Patent Publication Number: US-2005133774-A1

Title: Drive-through force transmission device and methods

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
      This application is a Non-Provisional Application, claiming priority under 35 U.S.C. 119(e) to U.S. Provisional Application Ser. No. 60/526,693, filed Dec. 3, 2003, which is incorporated herein by reference in its entirety.  
    
    
     BACKGROUND  
      This invention relates to apparatus for lifting/lowering, manipulating and/or otherwise controlling loads. Such lifting/lowering devices include winches, elevator drive mechanisms, dumb waiter drive mechanisms, and others. This invention also relates to methods of manipulating and/or otherwise controlling loads, and to methods of operating such apparatus.  
      Specifically, this invention relates to braking devices used in conjunction with lifting/lowering devices to control the lifting/lowering, manipulating and/or otherwise controlling of loads.  
      Conventional lifting/lowering devices comprise a drive unit such as a motor or other prime mover, and an associated winding unit which is driven by the prime mover. In some conventional lifting/lowering devices, the prime mover directly rotates the winding unit. Typically, however, a gear box provides the interface between the prime mover and the winding unit. The gear box can be integral with the prime mover, integral with the winding unit, or may be a standalone separate and distinct unit, which is not part of either the prime mover or the winding unit.  
      Some lifting/lowering devices further comprise a brake to additionally control the lifting/lowering, manipulating and/or otherwise controlling of a load. Such brake can be of a plate-type design, a drum-type design, or other design.  
      Typical plate-type brakes incorporate at least one relatively stationary device, e.g. stator disc, which does not rotate about an axis, and at least one relatively mobile device, e.g. rotor disc, which correspondingly rotates with the winding unit. A biasing unit urges the rotor disc/discs and the stator disc/discs into intimate communication, whereby the friction between the rotor disc/discs and the stator disc/discs is effective to slow and/or stop the rotation of the rotor disc/discs and correspondingly slow and/or stop the rotation of the winding drum.  
      Other known plate-type braking devices utilize a rotor and biasing units, without stator discs. Such plate-type braking devices rely on the frictional force between the rotor and the biasing unit to slow and/or stop the rotation of the rotor and correspondingly slow and/or stop the rotation of the winding drum.  
      Conventional biasing units of plate-type braking devices cyclically increase and decrease, including engage and release, the axial load applied by the biasing unit, accordingly raising and lowering the load being addressed by the braking device. Typically, fluid pressure, e.g. pneumatic pressure or hydraulic pressure, forces the axial movement of the biasing unit. However, some plate-type braking devices utilize electrical energy, or an electromechanical process to effect axial movement of the biasing unit.  
      Creating ancillary force to operate a biasing unit of a braking device requires energy consumption. In addition, the effectiveness of the biasing unit in a braking device is related to, and limited by, the ancillary force used, and the integrity of the transmission of such ancillary force to the biasing unit.  
      Therefore, it is an object of this invention to provide force transmission devices which utilize mechanical load compensation as a braking component.  
      It is another object of the invention to provide force transmission devices having drive through braking capability.  
     SUMMARY  
      This invention provides novel force transmission devices, and novel methods of lifting/lowering, manipulating and/or otherwise controlling loads. Force transmission devices of the invention use gravitational energy, applied to a suspended load, to realize a mechanical load compensation. The mechanical load compensation is embodied by a braking force applied to the lifting/lowering apparatus as powered, at least in part, by the potential energy and/or kinetic energy of a load suspended by the lifting/lowering apparatus.  
      In a first family of embodiments, the invention comprehends a force transmission device, comprising: (a) a prime mover; (b) a clutch/brake assembly communicating with the prime mover; (c) a winding drum communicating with the clutch/brake assembly; and (d) a force converter communicating with the clutch/brake assembly and the winding drum and, the clutch/brake assembly comprising a clutch/brake housing having a housing inner surface, a plurality of discs defining a collective outer perimeter surface, including at spaces between the discs, the discs being generally concentrically disposed within the clutch/brake housing, and at least one braking element disposed between the housing inner circumferential surface and the collective outer perimeter surface of the plurality of discs, thereby to realize a frictional coupling between the discs and the inner surface of the clutch/brake housing.  
      In some embodiments the at least one braking element communicates with the collective perimeter surface of the plurality of discs; and is adapted and configured to bias between a first position in which the at least one braking element is relatively frictionally engaged with the inner surface of the clutch/brake housing, and a second position in which the at least one braking element is relatively frictionally disengaged with the inner surface of the clutch/brake housing.  
      In some embodiments, the plurality of discs being adapted to rotate about an axis of rotation, each of the plurality of discs being generally circular and having opposing generally flat surfaces, and defining an outer perimeter, including an imaginary outer circumference, at least one of the discs having a disc land at the corresponding outer perimeter, and extending from such imaginary outer circumference, the land defining an angle greater than zero degrees relative to a tangent to such outer circumference, which tangent touches such imaginary outer circumference at a locus underlying or touching the land.  
      In some embodiments, the disc land having first and second terminal ends, the at least one braking element being movable along the disc land between a first position in which the at least one braking element is proximate one of the first and second terminal ends of the disc land, and a second position in which the at least one braking element is displaced from one of the first and second terminal ends of the disc land.  
      In some embodiments, the disc land having first and second terminal ends, the at least one braking element being rotationally movable along the disc land between a first position in which the at least one braking element is proximate one of the first and second terminal ends of the disc land, and a second position in which the at least one braking element is displaced from one of the first and second terminal ends of the disc land.  
      In some embodiments, the clutch/brake assembly comprises a pressure plate, and at least one clutch disc having a generally serrated outer circumferential surface.  
      In some embodiments, the clutch/brake assembly further comprises at least one friction disc coaxial with, and adjacent, at least one of the pressure plate and the clutch disc whereby the friction disc is adapted and configured to frictionally engage with at least one of the pressure plate and the clutch disc.  
      In some embodiments, the force transmission further comprising a drive shaft having a length and an outer circumferential surface and communicating with the prime mover and extending generally medially axially through the clutch/brake assembly and the winding drum.  
      In some embodiments, the force converter comprises a generally cylindrical body having an outer perimeter surface and at least one groove in the outer perimeter surface.  
      In some embodiments, the force converter has an axis of rotation and the at least one groove of the generally elongate cylindrical body defines a first groove portion and a second groove portion, one of the first and second groove portions being generally parallel to the axis of rotation and the other of the first and second groove portions extending generally helically along a portion of the outer perimeter surface of the generally cylindrical body of the force converter.  
      In some embodiments, the force transmission device further comprising a pressure plate having first and second generally annular ends, one of the first and second generally annular ends generally defining a collar, and a cavity extending from the collar inwardly into the pressure plate, the force transmission device yet further comprising a generally cylindrical body having an outer circumferential surface, at least a portion of the generally cylindrical body of the force transmission device being generally slidingly and rotatably housed in at least a portion of the cavity of the pressure plate, the pressure plate being adapted and configured to generally axially slide with respect to, and to generally rotate with respect to, the generally cylindrical body of the force transmission device.  
      In some embodiments, the pressure plate being adapted and configured to axially and rotatably actuate between a first position in which relatively less of the generally cylindrical body is covered by the pressure plate, and a second position in which relatively more of the generally cylindrical body is covered by the pressure plate.  
      In some embodiments, wherein when the pressure plate is in the first position, ones of the plurality of discs generally rotationally slip with respect to each other.  
      In some embodiments, wherein when the pressure plate is in the second position, ones of the plurality of plates generally frictionally couple with respect to each other.  
      In some embodiments, the at least one braking element communicating with the collective outer perimeter surface of the plurality of plates and generally loosely interfacing with the inner circumferential surface of the clutch/brake housing.  
      In some embodiments, the at least one braking element communicating with the collective outer perimeter surface of the plurality of plates and generally snugly interfacing with the inner circumferential surface of the clutch/brake housing, whereby the at least one braking element provides frictional braking force against the inner circumferential surface of the clutch/brake housing.  
      In some embodiments, the force transmission device further comprising an interfacing plate between the disc land and the at least one brake element.  
      In a second family of embodiments, the invention comprehends a force transmission device, comprising: (a) drive shaft; (b) a force converter comprising a first actuation member and a second actuation member, the force converter being drivingly engaged with the drive shaft; (c) a clutch communicating with the force converter; and (d) a winding drum drivably engaged with the force converter; the first actuation member and the second actuation member being engaged with each other so as to effect axial movement of at least one of the first and second actuation members relative to the other of the first and second actuation members, and wherein the axial movement of the at least one of the first and second actuation members corresponds to respective engagement and/or disengagement of the clutch.  
      In some embodiments, the device further comprises a brake communicating with the clutch and comprising a brake housing having at least one braking element engagably communicating with the brake housing.  
      In some embodiments, the brake housing is generally concentric with, and generally surrounds the clutch.  
      In some embodiments, the clutch defining an outer perimeter surface and the brake housing comprising an inner circumferential surface, at least one braking element communicating with each of the outer perimeter surface of the clutch and the inner circumferential surface of the brake housing.  
      In some embodiments, the clutch being adapted and configured to rotate about an axis of rotation, the at least one braking element being adapted and configured to bias between a first position in which the braking element is relatively frictionally engaged with the inner surface of the brake housing, and a second position in which the braking element is relatively frictionally disengaged with the inner surface of the brake housing.  
      In some embodiments, the at least one braking element has a length extending generally parallel to the axis of rotation, the braking element being adapted and configured to move with respect to the disc land.  
      In some embodiments, the disc having first and second terminal ends, the at least one braking element being slidably moveable along the disc land between a first position in which the at least one braking element is proximate one of the first and second terminal ends of the disc land, and a second position in which the at least one braking element is displaced from the one of the first and second terminal ends of the disc land.  
      In some embodiments, the force transmission device further comprising an interfacing plate between the disc land and the at least one brake element.  
