Abstract:
A force transmitting assembly includes a mounting flange having a central opening to receive a shaft, wherein the mounting flange is mountable on a frame, a rotor disc mountable on the shaft and rotatable with the shaft, the rotor disc having a first planar face and a second planar face, a float plate having a first friction surface engageable with the first planar face, and a pressure plate having a second friction surface engageable with the second planar face. The brake assembly also includes a spring housing, which operates as a piston, and a cylinder coupled to the spring housing to form a fluid pressure chamber, wherein the spring housing moves in a first direction when pressurized fluid enters the fluid pressure chamber and the spring housing moves in a second direction when pressurized fluid exits the fluid pressure chamber. The assembly further includes a plurality of nested tube subassemblies supporting the float plate, the pressure plate, and the spring housing to allow axial movement of at least one of the float plate, the pressure plate, and the spring housing. The nested tube subassemblies also transmit torque from the rotor to the mounting flange during the engaged condition of the brake assembly.

Description:
TECHNICAL FIELD 
       [0001]    The present teachings relate to a force transmitting assembly, such as a brake or a clutch, and more particularly to such an assembly with floating components. 
       BACKGROUND 
       [0002]    The term “assembly” as used in this disclosure refers to an assembly, such as a brake assembly, that can function as a brake, a clutch, and/or both. While the assembly described herein is particularly suited for use as a brake assembly and will be discussed primarily in the braking context, those of ordinary skill in the art will understand that the assembly is equally capable of functioning as a clutch. For simplicity, the term “assembly” will primarily be used, but the term “assembly,” “force transmitting assembly,” “brake assembly,” and “clutch assembly” are all interchangeable in the description below. 
         [0003]    Known force transmitting assemblies have been connected with a shaft to control power transmission. These known assemblies have been used in various applications, such as draglines, power shovels, conveyors, shears, power presses, and other machines. 
         [0004]    Typical assemblies include one or more rotor discs that rotate on a shaft. Braking occurs when friction linings attached to plates on either side of the rotor disc clamp down onto the rotor disc. The engagement between the rotor disc faces and the friction linings creates braking action, slowing and eventually stopping rotation of the rotor disc. Pressure may be applied using a spring set within the assembly. These assemblies attach the rotor disc and shaft together via a splined coupling to allow axial movement of the rotor disc during an engagement operation. However, splined couplings experience high wear, regardless of how often it is engaged, from the continuous forces applied to the splines. 
         [0005]    There is a desire for an assembly that minimizes wear within the assembly without sacrificing performance. It is further desirable to provide an assembly with a reduced envelope size, reduced overall weight, and lower cost of assembly yet maintaining the same functionality as a larger sized assembly for use in a wide variety of applications, like mining applications. 
       SUMMARY 
       [0006]    A force transmitting assembly includes a mounting flange having a central opening to receive a shaft, wherein the mounting flange is mountable on a frame, a rotor disc constructed for mounting on the shaft and for rotation with the shaft, the rotor disc having a first planar face and a second planar face, a float plate having a first friction surface engageable with the first planar face, and a pressure plate having a second friction surface engageable with the second planar face. The assembly also includes a spring housing which functions as a piston, and a cylinder coupled to the spring housing to form a fluid pressure chamber, wherein the spring housing moves in a first direction when pressurized fluid enters the fluid pressure chamber and the spring housing moves in a second direction when pressurized fluid exits the fluid pressure chamber. The assembly further includes a plurality of nested tube subassemblies supporting the float plate, the pressure plate, and the spring housing to allow axial movement of at least one of the float plate, the pressure plate, and the spring housing. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a perspective view of a force transmitting assembly according to one aspect of the teachings; 
           [0008]      FIG. 2  is a schematic view of a portion of the assembly of  FIG. 1  in an engaged condition; 
           [0009]      FIG. 3  is a schematic view of a portion of the assembly of  FIG. 1  in a released condition; and 
           [0010]      FIG. 4  is a schematic view of an enlarged portion of the assembly of  FIG. 1  in an engaged condition. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]      FIGS. 1 through 4  illustrate a force transmitting assembly, such as a brake assembly  10 , according to one aspect of the present teachings. The assembly  10  includes a rotor disc  12  having a first planar face and a second planar face on each side, which can be driven by a motor (not shown), and a housing  14 . The rotor disc  12  may be fixed on a motor shaft  15  in any known manner; in the illustrated example, the motor shaft  15  is a tapered shaft, and the rotor disc  12  is rigidly attached to the motor shaft  15  via a wedge-action coupling  15   a . The assembly  10  of the present disclosure may be used with any shaft lock assembly tapered or straight. 
