Abstract:
A circuit breaker arrangement is disclosed. It comprises a cart ( 1 ) on which slides a circuit breaker. A lead screw ( 14 ) drives the circuit breaker along a linear path by moving a drive block ( 15 ), an upper protuberance ( 211 ) of which engages the circuit breaker. The arrangement provides for an automatic uncoupling of the circuit breaker at an end position of the drive block ( 15 ), where a handle inserted into a hole ( 24 ) may turn an end of the lead screw and rock the drive block with a meshing mechanism ( 43 ) so that the protuberance ( 211 ) escapes the circuit breaker. It is therefore very easy to mount, dismount or replace the circuit breaker. A similar advantage based on unlatching an interlock may be obtained for dismounting the electrical motor ( 12 ) that normally drives the lead screw ( 14 ). The invention can well take place in the medium voltage industry.

Description:
BACKGROUND 
       [0001]    The present invention relates to a circuit breaker arrangement. 
         [0002]    In the current medium voltage industry, the central removable switch cabinet plays a predominate role, and the primary characteristic thereof is that the circuit breaker can be separated from the switch cabinet. Based on the position of the circuit breaker within the switch cabinet, there are three different states: operating position, intermediate position and testing position. When the circuit breaker is at the operating position, the circuit breaker can be coupled with the main circuit of the switch cabinet; and when the circuit breaker is at the testing position, the circuit breaker maintains an isolation state from the main circuit of the switch cabinet. Wherein, the circuit breaker can only be drawn out from the switch cabinet when being in the testing position. 
         [0003]    The movement of the circuit breaker can be achieved by a carrying cart. The existing carrying carts for the circuit breaker are mostly mounted onto the circuit breaker as an auxiliary for the circuit breaker. Such a conventional cart for the circuit breaker has become the only choice for most of the domestic switch cabinet companies. However, the existing carts for the circuit breaker present much problem as follows: 
         [0004]    The cart and the circuit breaker are coupled into one entirety through bolt fastening, so that the circuit breaker and the cart wholly have a greater volume, are cumbersome, and the weight thereof is at least 15 kg, resulting in a higher package and transportation cost. 
         [0005]    It has too little functions, lacks positional mechanical indication, has no emergency braking button and linkage dispersing, and the linkage for the low voltage plug is mounted on the switch cabinet. In addition, the existing cart also has no padlock and key lock. 
         [0006]    In the swaying in/out process of the cart, the circuit breaker would be rocked, causing damage to the lead-screw. 
         [0007]    The switching mechanism for the position switch is complicated, and the switching is unreliable. 
         [0008]    The circuit breaker is swayable in/out when the door of the switch cabinet is in an open state, and the door can be opened when the circuit breaker is at intermediate position, which causing low safety. 
         [0009]    The electrical arrangement is complicated to be implemented. 
         [0010]    And according to a further aspect of the invention, an increasing number of medium-voltage switch cabinets requires electrodynamic mechanism, the operating position and isolated location of the circuit breaker accommodated in the cabinet is needed to have the ability of automatic switchover. Due to the possibility of the electrical motor occurring failure, it&#39;s necessary for the electrical motor to be able to facilitate assembly and disassembly, and at the same time, when manual operation is required, the electrical motor needs to be powered off. In the medium-voltage switch cabinet, the electrical motor driver mechanism, which drives the circuit breaker through the cart, generally moves along with the circuit breaker, and the electrical motor driver mechanism is commonly coupled with the drive lead screw of the cart via rack-and-gear. As such, additional 4 to 5 gears as well as chains would be added, and the transmission efficiency is lower, the adding of the chains also increases greatly the risk of failure. The cost is also increased. Using such a way that the electrical motor driver mechanism is cooperated with the drive lead screw of the cart, the circuit breaker will have to lifted by a crane when failure occurs for the electrical motor, the chassis, i.e., the aforementioned cart, is disassembled from the circuit breaker, then a screwdriver is used to unload the screw of the electrical motor and a new electrical motor is transferred to replace the used one, and the screwdriver is again used to fix the electrical motor onto the cart, then the cart is mounted to the circuit breaker. 
         [0011]    It can be appreciated that such a manner, in which the electrical motor driving mechanism is coupled with the drive lead screw of the cart, makes it difficult to replace the inactive electrical motor, to perform assembly and maintenance, and further, the use of additional gears and chains would increase the manufacturing cost. 
         [0012]    Thus, a drawback of conventional circuit breaker arrangements is that some heavy and cumbersome components are difficult to dismount and mount again on the cart of the cabinet, although this may become necessary for repair or replacement. The general purpose of this invention is to make easier the mounting and dismounting of these components with a modular construction of the circuit breaker arrangement. 
         [0013]    According to a general definition, the invention relates to a circuit breaker arrangement, comprising:
       a circuit breaker;   a cart on which the circuit breaker slides, the cart comprising a lead screw and a circuit breaker drive block, said drive block being threaded on the lead screw and driving the circuit breaker;   an electrical motor that rotates the lead screw;   characterized in that the circuit breaker and/or the electrical motor are mounted on the cart through connections consisting of interlocked parts, a latch for engaging one of the interlocked parts and maintaining said interlocked parts in an interlocked state, and a mechanism for releasing the latch.       
 
         [0018]    The connection between the cart and the separable modules comprising the circuit breaker and/or the electrical motor is based on an interlock of mating parts. The interlock can be made easily, by simple approach movements of the mating parts. When it is made, a right positioning of the modules on the cart is ensured. The latch safely maintains the interlock afterwards, until the mechanism is actuated. No complicated operations like installing and screwing bolts, or assembling the loose parts of a power transmission mechanism, are present in the invention. 
         [0019]    When the invention is embodied for the circuit breaker module, the interlocked parts favorably comprise a protuberance on the drive block and an aperture in a floor of the circuit breaker, the protuberance entering the aperture in the interlocked state. The interlock can be made or interrupted by a mere movement of the protuberance, which may result from a rotation of the drive block. The circuit breaker module remains free on the cart when the interlock is interrupted and it may be removed by sliding on the cart upper surface. No particular accuracy is required from the operators. 
         [0020]    Further, the latch may comprise static means provided on the cart for impeding a rotation of the drive block. Static means are likely to be safe and durable. An example consists in edges of an elongated slot parallel to the lead screw, said edges being adjacent to the protuberance, the elongate slot extending along a stroke of the drive block along the lead screw except at a disconnecting position for the circuit breaker. The disconnection of the circuit breaker module is possible only at a single position of the circuit breaker then, which could correspond to the testing position, and a safe connection of the module is ensured at the other positions, especially the operating positions. 
