WO 2007/005122 PCT/US2006/018936 A SELF-ERECTING SUSPENSION PLATFORM SYSTEM WO 2007/005122 PCT/US2006/018936 REFERENCE TO RELATED DOCUMENTS This application claims the benefit of a previous application filed in the United States Patent and Trademark Office by George Anasis, Robert E. Eddy, and Jean-Francois 5 DeSmedt; on June 29, 2005, titled "Self-Erecting Suspension Platform System;" and given serial number 11/170684. TECHNICAL FIELD The instant invention relates to self-erecting suspension platform systems, particularly a ground based tower supported suspension type work platform. BACKGROUND OF THE INVENTION Suspension type work platforms are well-known in the art. They are traditionally mounted from the roof or upper stories of a building by means of temporary roof beams or permanent mounting davits, and often employ a track-based roof carriage, or monorails, to provide movable anchoring points for a work platform system. Obviously, a roof-mounted suspension platform system requires a usable roof, and therefore such a design is inherently unusable for a vertical structure under construction, for structures having a roof covered in large part with mechanical equipment for the HVAC system, or for a sloping roof. Alternatively, work platforms may be raised from the ground by means of a lift, such as seen in various "cherry-picker" type work baskets; or with a scissors-like arrangements as seen in U.S. Pat. No. 4,114,854; or by means of an extending'tower, as seen in U.S. Pat. No. 4,068,737. These ground based systems have the advantage of easy mobility, but all share the obvious shortcoming of being severely limited in the height to which the platform may be raised, which is generally limited to a very few stories of building elevation. Alternatively, ground based systems may utilize scaffolding supports that are built-up from sections in order to reach variable heights. A typical example is that seen in U.S. Pat. No. 4,294,332, in which rectangular scaffolding sections may be built up alongside a 2 WO 2007/005122 PCT/US2006/018936 platform that climbs the scaffold sections by means of a rack and pinion system. A suspension platform design has also been designed, in which chains hooked to the scaffold section, or towers, serves to raise the platform. Safety is of paramount concern when working from an elevated, or suspended, work platform. Prior art devices share many severe safety shortcomings. Firstly, modular sections should be easily raised and locked into position from inside the relative safety of the work platform. Such modular sections should be easily connected by secure, yet easily releasable connections that do not require a worker to struggle or lean outside of the work platform boundary. Secondly, the modular sections must be readily attachable to the vertical surface alongside of which the sections, or towers, are erected, in order to allow significant height to be achieved safely. Thirdly, redundant safety systems are highly desirable, to prevent the work platform from accidentally falling in case of equipment malfunction such as a separation of the hoisting and safety locking mechanism into separate components, and most desirably with more than a single safety lock system. What has been missing in the art has been a system by which a self erecting work platform may be raised on a tower system of easily interlocking sections, all of which may be easily raised from within the safety of the work platform, and which utilizes a motor and cable lift to raise and lower the platform system that is entirely separate from the safety lock mechanisms that operate to lock the work platform in place while tower sections are being added or removed. SUMMARY OF INVENTION In its most general configuration, the present invention advances the state of the art with a variety of new capabilities and overcomes many of the shortcomings of prior devices 5 in new and novel ways. In its most general sense, the present invention overcomes the shortcomings and limitations of the prior art in any of a number of generally effective configurations. The instant invention demonstrates such capabilities and overcomes many of the shortcomings of prior methods in new and novel ways. 3 WO 2007/005122 PCT/US2006/018936 The present invention is a self-erecting suspension platform system intended for use in the construction, maintenance, and cleaning of structures, or any other access solution. The platform system comprises a work platform suspended between a sinistral modular mast and a dextral modular mast by a hoisting system. 5 The sinistral modular mast and the dextral modular mast are each composed of at least two mast units stacked vertically and attached to one another. Each mast unit has a distal end, a proximal end, a multifunction rail extending from the distal end to the proximal end including a plurality of safety engagement devices and a stabilizer guide device, a unit interconnection device located substantially near the distal end, and a unit assembly guide. 