ultimate state, so the brake block  31  cannot move upwards any more, and the brake pedal  32  cannot be pressed down any more. The retaining spring  33  plays a restriction role on the upward movement of the brake block  31 . 
         [0045]    A slope  316  is arranged on the main body of the brake block  31 , and the ejector rod  412  of the brake release pedal  41  butts against the slope  316 . When the brake release pedal  41  is pressed down, the ejector rod  412  of the brake release pedal  41  moves downwards long the restriction rail  141 , therefore the ejector rod  412  butts against the slope  316  of the brake block  31 , the brake block  31  receives a downward force, the brake block  31  moves downwards, and the top sheet  315  on the brake block  315  separates from the lower gear  522  of the swivel assembly  5  then the swivel caster obtains the ability of universal rotation again, and the second brake engaging tooth  3121  of the brake pad  312  of the brake block  31  separates from the first brake engaging tooth  2121  of the wheel sheet  21  so as to endow the wheel sheet with the ability of rotating again. So the swivel caster is released from the “double locked” state. When the brake block  31  moves downwards, it takes the brake pedal  32  to rotate around the center hole  3211 , and the pedal  322  of the brake pedal  32  moves upwards and resets to initial state. 
         [0046]    Specifically, the slope  316  locates in an acute angle of  20  to  40  degrees with the vertical horizon. If the slope  316  has an unreasonable arrangement, the brake block  31  cannot be pressed down when the brake release pedal  41  is pressed down, so the action of braking cannot be performed. 
         [0047]    In particular, please refer to FIGS.  3  to  4 - 2  and  FIG. 8 , a brake release groove  14  and a restriction rail  141  disposed along the axis thereof are arranged on the caster main frame  1 , and a brake release module  4  containing a brake release pedal  41  and a spacing shaft  43  is arranged inside the brake release groove  14 , wherein the brake release pedal  41  contains a pedal  411  and an ejector rod  412  perpendicular to the pedal  411 , a spacing hole  413  for spacing shaft  43  passing through is disposed on the ejector rod  412 , the spacing shaft  43  is arranged through the spacing hole  413  of the ejector rod  412  and it is movable along the restriction rail  141  of the caster main frame, the ejector rod  412  butts against the brake module  3 , and the brake release module  41  further contains a return spring  42  arranged on the ejector rod  412  of the return spring  42 . The brake release groove  14  is arranged above the caster main frame  1 . The pedal  411  is disposed outside the brake release groove  14  so it can be stepped and controlled, the ejector rod  412  connected with the pedal  411  is inserted into the brake release groove  14 . A restriction rail  141  is disposed on the brake release groove  14  along the axis thereof, the restriction rail  141  is a long middle hole capable of running through the left and right wheel sheet slots  12  arranged on the left and right wheel sheet slots  12  of the caster main frame  1 , and the long middle hole is arranged along the axis of the brake release groove  14 . The spacing shaft  43  is set up through the long middle hole, and it is movable along the long middle hole. Both ends of the spacing hole  413  arranged on the ejector rod  412  can connect with the long middle hole of the caster main frame  1 , as a result the spacing shaft  43  can move through both the restriction rail  141  and spacing hole  413  back and forth, that is, the spacing shaft  43  can move along the axis direction of the brake release groove  14  back and forth. Accordingly, the ejector rod  412  can only move along the axial direction of the brake release groove  14  under the interaction between the spacing shaft  413  and the restriction rail  141 . When the brake pedal  41  is pressed down, the brake pedal  41  moves along the axial direction of the brake release groove  14 . Further, the ejector rod  412  contains a return spring  42  arranged thereon, which butts against the connection portion between the pedal  411  and the ejector rod  412  by one end and against the bottom of the brake release groove  14  by the other end. When the brake release pedal  41  is pressed down, the pedal  411  receives a downward force at the same time, therefore the ejector rod  412  butts against the brake module  3  and forces the brake module  3  to move downwards, so as to release the brake action of the brake module  3 . After releasing the pedal  411 , the pedal  411  moves upwards to reset automatically under the function of the return spring  42 , and the ejector rod  412  separates from the brake module  3 . The movement of the brake release pedal  41  is just the reciprocating motion along the axial direction of the brake release groove  14 , and it only controls the brake module  3  and does not make any effect on other components of the caster. 
         [0048]    In summary, the double-pedal controlled swivel caster according to the present application contains a swivel assembly, and the caster can rotate universally, it also contains a brake module  3  capable of locking the wheel sheet  21  of the caster by means of the brake pedal  3  so as to prohibit its rotation, the brake module  3  can also forbid the rotation of the whole caster by locking it. Meanwhile, there is a brake release module  4  capable of releasing the caster from the double locked status by means of the brake release pedal  41  having the same orientation with the brake module  3 , in particular, as the brake release pedal is pressed, the brake block  31  of the brake module  3  is pushed down so the caster obtains the movement of freedom, and the brake release module  4  eliminates the painful lift of the brake pedal for the brake release, therefore both the actions of brake and release are easy to perform. 
         [0049]    The embodiments above are merely the preferable embodiments of the present application and not intended to limit the present application. And all changes equivalent substitution and improvements which come within the meaning and range of equivalency of the present application are intended to be embraced therein.