         [0021]    The mechanism for releasing the latch may consist in means for rotating the drive block. This mechanism may depend on a handle normally not present on the apparatus, so that the unlatching only occurs with a voluntary action. It may be actuated by a particular rotation of the lead screw, either with the separate handle or with the electrical motor. In either case the unlatching occurs only when a determined position of the drive block is reached, which imposes a voluntary action anyway. In particular embodiments of the invention, this means comprises meshing elements provided on the drive block and on a support rotating with the lead screw. It may further comprise a guiding sleeve slidably and rotatably retained in a plate of the cart, a spring for biasing the sleeve at a set angular position and at a distance of the support, and the guiding sleeve comprises meshing elements which mesh with the elements of the drive block and of the support. 
         [0022]    Also, the cart may comprise a front panel, which is provided with a handle inserting hole registering with a free end of the lead screw. The front panel may carry various knobs, warning lights, etc. for a convenient and elaborate operation of the apparatus. However, the handle inserting hole provides for the mentioned voluntary unlatching operation. This hole may remain obstructed during the normal operation of the apparatus. 
         [0023]    When the invention is embodied on the electrical motor, the interlocked parts may comprise at least one pin and one mating pilot hole, the pin and the pilot hole being provided on a mounting first plate of the electric motor and on a second mounting plate provided on the cart. A better positioning is obtained with two pilot holes and two pins. This interlock is particularly easy to establish and to interrupt, with straightforward movements of the motor module. 
         [0024]    In a particular embodiment, the second mounting plate is elbow-shaped, and the lead screw is provided with a third mounting plate, the third mounting plate being fixed to an upper side of the second mounting plate and the first mounting plate standing opposite another, vertical side of the second mounting plate. Such a construction facilitates an automatic coupling of the motor output shaft to the lead screw when the motor module is mounted to the cart. The coupling may include the engagement of a key (having a non-circular cross-section) into a mating keyway. A clutch may be present between the motor and the lead screw. 
         [0025]    In such embodiments, the latch may simply comprise a mobile plate connected to a part in which the pilot holes are provided, and penetrating in grooves of the register pins, and the mechanism for releasing the latch may then comprise comprises a fourth mounting plate, and a pin provided on the fourth mounting plate and about which the mobile plate rotates. 
         [0026]    In favorable embodiments of the apparatus, there is provided a swayable in/out driver mechanism for the circuit breaker, the driver mechanism comprises: a cart body which is fixed to the switch cabinet and does not move along with the circuit breaker in the switch cabinet; a lead-screw mounted onto the cart body by means of a lead screw anchor support and being only rotatable, wherein the lead-screw can be directly driven with a handle or electrical motor; a circuit breaker driver block engaged with the lead-screw, which moves forward and backward along the lead-screw under the rotation of the lead-screw, so as to bring the circuit breaker to switch between the operating position and the testing position, wherein when the circuit breaker is at the testing position, the connection or separation between the driver block and the circuit breaker can be achieved. 
         [0027]    The driver mechanism further comprises: a front panel for the cart, which panel can protrude from the door of the switch cabinet so as to operate the circuit breaker and also comprises the functions of information indication and linkage. 
         [0028]    The front panel for the cart comprises an emergency braking button, a padlock, a key lock, an insertion aperture for handle operation, an indicating device for the position of the circuit breaker and an indicating device for linkage state. 
         [0029]    The emergency braking button comprises the following functions: (1) emergency braking, (2) improper operation proofing, and (3) mechanical and electrical block, and the emergency braking button has striking colors, and when the door is closed, operators perform operations to the emergency braking button through the pushing, moving and releasing operations. 
         [0030]    The driver mechanism further comprises a handle slide for achieving the function where the circuit breaker can only be swayed in/out when the door is closed. 
         [0031]    The driver mechanism also comprises a key lock, so that, only on occasions that it&#39;s unlocked in advance, could the handle slide be slid. 
         [0032]    The driver mechanism can also control the driving operation through low voltage plug linkage, such that, when no low voltage plug is inserted, the cart can not be swayed. 
         [0033]    The driver mechanism further comprise a gain on the door linking plate, so that when the circuit breaker is at the intermediate position, the gain on the door linking plate locks the stop pin on the door of the switch cabinet. 
         [0034]    The driver mechanism is further provided with a grounding blade linkage associated with the grounding blade, such that, when the grounding blade is switched-on, the circuit breaker can not be swayed in, and when the circuit breaker is in the intermediate position, the grounding blade can not be switched-on. 
         [0035]    When the circuit breaker is in the operating position, switching-on can only be enabled when the handle is drawn out. 
         [0036]    The circuit breaker according to the present invention comprises the following advantages: 
         [0037]    The cart has a much lighter weight which is ⅓ of that of the existing cart, and also has a lower cost than the existing cart. 
         [0038]    The cart functions even more perfectly, integrates components which are previously arranged on the switch cabinet, such as the emergency braking button, linkage of the low voltage plug states, and is newly added with functions, such as a circuit breaker which is swayable in/out only when the door is closed, the door being unable to be opened when the cart is at the intermediate position, and status indication of the position of the circuit breaker and so on. 
         [0039]    It&#39;s newly added with a key lock and a padlock, so that the safety is further improved. 
         [0040]    An electrical motor may be directly mounted onto the lead-screw for driving the circuit breaker cart, so as to achieve motor driving. 
         [0041]    The circuit breaker cart is mounted onto the switch cabinet, such that the transmission of the cart is more stable without any misalignment, and the cart and the circuit breaker are separated from each other, which enables more stable mechanical characteristics of the circuit breaker. 
         [0042]    The forward and backward movement of the driver block for the cart provides for a more reliable switchover of the travel switch. 
         [0043]    The present design concept differs obviously from existing chassis carts available on the market, existing problems may be avoided finely. 
         [0044]    In other embodiments of the apparatus, there is provided a rack in/out mechanism having simple configuration and being easy for assembly and maintenance, the rack in/out mechanism is especially used for the circuit breaker in the switch cabinet, and also can be used for other apparatus mounted within the cabinet and required to be moved by the electrical motor. The most direct and effective way adopted by the present invention is to joint the drive lead screw of the driver unit for the circuit breaker directly with the electrical motor, no tools and screws are needed for the assembly and disassembly of the electrical motor. The technical solution for the rack in/out mechanism of the present invention is a rack in/out mechanism, which comprises an electrical motor, a retarding mechanism, a drive lead screw, a first mounting plate, a second mounting plate and a third mounting plate, the electrical motor drives the retarding mechanism to move, and the retarding mechanism is coupled with the drive lead screw to drive the drive lead screw, wherein both the electrical motor and the retarding mechanism are assembled onto the first mounting plate at the corresponding positions and are connected through the first mounting plate, the first mounting plate is provided with at least one register pin and/or at least one pilot hole, and both of the drive lead screw and the second mounting plate are fixed onto the third mounting plate at corresponding positions, the second mounting plate is provided with a pilot hole for receiving the register pin and/or a register pin for inserting into the pilot hole, the second mounting plate is fitted with the first mounting plate via the register pin and corresponding to pilot hole, and a output shaft of the retarding mechanism is directly jointed with the drive lead screw to drive the drive lead screw. 