10 When the mast units are stacked upon one another the multifunction rail of each mast unit substantially aligns with the multifunction rail of the adjacent mast unit. The modular mast units may be virtually any shape and configuration. The work platform serves as the stage upon which a user, or users, works to construct walls, wash windows, or any number of other elevated tasks. The work platform has a 15 sinistral end and a dextral end. The work platform is designed to be suspended between the sinistral modular mast and the dextral modular mast. Therefore, the distance from the sinistral end to the dextral end of the work platform is less than, or substantially equal to, the mast separation distance. The work platform also has a sinistral mast stabilizer and a dextral mast stabilizer attached to the platform and is configured to cooperate with the sinistral and dextral 20 mast stabilizer guide devices of the sinistral and dextral mast multifunction rails to prevent undesired swaying of the suspended work platform. The work platform also has a sinistral platform mast engager and a dextral platform mast engager attached to the platform and configured to cooperate with at least one of the plurality of sinistral and dextral mast safety 4 WO 2007/005122 PCT/US2006/018936 engagement devices of the sinistral and dextral mast multifunction rails to releasably lock the platform to the modular mast thereby preventing unintentional descent of the platform. The hoisting system suspends the working platform from the modular masts. The hoisting system includes a sinistral carriage, a dextral carriage, a sinistral mast hoist, a dextral 5 mast hoist, a sinistral mast cable, and a dextral mast cable. Each carriage is adapted to cooperatively receive the associated modular mast so that the carriage may be conveniently slid up and down the associated modular mast by a user. Each carriage also has a proximal end, a distal end, a body, a cable connector, an operator handle, and a carriage mast engager. The carriage mast engager is configured to releasably lock the carriage to the associated 10 modular mast thereby preventing unintentional descent of the carriage. The mast hoists are attached to the working platform and the associated mast cable, which is then attached to the cable connector of the associated carriage thereby suspending the working platform from the carriages. The mast hoists adjust the elevation of the working platform by extending and retracting the mast cables. 15 Lastly, the platform system includes a control system having a central control station for user control. The central console station is in communication with each mast hoist thereby controlling the elevation of the work platform. These variations, modifications, alternatives, and alterations of the various preferred embodiments may be used alone or in combination with one another as will become more 20 readily apparent to those with skill in the art with reference to the following detailed description of the preferred embodiments and the accompanying figures and drawings. 5 WO 2007/005122 PCT/US2006/018936 BRIEF DESCRIPTION OF THE DRAWINGS Without limiting the scope of the present invention as claimed below and referring now to the drawings and figures: 5 FIG. 1 is a schematic side elevation view of the self-erecting suspension platform, not to scale; FIG. 2 is a schematic top plan of the self-erecting suspension platform, not to scale; FIG. 3 is a schematic side elevation view of the self-erecting suspension platform, not to scale; 10 FIG. 4 is a schematic side elevation view of the self-erecting suspension platform, not to scale; FIG. 5 is a schematic side elevation view of the self-erecting suspension platform, not to scale; FIG. 6 is a schematic side elevation view of the self-erecting suspension platform, not 15 to scale; FIG. 7 is a schematic side elevation view of a portion of the sinistral modular mast, not to scale; FIG. 8 is a schematic side elevation view of a portion of the dextral modular mast, not to scale; 20 FIG. 9 is a schematic front elevation view of a portion of the dextral modular mast, not to scale; FIG. 10 is a schematic side elevation view of an embodiment of the sinistral carriage, not to scale; 6 WO 2007/005122 PCT/US2006/018936 FIG. 11 is a schematic side elevation view of an embodiment of the dextral carriage, not to scale; FIG. 12 is a schematic top plan view of an embodiment of the sinistral carriage, not to scale; 5 FIG. 13 is a schematic top plan view of an embodiment of the sinistral carriage, not to scale; FIG. 14 is a schematic top plan view of an embodiment of the sinistral carriage, not to scale; FIG. 15 is a schematic top plan view of an embodiment of the sinistral carriage, not to 10 scale; FIG. 16 is a schematic top plan view of an embodiment of the multifunction rail, not to scale; FIG. 17 is a schematic front elevation view of an embodiment of the multifunction rail, not to scale; 15 FIG. 18 is a schematic top plan view of an embodiment of the multifunction rail, not to scale; FIG. 19 is a schematic front elevation view of an embodiment of the multifunction rail, not to scale; FIG. 20 is a schematic top plan view of an embodiment of the multifunction rail, not 20 to scale; FIG. 21 is a schematic front elevation view of an embodiment of the multifunction rail, not to scale; FIG. 22 is a schematic elevated perspective view of an embodiment of the multifunction rail and platform mast stabilizer, not to scale; 7 WO 2007/005122 PCT/US2006/018936 FIG. 23 is a schematic top plan view of an embodiment of the multifunction rail and platform mast stabilizer, not to scale; FIG. 24 is a schematic top plan view of an embodiment of the multifunction rail and platform mast stabilizer, not to scale; 5 FIG. 25 is a schematic partial cross-section of several elements of the present invention, not to scale; FIG. 26 is a schematic partial cross-section of several elements of the present invention, not to scale; FIG. 27 is a schematic partial cross-section of several elements of the present 10 invention, not to scale; FIG. 28 is a schematic partial cross-section of several elements of the present invention, not to scale; FIG. 29 is a schematic partial cross-section of several elements of the present invention, not to scale; 15 FIG. 30 is a schematic partial cross-section of several elements of the present invention, not to scale; FIG. 31 is a schematic front elevation view of a portion of the sinistral modular mast, not to scale; FIG. 32 is a schematic front elevation view of a portion of the dextral modular mast, 20 not to scale; FIG. 33 is a schematic side elevation view of an embodiment of a unit assembly guide, not to scale; FIG. 34 is a schematic side elevation view of an embodiment of a unit assembly guide, not to scale; 8 WO 2007/005122 PCT/US2006/018936 FIG. 35 is a schematic top plan view of an embodiment of the sinistral modular mast and multifunction rails, not to scale; and FIG. 36 is a schematic top plan view of an embodiment of the dextral modular mast and multifunction rails, not to scale. 