      In a third family of embodiments, the invention comprehends a force transmission device comprising: (a) a drive shaft; (b) a force converter drivingly engaged with the drive shaft; and (c) a winding drum drivably engaged with the force converter; the force converter further comprising a first actuation member and a second actuation member, the force converter being adapted and configured so as to enable at least one of the first and second actuation members to axially move relative to the other of the first and second actuation members, whereby a torsional force applied to at least one of the first actuation member and the second actuation member realizes an axial advancement or regression of at least one of the first actuation member and the second actuation member relative to the other one of the first actuation member and the second actuation member.  
      In some embodiments, wherein the at least one of the first and second actuation members moves axially when a torsional force is applied to the actuation member.  
      In some embodiments, wherein at least one of the first and second actuation members is adapted and configured to rotate in combination with axial movement relative the other of the first and second actuation members.  
      In some embodiments, the force transmission device further comprising a pressure plate having first and second generally annular ends, one of the first and second generally annular ends generally defining a collar and a cavity extending from the collar inwardly into the pressure plate, the force transmission device yet further comprising a generally elongate cylindrical body having an outer circumferential surface, at least a portion of the generally cylindrical body of the force transmission device being generally slidingly and rotatably housed in at least a portion of the cavity of the pressure plate, the pressure plate being adapted and configured to generally axially slide with respect to, and to generally rotate with respect to, the generally cylindrical body of the force transmission device.  
      In some embodiments, wherein the device further comprises a clutch communicating with the force converter and having a plurality of discs generally defining an outer perimeter surface, including space between the discs, and wherein the pressure plate in the first position corresponds to a generally rotationally slipping relationship between ones of the plurality of discs.  
      In some embodiments, wherein such device further comprises a clutch communicating with the force converter the clutch having a plurality of discs generally defining an outer perimeter surface, including spaces between the discs, and wherein the pressure plate in the second position corresponds to a generally frictional coupling relationship between respective ones of the plurality of discs.  
      In some embodiments, wherein such device further comprises a brake having a clutch/brake housing which defines an inner circumferential housing surface, and at least one braking element, the at least one braking element communicating with the outer perimeter surface of the plurality of discs and, in the first position, generally loosely interfacing with the inner circumferential surface of the clutch/brake housing.  
      In some embodiments, wherein the device further comprises a brake, and a clutch/brake housing which defines an inner circumferential housing surface, and at least one braking element, the at least one braking element communicating with the outer perimeter surface of the plurality of discs and, in the second position, generally snugly interfacing with the inner circumferential surface of the clutch/brake housing, whereby the at least one braking element provides a frictional braking force between the inner circumferential surface of the clutch/brake housing and the outer perimeter surface of the plurality of discs.  
      In some embodiments, wherein the device further comprises a brake housing and a brake element between the brake housing and the plurality of discs, and a interface plate between the brake element and the plurality of discs.  
      In some embodiments, wherein one of the first and second actuation members has an outer surface, and grooves disposed in the outer surface, and wherein the other one of the first and second actuation members comprises a collar having an inner surface with projections extending inwardly at the inner surface, the projections cooperating with the grooves in the outer surface.  
      In some embodiments, wherein the grooves in the outer surface are adapted and configure to guide movement of one of the projections of the collar and the other one of the first and second actuation members, upon application of a rotational force to the one of the actuation members, in a direction of an axis extending through the generally cylindrical body.  
      In some embodiments, the collar having an outer surface communicating with the winding drum whereby a torsional force applied to the winding drum is transferred to the collar.  
      In some embodiments, wherein the first actuation member comprises a helical gear, and wherein the second actuation member comprises a ring gear cooperatively compatible with the helical gear, the helical gear and the ring gear being rotatably slidingly engaged with each other.  
      In some embodiments, the force converter being adapted to convert a torque force applied to a first one of the first and second actuation members into axial movement of one of the first and second actuation members.  
      In a forth family of embodiments, the invention comprehends a drive-through clutch/brake comprising: (a) a clutch assembly including at least one clutch disc, at least one friction disc, a helical gear, and a helical drive; (b) a brake housing; (c) at least one brake element effective to engage the clutch assembly at the at least one clutch disc and/or the at least one friction disc, and the brake housing.  
      In some embodiments, the clutch assembly capable of rotating in a first direction of driving whereby the at least one brake element is generally disengaged from the brake housing.  
      In some embodiments, the clutch assembly capable of rotating in a second, opposite, direction of driving whereby the at least one brake element is generally engaged with the brake housing and remains engaged with the brake housing during rotation of the clutch assembly in such second direction.  
      In a fifth family of embodiments, the invention comprehends a method of automatically controlling a load, comprising: (a) suspending a gravitationally-actuated load from a force transmission device, the force transmission device comprising a winding drum, a force converter, and a brake; (b) transferring the gravitationally actuated load through a cable, to the winding drum and thereby converting the gravitational force to a torsional force; (c) transferring at least some of the force from the winding drum, through the force converter, and into the brake; and (d) converting at least some of the torsional force from the winding drum into axial movement, and thereby developing a braking force in the brake.  
      In some embodiments, wherein the force transmission device further includes a prime mover, and a drive train connecting the prime mover to the force transmission device, the method further comprising: (e) energizing the prime mover so as to provide a rotational driving force, through the drive train, to the force converter, in a first rotational direction and correspondingly rotating the winding drum in a first direction of rotation and thereby removing at least part of the braking force from the brake; the magnitude of the braking force removed from the brake being sufficient to enable the prime mover to lift the load.  
      In some embodiments, the method further comprising: (f) energizing the prime mover so as to provide a rotational driving force in a second, opposite rotational direction and correspondingly rotating the winding drum in a second, opposite direction of rotation; and (g) rotating the winding drum with a magnitude of rotational driving force sufficiently great to overcome the braking force provided by the brake; whereby the magnitude of the rotational driving force is sufficiently great to enable the prime mover to drive through the braking force of the brake and correspondingly to lower the load.  
      In a sixth family of embodiments, the invention comprehends a method of controlling a load, comprising: (a) applying a loading force, in a loading direction, to a force transmission device comprising a force receiver, a force converter, and a brake; (b) applying sufficient braking energy to the brake to prevent the loading force from causing motion; and (c) applying driving energy from a prime mover to the force transmission device, in a direction such that the driving energy force is additive to the loading force, and in sufficient amount to overcome the braking force provided by the brake, thereby to enable movement of the load in accord with the direction of the loading force while the braking energy is being applied.  
      In some embodiments, the method further comprising: (d) applying driving energy from a prime mover to the force transmission device, in a direction generally opposite the direction of the loading force, and in sufficient amount to reduce the braking force provided by the brake, thereby to enable movement of the load in accord with the direction of the driving energy force and generally opposite the direction of the loading force.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1A  shows a perspective view of a first embodiment of force transmission devices of the invention connected to a load, the load being illustrated in schematic form.  
       FIG. 1B  shows a perspective view of a second embodiment of force transmission devices of the invention connected to a load, the load being illustrated in schematic form.  
       FIG. 2A  shows an exploded perspective view of the winding assembly of the force transmission device of  FIG. 1A .  
       FIG. 2B  shows a cross-sectional perspective view of the force transmission device of  FIG. 1B , taken along axis of rotation “A.” 
       FIG. 3A  shows an exploded perspective view of a first embodiment of a disc pack assembly of the invention.  
       FIG. 3B  shows an exploded perspective view of a second embodiment of a disc pack assembly of the invention.  
       FIG. 4  shows a side elevation of a portion of the force transmission device of  FIG. 2B , with portions of the winding assembly removed.  
       FIG. 5  shows a cutaway perspective view of portions of the clutch/brake assembly of the force transmission device of  FIG. 2B . 
    
    
      The invention is not limited in its application to the details of construction or the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments or of being practiced or carried out in other various ways. Also, it is to be understood that the terminology and phraseology employed herein is for purpose of description and illustration and should not be regarded as limiting. Like reference numerals are used to indicate like components.  
     DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS  
       FIG. 1A  illustrates a first embodiment of force transmission devices  8  of the invention which are used for lifting, lowering, manipulating and/or otherwise controlling a load; hereinafter referred to as “lifting/lowering” a load. In general, force transmission device  8  has a base plate  10  upon which winding assembly  11 , gearbox  72 , and a prime mover, e.g. electric motor  74  is each mounted, directly or indirectly. Winding assembly  11  includes first and second winding drums  16 A,  16 B. Each of the winding drums  16 A,  16 B has one end of a cable  62 A,  62 B respectively attached thereto. The other end of each of cables  62 A,  62 B is attached to, optionally removably attached to, load  66 .  
      As will be described in greater detail hereinafter, force transmission device  8  is adapted and configured (i) to provide a passive braking force when motor  74  is not energized to e.g. resist a generally downward gravitational force applied to load  66 , and (ii) to actively drive through the passive braking force so as to actively drive load  66  generally downwardly.  
      Base plate  10 , of force transmission device  8 , defines a length dimension, a width dimension, an upper surface a lower surface, first and second lateral portions  12 A,  12 B, a medial portion  13 , and first and second elongate projections  21 . The upper surface of base plate  10  faces generally upwardly e.g. generally toward the rest of the assemblage of force transmission device  8 , and the lower surface of base plate  10  faces generally downwardly, e.g. generally away from the rest of the assemblage of force transmission device  8 , toward a mounting substrate.  
      The first and second lateral portions of base plate  10  extend along the length of base plate  10 , and each have an inner edge and an outer edge. A plurality of through bores  9  extends through each of the first and second lateral portions, between their respective inner and outer edges. Each through bore is adapted and configured to receive mounting hardware therethough which enables force transmission device  8  to be mounted to e.g. a suitable mounting substrate.  
      The medial portion of base plate  10  extends along the length of base plate  10  and provides, in the illustrated embodiment, a generally planar surface. The medial portion of base plate  10  lies generally between, and is generally parallel to and generally above e.g. not coplanar with, the first and second lateral portions of base plate  10 .  