         [0045]    In this rack in/out mechanism, the electrical motor and the retarding mechanism are firstly positioned on the first mounting plate at corresponding positions, the drive lead screw and the second mounting plate are positioned on the third mounting plate at corresponding positions, the corresponding positions mean the where the rack in/out mechanism can achieve its functions, and based on different types and models of the adopted electrical motor, the retarding mechanism and/or the drive lead screw, such corresponding positions may be properly regulated to suit different requirements. By means of the register pins and pilot holes respectively provided on the first mounting plate and the second mounting plate and by arranging the positions thereof, it&#39;s possible to directly joint the output shaft of the retarding mechanism with the drive lead screw. Using the rack in/out mechanism with such an arrangement, the assembly of the electrical motor and its retarding mechanism is independent of the drive lead screw, and jointing with the drive lead screw may be made after the assembly of the electrical motor and the retarding mechanism, thus when failure occurs for the electrical motor or the retarding mechanism, the electrical motor and the retarding mechanism may also be directly decoupled from the drive lead screw, thereby the service and maintenance for the electrical motor is unlikely influenced by the positions of the drive lead screw and the positions of the devices driven by the drive lead screw, facilitating the replacement of the faulted electrical motor. Moreover, such a rack in/out mechanism provides a simple and reliable manner for transmitting power, by which desired velocity ratio can be obtained through selecting a favorable retarding mechanism, and the retarding mechanism may be the conventional existing products, which reduces the production cost. 
         [0046]    Preferably, the electrical motor and the retarding mechanism are mounted onto the first mounting plate at opposite two sides, the output shaft of the electrical motor drives the retarding mechanism to move, the second mounting plate is elbow-shaped or ‘┌’-shaped, a side of the ‘┌’ shape is fitted on a side of the third mounting plate, and the other side mates with the register pin and/or pilot hole on the first mounting plate through the pilot hole and/or the register pin located at this side, the drive lead screw is positioned at opposite another side of the third mounting plate, the positions of the drive lead screw, the register pin and the pilot hole, the third mounting plate, the second mounting plate and the first mounting plate are arranged in such a way that when the register pins mate with the pilot holes and the rack in/out mechanism is kept in an assembled state, the output shaft of the retarding mechanism is directly jointed with the drive lead screw. 
         [0047]    Preferably, the coupling between the retarding mechanism and the drive lead screw is achieved through a clutch. By achieving the connection between the retarding mechanism and the drive lead screw via a clutch, it&#39;s easy to achieve the connection and disconnection of the power transmission between the retarding mechanism and the drive lead screw. 
         [0048]    Preferably, the retarding mechanism and the clutch are integrated into a housing to create a power transmission mechanism for transmitting the power from the electrical motor, for inputting power to the drive lead screw. With the integration of the retarding mechanism and the clutch, module production is facilitated, and according to the requirement for power input by the drive lead screw, it&#39;s possible to select the suitable power transmission mechanism and electrical motor. Preferably, at least a portion of the end of the output shaft of retarding mechanism is a polygonal output shaft, the end of the drive lead screw is formed with a polygonal hole for receiving the polygonal output shaft, the polygonal output shaft cooperates with the polygonal hole so as to transmit the power output from the output shaft of the retarding mechanism to the drive lead screw and rotate the drive lead screw. By designing a portion of the end of the output shaft of the retarding mechanism to be a polygonal output shaft, and the end of the drive lead screw being formed with a polygonal hole for accommodating the polygonal output shaft, it&#39;s possible to cooperate the polygonal output shaft with the polygonal hole, thereby the power transmission between the retarding mechanism and the drive lead screw can be achieved by such a cooperation, driving the drive lead screw to move. 
         [0049]    Preferably, at least a portion of the end of the drive lead screw is a polygonal output shaft, the end of output shaft of the retarding mechanism is formed with a polygonal hole for receiving the polygonal output shaft, the polygonal output shaft cooperates with the polygonal hole so as to transmit the power output from the output shaft of the retarding mechanism to the drive lead screw and rotate the drive lead screw. With such a design, it&#39;s still possible to achieve the power transmission between the retarding mechanism and the drive lead screw, thus driving the drive lead screw to move. 
         [0050]    Preferably, the polygon is a regular hexagon, a square or an equilateral triangle. 
         [0051]    The regular hexagon, the square and the equilateral triangle are shapes easy to be machined.Preferably, at least a portion of the end of the output shaft of the retarding mechanism is formed with key outward protruding from the output shaft, and the end of the drive lead screw is formed with keyway for receiving the key, and by the cooperation of the key and the keyway, the power output from the output shaft of the retarding mechanism is transmitted to the drive lead screw and rotates the drive lead screw. 
         [0052]    Preferably, the rack in/out mechanism is further provided with a rotating side plate which is fixed to the fourth mounting plate via a rotary pin and may pivot around the rotary pin, the fourth mounting plate and the side of the second mounting plate provided with the register pin and/or the pilot hole are connected together, the first mounting plate is provided with two register pins or two pilot holes, and the second mounting plate is provided with two pilot holes or two register pins corresponding to the two register pins or two pilot holes on the first mounting plate, the register pin is formed with a groove, the shape and position of the rotating side plate are designed in such a way that when the rotating side plate is rotated to a certain position, the edge of the rotating side plate is caught into the groove of the register pin to lock the first mounting plate and the second mounting plate. 
         [0053]    By designing the fourth mounting plate and the rotating side plate with such a configuration, the edge of the rotating side plate may be caught into the groove of the pin when the rotating side plate is rotated, thus the first mounting plate and the second mounting plate is locked, and in such an assembly manner, it&#39;s possible to lock the first mounting plate and the second mounting plate without requiring the connecting manner, such as threaded connection, soldering and the like, allowing for simple assembly and disassembly manners, the rotating side plate is only required to be rotated in opposite direction to unlock the relative fixation between the first mounting plate and the second mounting plate. 
         [0054]    Preferably, the rotating side plate is provided with a knob for facilitating the rotation of the rotating side plate. 
         [0055]    The knob provided on the rotating side plate makes it convenient for the user to rotate the rotating side plate, thus meeting the human engineering design. 
         [0056]    Preferably, the rack in/out mechanism is used for a circuit breaker driven by a cart, and the cart is driven by a driver block provided on the drive lead screw, which driver block transforms the rotary motion of the drive lead screw into linear motion. 
         [0057]    Preferably, the third mounting plate is a baseplate of the switch cabinet for accommodating the circuit breaker. 
         [0058]    The rack in/out mechanism is especially adapted to be used for the driving of the circuit breaker driven by a cart within the switch cabinet, and overcomes the deficiencies in prior art that the electrical motor of the cart for driving the circuit breaker is difficult to repair and has lower transmission efficiency. 