5 DETAILED DESCRIPTION OF THE INVENTION The self-erecting suspension platform system (10) of the instant invention enables a significant advance in the state of the art. The preferred embodiments of the device accomplish this by new and novel arrangements of elements and methods that are configured 10 in unique and novel ways and which demonstrate previously unavailable but preferred and desirable capabilities. The detailed description set forth below in connection with the drawings is intended merely as a description of the presently preferred embodiments of the invention, and is not intended to represent the only form in which the present invention may be constructed or utilized. The description sets forth the designs, functions, means, and 15 methods of implementing the invention in connection with the illustrated embodiments. It is to be understood, however, that the same or equivalent functions and features may be accomplished by different embodiments that are also intended to be encompassed within the spirit and scope of the invention. The present invention is a self-erecting suspension platform system (10) intended for 20 use in the construction, maintenance, and cleaning of structures, or any other access solution. With reference to FIG. 1, the platform system (10) comprises a work platform (300) located between a sinistral modular mast (100) and a dextral modular mast (200), wherein a hoisting system (400) suspends the work platform (300) from the modular masts (100, 200).
WO 2007/005122 PCT/US2006/018936 First, the modular masts (100, 200) will be disclosed in detail. The sinistral modular mast (100), illustrated in FIG. 7, has at least a second sinistral mast unit (110b) stacked vertically on, and releasably attached to, a first sinistral mast unit (110 a). The first sinistral mast unit (110 a) and the second sinistral mast unit (110b) are substantially identical. Each 5 sinistral mast unit (1 I0a, 110b) has a distal end (112), a proximal end (114), a multifunction rail (116) extending from the distal end (112) to the proximal end (114) including a plurality of safety engagement devices (117) and a stabilizer guide device (122), illustrated in FIG. 31 only, a unit interconnection device (135), seen in FIG. 7, located substantially near the distal end (112), and a unit assembly guide (140) located substantially near the distal end (112). 10 When the sinistral mast units (1 I0a, 110b) are stacked upon one another the multifunction rails (116) of each mast unit (110 a, 110b) substantially align. The sinistral modular mast (100) is constructed on a sinistral base plate (113) in contact with the ground for stability and to distribute the load of the sinistral modular mast (100). Similarly, the dextral modular mast (200), seen in FIGS. 8 and 9, has at least a second 15 dextral mast unit (210b) stacked vertically on, and releasably attached to, a first dextral mast unit (210a). The first dextral mast unit (210a) and the second dextral mast unit (21Gb) are substantially identical, and are substantially identical to the sinistral mast units (11 Ga, 11Gb). Each dextral mast unit (210a, 210b) has a distal end (212), a proximal end (214), a multifunction rail (216) extending from the distal end (212) to the proximal end (214) 20 including a plurality of safety engagement devices (217) and a stabilizer guide device (222), seen only in FIG. 32, a unit interconnection device (235) located substantially near the distal end (212), and a unit assembly guide (240) located substantially near the distal end (212). When the dextral mast units (21 Ga, 21Gb) are stacked upon one another the multifunction rails (216) of each mast unit (21 Ga, 21Gb) substantially align. The dextral modular mast (200) 10 WO 2007/005122 PCT/US2006/018936 is constructed on a dextral base plate (213) in contact with the ground for stability and to distribute the load of the dextral modular mast (200). Further, one with skill in the art will appreciate that the multifunction rails (116, 216) need not be located at the middle of one of the sides of the modular masts (100, 200). In fact, by offsetting the multifunction rails (116, 5 216) the working platform (300) may be placed closer to the structure upon which work is being performed. The sinistral mast units (1 I0a, 110b) are configured such that when a portion of the distal end (112) of a second sinistral mast unit (110b) is placed in contact with the proximal end (114) of the adjacent first sinistral mast unit (11 0a), during assembly of the sinistral 10 modular mast (100), the unit assembly guide (140) pivotably secures the second sinistral mast unit (11 Ob) to the first sinistral mast unit (11 Oa) such that the second sinistral mast unit (11 Ob) may be securely rotated into a vertical position such that the sinistral unit interconnection device (135) attaches the second sinistral mast unit (11 Ob) to the first sinistral mast unit (11 Oa), as seen in FIG. 7. Similarly, the dextral mast units (21 Oa, 2 1Ob), illustrated 15 best in FIGS. 3, 8, and 9, are configured such that when a portion of the distal end (212) of a second dextral mast unit (21 Gb) is placed in contact with the proximal end (214) of the adjacent first dextral mast unit (210a), during assembly of the dextral modular mast (200), the unit assembly guide (240) pivotably secures the second dextral mast unit (21 Ob) to the first dextral mast unit (21 0a) such that the second dextral mast unit (21 Gb) may be securely rotated 20 into a vertical position such that the dextral unit interconnection device (235) attaches the second dextral mast unit (21Gb) to the first dextral mast unit (11 0a). The dextral modular mast (200) is separated from the sinistral modular mast (100) by a mast separation distance (50). 