      First and second elongate projections  21  of base plate  10  extend along the length of base plate  10  and upwardly away from, as well as generally perpendicular to, the first and second lateral portions  12 A,  12 B, respectively. The first and second elongate projections communicate with the inner edges of lateral portions  12 A,  12 B and the outer edges of medial portion  13 , whereby the first lateral projection connects to the first lateral portion and the medial portion, and the second lateral projection connects to the second lateral portion and medial portion.  
      Accordingly, the first and second lateral portions  12 A,  12 B, the elongate projections  21 , and the medial portion  13  of base plate  10 , in combination, provide mounting surfaces/structures in two distinct yet generally complementary surfaces and enable the remaining assemblage of force transmission device  10  to be mounted to base plate  10  and base plate  10  to be mounted, in turn, to e.g. a suitable mounting substrate via bores  9 .  
      Referring now to  FIGS. 1A and 1B , winding assembly  11  includes clutch/brake assembly  14  which will be described in greater detail hereinafter, winding drums  16 A,  16 B and/or  16 C ( FIGS. 1B, 2B ), and defines an outer surface. Winding assembly  11  is adapted and configured to function as a clutch and/or a brake, the outer surface of winding assembly  11  corresponds to the outer surfaces of at least one of clutch/brake assembly  14 , and winding drums  16 A,  16 B and/or  16 C.  
      Clutch/brake assembly  14  includes a clutch and/or brake housing, e.g. fixed housing  15 A ( FIG. 2A ). Flange “F” is an elongate projection or “mounting tab” extending downwardly from fixed housing  15 A. In clutch/brake assembly  14 , flange “F” is fixedly attached to base plate  10 , as well as to housing  15 A, thereby generally fixing parts of clutch/brake assembly  14  to base plate  10 . Namely, the fixed attachment of flange “F” to base plate  10  ensures that housing  15 A ( FIG. 2A ) does not rotate relative to base plate  10 . Those skilled in the art are well aware of attachment means suitable to attach flange “F” to base plate  10  including but not limited to welding, riveting, bolting, and/or other known attachment means suitable to attach components of clutch/brake assembly  14  to the base plate  10 .  
      Winding drums  16 A,  16 B, and/or  16 C ( FIGS. 1A, 1B ,  2 B) rotatably communicate with, and are generally coaxial with, clutch/brake assembly  14 . Each of winding drums  16 A,  16 B, and/or  16 C ( FIGS. 1A, 1B ,  2 B) has first and second generally circular end walls  23 , and a length dimension defined therebetween. Each winding drum is adapted and configured to rotate about an axis of rotation, e.g. axis of rotation “A.” 
      Outer circumferential wall  26  extends generally along the length dimension of winding assembly  11 , extends circumferentially around axis of rotation “A,” and has surface characteristics, such as, but not limited to, a helical guide groove which is formed into the outer surface of the outer circumferential wall, extends helically circumferentially around the outer surface of the outer circumferential wall, and defines a concave groove perimeter having a generally uniform groove radius. The surface characteristics of the outer circumferential wall define a cooperating relationship with surface characteristics of corresponding parts of force transmission device  8 , e.g. cables  62 A,  62 B. First and second generally circular end walls  23 , and outer circumferential wall  26  of winding drums  16 A,  16 B, and/or  16 C, in combination, define a generally cylindrical assemblage of winding assembly  11 .  
      Winding assembly  11  rotatably communicates with, and is generally coaxial with, bearing assembly  17  which includes a bearing housing which has a generally arcuate projection, a mounting flange, and at least one bearing. The generally arcuate projection of bearing assembly  17  has a thickness dimension and a bore which defines an opening bore diameter and extends into and/or entirely through the generally arcuate projection, e.g. at least partially along the thickness dimension of the generally arcuate projection of bearing assembly  17 .  
      Each of the bearings of bearing assembly  17  has an outer race diameter which corresponds in magnitude to the magnitude of the opening bore diameter, and an inner race diameter, defined by an inner race bore which extends generally through the bearing. The relationship between the magnitudes of bearing outer race diameter and the opening bore diameter of the generally arcuate projection enables the bearing to be slidingly received, and/or press fit, into the generally arcuate projection of bearing assembly  17 .  
      Cables  62 A,  62 B are generally flexible and elongate and have generally uniform diameters and radii. The outer surfaces of cables  62 A,  62 B define arcs which generally correspond to the arcuate shapes of the concave helical guide grooves formed in the outer circumferential surfaces of the respective winding drums  16 A,  16 B,  16 C whereby cables  62 A,  62 B are adapted and configured to be windingly received by the helical guide grooves of respective ones of drums  16 A,  16 B,  16 C. Cables  62 A,  62 B comprehend any of the variety of cable, wire, wire rope, and/or rope materials commonly known/used in the lifting/lowering industry, including but not limited to e.g. multi-strand wound steel cable, woven steel cable, and/or others.  
      Each of sheaves “S” is generally circular and/or cylindrical. Each sheave “S” has first and second generally circular ends, and a circumferential outer surface which is adapted and configured to rotatably receive, for example, cable  62 A and/or  62 B thereupon. Sheave “S” acts as e.g. a pulley which may be adapted and configured to rotate about an axis of rotation, by a distance which corresponds to a length of cable  62 A and/or  62 B which communicates with, and travels across, the outer circumferential surface of sheave “S.” 
      Cables  62 A,  62 B are attached to, optionally removably attached to, load  66  which can include any of a variety of structures/objects having mass. Such structures/objects include but are not limited to structures/objects which are desirable to lift/lower between a first, relatively higher position and a second, relatively lower position, e.g. elevator cars, dumb waiters, window washer platforms, construction/building material hoisting platforms, etc.  
      Gearbox  72  includes a gearbox housing, a gear assembly, an input shaft, and an output shaft. Gearbox  72  is in driving communication with winding assembly  11  and is attached to, e.g. generally fixedly secured to, base plate  10 . The input and output shafts of gearbox  72  are respectively in driving communication with, and driven communication with, the gear assembly of gearbox  72 . The gear assembly of gearbox  72  is adapted and configured to convert and/or transmit at least one of a direction of torque, a magnitude of torque, and a speed of rotation realized by the input shaft of gearbox  72  into a corresponding, but not necessarily equal, direction of torque, magnitude of torque, and/or speed of rotation realized by the output shaft of gearbox  72  which enables force transmission device  8  to lift/lower load  66  at a desirable rate of speed/distance of travel.  
      Those skilled in the art are well aware of gear assemblies which are suitable to convert and/or transmit at least one of a direction of torque, a magnitude of torque, and a speed of rotation realized by the input shaft of gearbox  72  into a corresponding, but not necessarily equal, direction of torque, magnitude of torque, and/or speed of rotation realized by the output shaft of gearbox  72  which enables force transmission device  8  to lift/lower load  66  at a desirable rate of speed/distance of travel. Such suitable gear assemblies include but are not limited to worm gear assemblies, spur gear assemblies, helical gear assemblies, crossed helical gear assemblies, bevel gear assemblies, spiral bevel gear assemblies, ring and pinion assemblies, planetary gear assemblies, and others.  
      Motor  74  is an AC or DC electric motor and optionally a single-phase AC or DC electric motor, which includes a motor output shaft in driving communication with the input shaft of gearbox  72  and optionally comprises the input shaft of gearbox  72  in its entirety. Motor  74  realizes a working speed and working torque sufficiently great in magnitude to suitably rotate the input shaft of gearbox  72 , the gears of gearbox  72 , and the output shaft of gearbox  72  so as to lift and/or lower load  66  as desired, e.g. at a desired rate of travel, while still proving relatively economical to operate in terms of power consumption, maintenance, and other operating costs.  
      Conventional mounting hardware such as bolts, screws, and/or other suitable types of conventional mounting hardware, extend through each of the plurality of through bores  9  which extend through each of the first and second lateral portions  12 A,  12 B of base plate  10  and thereby attach base plate  10  to the suitable and/or desirable mounting substrate which can be a wall, a ceiling, a floor, a gantry crane, or other suitable mounting substrates. In addition, conventional mounting hardware attaches piece-parts and/or subassemblies of force transmission device  8 , including but not limited to ones of bearing assembly  17 , gearbox  72 , and motor  74 , to base plate  10  thereby mounting force transmission device  8  in its entirety to such suitable substrate.  
      Flange “F” of clutch/brake assembly  14  and the mounting flange of bearing assembly  17  are each attached to base plate  10  along the length of base plate  10  and at locations distinct from, and typically coplanar with, each other.  
      Typically, of the clutch/brake assembly  14 , winding drums  16 A,  16 B, and the bearing and/or bearings of bearing assembly  17  are generally concentric, and coaxial with respect to the axis of rotation “A.” Accordingly, ones of the clutch/brake assembly  14 , winding drums  16 A,  16 B, and the bearing and/or bearings of bearing assembly  17  are generally coaxial with other ones of the clutch/brake assembly  14 , winding drums  16 A,  16 B, and the bearing and/or bearings of bearing assembly  17 . And the length of each of the clutch/brake assembly, the winding drums, and the bearing and/or bearings is each generally perpendicular to the direction which cables  62 A,  62 B extend away from winding drums  16 A,  16 B.  
      Sheaves “S” are positioned and/or installed where desired so as to enable a rotational movement of winding drums  16 A,  16 B to be converted to e.g. generally vertically actuated linear movement of load  66 . Those skilled in the art are well aware of suitable methods of mounting, suitable hardware for mounting with, suitable substrates to mount to, and suitable positional orientations in which to mount, sheaves “S” relative to force transmission device  8  and load  66  to facilitate lifting/lowering load  66  in a desired manner.  
      Referring now to  FIG. 2A , winding assembly  11  includes clutch/brake assembly  14 , winding drums  16 A,  16 B, and drive core  18 . Clutch/brake assembly  14  includes housing  15 A, disc pack assembly  28 , and force converter  43 A.  