         [0059]    There is also provided a method for assembling the above rack in/out mechanism, comprising steps as follows, assembling the electrical motor and the retarding mechanism together through the first mounting plate, assembling the drive lead screw and the second mounting plate onto the third mounting plate, assembling the fourth mounting plate and the rotating side plate together, then assembling the fourth mounting plate and the second mounting plate together, positioning the assembled electrical motor and the retarding mechanism by the cooperation between the register pin and the pilot hole, directly jointing the output shaft of the retarding mechanism with the drive lead screw, then rotating the above-mentioned rotating side plate to lock the first mounting plate and the second mounting plate. 
         [0060]    By assembling the second mounting plate and the third mounting plate as well as assembling the second mounting plate with the fourth mounting plate, which assembling are all achieved by threaded connection, the holes through which the bolts pass are aligned with each other by the above cooperation, thus it&#39;s possible to achieve firstly positioning the second mounting plate on the third mounting plate at appropriate position, and then positioning the fourth mounting plate on the second mounting plate at appropriate position, generally the third mounting plate is commonly an unmovable plate, hence, by selecting the position of the holes through which the bolts pass, the second mounting plate and the fourth mounting plate may be well placed at desired positions, so as to eventually achieve the directly jointing of the output shaft of the retarding mechanism with the drive lead screw. 
         [0061]    The rack in/out mechanism according to the present invention overcomes the weakness of the rack in/out mechanism in prior art that the electrical motor thereof is difficult to repair and replace, while providing higher transmission efficiency and lower manufacturing cost. 
         [0062]    A detailed description of an embodiment of the invention with reference to the figures beings now. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0063]    In the drawings: 
           [0064]      FIG. 1  is a view showing the entirety of the relative position between the circuit breaker cart and the circuit breaker; 
           [0065]      FIG. 2  is a schematic view showing the concrete configuration of the circuit breaker cart; 
           [0066]      FIG. 3  is a schematic view showing the connection state between the driver block for the circuit breaker cart and the circuit breaker; 
           [0067]      FIG. 4  is a schematic view showing the disconnection state between the driver block for the circuit breaker cart and the circuit breaker; 
           [0068]      FIG. 5  is a schematic view showing a circuit breaker and a cart after they are joined, with the circuit breaker being in a testing position; 
           [0069]      FIG. 6  is a schematic view showing a separating device in separating state, with the circuit breaker being in the testing position; 
           [0070]      FIGS. 7A and 7B  is a local enlarged schematic view of a circle C in  FIG. 6 ; 
           [0071]      FIG. 8  is a structural schematic view of a rack in/out mechanism according to the present invention; 
           [0072]      FIG. 9  are front view and right view of the assembled electrical motor and the retarding mechanism; 
           [0073]      FIG. 10  is a sectional view of the second mounting plate; 
           [0074]      FIG. 11  are the front view and right view of the assembled rotating side plate, the handle and the fourth mounting plate; 
           [0075]      FIG. 12  is a schematic view showing the state where the edge of the rotating side plate is not caught into the groove of the register pin; 
           [0076]      FIG. 13  is a schematic view showing the state where the edge of the rotating side plate is caught into the groove of the register pin when the rotating side plate is rotated to a certain position; 
           [0077]      FIG. 14  is a structural schematic view of the rotating side plate; 
           [0078]      FIG. 15  is a structural schematic view of the fourth mounting plate; 
           [0079]      FIG. 16  is a structural schematic view of the register pin; 
           [0080]      FIG. 17  is a structural schematic view of the drive lead screw; 
           [0081]      FIG. 18  is a structural schematic view showing the state in which the rack in/out mechanism according to the present invention is assembled into the switch cabinet. 
       
    
    
     DETAILED DESCRIPTION 
       [0082]    The present invention discloses a novel swayable in/out driver mechanism, that is, for a circuit breaker cart  1 . The circuit breaker cart  1  and the circuit breaker  2  are arranged separately. Specifically, the circuit breaker cart  1  is fixedly mounted onto the switch cabinet, and a small-sized circuit breaker drive block  15  is used to drive the circuit breaker  2  move forward and backward. The circuit breaker drive block  15  could be stopped and reversed so as to separate the circuit breaker cart  1  from the circuit breaker  2 , to push out or load in the circuit breaker  2 . 
         [0083]    Hereinafter, the configuration and working principle for the cart would be specifically described in conjunction with the drawings.Referring  FIG. 1 , the circuit breaker cart  1  is located right below the circuit breaker  2 , fixed with respect to the switch cabinet, connected with the circuit breaker  2  via the circuit breaker drive block  15  in the cart. The circuit breaker  2  is brought to move backward or forward electrically or manually with the rotation of the lead-screw. FIG. 2  is a schematic view showing the concrete configuration of the circuit breaker cart  1 . Wherein the circuit breaker cart  1  comprises a cart body  11 , an electrical motor  12 , a clutch  13 , a lead-screw  14 , the circuit breaker drive block  15  and so on. The cart body  11  is fixed onto the switch cabinet, the lead-screw  14  is assembled onto the cart body through the lead-screw anchor support  16 , and the lead-screw  14  can only rotate and be directly driven via a handle or an electrical motor. The output shaft of the electrical motor  12  is oppositely jointed to the main shaft of the lead-screw  14 , and may drive the circuit breaker drive block  15  to move forward and backward along the lead-screw  14  with the rotation of the lead-screw  14 . 
         [0084]    The circuit breaker drive block  15  may drive the circuit breaker  2  to switch between the operating position and the testing position. 
         [0085]    The circuit breaker drive block  15  is coupled with the lead-screw  14  via thread. When the lead-screw  14  rotates, due to the circuit breaker drive block  15  is located within the elongated slot and thus moves forward and backward along the lead-screw  14 , it&#39;s possible to make the circuit breaker to switch between the operating position and the testing position. When the circuit breaker is approaching the testing position, the circuit breaker drive block  15  may turn upward by 90° from the state shown in  FIG. 3 , such that the circuit breaker drive block  15  and the circuit breaker  2  are disconnected from each other and present the state shown in  FIG. 4 ; and in the disconnection state (as shown in  FIG. 4 ), it&#39;s also possible for the circuit breaker drive block  15  and the circuit breaker  2  to turn downward by 90°, so as to achieve the connection between the circuit breaker drive block  15  and the circuit breaker  2 , i.e., the state shown in  FIG. 3 . 
         [0086]    The circuit breaker cart  1  further comprises a front panel  20  of the cart, which panel can protrude from the door of the switch cabinet so as to operate the circuit breaker  2  and also comprises the functions of information indication and linkage. 
         [0087]    Referring to  FIG. 2 , the front panel  20  of the cart comprises an emergency braking button  21 , a padlock  22 , a key lock  23 , an insertion aperture  24  for handle operation, and various status indication device  25  and so on. Wherein, the emergency braking button  21  comprises the following functions: (1) emergency braking, (2) improper operation proofing, and (3) mechanical and electrical block. The emergency braking button  21  has a striking color, for example, red color. When the door of the switch cabinet is closed, the operator may use one simple action to complete a series of motions, namely pressing the emergency braking button  21  and moving laterally, then releasing the emergency braking button  21 , without complicated operations required in traditional emergency braking button, for example, rotation and the like. 