11 WO 2007/005122 PCT/US2006/018936 As one with skill in the art will recognize, the modular mast units (11 0a, 110b, 210a, 21 0b) may be virtually any shape and configuration. The design and construction of the modular mast units (1 I0a, 110b, 210a, 21Gb) depends largely on the size and load of the work platform (300), as well as the elevation that the work platform (300) must reach. For 5 example, the modular mast units (1 I0a, 11Gb, 210a, 21Gb) may be a predetermined size and configuration for use with ten foot long work platforms (300) that will reach an elevation of no more than sixty feet. Further, then modular mast units (11 Ga, 11Gb, 21 0a, 210b) for use with longer more heavily loaded work platforms (300) may be a different configuration and level of reinforcing such that for safety concerns the modular mast units (110 a, 11Gb, 21 Ga, 10 2 1Gb) of one particular work platform (300) and application criteria may not be used with modular mast units (1 I0a, 110b, 210a, 21Gb) of a different work platform (300) and application criteria. As with many structural tower systems, generally a triangular cross sectioned truss construction tower provides the greatest utility, however any number of widely known structural shapes may be used. 15 Further, the unit assembly guides (140, 240) may be constructed in any number of effective arrangements. In one embodiment, the unit assembly guides (140, 240) includes a hook device (142, 242), seen in FIGS. 33 and 34, located substantially near the distal end (112, 212) and configured such that when a portion of the distal end (112, 212) of a second mast unit (11Gb, 21Gb) is placed in contact with the proximal end (114, 214) of the adjacent 20 first mast unit (1 I0a, 210a) in the vertical position that the hook device (142, 242) pivotably secures the second mast unit (110b, 21Gb) to the first mast unit (110 a, 21 Ga) such that the second mast unit (11Gb, 21Gb) may be securely rotated into a vertical position such that the unit interconnection device (135, 235) attaches the second mast unit (11Gb, 210b) to the first mast unit (11 0a, 210a). Similarly, the unit interconnection devices (135, 235) may be 12 WO 2007/005122 PCT/US2006/018936 constructed in any number of effective arrangements. Perhaps the most simple embodiment of the unit interconnection devices (135, 235) barb-type finger, as seen in FIGS. 7 and 8, that deflects and snaps over a portion of the adjacent mast unit (11 Oa, 1 Ob, 210a, 2 1Ob), and requires intentional manipulation of the finger to release the adjacent mast unit (11 Oa, 11 Ob, 5 210a, 210b). Next, with reference again to FIG. 1, the work platform (300) serves as the stage upon which a user, or users, works to construct walls, wash windows, or any number of other elevated tasks. The work platform (300) has a sinistral end (302) and a dextral end (304), as seen in FIG. 3. Since the work platform (300) is designed to be suspended between the 10 sinistral modular mast (100) and the dextral modular mast (200), the distance from the sinistral end (302) to the dextral end (304) of the work platform (300) is less than, or substantially equal to, the mast separation distance (50), shown in FIG. 5. The work platform (3 00) is located between the sinistral modular mast (100) and the dextral modular mast (200) such that the work platform sinistral end (302) is adjacent to the sinistral modular mast (100) 15 and the work platform dextral end (304) is adjacent to the dextral modular mast (200). The work platform (300) has a railing (310), seen in FIG. 3. The work platform (300) also has a sinistral mast stabilizer (320) and a doxtral mast stabilizer (330) attached to the platform (300) and configured to cooperate with the sinistral and dextral mast stabilizer guide device (122, 222), seen in FIGS. 31 and 32, of the sinistral and dextral mast multifunction rails (116, 20 216) to prevent undesired swaying of the suspended work platform (300). Additionally, the work platform (300) has a sinistral platform mast engager (340) and a dextral platform mast engager (350) attached to the platform (300) and configured to cooperate with at least one of the plurality of sinistral and dextral mast safety engagement devices (117, 217) of the sinistral 13 WO 2007/005122 PCT/US2006/018936 and dextral mast multifunction rails (116, 216) to releasably lock the platform (300) to the modular mast (100, 200) thereby preventing unintentional descent of the platform (300). With reference now to FIG. 4, the hoisting system (400) suspends the working platform (300) from the sinistral modular mast (100) and the dextral modular mast (200). The 5 hoisting system (400) includes (a) a sinistral carriage (450), (b) a dextral carriage (470), (c) a sinistral mast hoist (430), (d) a dextral mast hoist (440), (e) a sinistral mast cable (410), and (f) a dextral mast cable (420). The sinistral carriage (450) is adapted to cooperatively receive the sinistral modular mast (100) so that the sinistral carriage (450) may be conveniently slid up and down the 10 sinistral modular mast (100) by a user. As seen in FIGS. 10, 12, and 14, the sinistral carriage (450) has a proximal end (466), a distal end (467), a body (452), a cable connector (454), an operator handle (456), and a carriage mast engager (460). The carriage mast engager (460) is configured to releasably lock the sinistral carriage (450) to the sinistral modular mast (100) thereby preventing unintentional descent of the sinistral carriage (450). 