      Housing  15 A is generally cylindrical, has a first outer facing surface  24  which faces a first direction, and a second outer facing surface  60  which faces a second, opposite direction, and a bore which extends therethrough, from first outer facing surface  24  to second outer facing surface  60 , and defines an inner surface of housing  15 A. Housing  15 A further includes an outer circumferential surface which extends circumferentially between first outer facing surface  24  and second outer facing surface  60  and has an elongate projection, e.g. flange “F” which is adapted and configured to interface with base plate  10 , and which extends downwardly from outer facing surface  24 .  
      Disc pack  28  includes a plurality of discs, the assemblage of which is generally cylindrical, and which generally defines an outer circumferential surface. Disc pack  28  has a length and a through bore which extends along the length of disc pack  28  and is generally coaxial with the outer circumferential surface of disc pack  28 .  
      Force converter  43 A includes, as first and second actuation members, helical gear  44  and pressure plate  50 A, respectively. Helical gear  44  is generally cylindrical, has first and second generally circular ends which define a length dimension of the gear therebetween, an outer circumferential surface which has at least one helical spline element, e.g. a helical/diagonal projection extending therefrom and/or a helical/diagonal groove, extending thereinto.  
      A through bore  55  extends from approximately the middle of one of the first and second generally circular ends to approximately the middle of the other one of the first and second generally circular ends of helical gear  44 , e.g. extends generally medially through the middle of helical gear  44  along the entire length of helical gear  44 .  
      A plurality of apertures  48  extend through helical gear  44 . Each aperture  48  extends through helical gear  44  generally parallel to through bore  55 , and is disposed between the through bore and the outer circumferential surface of gear  44 , and is spaced from other ones of apertures  48 .  
      Pressure plate  50 A is generally cylindrical, has first and second generally circular ends which define housing facing end surface  58 A and winding drum facing end surface  58 B. End surfaces  58 A,  58 B define a thickness dimension therebetween. Pressure plate  58  further defines an outer circumferential surface  53  which has at least one aperture  56  which extends thereinto. Apertures  56  extend from the outer circumferential surface  53  radially inwardly toward the axis of rotation of pressure plate  50 A. A generally cylindrical opening extends through pressure plate  50 A, between end surfaces  58 A,  58 B, and defines inner perimeter surface  51 , which is adapted and configured to cooperate with the outer surface of helical gear  44 , whereby to enable combined rotational and axial sliding communication between helical gear  44  and pressure plate  50 A.  
      Winding drums  16 A,  16 B are each substantially cylindrical, have first and second terminal ends, and an outer circumferential surface which has at least one aperture  20  extending therethrough. At least one of the first and second terminal ends of each of winding drums  16 A,  16 B defines a cavity “C,” which each of apertures  20  extend into, and which are adapted and configured to receive parts of other components of winding assembly  11  therein, e.g. adapted and configured to receive parts of drive core  18  and/or pressure plate  50 A therein.  
      Drive core  18  comprises flange  19  which has a first generally flat and circular end surface  57  and an outer circumferential surface which defines a first, relatively larger diameter. Drive core  18  further comprises drive hub  25 A, which has a second generally flat and circular end surface  59  and an outer circumferential surface  61  which defines a second, relatively smaller diameter. The generally flat and circular end surfaces  57 ,  59  of flange  19  and drive hub  25 A face generally opposing directions, relative to each other. At least one aperture  22  extends inwardly from the outer circumferential surface of flange  19  toward the axis of rotation of flange  19 .  
      The outer circumferential surface of drive hub  25 A has a plurality of interfacing structures, such as splines, extending therefrom or thereinto. An opening  27  extends longitudinally through the center of and along the length of, drive core  18 , generally defining an inner perimeter surface. The generally flat and circular end surface of drive hub  25 A has a plurality of threaded bores extending thereinto, generally parallel to opening  27  and each being disposed between opening  27  and outer circumferential surface  61 , which threaded bores are adapted and configured to correspond to and are aligned with apertures  48  which extend through helical gear  44 , in the assembled device.  
      The inner perimeter surface defined by opening  27  includes a keyway “K” which extends, as is a slot along a part of the length of drive core  18 . Drive hub  25 A of drive core  18  extends through and is rotatably housed in housing  15 A.  
      Elongate drive shaft  68  has a length, and a generally cylindrical outer surface. The outer circumferential surface of drive shaft  68  further has at least one keyway, e.g. slot  70  extending along at least a part of the length of shaft  68 .  
      Drive shaft  68  extends medially through respective components of winding assembly  11  and is disposed radially inwardly with respect to disc pack assembly  28 , housing  15 A, gears  44 ,  50 A, and winding drums  16 A,  16 B, and  16 C ( FIGS. 1B, 2A ,  2 B). Referring now to  FIG. 2A , the outer diameter of drive shaft  68  corresponds generally to the inner diameter of the opening which extends through drive core  18 . Keyway “K” of drive core  18  and slot  70  of shaft  68  are generally aligned with each other and interface with each other and with a key  64 . Keyway “K,” slot  70 , and key  64  are cooperatively sized and configured such that when the key is disposed in the aligned keyway and slot, a driving connection is realized between the shaft and the drive core. Accordingly, slot  70  of drive shaft  68 , along with corresponding hardware such as keys, pins, or other conventional hardware, enable parts/components of force transmission device  8  to communicate with and/or drivingly engage other parts/components of force transmission device  8 , such as e.g. to realize a driving connection between gearbox  72  ( FIG. 1A ) and drive core  18 .  
      A first cable-receiving winding drum  16 A is mounted over the outer surface of flange  19  of drive core  18 . Namely, flange  19  is housed in cavity “C” of winding drum  16 A. Winding drum  16 A is secured to flange  19  by screws which extend through apertures  20  which extend radially inwardly from the outer circumferential surface of winding drum  16 A, and into aligned apertures  22  in the outer circumferential surface of flange  19 , whereby winding drum  16  and flange  19  are secured to each other so as to necessarily rotate together.  
      Drive core  18  rides/rotates against outer facing surface  24  of fixed housing  15 A at flange  19  and drive hub  25 A of drive core  18  projects into the fixed housing  15 A when the device is fully assembled, so that drive hub  25 A and housing  15 A are generally coaxially aligned, and with housing  15 A being generally concentrically outward of drive hub  25 A.  
      The outer splined surface of drive hub  25 A engages with disc pack  28  through an interfacing relationship between the outer splined surface of drive hub  25 A and the surface characteristics of the through bore which extends through the assemblage of disc pack  28 , e.g. with friction discs  38  ( FIGS. 3A, 3B ) which will be described in greater detail hereinafter.  
      One of the first and second generally circular ends of helical gear  44  interfaces the correspondingly facing and generally flat and circular end surface of drive hub  25 A, and apertures  48  which extend through helical gear  44  are generally in coaxial alignment with the threaded bores which extend into the generally flat and circular end of drive hub  25 A. Bolts  46  extend through apertures  48  and threadedly into the threaded bores of drive hub  25 A whereby to realize a mechanical mounting of drive hub  25 A to helical gear  44 , e.g. to mechanically mount drive core  18  to helical gear  44 . With gear  44  and drive core  18  so mounted to each other through housing  15 A, disc pack  28  is disposed inside housing  15 A and drive hub  25 A is disposed inside the central opening in disc pack  28 .  
      Pressure plate  50 A and helical gear  44  are in actuating communication with each other, when assembled, as enabled by the cooperating surface characteristics of the inner perimeter surface  51  of pressure plate  50 A and the outer circumferential surface of helical gear  44 . As one non-limiting example, the inner perimeter surface  51  includes a plurality of inwardly facing helical teeth whereby pressure plate  50 A is an annular helical ring gear with an inner helically toothed surface adapted and configured to cooperate with the outer toothed circumferential surface of helical gear  44 . The cooperating relationship between pressure plate  50 A and helical gear  44  provides means for combined rotational and axial sliding communication between helical gear  44  and pressure plate  50 A realized by the cooperating relationship between e.g. the inwardly facing helical teeth on the inner perimeter surface  51  of pressure plate  50 A and the outwardly facing helical teeth of helical gear  44 .  
      Pressure plate  50 A is mounted to, and inwardly of part of, cable-receiving winding drum  16 B. Namely, pressure plate  50 A is received in cavity “C” of winding drum  16 B. Screws and/or other conventional hardware (not shown) extend through apertures  20  which extend through the outer circumferential surface of winding drum  16 B, and into corresponding aligned apertures  56  in outer circumferential surface  53  of pressure plate  50 A, whereby pressure plate  50 A is drivingly coupled to winding drum  16 B for common rotation therewith. In the assembled mechanism, housing facing end surface  58 A of pressure plate  50 A is in generally surface-to-surface contact with end surface  60  of fixed housing  15 A.  
      Referring to  FIGS. 2A, 3A , and  3 B, disc pack assembly  28  is slidably received on drive core  18  and rotatably received within fixed housing  15 A. Disc pack assembly  28  comprises clutch discs  36  which have relatively larger diameters defined by inner and outer perimeters, friction discs  38  which have relatively smaller diameters defined by inner and outer perimeters, a plurality of braking elements  32 A,  32 B, and a plurality of interfacing plates  34 .  
      Disc pack assembly  28  generally defines an axis of rotation, and a length, and comprises a sequential alternate stacking of clutch discs  36 , and friction discs  38 , mounted concentrically inside housing  15 A and concentrically outside of opening  27  and drive hub  25 A. The outer extremities of the outer perimeters of clutch discs  36  approximate the diameter of the inner surface of fixed housing  15 A, with suitable clearance to allow for rotation of the clutch discs  36  with respect to, and inside the inner surface of, fixed housing  15 A.  
      Referring now to  FIGS. 3A, 3B , each clutch disc  36  is generally flat and circular, and has an inner perimeter surface which defines an opening formed therethrough. The outer perimeter of each clutch disc  36  is generally serrated, defining a plurality of regularly-spaced projections, e.g. teeth  40 , and plate lands e.g. lands  42  located between respective ones of the teeth. Each land  42  defines first and second terminal ends and a surface which extends therebetween in a generally straight line, optionally with relatively shallow curvature.  