         [0088]    The insertion aperture  24  for handle operation is used for inserting the handle to perform manual operation. When the circuit breaker  2  is at the testing position, if it&#39;s required to pull out the circuit breaker  2  from the switch cabinet, the circuit breaker driver block  15  and the circuit breaker  2  is must be separated from each other, the mechanism according to the present invention can automatically achieve the connection and separation of the circuit breaker drive block  15  and the circuit breaker  2  by swaying the handle, no additional operation is needed. 
         [0089]    Also, the driver mechanism of the present invention may achieve the function in which only when the door is closed could the circuit breaker be swayed in/out. When the front door of the switch cabinet is not closed, the handle slide blocks the handle insertion aperture  24 , so that it&#39;s impossible to sway in/out the circuit breaker by manually swaying the handle, and the micro-switch on the door does not switch, the power-driven circuit is disconnected. 
         [0090]    When the front door of the switch cabinet is closed, the front door of the switch cabinet pushes the door linking plate, presses down the opening button, while slides leftwards into the stop hole, the handle slide yields from the handle insertion aperture and thus the handle can be inserted to carry out manual operation.During the above operations, by a connection plate disconnecting the power-driven circuit, the driver mechanism of the present invention may also achieve the function which can not be electrically achieved in the case of manually implementation.The driver mechanism of the present utility model may also be optionally assembled with a key lock. In such a case, the lock must be unlocked in advance, so that the handle slide can be slid. 
         [0091]    The driver mechanism of the present invention may also control the driving operation through low voltage plug linkage, such that, when no low voltage plug is inserted or reliably inserted, the cart can not be swayed. 
         [0092]    According to the driver mechanism of the present utility model, when the circuit breaker is in the intermediate position, the door of the switch cabinet cannot be opened; the cart and the gain on the door linking plate lock the stop pin on the door. 
         [0093]    The driver mechanism is further provided with a grounding blade linkage associated with the grounding blade, such that, when the grounding blade is switched-on, the circuit breaker can not be swayed in, and when the circuit breaker is in the intermediate position, the grounding blade can not be switched on. When the circuit breaker is in the intermediate position, the grounding blade can not be switched on. 
         [0094]    When the circuit breaker is swayed into the operating position, switching-on can only be enabled when the handle is drawn out. 
         [0095]    The output shaft of the electrical motor is directly coupled with the main shaft of the cart, and positioning panel for the electrical motor is used to prevent the detachment of the output shaft of the electrical motor, so as to attain the purpose of direct driving the circuit breaker cart. Other details of this part of the invention will be given now. 
         [0096]    The circuit breaker  2  may be moved between a testing position ( FIG. 1 ) and a working position. As shown in  FIG. 4 , the circuit breaker  2  may comprise a floor  31  on which there is provided an aperture  32  which can be used for accommodating a drive protuberance  211  for driving the circuit breaker  2  to move between the testing position and the working position (as shown in  FIG. 6 , which will be described below in detail). The cart  1  may be fixedly mounted on the switch cabinet (not shown) and mounted to the circuit breaker  2 . The cart  1  may be provided with an elongate slot  70  (shown in  FIGS. 7A and 7B ) on its top  71 , which extends in a direction from the testing position to the working position of the circuit breaker  2  (referred as to a first direction P 1  hereinafter) and which extends vertically under the aperture  32 , such that the drive protuberance  211  on the drive block  15  for driving the circuit breaker  2 , which moves between the testing position and the working position may protrude into the circuit breaker  2  from the elongate slot. Referring now to  FIG. 5 , a device  3  for automatically separating and joining the circuit breaker  2  and the cart  1  is mounted in the cart body  11 . The device comprise the drive block  15 , a lead screw  14 , a lead screw fixing support  43  for fixing and carrying the lead screw  14 , a guiding device  44 . The guiding device  44  may be used to drive the drive block  15  to rotate between the separating position and the joining position, as explained in detail below. 
         [0097]    The lead screw fixing support  43  may be fixedly mounted within the cart body 11 , for carrying the lead screw rod  14 . 
         [0098]    The drive block  41  may be sheathed on the lead screw  14 , with its threads being engaged with those of the lead screw  14 . The drive block  15  may be provided with the drive protuberance  211  thereon, which may pass through the elongate slot  70  arranged on the top  71  of the cart  1  and be engaged in the aperture  32  in the floor  31  of the circuit breaker  2 . The drive block  15  may rotate between a joining position and a separating position at an end of its stroke along the lead screw  14 , wherein the joining position corresponds to a position in which the drive protuberance  211  of drive block  15  protrudes out of the elongate slot arranged on the top of the truck  1  and is engaged in the aperture  32  of the bottom of the circuit breaker  2 , for example, referring to  FIG. 6 , here the drive protuberance  211  of the drive block  21  is in a vertical position. The elongate slot has a width substantially equal to that of the drive protuberance  211 , so as to prevent rotation of the drive block  15  relative to the cart body  11  and the circuit breaker  2  during the rotation of the screw rod, and to allow the translation movement of the drive block  15  along an axial direction of the lead screw  14 . The separating position of the drive block  15  corresponds to a position in which the drive protuberance  211  of drive block  15  is not engaged with the elongate slot arranged on the top of the cart  1  and therefore is not engaged with the opening of the bottom of the circuit breaker  2  so as to make circuit breaker  2  detach from the truck, for example, referring to  FIG. 5 , here the drive protuberance  211  of drive block  15  falls down to be at a horizontal position. 
         [0099]    A positioning protuberance  212  may further be provided on the drive block  15 , which is used for positioning the circuit breaker  2  on the cart  1  when the circuit breaker  2  and the cart  1  are being mounted. The positioning protuberance  212  may have a height less than that of the drive protuberance  211 , and is offset with respect to the drive protuberance  211  in the first direction P 1 , such that the positioning protuberance  212  would not protrude from the elongate slot of the top of the cart  1  so as to engage in the opening of the bottom of the circuit breaker  2  when the drive block  15  rotates from the separating position to the joining position. 
         [0100]    The separating-joining device may also comprise a handle inserting hole  27  arranged in an end of the lead screw  14  close to the front face of the cart  1 . The position of the handle inserting hole  27  corresponds to that of the handle operation hole  24  on the cart body  11 , such that the handle may enter the handle inserting hole  27  when inserted through the handle operation hole  24 . 