         [0012]    The housing  14  can include a mounting flange  16  adapted to be mounted on a customer part  17 , such as a motor frame (when the assembly  10  is used as a brake) or a driven shaft (when the assembly  10  is used as a clutch). In one aspect of the teachings, the mounting flange  16 , as well as other portions of the housing  14 , are mounted with a plurality of studs  18  arranged in a circular array. As will be explained in greater detail below, the studs  18  act as rigid supports are disposed within a plurality of nested tube subassemblies  19  that include guide tubes  20  thereon followed by sliding hollow studs  21  on the guide tubes  20 , and then spacer clamp tubes  25  disposed on a portion of the hollow studs  21  to guide and assist in transmitting the axial movement and required forces of the other components of the housing  14 . Each nested tube subassembly  19  includes the stud  18 , the guide tube  20  thereon, and the sliding hollow stud  21  on the guide tube. Fasteners, such as nuts  23  may be disposed on the studs  18  to hold the assembly  10  together. The torque in this assembly  10  is transferred through the nested tube subassemblies  19  of the studs  18 , guide tubes  20 , hollow studs  21 , and spacer clamp tubes  25 . The nested tube subassemblies  19  also transmit torque from the rotor disc  12  to the mounting flange  16  during an engaged condition of the brake assembly  10 . The sliding hollow studs  21  transmit axial forces and torque during braking and clutching in a manner unlike those of other previous assemblies. 
         [0013]    The housing  14  includes a float plate  22  and a pressure plate  24  disposed on opposite sides of the rotor disc  12 . The float plate  22  and pressure plate  24  are both slidingly supported by the nested tube subassemblies  19  so they are axially movable thereon. Friction linings  26   a ,  26   b  are disposed on the float plate  22  and the pressure plate  24 , respectively, on either side of the rotor disc  12 . The friction linings  26   a ,  26   b  may be fastened in any known manner such as with fasteners. The friction linings  26   a ,  26   b  may be made of any appropriate friction material normally used in brake or clutch assemblies. The friction linings  26   a ,  26   b  are designed to frictionally engage with the rotor disc  12  to retard rotation of the rotor disc  12 . In one aspect of the teachings, the friction linings  26   a ,  26   b  may be divided into wedge-shaped segments to allow easy removal of the friction linings  26   a ,  26   b  without disassembling the entire assembly  10 . 
         [0014]    The assembly  10  can include a spring housing  28  and a cylinder  30 . The spring housing  28  cooperates with the cylinder  30  and operates as a piston. The spring housing  28  and the cylinder  30  together form a fluid pressure chamber  32  with a port (not shown) that allows fluid, such as air or hydraulic fluid, to enter and exit the fluid chamber  32 . A bolt  35  may connect the cylinder  30  to the pressure plate  24  so that there is no relative movement between the cylinder  30  and the pressure plate  24 . Connecting the cylinder  30  with the pressure plate  24  prevents relative axial movement between the two members. Threaded hollow studs  21  are attached at one end to the float plate  22  with a threaded joint  27  and by way of fasteners  34 , like self-locking nuts, to retain the spring housing  28  on one side and with the assistance of the spacer clamp tubes  25  on the other side. The hollow studs  21  provide a rigid connection between the float plate  22  and the spring housing  28  to ensure that the float plate  22  and the spring housing  28  do not move relative to one another. As a result, the float plate  22  and the spring housing  28  move together as a single unit. The nested tube subassemblies  19  of the studs  18 , guide tubes  20 , hollow studs  21 , and spacer clamp tubes  25  create a large bearing area that provides better support to the floating parts (e.g., the float plate  22 , pressure plate  24 , and spring housing  28 ) than previous assembly designs with the advantage of a smaller package or envelope size, reduction in overall weight, and assembly cost. When the assembly  10  goes from an engaged to a disengaged condition, the pressure plate  24  slides or floats on the spacer clamp tubes  25  that are locked in position between the float plate  22  and the spring housing  28 . The float plate  22  and the spring housing  28  are move together with the sliding hollow studs  21  which float on the guide tubes  20 . Manufacturing the guide tubes  20  of an aluminum bronze, nickel aluminum bronze, or like material may reduce friction and power loss during movement. The hollow studs  21  material may be made of nickel aluminum bronze or may differ as per the application need for metals of differing strengths. Any high strength low wear friction coefficient material may be used for the hollow studs  21 . 
         [0015]    A release spring  36  can be disposed on the other end of the hollow studs  21  (the end not attached to the float plate  22 ) between washers  37  located between the nuts  34  threaded on hollow studs  21  and nuts  23  at the end of the studs  18 . When the brake assembly is in the released or disengaged position, the float plate  22  moves to the left away from the rotor disc  12 . Nuts  34  threaded on the hollow studs  21  on one side of the spring housing  28  and spacer clamp tubes  25  on the other side of the spring housing  28  together urge the float plate  22  to move to the left away from the rotor disc  12  simultaneously the pressure plate  24  is caused to move away from the rotor disc  12  in the opposite direction (to the right). One or more seals  39  may be disposed on the spring housing  28  to form a fluid-tight seal between the spring housing  28  and the cylinder  30 . A plurality of compression springs  38  in spring housing  28  which may consist of inner and outer springs are disposed between the pressure plate  24  and the spring housing  28  to bias the pressure plate  24  and spring housing  28  away from each other. 
         [0016]    The release spring  36  is biased to push the float plate  22  away from the rotor disc  12  during a release operation. More particularly, when the release spring  36  pushes against the spring housing  28  toward the left, the float plate  22  moves to the left away from the rotor disc  12 . 