15 The dextral carriage (470) is adapted to cooperatively receive the dextral modular mast (200) so that the dextral carriage (470) may be conveniently slid up and down the dextral modular mast (200) by a user. As seen in FIGS. 11 and 13, the dextral carriage (470) has a proximal end (486), a distal end (487), a body (472), a cable connector (474), an operator handle (476), and a carriage mast engager (480) to releasably lock the dextral 20 carriage (470) to the dextral modular mast (200) thereby preventing unintentional descent of the dextral carriage (470), Referring again to FIG. 4, the sinistral mast hoist (430) is attached to the working platform (300) near the sinistral end (302) and the dextral mast hoist (440) is attached to the working platform (300) near the dextral end (304). Further, the sinistral mast cable (410) is 14 WO 2007/005122 PCT/US2006/018936 attached to the cable connector (454) of the sinistral carriage (450) and the sinistral mast hoist (430) and the dextral mast cable (420) is attached to the cable connector (474) of the dextral carriage (470) and the dextral mast hoist (440) thereby suspending the working platform (300) from the sinistral carriage (450) and the dextral carriage (470). The mast hoists (430, 5 440) adjust the elevation of the working platform (300) by extending and retracting the sinistral mast cable (410) from the sinistral mast hoist (430) and the dextral mast cable (420) from the dextral mast hoist (440). The mast hoists (430, 440) are generally commercially available electrically powered hoists, but they may be manual hoist systems. Lastly, the platform system (10) includes a control system (500) having a central 10 control station (510) for user control. The central console station (510) is in communication with the sinistral mast hoist (430) and the dextral mast hoist (440) thereby controlling the elevation of the work platform (300) by extending and retracting the sinistral mast cable (410) and the dextral mast cable (420) from the sinistral mast hoist (430) and the dextral mast hoist (440). The control system (500) may incorporate any number of electrical interlocks for 15 improved safety. For instance, the control system (500) may include an accelerometer that activates the safety engagement devices (117, 217) upon sensing a predetermined acceleration or velocity. Additional safety features may include top limit switch(s), bottom limit switch(s), and a payload overload detection system. Now the various elements discussed above will be reviewed in more detail and as 20 applied to various embodiments. The plurality of safety engagement devices (117, 217) of the multifunction rails (116, 216) may be formed as locking recesses (118, 218) formed in the multifunction rail (116, 216) in some embodiments, as seen in FIGS. 17 and 22, and may be formed as locking projections (119, 219) extending from the multifunction rail (116, 216) in other embodiments, as seen in FIGS. 19, 20, and 23. The locking recesses (118, 218) of 1 5 WO 2007/005122 PCT/US2006/018936 FIGS. 17 and 22 formed in the multifunction rail (116, 216) are generally openings that extend all the way through the multifunction rail (116, 216), however they may simply be recesses formed in the multifunction rail (116, 216). The sinistral carriage mast engager (460) and the dextral mast engager (480) 5 cooperate with their associated modular mast (100, 200) to prevent unintentional descent of the carriages (450, 470). The carriage mast engagers (460, 480) may be virtually any device that can selectively lock the associated carriage (450, 470) to the associated mast (100, 200). Most embodiments the carriage mast engagers (460, 480) include some form of a locking tongue. For instance, one embodiment, illustrated in FIGS. 25 and 26, includes a sinistral 10 carriage.locking tongue (462) formed to cooperate with the sinistral locking recesses (118) so that the sinistral carriage locking tongue (462) can extend into, and retract from, any one of the sinistral locking recesses (118) to releasably secure the sinistral carriage (450) to the sinistral multifunction rail (116). Similarly, in this embodiment, the dextral carriage mast engager (480) includes a dextral carriage locking tongue (482) formed to cooperate with the 15 dextral locking recesses (218) so that the dextral carriage locking tongue (482) can extend into, and retract from, any one of the dextral locking recesses (218) to releasably secure the dextral carriage (470) to the dextral multifunction rail (216), not illustrated but identical to FIGS. 25 and 26. However, in alternative embodiments the carriage mast engagers (460, 480) may directly attach to the mast (100, 200), not the multifunction rail (116, 216). The 20 actuation of the carriage locking tongues (462, 482) may be manually initiated by the force of the user or may be power actuated via hydraulics, pneumatics, or electromagnetics, just to name a few power sources. Similar to the carriage mast engagers (460, 480) just discussed, the work platform (300) incorporates a sinistral platform mast engager (340) and a dextral platform mast 16 WO 2007/005122 PCT/US2006/018936 engager (350), seen in FIG. 3, both of which are attached to the platform (300), configured to cooperate with at least one of the plurality of sinistral and dextral mast safety engagement devices (117, 217) of the sinistral and dextral mast multifunction rails (116, 216). The platform mast engagers (340, 350) serve to releasably lock the platform (300) to the modular 5 masts (100, 200) via the multifunction rails (116, 216) thereby