         [0101]    The guiding device  44  may comprise, for example, a fixing plate  241 , a guiding sleeve  242 , an elastic member such as a torsion spring  243 . The fixing plate  241  may be mounted to the lead screw fixing support  43  fixedly, situated on a side of the lead screw fixing support  44  opposite to the handle inserting hole  27 . The guiding sleeve  242  may be sheathed on the screw rod and pass through the fixing plate  241 , situated between the drive block  15  and the lead screw fixing support  45 . A guiding pin  244  is provided on an end of the guiding sleeve  242  away from the handle inserting hole  27 . The guiding pin  244  protrudes in a direction facing away from the handle inserting hole  27 . The guiding pin  244  may be connected to a corresponding guiding pin connection (numbered as  213  in  FIG. 7  A), for example a hole, arranged in the drive block  15 , for the union rotation of the guiding sleeve  242  and the drive block, for example 90 degrees, so as to drive the drive block  15  to rotate between the separating position and the joining position. 
         [0102]    Teeth  221  may be provided at an end of the lead screw rod  14  close to the handle inserting hole  27 . The teeth  221  may be fixed with respect to and rotate with the screw rod  22 . Meanwhile, external teeth  2421  may be provided at an end of the guiding sleeve  242  close to the handle inserting hole  27 , for meshing with the teeth  221  of the lead screw  14 . When the two are meshed, the guiding sleeve  242  may be rotate fixedly with the lead screw  14  when the handle is turned to make the lead screw  14  to rotate, so as to make the drive block  15  rotate with the two. Optionally, the teeth  221  of the lead screw  14  may be gear structure, helical teeth, or spline structure. 
         [0103]    Referring to  FIGS. 7A and 7B , they are enlarged schematic views of a circle C in  FIG. 6 , wherein the drive block  15  is located in the joining position. A step  2411  may also be provided on the fixing plate  241 , on a side of the fixing plate  241  facing towards the handle inserting hole  24 . An end of the guiding sleeve  242  having the external teeth  2421  is located on the same side as the step  2411  and cooperates with the step  2411  for assisting in the full meshing of the teeth  221  of lead screw  14  and the external teeth  2421  on the guiding sleeve  242 . 
         [0104]    The torsion spring  243  may be sheathed on the guiding sleeve  242 , one end of which is connected against the fixing plate  241  and the other end of which is connected against to a circular convex part arranged on the guiding sleeve, for separating the external teeth  2421  of guiding sleeve  242  from the teeth  221  of screw rod  22  by means of the effect of the torsion spring  243  when the drive block  15  is turned from the joining position to the separating position. Those skilled in the art should understand that the guiding device  24  may have other forms, as long as the rotation of the drive block  15  between the separating position and the joining position can be obtained. 
         [0105]      FIGS. 7A and 7B  show that the edges  72  of the elongate slot  70  prevent the drive block  15  from rotating by retaining the protuberance  211 , but the rotation becomes possible at the position in which the drive block  15  has left the elongate slot  70  and the protuberance  211  is free. 
         [0106]    The working mode of the separating-joining device  3  for automatically separating the circuit breaker  2  and the cart  1  will be described in detail below. As shown in  FIGS. 7A and 7B , when the circuit breaker  2  is located in the working position and it is desired to separate the circuit breaker  2  and the cart  1 , the handle is inserted into the handle operation hole  24  on the front face of the cart body  11 , and thus inserted into the handle inserting hole  27  of separating-joining device  3 . The handle is rotated in a first rotation direction R 1  (in this example, anticlockwise direction). Herein, the drive protuberance  211  of drive block  15  passes through the elongate slot (not shown) of top of the truck, while the rotation of the handle drive the lead screw  14  to rotate, such that the drive block  15  sheathed on the lead screw rod  14  drives the circuit breaker  2  to translate towards a reverse direction to the first direction (i.e. towards the testing position). When the drive block  15  is close to the testing position, the drive block  15  may contact the guiding sleeve  242  and be connected to the guiding sleeve  242  through the guiding pin  244 . As the lead screw  14  rotates further, the drive block  15  continues to move towards the testing position, so as to press the guiding sleeve  242  towards a reverse direction of the first direction to make the external teeth  2421  of the guiding sleeve  242  to mesh the teeth  221  fixed to the lead screw  14 . When they are meshed, the drive block  15  and the guiding sleeve  242 , together with the teeth  221 , move in the first rotation direction R 1 . At same time, the step  2411  on the fixing plate  241  can cause the external teeth  2421  of the guiding sleeve  242  and the teeth  221  to mesh completely. Then, the handle is turned to cause the drive block  15  to rotate 90 degrees along the first rotation direction R 1 , the drive protuberance  211  may disengage from the elongate slot and the drive block  15  reaches the separating position, such that the circuit breaker  2  is separate from the cart  1 . 
         [0107]    When the circuit breaker  2  is located in the testing position and it is desired to join the circuit breaker  2  and the cart  1  automatically, the drive block  15  is located in the separating position as shown in  FIG. 6 , the handle is turned to cause the drive block  15  to rotate 90 degrees along a direction reverse with respect to the first rotation direction R 1  (for example, clockwise direction) to the joining position. Then, the drive protuberance  211  on the drive block  15  is engaged in the elongate slot, and the teeth  221  are dis-meshed and thus separate from the external teeth  2421  on the guiding sleeve  242  by means of the torsion spring  45 . The handle is turned continuously ; since the drive protuberance  211  is engaged in the elongate slot, such that the separated drive block  15  is translated along an axis of the lead screw  14  towards the testing position in the first direction P 1  without rotation. The device for automatically separating and joining the circuit breaker and the truck is described above. 
         [0108]    Hereinafter, reference will be made to  FIGS. 8 to 18  to describe the detailed embodiments of the rack in/out mechanism according to the present invention in detail. Through description of these detail embodiments, the skilled in this art may comprehend the present invention even more clearly. It should be noted that the protective scope of the present invention is not limited to the specific embodiments explained in detail, the modifications of the present invention made by the skilled in this art based on the teaching of the present disclosure also fall in the protective scope of the present invention. 
         [0109]      FIG. 8  is a schematic view showing the rack in/out mechanism according to the present invention, the rack in/out mechanism comprises the electrical motor  12 , a retarding mechanism  52 , the lead screw  14 , a first mounting plate  56 , a second mounting plate  57  and a third mounting plate  58 , the electrical motor  12  drives the retarding mechanism  52  to move, the retarding mechanism  52  is coupled with the lead screw  14  through the clutch  13 , the output shaft  62  of the retarding mechanism  52  (see  FIG. 9 ) is connected with the lead screw  14  to drive the lead screw  14  to move, and both the electrical motor  12  and the retarding mechanism  52  are assembled onto the first mounting plate  56  and are connected through the first mounting plate  56 , and both the lead screw  14  and the second mounting plate  57  are fixed onto the third mounting plate  58 , the first mounting plate  56  is provided with at least one register pin  54 , the second mounting plate  57  is formed with a pilot hole  65  for receiving the register pin  54  (see  FIG. 10 ), the second mounting plate  57  is fitted with the first mounting plate  56  via the register pin  54  and the corresponding pilot hole  68 , so as to directly joint the output shaft  62  of the retarding mechanism  52  with the lead screw  14  to move the lead screw  14 . Although the register pin  53  in this embodiment is provided on the first mounting plate  56  and the pilot hole  68  is formed in the second mounting plate  57 , it&#39;s also possible to provide the pilot hole  68  in the first mounting plate  56  and provide the register pin  54  on the second mounting plate  57 , or alternatively, it&#39;s further possible to provide the register pin  54  and the pilot hole  68  on the first mounting plate  56  simultaneously while providing the pilot hole  68  and the register pin  54  mated therewith on the second mounting plate  57 . 