      The surface of a given land, which extends between the first and second terminal ends of the land, is disposed at an angle with respect to the tangent to the maximum outer diameter of the clutch disc  36 , namely the diameter of an e.g. circle which touches the outer extremities of the respective teeth  40 . Accordingly, each land  42  is disposed at an angle to the tangent of the outer perimeter of the clutch disc/plate, where the outer perimeter is defined at the extremities of the respective teeth.  
      Each friction disc  38  is generally flat and circular and has e.g. a maximum outer diameter generally smaller than the maximum outer diameter of clutch disc  36 . Friction disc  38  has an inner perimeter surface, which defines an opening formed through the friction disc. The inner perimeter surface of friction disc  38  has projections/splines, which correspond to respective splines of drive hub  25 A of drive core  18 . In the assemblage of disc pack assembly  28 , the inner perimeter surfaces of friction discs  38 , in combination, define a through bore which extends through disc pack assembly  28 . The through bore defined by the friction discs has surface characteristics which correspond with, and are adapted and configured to cooperate with, the outer circumferential surface of drive hub  25 A.  
      Referring now to  FIG. 3A , each braking element  32 A has a length, which generally corresponds to the length of disc pack assembly  28 . Each braking element  32 A has a frontwardly facing edge  33  and a rearwardly facing edge  35 . The rearwardly facing edge  35  of a corresponding braking element  32 A has a first, relatively greater height, as measured generally along the radius of disc pack assembly  28 , and the frontwardly facing edge has a second, relatively lesser height as measured generally along the radius of disc pack assembly  28 . Accordingly, each braking element is generally tapered toward the frontwardly facing edge  33 , from the first relatively greater height at the rearwardly facing edge to the second, relatively lesser height at the frontwardly facing edge.  
      Referring now to  FIG. 3B , in another set of embodiments, disc pack assembly  28  includes braking elements  32 B which are each substantially cylindrical columns, e.g. rollers, and each defines a diameter and a length.  
      The cross-section, e.g. diameter of each cylindrical braking element  32 B is substantially consistent along the entire length of the respective braking element  32 B. T cross-section of a given braking element  32 B is smaller than the distance between the inner surface of housing  15 A,  15 B and the lowest point of land  42  of a clutch disc  36 , e.g. the point on land  42  which is most distal from the inner surface of housing  15 A,  15 B. Further, the cross-section of a given braking element  32 B is greater than the distance between the inner surface of housing  15 A,  15 B and the highest point of land  42  of a clutch disc  36 , e.g. the point on land  42  which is closest to the inner surface of housing  15 A,  15 B.  
      The length of each cylindrical braking element  32 B corresponds generally to the length of disc pack assembly  28 . In some embodiments, the lengths of braking elements  32 B are equal to at least the distance between the two clutch discs  36  which are spaced furthest from each other, so that braking element  32 B can effectively engage and lock all of the clutch discs  36  in disc pack  28  in rotational unison.  
      Referring now to  FIGS. 3A , and  3 B, each of interfacing plates  34  has a length, which corresponds generally to the length of disc pack assembly  28 . Interfacing plate  34  has an upper surface and a lower surface. In the illustrated embodiments, both the upper surface and the lower surface of interfacing plate  34  are generally planar or optionally define shallow, gentle curvatures. In the embodiments illustrated, the upper surface and lower surfaces of interfacing plates  34  are generally parallel to each other so as to define a generally uniform thickness of a given plate  34 .  
      Friction discs  38  have relatively smaller inner and outer perimeters as compared to clutch discs  36 , when considering the average radius along the inner perimeter and the average radius along the outer perimeter. The inner perimeter surface of each of friction disc  38  is adapted and configured to engage the splined surface of drive hub  25 A of drive core  18 . Because friction discs  38  are mounted by a spline configuration to drive core  18 , the friction discs, in general, rotate independently of any rotation of clutch discs  36 , except for any friction which may be applied between friction discs  38  and clutch discs  36  at interfacing areas of their surfaces.  
      Interfacing plates  34  lie against, and are supported on, lands  42 , in orientations which are generally perpendicular to clutch discs  36 . The width of a given interfacing plate extends substantially the full length of a respective land  42  between respective ones of the teeth. The teeth  40  on clutch discs  36  are collectively aligned with each other along the length of disc pack assembly  28  whereby the corresponding lands  42  are also aligned with each other. A given line of lands, extending in the direction of axis “A” thus defines a receiving bed which extends generally the full length of the disc pack assembly. A given interfacing plate has a length which extends over all of the lands underlying a given receiving bed, with sufficient additional length to support locating tabs  41  which bear against the outer surface of the outermost clutch discs  36  on opposing ends of the disc pack assembly. Tabs  41  thus lock a given interfacing plate  34  against longitudinal movement of the interfacing plate relative to the clutch discs.  
      The width of an interfacing plate corresponds to the width of a respective receiving bed at lands  42 . Accordingly, with the interfacing plate in a receiving bed, and extending along the length of the disc pack assembly, e.g. generally parallel to axis “A,” and extending generally between respective ones of the teeth, the interfacing plate prevents the clutch discs from rotating with respect to each other. As a result, the interfacing plates  34 , one at each land about the circumferences of the respective clutch discs  36 , rotatably lock clutch discs  36  together for common rotation, such that all of clutch discs  36  rotate in unison.  
      In the completed assemblage of disc pack assembly  28 , braking elements  32 A,  32 B extend lengthwise of fixed housing  15 A, as do the interfacing plates  34 , and thus are axially aligned with the axis of rotation of the clutch discs  36 ; and the lengths of the braking elements extend parallel with the interfacing plates with the braking elements thus being positioned between fixed housing  15 A and respective ones of the interfacing plates. In some embodiments, braking elements  32 A are elongate wedges, which define arcuate wedge angles corresponding generally to the angles between the lands  42  of the clutch discs  36  and tangents to circles which are coaxial with the maximum radii of the clutch discs  36 . The braking elements fit loosely, but rather snug, between the interfacing plates on lands  42 , and the inner surface of fixed housing  15 A.  
      Lands  42  of the clutch discs  36 , through interfacing plates  34 , hold the outer surfaces of the braking elements in surface-to-surface alignment with the inner surface of fixed housing  15 A. Because all of the lands  42  define the same angle with the tangent to the maximum radii of the clutch discs  36 , which define circumferences which are concentric with the inner surface of the fixed housing, when the clutch is rotated in a first direction, the braking elements  32 A,  32 B are urged by the fixed angles of the interfacing plates and lands  42 , in a wedging action, against the inner surface of the fixed housing, causing a braking action. When the clutch is rotated in the opposite direction, the angles of lands  42  and interfacing plates  34  do not urge the braking elements  32 A,  32 B against the inner surface of the fixed housing, whereby the clutch offers generally no friction resistance to rotation of drive shaft  68 .  
      In other embodiments, not shown, interfacing plates  34  are omitted. In such embodiments, braking elements  32 A,  32 B take on the additional role of preventing rotation of the cutch discs relative to each other. Considering the necessity for the braking elements to move in the receiving beds to perform the braking function, in such embodiments where the braking elements are used to prevent rotation of clutch discs  36  relative to each other, some limited rotation of the clutch discs relative to each other is experienced. However, such is limited to rotation of about the distance between teeth on a clutch disc.  
      Referring now to  FIG. 3B , in the illustrated embodiments, disc pack assembly  28  includes a plurality of springs “SP” which are generally arcuate and are adapted and configured to biasingly urge braking elements  32 A,  32 B outwardly toward/against housing  15 A,  15 B. Namely, springs “SP” are leaf-type springs which can be made from, for example, relatively flat and elongate pieces of spring steel, other spring-type materials, and/or other materials which can suitably biasingly urge braking elements  32 A,  32 B outwardly toward/against housing  15 A,  15 B.  
      Each of springs “SP” has first and second terminal ends and a medial portion therebetween. The medial portion of spring “SP” curves generally outwardly between the first and second terminal ends and is thus positioned generally radially outwardly from the first and second terminal ends.  
      The first and second terminal ends of springs “SP” communicate with interfacing plate  34  and the medial portions of springs “SP” communicates with braking element  32 B. Accordingly, springs “SP” provide a biasing force between the interfacing plate  34  and braking elements  32 B which enables braking elements  32 A,  32 B to biasingly urge outwardly toward/against housing  15 A,  15 B.  
      Referring now to  FIGS. 1A, 2A ,  3 A, and  3 B, in use, a left cable  62 A is wound about the outer surface of left winding drum  16 A and a right cable  62 B is wound about the outer surface of right winding drum  16 B. As illustrated in  FIG. 1A , cables  62 A and  62 B extend from the winding drums to load  66 , such as an elevator car.  
      Weight of load  66  which passes through cable  62 A, passes through winding drum  16 A through the screws holding the winding drum to flange  19  of drive core  18 , and from drive core  18  to drive shaft  68  through the combination of keyway “K,” a suitable key (not illustrated), and slot  70 , thus to drive shaft  68 . Drive shaft  68  is connected to gear box  72 , thence to the electric drive motor  74  which lifts and lowers load  66 .  
      The weight of load  66 , which passes through cable  62 B, passes through winding drum  16 B and from winding drum  16 B through the screws which hold winding drum  16 B to pressure plate  50 A. The weight force passes from pressure plate  50 A, by way of the inwardly disposed spline teeth of pressure plate  50 A, and interfaces with the outwardly disposed spline teeth of helical gear  44 , thereby to exert rotational torque on gear  44  and correspondingly on driving core  18 . Since gear  44  and drive core  18  rotate in common with shaft  68 , since shaft  68  rotates only in common with gearbox  72  and motor  74 , the force applied to gear  44  by load  66  through cable  62 B, thence through pressure plate  50 A, is resisted by gear  44 . Pressure plate  50 A thus rotationally actuates, and axially actuates (as dictated by the helical interfacing structures of helical gear  44  and pressure plate  50 A) whereby pressure plate  50 A interfaces with, and applies an axial force to, disc pack assembly  28 . As the axial force is applied to disc pack assembly  28 , the alternatingly stacked clutch discs  36  and friction discs  38  are urged closer to each other, which correspondingly increases the frictional engagement between clutch discs  36  and friction discs  38 .  