preventing unintentional descent of the platform (300). Further, systematic locking of the platform (300) to the modular masts (100, 200) is required during the operation of the suspension platform system (10). The platform mast engagers (340, 350) may be virtually any device that can selectively lock the associated side of the work platform (302, 304) to the associated multifunction rail 10 (116, 216). Most embodiments the platform mast engagers (340, 350) include some form of a locking tongue. For instance, one embodiment, illustrated in FIGS. 25 and 26, includes a sinistral platform locking tongue (342) formed to cooperate with the sinistral locking recesses (118) so that the sinistral platform locking tongue (342) can extend into, and retract from, any one of the sinistral locking recesses (118) to releasably secure the work platform sinistral end 15 (302) to the sinistral multifunction rail (116). Similarly, in this embodiment, the dextral platform mast engager (350) includes a dextral platform locking tongue (352) formed to cooperate with the dextral locking recesses (218) so that the dextral platform locking tongue (352) can extend into, and retract from, any one of the dextral locking recesses (218) to releasably secure the work platform dextral end (304) to the dextral multifunction rail (216), 20 not illustrated but identical to FIGS. 25 and 26. As previously mentioned, in some embodiments the plurality of safety engagement devices (117, 217) of the multifunction rails (116, 216) may be formed as locking projections (119, 219) extending from the multifunction rail (116, 216), as seen in FIGS. 18-21. In these embodiments, the plurality of sinistral safety engagement devices (117) are sinistral locking 17 WO 2007/005122 PCT/US2006/018936 projections (119) extending from the sinistral multifunction rail (116), and the plurality of dextral safety engagement devices (217) are dextral locking projections (219) extending from the dextral multifunction rail (216). Similar to the embodiments previously described, most embodiments incorporating locking projections (119, 219) also incorporate carriage mast 5 engagers (460, 480) in the form of a locking tongue that cooperates with the locking projections (119, 219). For example, in one embodiment the sinistral carriage mast engager (460) includes a sinistral carriage locking tongue (462) formed to cooperate with the sinistral locking projections (119) so that the sinistral carriage locking tongue (462) can engage with, and disengage from, any one of the sinistral locking projections (119) to releasably secure the 10 sinistral carriage (450) to the sinistral multifunction rail (116), as seen in FIGS. 27 and 28, and the dextral carriage mast engager (480) includes a dextral carriage locking tongue (482) formed to cooperate with the dextral locking projections (219) so that the dextral carriage locking tongue (482) can engage with, and disengage from, any one of the dextral locking projections (219) to releasably secure the dextral carriage (470) to the dextral multifunction 15 rail (216), not illustrated but similar to FIGS. 27 and 28. The actuation of the carriage locking tongues (462, 482) may be manually initiated by the force of the user or may be power actuated via hydraulics, pneumatics, or electromagnetics, just to name a few power sources. In one particular embodiment seen in FIGS. 10 and 11, the carriage operator handle (456, 476) includes a engager activation device (457, 477) that activates and deactivates the 20 carriage mast engager (460, 480) to releasably lock the carriage (450, 470) to the modular mast (100, 200) thereby preventing unintentional descent of the carriage (450, 470). In the embodiments incorporating locking projections (119, 219), the work platform (300) incorporates a sinistral platform mast engager (340) and a dextral platform mast engager (350), both of which are attached to the platform (300), configured to cooperate with 18 WO 2007/005122 PCT/US2006/018936 at least one of the plurality of sinistral and dextral mast locking projections (119, 219) of the sinistral and dextral mast multifunction rails (116, 216). The platform mast engagers (340, 350) serve to releasably lock the platform (300) to the modular masts (100, 200) via the multifunction rails (116, 216) thereby preventing unintentional descent of the platform (300), 5 as seen in one embodiment in FIGS. 25 and 26. Further, systematic locking of the platform (300) to the modular masts (100, 200) is required during the operation of the suspension platform system (10). The platform mast engagers (340, 350) may be virtually any device that can selectively lock the associated side of the work platform (302, 304) to the associated multifunction rail (116, 216). Most embodiments of the platform mast engagers (340, 350) 10 include some form of a locking tongue. For instance, one embodiment includes a sinistral platform locking tongue (342) formed to cooperate with the sinistral locking projection (119) so that the sinistral platform locking tongue (342) can engage and disengage any one of the sinistral locking projections (119) to releasably secure the work platform sinistral end (302) to the sinistral multifunction rail (116). Similarly, in this embodiment, the dextral platform 15 mast engager (350) includes a dextral platform locking tongue (352) formed to cooperate with the dextral locking projections (219) so that the dextral platform locking tongue (352) can engage and disengage any one of the dextral locking projections (219) to releasably secure the work platform dextral end (304) to the dextral multifunction rail (216). In one particular embodiment illustrated in FIGS. 27 and 28 the sinistral carriage 20 locking tongue (462) is a locking wedge (463) rigidly attached to