         [0110]    In the rack in/out mechanism according to the present invention, the electrical motor  12  and the retarding mechanism  52  are firstly positioned on the first mounting plate  54 , the lead screw  14  and the second mounting plate  57  are positioned on the third mounting plate  58 , the mounting positions are designed such that the rack in/out mechanism can eventually achieve the position for the directly jointing of the output shaft  62  of the retarding mechanism  52  with the lead screw  14 . Based on different types and models of the adopted electrical motor, the retarding mechanism  52  and/or the lead screw  14 , such mounting positions may be properly regulated to suit different requirements. By means of the register pins  54  and pilot holes  68  respectively provided on the first mounting plate  56  and the second mounting plate  57  and by arranging the positions thereof, it&#39;s possible to directly joint the output shaft  62  of the retarding mechanism  52  with the lead screw  14 . Using the rack in/out mechanism with such an arrangement, the assembly of the electrical motor  12  and its retarding mechanism  52  is independent of the lead screw  14 , and directly jointing with the lead screw  14  may be made after the assembly of the electrical motor  12  and the retarding mechanism  52 , thus when failure occurs for the electrical motor  12  or the retarding mechanism  52 , the electrical motor  12  and the retarding mechanism  52  may also be directly uncoupled from the lead screw  12 , thereby the service and maintenance for the electrical motor  12  is unlikely influenced by the positions of the lead screw  14  and the positions of the devices driven by the lead screw  14 , facilitating the replacement of the faulted electrical motor  12 . Moreover, such a rack in/out mechanism provides a simple and reliable manner for transmitting power, by which a desired velocity ratio can be obtained through selecting a favorable retarding mechanism  52 , and the retarding mechanism may be the conventional existing products, which reduces the production cost. 
         [0111]      FIG. 9  illustrates the schematic view of the assembled electrical motor  12  and the retarding mechanism  52 ,  FIG. 10  shows a sectional view of the second mounting plate  57 . Further, in conjunction with  FIGS. 9 and 10 , the electrical motor  12  and the retarding mechanism  52  are respectively mounted onto the opposite two sides of the first mounting plate  56 , the output shaft of the electrical motor  12  drives the retarding mechanism  52  to move, the second mounting plate  57  is elbow-shaped or ‘┌’-shaped, and a side of the ‘┌’ shape, which is the upper one in  FIGS. 10 and 8 , is fitted at the underside of the third mounting plate  68 , and the other side, which is the left one in drawings, mates with the register pin  54  on the first mounting plate  56  through the pilot hole  68  at this side, the lead screw  14  is positioned at opposite upper side of the third mounting plate  58 , the positions of the lead screw  14 , the register pin  54  and the pilot hole  68 , the third mounting plate  58 , the second mounting plate  57  and the first mounting plate  56  are arranged in such a way that when the register pin  54  mates with the pilot hole  68  and the rack in/out mechanism is kept in an assembled state, the output shaft  62  of the retarding mechanism  52  is directly jointed with the lead screw  14 . 
         [0112]    By designing the second mounting  57  plate to be ‘┌’-shaped, locating the lead screw  14  above a side of the ‘┌’ shape, positioning the lead screw  14  above the third mounting plate  58 , and positioning the ‘┌’-shaped second mounting plate  57  below the third mounting plate  58 , the positions of the ‘┌’-shaped second mounting plate  57  and the lead screw  14  are relatively determined, and the other side of the ‘┌’-shaped second mounting plate  57  is used for the positioning of the electrical motor  12  and the retarding mechanism  52 , hence it&#39;s possible to achieve the positioning of the retarding mechanism  52  with respect to the lead screw  14  by the positioning of the second mounting plate  52  with respect to the lead screw  14 , thereby implementing the directly jointing of the output shaft  62  of the retarding mechanism  52  with the lead screw  24 . 
         [0113]    In this embodiment, the coupling between the retarding mechanism  52  and the lead screw  14  is achieved through the clutch  13 . 
         [0114]    By achieving the connection between the retarding mechanism  52  and the drive lead screw  14  via a clutch, it&#39;s easy to achieve the connection and disconnection of the power transmission between the retarding mechanism  52  and the lead screw  14 . 
         [0115]    The retarding mechanism  52  and the clutch  13  may also be integrated into a housing to create a power transmission mechanism for transmitting the power from the electrical motor, for inputting power to the drive lead screw. 
         [0116]    With the integration of the retarding mechanism  52  and the clutch  13 , module production is facilitated, and according to the requirement for power input by the lead screw  14 , it&#39;s possible to select the suitable power transmission mechanism and electrical motor  12 . 
         [0117]    At least a portion of the end of the output shaft  62  of the retarding mechanism  52  is a polygonal output shaft, the end of the lead screw  14  is formed with a polygonal hole  55  for receiving the polygonal output shaft  62 , the polygonal output shaft  62  cooperates with the polygonal hole  55  so as to transmit the power output from the output shaft  62  of the retarding mechanism  52  to the lead screw  14  and rotate the lead screw  14 . 
         [0118]    By designing a portion of the end of the output shaft  62  of the retarding mechanism  52  to be the polygonal output shaft  62 , and the end of the lead screw  14  being formed with the polygonal hole  55  for accommodating the polygonal output shaft, it&#39;s possible to cooperate the polygonal output shaft  62  with the polygonal hole  55 , thereby the power transmission between the retarding mechanism  52  and the lead screw  14  can be achieved by such a cooperation, driving the lead screw  14  to move. 
         [0119]    In this embodiment, the output shaft  52  being used is an outer hexagonal shaft, and the hole  55  mated therewith is an inner hexagonal mounting hole. It&#39;s to be noted that the output shaft  62  is not limited to the regular hexagonal shaft, the square shaft or the equilateral triangle shaft is also possible, as long as the shapes of the shaft and the hole  55  mated therewith are designed such that the power can be transmitted from the output shaft  62  to the lead screw  14 . 
         [0120]    In order to transmit the power from the output shaft  52  to the lead screw  14 , at least a portion of the end of the output shaft  52  of the retarding mechanism  62  may also be formed with a key outward protruding from the output shaft  52 , and the end of the lead screw  14  is formed with a keyway for receiving the key, and by the cooperation of the key and the keyway, the power output from the output shaft  62  of the retarding mechanism  52  is transmitted to the lead screw  14  and rotates the drive lead screw  14 . Such embodiments are not shown in the drawings. 