      The direction of rotation of the winding drums is selected in combination with the directional pitch of the helical gear  44  and the pressure plate  50 A so that the weight of load  66 , in combination with any resistance applied through shaft  68 , results in pressure plate  50 A applying an axial force on the disc pack assembly by way of clutch discs  36  and friction discs  38 . The axial force which frictionally engages-clutch discs  36  and friction discs  38  is related to, typically is proportional to, the magnitude of the weight of load  66  as transmitted through cable  62 B.  
      Accordingly, the greater the weight of load  66 , the greater the axial force which is exerted by pressure plate  50 A and correspondingly applied by the combination of helical gear  44  and pressure plate  50 A to the stack of clutch discs  36  and friction discs  38 . While load  66  is applying an axial force on the clutch discs  36  and friction discs  38  through helical gear  44 , load  66  is simultaneously applying a rotational force to drive shaft  68 , through drive core  18 . However, braking elements  32 A,  32 B, as appropriate, are oriented, by virtue of lands  42 , to constantly resist rotation of the winding drums in the direction of downward movement of load  66 .  
      Accordingly, the rotational force applied by the weight of load  66  tends to cause rotation of the drive shaft  68  thus to lower load  66 , which requires rotation of the friction discs  38  against the resistance of braking elements  32 A,  32 B as applied at the inner surface of fixed housing  15 A. Namely, any rotation of clutch discs  36  drives braking elements  32 A or  32 B toward the inner surface of housing  15 A, causing frictional engagement of the braking elements against the inner surface of housing  15 A. This frictional engagement of the braking elements against the inner surface of housing  15 A resists rotation of clutch discs  36  with respect to fixed housing  15 A in the direction of downward movement of load  66 . Thus, braking elements  32 A,  32 B provide a mechanical load compensation by introducing a braking function to resist rotation of the winding drum, in the absence of driving force from the drive motor. The magnitude of the braking friction is designed such that the magnitude of the braking force is always greater than the magnitude of the rotational force exerted by load  66  at drum  16 A and/or  16 B.  
      The cooperating spline angles on helical gear  44  and pressure plate  50 A are so selected that the downward rotational urge of the weight of load  66  on drive shaft  68  is always countered by enough axial loading of the clutch discs  36  and the friction discs  38  to prevent frictional sliding of the friction discs  38  with respect to the clutch discs  36  under the gravitational weight of load  66 .  
      Namely, the spline angle, in combination with the net friction between discs  36  and  38 , is such that any change in operating magnitude of load  66  is accompanied by a corresponding change in the magnitude of the axial force, sufficient to prevent downward movement of the load based on gravity forces alone. Since the clutch discs  36  are prevented from rotating by braking elements  32 A,  32 B, and since the winding drums can rotate a substantive distance only when friction discs  38  rotate, disc pack assembly  28  effectively prevents rotation of the winding drums when shaft  68  is not powered by motor  74 .  
      Thus, in a static situation, load  66  is automatically held at whatever is its elevation by the braking action of disc pack assembly  28 , including through braking elements  32 A,  32 B. Indeed, the braking action of braking elements  32 A,  32 B is being applied under all conditions of load except when the load is being lifted.  
      As mass, and thus weight, is added to or subtracted from the load, the resulting increase or decrease in weight passes through cable  62 B and provides a generally proportional increase or decrease in the axial loading on the discs  36 ,  38  thereby linearly increasing and/or decreasing the force with which the discs  36 ,  38  are coupled to/interface with, each other by frictional engagement. In addition, the increase or decrease in load provides a generally proportional increase or decrease in the rotational force which is applied to shaft  68  through gear  44  and drive core  18 , and whereby any incremental movement of clutch discs  36  causes corresponding movement of brake elements  32 A,  32 B along lands  42 , thus to increase or decrease the braking force between brake elements  32 A,  32 B and housing  15 A.  
      When load  66  is to be lowered, drive shaft  68  is powered by motor  74  and gear box  72  with sufficient force to overcome the existing frictional braking action of braking elements  32 A,  32 B against the inner surface of fixed housing  15 A. That existing braking friction is sufficient in magnitude to prevent gravitational movement of the load, sufficient to support load  66  under static conditions. The existing braking friction between braking elements  32 A,  32 B and housing  15 A remains in place and active while load  66  is being lowered. Correspondingly, the act of lowering the load requires that a driving force be applied to shaft  68  in the rotational direction of the shaft required for downward movement of the load. Thus, where downward movement of the load requires counterclockwise rotation of shaft  68 , then an active driving force must be applied by gear box  72 , driving shaft  68  in the counterclockwise direction to effect lowering of the load. Such driving of shaft  6  in lowering the load is resisted by an opposite direction resistance being applied by brake elements  32 A or  32 B. Thus, the net affect of brake elements  32 A,  32 B is to substantially transfer the effect of the weight of the load to brake elements  32 A,  32 B and housing  15 A, rather than to shaft  68 . As a result, the magnitude of the drive-through force required for lowering load  66  is predominately a function of the magnitude of the braking force being applied at brake elements  32 A,  32 B, rather than being predominately a function of the magnitude of load  66 . Any time a downward driving force is withdrawn from shaft  68 , the in-effect braking friction between braking elements  32 A,  32 B and fixed housing  15 A takes over and controls the load, holding the load at the elevation whereat the downward driving force was withdrawn. Accordingly, the braking force is always in place in the downward direction of movement of the load, and when the load is stationary, and controls/holds load  66  stationary any time the downward driving force of drive shaft  68  is withdrawn.  
      When load  66  is being lowered, the force required on the shaft  68 , e.g. required shaft torque, is at least nominally greater than the force required on the shaft  68  to lift load  66  without any braking force in place. Such shaft torque is applied in part by the downward gravitational force of the load, and the balance of the shaft torque is applied by motor  74  through gear box  72 . Accordingly, any time downward movement of the load is effected, a shaft torque input, in the direction of load lowering movement, is required from motor  74  to rotationally drive the shaft through the mechanical load compensation braking force which is applied by disc pack assembly  28 .  
      When load  66  is to be lifted, the motor drives the gear box in a suitable direction, which drives drive shaft  68 , in a lifting direction to lift load  66 . Since lands  42  bias the braking elements only in the downward direction of movement of load  66 , a lifting drive on shaft  68  releases the braking elements  32 A,  23 B from engagement with the inner surface of fixed housing  15 A, namely moves lands  42  relative to braking elements  32 A,  32 B, thereby to release the braking elements, whereby the force required to lift load  66  approximates the free wheeling lifting force required of a drive system not having disc pack assembly  28 .  
      In light of the above, it is clear that a positive driving force, in the rotational direction of shaft  68  whereby the load is lowered, is required to drive winding drums  16 A,  16 B when load  66  is to be moved in the downward direction. To move load  66  in the upward direction, a corresponding driving force, opposite in direction, is required at shaft  68 .  
      The magnitude of the driving force required to lower the load depends on the magnitude of the braking force which resists lowering the load. Accordingly, the magnitude of the driving force required for lowering the load can be greater than, or less than, the driving force required to lift the load.  
      For example, where the load is e.g. 500 pounds, and a braking force sufficient to support 600 pounds is effected by brake elements  32 A,  32 B, then a positive driving force of only 100 pounds is required to drive the load downwardly.  
      Correspondingly, where the load is e.g. 500 pounds, and a braking force sufficient to support 1200 pounds is effected by brake elements  32 A,  32 B, then a positive driving force of 700 pounds is required to drive the load downwardly.  
      In the upward lift direction, the brake is automatically released by movement of lands  42  relative to brake elements  32 A,  32 B, and is automatically and immediately applied, again by movement of lands  42  relative to braking elements  32 A,  32 B, when any movement in the downward direction is initiated.  
      A nominal amount of rotation of clutch discs  36  in the downward direction is required to bring braking elements  32 A,  32 B into engagement with housing  15 A by e.g. correspondingly urging braking elements  32 A,  32 B upwardly along lands  42  and into engagement with housing  15 A. Given such nominal movement, in the downward direction, to engage braking elements after upward movement of the load, a nominal distance movement of the load may be effected, whereupon the braking is again in place, and the drive shaft  68  drives through that braking force in moving load  66  in the downward direction.  
      Accordingly, force transmission device  8  is adapted and configured to provide a passive braking function, when motor  74  is not energized, so as to resist an e.g. gravitational or other force applied to load  66  which tends to urge drums  16 A,  16 B to unwind cable  62 A,  62 B therefrom. Namely, force transmission device  8  is adapted and configured to hold load  66  at a constant height when motor  74  is not energized. Further, the force being applied to hold load  66  in a fixed location, when driving force is withdrawn from shaft  68 , changes dynamically as the magnitude of load  66  changes. Also, force transmission device  8  is adapted and configured to actively drive through the passive braking force so as to drive load  66  generally downwardly.  
      The magnitude of the braking force applied by brake elements  32 A,  32 B and correspondingly the rotational force applied to shaft  68 , by load  66 , is largely controlled by the angle between the helical teeth on gear  44  and pressure plate  50 A and the direction of extension of axis of rotation “A.” Thus, one can design gear  44  and pressure plate  50 A to provide braking forces of any of a wide range of relationships to the gravitational force being applied by the load. Thus, the braking force can be only nominally greater than the load force; or the braking force can be greater than the load force by a ratio of 1.5/1; or 3/1; or 4.5/1; or any other desire ratio. The greater the ratio, the more secure the holding of the load, but the more the force needed for driving through the braking resistance when the load is to be lowered.  