the sinistral carriage (450) below the sinistral cable connector (454) and at, or above, the sinistral carriage proximal end (466). Similarly, in this embodiment the dextral carriage cable connector (474) is located substantially at the dextral carriage distal end (477) and the dextral carriage locking tongue (472) is a locking wedge (483) rigidly attached to the dextral carriage (470) below the dextral 19 WO 2007/005122 PCT/US2006/018936 cable connector (474) and at, or above, the dextral carriage proximal end (476), not illustrated by similar to FIGS. 27 and 28. Therefore, to move the sinistral carriage (450) of this embodiment relative to the sinistral modular mast (100) the sinistral carriage locking wedge (463) and the sinistral carriage proximal end (466) must be moved away from the sinistral 5 locking projections (119) so that the sinistral carriage locking wedge (463) may pass the sinistral locking projections (119) as the sinistral carriage (450) traverses the sinistral modular mast (100), as seen in FIG. 28. Such movement is generally accomplished by the user grabbing the operator handle (456) and rotating the carriage (450) as it is lifted, as indicated by the rotation arrow labeled R. Similarly, to move the dextral carriage (470) 10 relative to the dextral modular mast (200) the dextral carriage locking wedge (483) and the dextral carriage proximal end (486) must be moved away from the dextral locking projections (219) so that the dextral carriage locking wedge (483) may pass the dextral locking projections (219) as the dextral carriage (470) traverses the dextral modular mast (200). Therefore, upon application of a suspension force (SF) on the sinistral carriage cable 15 connector (454) the sinistral carriage locking wedge (463) engages at least one sinistral locking projection (119) thereby preventing movement of the sinistral carriage (450), as seen in FIG. 27. Similarly, upon application of a suspension force on the dextral carriage cable connector (474) the dextral carriage locking wedge (483) engages at least one dextral locking projection (219) thereby preventing movement of the dextral carriage (470). In this 20 embodiment, application of a suspension load on the cable connectors (454, 474), along with their location, creates a moment that tends to force the fixed locking wedges (463, 483) into the safety engagement device (117, 217) ensuring a reliable engagement of the carriage (450, 470) and the modular mast (100, 200). 20 WO 2007/005122 PCT/US2006/018936 In an alternative embodiment the carriage locking tongues (462, 482) may be biased locking pawls (464, 484) attached to the carriages (450, 470), as seen in FIGS. 29 and 30. To increase the elevation of the carriages (450, 470) relative to the modular mast (100, 200) the carriage (450, 470) is forced upward and the carriage biased locking pawl (464, 484) pivots 5 as it contacts the locking projections (119, 219), or the locking recesses (118, 218), so that the carriage (450, 470) may pass the locking projections (119, 219) as the carriage (450, 470) traverses the modular mast (100, 200). The biased locking pawl (464, 484) snaps back into an engaged position, due to the biased nature of the pawl, as soon as it passes the locking projections (119, 219), or locking recesses (118, 218). Further, upon application of a 10 suspension force on the carriage cable connector (454, 474) the carriage biased locking pawl (464, 484) engages at least one locking projection (119, 219), or locking recesses (118, 218) thereby preventing movement of the carriage (450, 470). While FIGS. 29 and 30 only illustrate the sinistral elements with respect locking recesses (118), one with skill in the art will appreciate that the biased locking pawl (464) applies equally as well to a dextral biased 15 locking pawl (484), as well as biased locking pawls (464, 484) for use with locking projections (119, 219). As previously mentioned, the work platform (300) also has a sinistral mast stabilizer (320) and a dextral mast stabilizer (330) attached to the platform (300), illustrated in FIG. 5, and configured to cooperate with the sinistral and dextral mast stabilizer guide device (122, 20 222), seen in FIGS. 31 and 32, of the sinistral and dextral mast multifunction rails (116, 216) to prevent undesired swaying of the suspended work platform (300). In one particular embodiment seen explicitly in FIGS. 16 and 17 and'generally in most of the figures, the sinistral stabilizer guide device (122) is integral to the sinistral multifunction rail (116) and the dextral stabilizer guide device (222) is integral to the dextral multifunction rail (216). In a 21 WO 2007/005122 PCT/US2006/018936 further embodiment seen in FIGS. 25 and 26, the work platform sinistral mast stabilizer (320) includes at least one sinistral platform roller (322) in rolling contact with the sinistral stabilizer guide device (122) to prevent swaying of the suspended work platform (300) and the work platform dextral mast stabilizer (330) includes at least one dextral platform roller 5 (332) in rolling contact with the dextral stabilizer guide device (222) to prevent swaying of the suspended work platform (300). In a further embodiment, the sinistral and dextral multifunction rails (116, 216) are U shaped multifunction rails (125, 225), illustrated in FIGS. 16-19 with respect to the sinistral elements, having a bearing surface (126, 226), a first sidewall (127, 227), and a second 10 sidewall (128, 228). In this configuration the mast stabilizers (320, 330) are retained between the first sidewall (127, 227) and the second sidewall (128, 228), as seen in FIG. 22. Alternatively, the sinistral and dextral multifunction rails (116, 216) may be V-shaped multifunction rails (130, 230) having a first bearing surface (131, 231) substantially orthogonal to a second bearing surface (132, 232), as seen in FIG. 23. In this embodiment the 15 mast stabilizers (320, 330) are retained between the first bearing surface (131, 232) and the second bearing surface (132, 232). This embodiment is particularly unique in that the multifunction rails (116, 216) may incorporate locking projections (119, 219) extending from the rails (116, 216) that do not interfere with the movement and wear of the mast stabilizers (320, 330). 