         [0121]    In addition to the above connecting type, the polygonal output shaft  62  may also be provided on the lead screw  14 , and the inner polygonal hole  55  corresponding to the polygonal output shaft  62  is formed in the output shaft  62  of the retarding mechanism  52 . The key may also be provided on the lead screw  14 , and the keyway is formed on the end of the output  62  shaft of the retarding mechanism  52 . All connecting types, as long as they can achieve the power transmission between the output shaft  62  of the retarding mechanism  52  and the lead screw  14 , may be used herein. 
         [0122]    The rack in/out mechanism is also provided with a rotating side plate  61 ,  FIGS. 11-15  illustrate structural schematic views of the rotating side plate  61  and a fourth mounting  59  plate in their state of being separated and assembled as well as being used in different state. As shown in  FIG. 19 , the rotating side plate  61  is fixed to the fourth mounting plate  59  via a rotary pin  63  and is pivotable around the rotary pin  63 , the fourth mounting plate  59  and the side of the second mounting plate  57  provided with the pilot holes  68  are connected together through a threaded connection, but other connection manners are also possible, the first mounting plate  56  is provided with two register pins  54 , and the second mounting plate  57  is provided with two pilot holes  68  corresponding to the two register pins  54  on the first mounting plate  56 , the register pins  54  are formed with a groove  64  (see  FIG. 16 ), the shape and position of the rotating side plate  61  are designed in such a way that when the rotating side plate  61  is rotated to a certain position, the edge of the rotating side plate  61  is caught into the groove  64  of the register pin  54  to lock the first mounting plate  56  and the second mounting plate  57 , the rotating side plate  61  is provided with a knob  60  to facilitate the rotation of the rotating side plate  61 . 
         [0123]    As shown in  FIGS. 12 and 13  respectively, in the position shown in  FIG. 12 , the edge of the rotating side plate  61  is not caught into the groove  64  of the register pin  54 , the first mounting plate  56  is not locked with the second mounting plate  57 , and in the position shown in  FIG. 13 , the edge of the rotating side plate  61  is caught into the groove  64  of the register pin  54 , and the first mounting plate  56  is locked with the second mounting plate  57 , and due to the restriction by the groove of the register pin  54 , the rotating side plate  61  cannot rotate downward any more, and the groove also restrict the forward and backward movement of the rotating side plate perpendicular to the paper surface, as is most clearly illustrated in  FIG. 8 , depending on such arrangement of the first mounting plate  56 , the second mounting plate  57 , the fourth mounting plate  59  and the rotating side plate  61 , the rotating side plate  61  can fix and lock the first mounting plate  56  and the second mounting plate  59 . 
         [0124]    By designing the fourth mounting plate  59  and the rotating side plate  61  with such a configuration, the edge of the rotating side plate  61  may be caught into the groove  64  of the register pin  54  when the rotating side plate  51  is rotated, thus the first mounting plate  56  and the second mounting plate  57  are locked, and in such an assembly manner, it&#39;s possible to lock the first mounting plate  56  and the second mounting plate  57  without requiring any connecting manner, such as threaded connection, soldering and the like, allowing for simple assembly and disassembly manners, the rotating side plate  61  is only required to be rotated in opposite direction to unlock the relative fixation between the first mounting plate  56  and the second mounting plate  57 . The knob  60  provided on the rotating side plate  61  makes it convenient for the user to rotate the rotating side plate  61 , thus meeting the human engineering design. 
         [0125]      FIG. 17  illustrates a structural schematic view of the lead screw  14 ; in this embodiment, the lead screw  14  is enclosed within housing, and the lead screw  14  is fixed above the third mounting plate  58  by this housing, so as to be positioned above the third mounting plate  58 . The drive lead screw  14  drives the cart assembled on the cart assembly parts  16  through the drive block  15  mated with the drive lead screw  14 , and here, the third mounting plate  59  is the base plate of the switch cabinet, that is, the lead screw  14  and the second mounting plate  57  are respectively mounted onto the inside and the outside of the base plate of the switch cabinet. 
         [0126]    The rack in/out mechanism according to the present invention is especially suitable for a circuit breaker driven on a cart, and the cart contains by a drive block of the circuit breaker provided on the drive lead screw, the drive block transforms the rotary motion of the drive lead screw into linear motion. 
         [0127]      FIG. 18  is a structural schematic view showing the state in which the rack in/out mechanism according to the present invention is assembled into the switch cabinet, where the circuit breaker  2  is illustrated. 
         [0128]    The rack in/out mechanism is especially adapted to be used for the driving of the circuit breaker driven by the cart  1  within the switch cabinet, and overcomes the deficiencies in prior art that the electrical motor  12  of the cart  1  for driving the circuit breaker  2  is difficult to repair and has lower transmission efficiency.The method for assembling the rack in/out mechanism of the present invention is as follows: assembling first the electrical motor  12  and the retarding mechanism  52  together through the first mounting plate  56 , assembling the lead screw  14  and the second mounting plate  57  onto the third mounting plate  58 , assembling the fourth mounting plate  59  and the rotating side plate  61  together, then assembling the fourth mounting plate  59  and the second mounting plate  57  together, positioning the assembled electrical motor  12  and the retarding mechanism  52  by the cooperation between the register pin  54  and the pilot hole  68 , directly jointing the output shaft  62  of the retarding mechanism  52  with the lead screw  14 , then rotating the above-mentioned rotating side plate  61  to lock the first mounting plate  56  and the second mounting plate  57 . By assembling the second mounting plate  57  and the third mounting plate  58  as well as assembling the second mounting plate  57  and the fourth mounting plate  59 , which assembling are all achieved by threaded connection, the holes through which the bolts pass are aligned with each other by the above cooperation, thus it&#39;s possible to achieve positioning first the second mounting plate  57  on the third mounting plate  58  at appropriate position, and then positioning the fourth mounting plate  59  on the second mounting plate  57  at appropriate position, the third mounting plate  58  is commonly an unmovable plate, hence, by selecting the position of the holes through which the bolts pass, the second mounting plate  57  and the fourth mounting plate  59  may be well placed at desired positions, so as to eventually achieve the directly jointing of the output shaft of the retarding mechanism with the drive lead screw. 
         [0129]    The rack in/out mechanism according to the present invention overcomes the weakness of the rack in/out mechanism in prior art that the electrical motor thereof is difficult to repair and replace, while providing higher transmission efficiency and lower manufacturing cost. 
         [0130]    The above provides detail introduction of the present invention, and the variations made by the skilled in this art based on the idea of the embodiment of present invention about particular embodiments and the range of application should not be construed as departing from the protective scope of the present invention, generally speaking, the specific embodiments in this specification should not be regarded as limiting to the present invention.