         [0017]    Previous brake assemblies operate by moving a rotor disc axially during braking action, leaving the housing of the assembly stationary. The assembly  10  shown in  FIGS. 1 through 4  operates in a different manner by keeping the rotor disc  12  stationary while axially moving the housing  14 . This operation will be explained in greater detail below with reference to  FIGS. 2 through 4 . 
         [0018]      FIG. 2  shows the assembly  10  in an engaged condition. In this condition, fluid is released from the fluid chamber  32  through the port (not shown) in the cylinder  30 . The lack of fluid pressure in the fluid chamber  32  allows the compression springs  38  to overcome the biasing force of the release springs  36 . As a result, the compression springs  38  force the pressure plate  24  to the left and the spring housing  28  to the right. The pressure plate  24  movement causes its associated friction lining  26   b  to contact the right face of the rotor disc  12  to generate braking action. 
         [0019]    At the same time, the movement of the spring housing  28  toward the right allows the hollow studs  21  to pull the float plate  22  toward the right. The float plate  22  moves with the spring housing  28  by the rigid connection of the hollow studs  21  to the float plate  22  through threaded joint  27 . Joint  27  may be any type of a rigid joint made by any suitable fastening means such as welding or other fasteners. The float plate  22  continues to move toward the right until its associated friction lining  26   a  contacts the left face of the rotor disc  12  to generate braking action. The combined braking action from the friction linings  26   a ,  26   b  on the rotor disc  12  slow and eventually stop rotation of the rotor disc  12 . Note that during this entire braking process, the rotor disc  12  remains axially stationary; only the housing  14  components move axially to generate the braking action. 
         [0020]      FIG. 3  shows the assembly  10  in a released condition. To release the assembly  10 , pressurized fluid enters the fluid chamber  32  through the fluid port (not shown). The fluid pressure pushes the cylinder  30  to the right, pulling the pressure plate  24  to the right as well due to the rigid attachment of the cylinder  30  to the pressure plate  24  by way of bolts  35 . Moving the pressure plate  24  to the right compresses the compression springs  38  and detaches the friction lining  26   b  on the pressure plate  24  from the right face of the rotor disc  12 . 
         [0021]    At the same time, the pressurized fluid in the fluid chamber  32  forces the spring housing  28  to move to the left. As the spring housing  28  axially moves to the left, the hollow studs  21  and spacer clamp tubes  25  disposed between the spring housing  28  and the float plate  22  causes the float plate  22  to move to the left as well, which causes its associated friction lining  26   a  to detach from the left face of the rotor disc  12 . The biasing force of the release spring  36  also applies pressure to the spring housing  28 , further urging the float plate  22  to the left, ensuring that the friction linings  26   a ,  26   b  do not touch the rotor disc  12  in the released condition. This leaves the rotor disc  12  free to rotate unencumbered. 
         [0022]    Note that in the released condition shown in  FIG. 3 , the float plate  22  movement is controlled by both the fluid pressure in the fluid chamber  32  and the biasing force from the release spring  36 , while the pressure plate  24  movement is controlled solely by the fluid pressure in the fluid chamber  32 . This is because the combined weight of the float plate  22 , the spring housing  28 , and the compression springs  38  is significantly greater than the combined weight of the cylinder  20  and the pressure plate  24 . Thus, more force is needed to move the float plate  22  (and the other components attached to it) than the pressure plate  24  during the released condition. The biasing force of the release spring  36  supplements the fluid force from the fluid chamber  32  to move the float plate  22 , while the pressure plate  24  is moved via fluid force alone. Accommodating for these different weights via the expansion release spring  36  allows the float plate  22  and the pressure plate  24  to separate from the rotor disc  12  at roughly the same rate. 
         [0023]    By axially moving the housing  14  instead of the rotor disc  12  during engagement and disengagement, the brake assembly  10  described above provides a more durable and robust structure. Keeping the rotor disc  12  axially stationary in turn may assist to retain the friction linings  26   a ,  26   b  by reducing rotational inertia in the assembly  10  and eliminating the possibility of the linings  26   a ,  26   b  flying off the rotor disc  12 . 
         [0024]    Note that although the illustrated aspect shows a single rotor disc design, the assembly  10  can be modified to include additional rotor discs  12  without departing from the scope of the teachings. Moreover, although the illustrated aspect is described with respect to a braking operation, the assembly  10  can be used as a clutch without departing from the scope of the teachings. 
         [0025]    It will be appreciated that the above teachings are merely exemplary in nature and are not intended to limit the present teachings, their application or uses. While specific examples have been described in the specification and illustrated in the drawings, it will be understood by those of ordinary skill in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present teachings as defined in the claims. Furthermore, the mixing and matching of features, elements and/or functions between various examples is expressly contemplated herein so that one of ordinary skill in the art would appreciate from this disclosure that features, elements and/or functions of one example may be incorporated into another example as appropriate, unless described otherwise, above. Moreover, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present teachings not be limited to the particular examples illustrated by the drawings and described in the specification as the best mode presently contemplated for carrying out the teachings of the present disclosure, but that the scope of the present disclosure will include any embodiments falling within the foregoing description and the appended claims.