      Referring now to  FIGS. 1B and 2B , in some embodiments, force transmission device  8  utilizes winding assembly  11  which includes clutch/brake assembly  14  that communicates with and is located between, only one winding drum  16 C, and gearbox  72 . As shown in  FIG. 1B , a force transmission device with one winding drum  16 C can utilize two, alternatively more, cables  62 A,  62 B. When using one winding drum  16 C and two cables  62 A,  62 B, both of cables  62 A and  62 B transfer the gravitational force applied by suspended load  66  onto drum  16 C, resulting in mechanical load compensation via disc pack assembly  28  ( FIGS. 2B, 3A ,  3 B,  4 , and  5 ).  
      Referring now to  FIG. 2B , clutch/brake assembly  14  includes (i) a clutch and/or brake housing, e.g. housing  15 B, which is generally cylindrical, and which includes first and second outer end caps E 1 , E 2 , and an outer circumferential surface, and (ii) force converter  43 B which includes parts of drive core  18  as a first actuation member, e.g. drive hub  25 B, and a second actuation member, e.g. pressure plate  50 B and pins “P.” 
      The outer circumferential surface of housing  15 B includes a plurality of cooling elements, e.g. circumferential projections extending therefrom, and/or grooves extending thereinto, which relatively increases the surface area of the outer circumferential surface of  15 B, as compared to a relatively planar outer circumferential surface. The cooling elements of housing  15 B enable housing  15 B to realize a relatively cooler operating temperature, as the relatively increased surface area can dissipate more heat than e.g. a relatively smoother circumferential surface.  
      End cap E 1  of housing  15 B is generally flat and circular, is adapted and configured to communicate with gearbox  72 , has an inner circumferential surface generally defined by a through bore which extends generally medially therethrough, and a plurality of mounting apertures which extend therethrough, generally parallel to the through bore and between the through bore and the outer circumferential surface. The inner circumferential surface of end cap E 1  includes receiving structure, such as but not limited to a groove, adapted and configured to receive/hold a seal e.g. an o-ring therein.  
      The mounting apertures which extend through end cap E 1  correspond to mounting structure and/or apertures which extend through a sidewall of gearbox  72 , enabling end cap E 1  to be fixedly attached to such sidewall of gearbox  72  by e.g. conventional hardware. Thus, flange “F” is absent from housing  15 B, because the attachment of housing  15 B to gearbox  72  holds housing  15 B in a fixed, non-rotatable position, the same as if housing  15 B were attached to plate  10  through flange “F.” 
      End cap E 2  of housing  15 B is generally flat and circular, and is adapted and configured to communicate with pressure plate  50 B. Namely, end cap E 2  is adapted and configure to rotatably house at least a portion of pressure plate  50 B therein. End cap E 2  further includes a radially inner circumferential surface generally defined by a through bore which extends generally medially therethrough and which has receiving structure, such as but not limited to a groove, adapted and configured to receive/hold a seal e.g. an o-ring therein, which enables pressure plate  50 B to rotate with respect to, and with a generally liquid tight relationship with, end cap E 2 .  
      Drive core  18  includes (i) flange  19  which has a generally flat and circular end surface and a generally annular projection AP extending medially therefrom, and (ii) drive hub  25 B which has a length and an outer circumferential surface, and a generally flat and circular end surface with a generally cylindrical projection CP which extends medially therefrom and defines an outer circumferential surface. The annular projection AP and the cylindrical projection CP, of drive core  18 , namely of flange  19  and hub  25 B respectively, each face generally opposing directions relative to the other.  
      The generally annular projection AP of flange  19  includes an outer circumferential surface which has receiving structure, such as but not limited to a groove  76 , adapted and configured to receive/hold a seal e.g. an o-ring therein. Such seal communicates with both of, and in between, the annular projection AP of flange  19  and the inner circumferential surface of end cap E 1 , which enables drive core  18  to rotate with respect to, and with a generally liquid tight relationship with, end cap E 1  of housing  15 B.  
      The outer circumferential surface of drive hub  25 B is adapted and configured to interface with pressure plate  50 B. Specifically, the outer circumferential surface of drive hub  25 B has a plurality of interfacing structures, such as splines and corresponding grooves “G,” defined therein, which extend longitudinally less than the entire length of hub  25 B. A first portion of a given spline or groove has a helical configuration or helical groove and extends to and opens into a corresponding non-helical portion of the groove “G,” thereby to define a multi-stage groove having a first, generally helical groove stage and a second, generally straight, or non-helical groove stage all as illustrated in  FIG. 5 .  
      Each of the annular projection AP, flange  19 , hub  25 B, and the cylindrical projection CP is in generally coaxial alignment with other ones of the annular projection AP, flange  19 , hub  25 B, and the cylindrical projection CP. An opening/bore extends medially through drive core  18 , namely through the annular projection AP, flange  19 , hub  25 B, and the cylindrical projection CP and defines an inner perimeter having an inner perimeter surface which is adapted and configured to cooperate with surface characteristics of the outer circumferential surface of drive shaft  68 , namely inner perimeter surface of the opening/bore which extends through drive core  18  has a keyway “K2” defined therein which is a slot extending at least partially along the length of drive core  18 .  
      Referring still to  FIG. 2B , keyway “K2” of drive core  18  and slot  70  of shaft  68  are generally aligned with each other and both interface with e.g. a key whereby to realize a driving connection therebetween. Accordingly, slot  70  of drive shaft  68 , along with corresponding hardware such as keys, pins, or other conventional hardware, enable parts/components of force transmission device  8  to communicate with and/or drivingly engage other parts/components of force transmission device  8 , such as e.g. to realize a driving connection between gearbox  72  ( FIGS. 1B, 2B ) and drive core  18 .  
      Referring now to  FIGS. 2B, 4 , and  5 , pressure plate  50 B includes a first, relatively greater diameter portion having an outer circumferential surface having a plurality of apertures which extend therethrough, and a second, relatively lesser diameter portion having an outer circumferential surface.  
      The relatively greater diameter portion of pressure plate  50 B defines a cavity formed therein whereby the greater diameter portion of pressure plate  50 B defines e.g. a collar, and a cavity opening defined at a terminal end of the greater diameter portion of pressure plate  50 B, which cavity opening provides access to the cavity. The cavity opening, and the cavity, of the greater diameter portion of pressure plate  50 B are adapted and configured to slidably communicate with and extend over at least part of drive hub  25 B. For example, pressure plate  50 B can be adapted and configured to rotatably and/or axially advance and/or regress between (i) a first position in which pressure plate  50 B covers, and/or extends over, a relatively lesser portion of the length of drive hub  25 B and (ii) a second position in which pressure plate  50 B covers, and/or extends over, a relatively greater portion of the length of drive hub  25 B along axis of rotation “A.” 
      Interfacing plates  34 , shown in  FIG. 5 , are received in receiving beds on lands  42 , and extend between end ones of clutch plates  36 . As in the earlier embodiments, interfacing plates  34  extend the full width of the lands  42  whereby plates  34  prevent substantial rotation of clutch plates  36  with respect to each other. As with the earlier embodiments, interfacing plates  34  can be omitted, whereupon limited clutch disc-to-clutch disc rotation is experienced, as discussed with respect to the previous embodiments.  
      Pins “P” are elongate relatively columnar structures, each having a shank “SH” which defines a shank diameter of a first, relatively lesser diameter and a head “HE” which defines a head diameter of a second, relatively greater diameter. The magnitude of the shank diameter corresponds in shape to, and is slightly less than, the magnitude of the opening defined by each of the plurality of apertures which extend through the relatively greater diameter portion of pressure plate  50 B, while the magnitude of the head is greater than, the magnitude of the openings defined by the apertures which extend through the relatively greater diameter portion of pressure plate  50 B.  
      Accordingly, each of pins “P” is adapted and configured to extend through the generally radially-extending apertures of the relatively greater diameter portion of pressure plate  50 B to the extent permitted by the head of pin “P.” Thus, the shank of each pin “P” is housed in the respective radial aperture which extends through the relatively greater diameter portion of pressure plate  50 B so that part of the shank protrudes into the cavity defined by pressure plate  50 B and the head of pin “P” interfaces with outer circumferential surface of pressure plate  50 B, which provides a mechanical interference preventing pin “P” from sliding inwardly entirely through the corresponding aperture.  
      The magnitude of the shank diameter corresponds to, and is slightly less than, the magnitude of the opening defined by the helical groove portion of groove “G” of drive hub  25 B. Accordingly, the terminal ends of pins “P” are adapted and configured to be slidingly received by, and slide within, the helical portion of groove “G.” 
      When a force is applied to pins “P” in a direction which corresponds to the direction of extension of the helical portion of a groove “G,” namely toward the intersection of the helical section and non-helical section of a groove, the respective pin “P” is rotationally and axially urged upwardly in the helical portion of the groove “G” which correspondingly urges pressure plate  50 B rotationally over drive hub  25 B, and axially across/along the length of drive hub  25 B and compressingly urges pressure plate  50 B against disc pack assembly  28 .  
      Pressure plate  50 B is adapted and configured to drivingly cooperate with, and/or be coupled with, winding drum  16 C by e.g. winding drum  16 C and pressure plate  50 B is coupled by the interfacing of corresponding structures of pressure plate  50 B and winding drum  16 C. The relatively lesser diameter portion of pressure plate  50 B has a plurality of channels/grooves which correspond to elongate projections which extend medially inwardly of winding drum  16 C, which enables a rotational force applied to winding drum  16 C to transfer generally in direction and magnitude to a rotational force applied to pressure plate  50 B enabling winding drum  16 C and pressure plate  50 B to rotate in unison.  
      Referring now to  FIGS. 1B, 2B ,  3 A, and  3 B, in use, a left cable  62 A and a right cable  62 B are wound about the outer surface of winding drum  16 C. As illustrated in  FIG. 1B , cables  62 A and  62 B extend from the winding drum  16 C to load  66 , such as an elevator car.  
      Weight of load  66  which passes through cables  62 A,  62 B, passes through winding drum  16 C through the coupling interfacing of winding drum  16 C and the relatively lesser diameter portion of pressure plate  50 B, thus to clutch/brake assembly  14 , and through the combination of keyway “K2” and slot  70 , to drive shaft  68 . Drive shaft  68  is connected to gear box  72 , thence to the electric drive motor  74  which lifts and lowers load  66 .  
      The weight of load  66 , which passes through cables  62 A,  62 B, passes through winding drum  16 C and from winding drum  16 C to pressure plate  50 B, and through the pins “P” which interface with the helical portions of grooves “G” of drive hub  25 B. As the weight force passes to pins “P,” the pins “P” are urged further into the helical portions of grooves “G,” and as drive core  18  is held relatively static by e.g. the relatively static state of drive shaft  68 , pressure plate  50 B is urged to rotationally actuate, and axially actuate, as dictated by the helical interfacing structures of helical grooves “G” and pins “P,” whereby pressure plate  50 B interfaces with, and applies an axial force to, disc pack assembly  28 . As axial force is applied to disc pack assembly  28 , the alternatingly stacked clutch discs  36  and friction discs  38  are urged closer to each other, which correspondingly increases the frictional interface therebetween.  
      The direction of rotation of the winding drum  16 C is selected in combination with the directional pitch of the helical portion of grooves “G” so that the weight of load  66  causes pressure plate  50 B to apply an axial force on clutch discs  36  and friction discs  38  of disc pack assembly  28  wherein the axial force is related to the magnitude of the weight of load  66 .  
      The greater the weight of load  66 , the greater the axial force which is transmitted to pressure plate  50 B and, correspondingly, the greater the axial force which is applied by the combination of the stack of clutch discs  36  and friction discs  38 . While load  66  is applying an axial force on clutch discs  36  and friction discs  38  through the helical portion of grooves “G” and pressure plate  50 B, load  66  is simultaneously applying a rotational force to drive shaft  68 , also through the helical portion of grooves “G” and pressure plate  50 B, and in combination with disc pack assembly  28 . However, braking elements  32 A,  32 B are oriented, by virtue of lands  42 , to constantly resist rotation of the winding drums in the direction of downward movement of load  66 .  
      Accordingly, the rotational force applied by the weight of load  66  tends to cause rotation of the drive shaft  68  enabling lowering of load  66 , which requires rotation of the friction discs  38  against the resistance of braking elements  32 A,  32 B as applied at the inner surface of fixed housing  15 B. Namely, braking elements  32 A,  32 B urge non-rotation of clutch discs  36  with respect to fixed housing  15 B in the direction of downward movement of load  66 , and thereby provide a mechanical load compensation by introducing a braking function to resist rotation of the winding drum in the downward load direction, in the absence of driving force from drive motor  74 .  
      The cooperating spline/groove angles on the helical portions of grooves “G” are so selected that the downward rotational urge of the weight of load  66  on drive shaft  68  is always countered by enough axial loading of the clutch discs  36  and the friction discs  38  to effectively engage braking elements  32  against the inner surface of housing  15 B, thereby to prevent frictional sliding of the friction discs  38  with respect to the clutch discs  36  under the gravitational weight of load  66  and movement of the braking elements  32 A,  32 B relative to housing  15 B.  
      Namely, the spline/groove angle, in combination with the net friction between discs  36  and  38 , and between brake elements  32  and housing  15 B is such that any change in operating magnitude of load  66  is accompanied by a corresponding change in the axial force and braking force, sufficient to prevent downward movement of the load based on gravity forces alone.  
      Therefore in a static state, since the clutch discs  36  are prevented from rotating by braking elements  32 , and since the winding drum  16 C can only rotate when the friction discs  38  rotate, disc pack assembly  28  effectively prevents rotation of the winding drums when shaft  68  is not powered by motor  74  through gear box  72 , whereby a passive braking force, as a mechanical load compensation, is realized in the static situation in which load  66  is automatically held at whatever is its elevation when motor  72  is stopped, by the braking action of disc pack assembly  28 , including through the braking interfacing action of braking elements  32  against the inner surface of fixed housing  15 B.  
      Accordingly, when load  66  is to be lowered, a shaft torque input, which drives drive shaft  68  in a first rotational direction, is required from motor  74  to drive through the passive braking force/mechanical load compensation which is applied by disc pack assembly  28  any time downward movement of the load is desired, in order to lower load  66 .  
      When load  66  is to be lifted, the motor drives the gear box in a suitable direction, which drives drive shaft  68  in a second, opposite direction, namely in a lifting direction to lift load  66 . Since lands  42  bias braking elements  32  only in the downward direction of movement of load  66 , a lifting drive on shaft  68  releases the braking elements  32  from engagement with the inner surface of fixed housing  15 B, whereby braking elements  32  can move generally downwardly into/across lands  42 , relatively nearer the axis of rotation “A,” whereby the force required to lift load  66  approximates the free wheeling lifting force required of a drive system not having disc pack assembly  28 .  
      In some embodiments, disc pack assembly  28  operates in a dry clutch environment. In other embodiments, disc pack assembly  28  operates in a wet clutch environment, wherein at least part of disc pack assembly  28  is submerged in a liquid lubricant and/or coolant, such as gear oil, automatic transmission fluid, or others. In such embodiments the interfaces between, for example gear box  72  and housing  15 A,  15 B, as well as others, include o-rings and/or other commonly known/used seals, which creates a generally liquid tight environment.  
      In yet other embodiments, winding drum  16 C does not have a cavity formed therein. Rather, pressure plate  50  is mounted outside, yet adjacent, winding drum  16 C, wherein winding drum  16 C covers relatively less, or more of housing  15 B. In some embodiments, winding drum  16 C has a cavity which extends relatively further therein than the drums  16 A,  16 B illustrated. In such embodiments, winding drum  16 C covers most, optionally all, of housing  15 B.  
      Force transmission devices  8  are made of materials which resist corrosion in the expected use environment, and are suitably strong and durable for normal extended use. Those skilled in the art are well aware of certain metallic and non-metallic materials which possess such desirable qualities for use in force transmission devices, and appropriate methods of forming such materials.  
      Appropriate metallic materials for components of, or parts of components of, force transmission device  8  e.g. at least parts of sheave “S,” plate  10 , winding assembly  11 , gearbox  72 , motor  74 , and others, can be selected from but are not limited to, aluminum, steel, stainless steel, titanium, magnesium, brass, and their respective alloys. Common industry methods of forming such metallic materials include casting, forging, shearing, bending, machining, grinding, riveting, welding, powdered metal processing, extruding and others.  
      Non-metallic materials suitable for components of force transmission device  8 , e.g. various seals/o-rings, parts of bearing assembly  17 , friction discs  38 , and others, can be selected from various polymeric compounds, such as for example and without limitation, various of the polyolefins, such as a variety of the polyethylenes, e.g. high density polyethylene, or polypropylenes. There can also be mentioned as examples such polymers as polyvinyl chloride and chlorinated polyvinyl chloride copolymers, various of the polyamides such as nylon which, for example, can be used in friction discs  38  as nylon is relatively heat tolerant compared to certain other cost effective polymeric materials; polycarbonates, and others.  
      For any polymeric materials employed in structures of the invention, any conventional additive package can be included such as, for example and without limitation, slip agents, anti-block agents, release agents, anti-oxidants, fillers, and plasticizers, to assist in controlling e.g. processing of the polymeric material as well as to stabilize and/or otherwise control the properties of the finished processed product, also to control hardness, bending resistance, and the like.  
      Common industry methods of forming such polymeric compounds will suffice to form such non-metallic components of force transmission device  8 . Exemplary, but not limiting, of such processes are the various commonly-known plastics converting processes.  
      Individual components of force transmission device  8  can be assembled as subassemblies, including but not limited to, clutch/brake assembly  14  which includes housing  15 A,  15 B, disc pack assembly  28 , and force converter  43 A,  43 B winding drum  16 A,  16 B,  16 C, bearing assembly  17 , cable  62 A,  62 B, gearbox  72 , motor  74 , and others. Each of the aforementioned sub-assemblies is then assembled to respective other ones of the sub-assemblies to develop force transmission device  8 . Those skilled in the art are well aware of certain joinder technologies and hardware suitable for the assembly of such subassemblies in assembling force transmission device  8 .  
      As can be seen from the above description of the illustrated embodiments, the force transmission devices of the invention receive a load typically in a straight line expression of one or more forces by cables  62 A,  62 B. The straight line force is converted to a rotational force at winding drum  16 A, and  16 B, or  16 C. The rotational force is converted in part to a straight-line axial force causing e.g. movement of helical gear  44 , and in part to a radial force in the frictional engagement of brake elements  32 A,  32 B,  32  between clutch plates  36  and the inner surface of housing  15 A,  15 B. In summary, a straight-line load force is converted first to a rotational/torsional force, and thereafter is converted to axial and radial forces.  
      In some embodiments, braking elements  32 A,  32 B,  32  are omitted from the assembly whereby the entirety of the rotational force is converted to the axial force, and no radial force is developed. In such case, force transmission device  8  operates as a clutch, but not as a brake, whereupon any desired braking function is provided by other structure.  
      Those skilled in the art will now see that certain modifications can be made to the apparatus and methods herein disclosed with respect to the illustrated embodiments, without departing from the spirit of the instant invention. And while the invention has been described above with respect to the illustrated embodiments, it will be understood that the invention is adapted to numerous rearrangements, modifications, and alterations, and all such arrangements, modifications, and alterations are intended to be within the scope of the appended claims.  
      To the extent the following claims use means plus function language, it is not meant to include there, or in the instant specification, anything not structurally equivalent to what is shown in the embodiments disclosed in the specification.  
      While the present invention is illustrated with reference to force transmission devices having particular configurations and particular features, the present invention is not limited to these configurations or to these features, and other configurations and features can be used.  
      Similarly, while the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the invention is embodied in other structures in addition to the illustrated exemplary structures. The scope of the invention is defined in the claims appended hereto.