20 The carriages (450, 470) may be constructed in a number of arrangements. The carriage bodies (452, 472) may completely encircle the modular mast perimeters (145, 245), as seen in FIG. 14, or the carriage bodies (452, 472) may only partially enclose the modular masts (100, 200), as seen in FIG. 15. Further, the carriages (450, 470) may include a guide (458, 478) configured to cooperate with the associated multifunction rail (116, 216) and 22 WO 2007/005122 PCT/US2006/018936 constrain the movement of the carriage (450, 470) on the modular mast (100, 200), as seen in FIGS. 12 and 13. As seen in FIGS. 10 and 11, the operator handle (456, 476) of the carriage (450, 470) generally extends beyond the distal end (467, 487) of the carriage (450, 470) so that the user can easily maneuver the carriage (450, 470) to an elevation beyond the normal 5 reach of the user. Additionally, the construction of the carriages (450, 470) generally varies with the type of safety engagement devices (117, 217). For example, in the previously disclosed embodiments wherein the carriage (450, 470) incorporates a rigidly attached locking wedge (463, 483) the carriage (450, 470) must fit relatively loosely around the modular masts (100, 200) so that the carriage locking wedges (463, 483) may be moved by 10 manipulation of the carriage (450, 470) to pass the locking projections (119, 219), as seen in FIGS. 27 and 28. Alternatively, embodiments having safety engagement devices (117, 217) that simply extend and retract, as in the embodiments of FIGS. 25 and 26, or rotate such as the biased locking pawls (344, 444) of FIGS. 29 and 30, to lock the carriages (450, 470) to the modular masts (100, 200) may have much tighter fits between the carriages (450, 470) 15 and the modular masts (100, 200). Now, with the numerous embodiments described, the general sequence of operation may be disclosed. Operation of the system (10) begins with the positioning of the fist mast units (1 Oa, 210a) and the work platform (300), as seen in FIG. 3. Next, second mast units (11 Ob, 2 1Ob) are lifted so that at least one portion of the second mast unit (11 Ob, 2 1Ob) may 20 be positioned on top of a portion of the first mast unit (1 10a, 210a). This positioning allows the user to use the unit assembly guide (140, 240) to permit secure rotation of the second mast unit (11 Ob, 210b) into place. As the second mast units (11 Ob, 210b) are rotated to the vertical position, the unit interconnection devices (135, 235), seen in FIGS. 7 and 8), releasably lock the second mast units (11 Ob, 21 Ob) to the first mast units (11 Oa, 21 0a). The WO 2007/005122 PCT/US2006/018936 mast units (11 Oa, 11 Ob, 21 Oa, 21 Ob) may also be releasably secured together with traditional fastening devices such as bolts. The first pair of second mast units (11 Ob, 21 Ob) are generally installed with the carriages (450, 470) already in place, as seen in FIG. 3. Now, with the mast units (11 Oa, 11 Ob, 21 Oa, 21 Ob) in the vertical position, the 5 hoisting system cables (410, 420) are attached to the cable connectors (454, 474) and the hoists (430, 440). The hoists (430, 440) are then activated at the central control console (510) thereby drawing the cables (410, 420) taunt and lifting the work platform (300) to the position shown in FIG. 5. Once the work platform (300) has been lifted approximately the length of one mast unit (1 Oa, 11 Ob, 210a, 2 1Ob), the platform mast engagers (330, 340) are 10 activated to secure the work platform (300) to the masts (100, 200). Next, the user may install a third set of modular mast units (1 Oc, 210c). A portion of the cables (410, 420) may be withdrawn from the hoists (430, 440) allowing the user to advance the carriages (450, 470) to the proximal end (114, 214) of the third set of modular mast units (11 Oc, 210c), at which point the carriages (450, 470) are locked to the masts (100, 200). Then the sequence of (a) 15 raising the carriages (450, 470) as far as possible and engaging the masts (100, 200), (b) engaging the hoists (430, 440) to retract the cables (410, 420) and lift the work platform (300) to the elevation of the carriages (450, 470), (c) locking the work platform (300) to the masts (100, 200) via the platform mast engagers (340, 350), (d) releasing the cables (410, 420) from the hoists (430, 440), and (e) releasing the carriages (450, 470) from the masts (100, 200) so 20 that they may be advanced. An alternative embodiment includes secondary safety cables that may be attached from the work platform (300) to the masts (100, 200) as the carriages (450, 470) are moved so that the security of the work platform (300) is not solely dependent on the platform mast engagers (340, 350) as the carriages (450, 470) are moved. 24 - WO 2007/005122 PCT/US2006/018936 In one particular embodiment, the hoists (430, 440) contain enough cable (410, 420) such that the work platform (300) may be lowered from the highest elevation to the ground without having to reposition the carriages (450, 470). Such is particularly beneficial when the user needs to return the work platform (300) to ground level to obtain more supplies or take a 5 break. As one with skill in the art will appreciate, each modular mast (100, 200) may have more than one multifunction rail (116, 216), as seen in FIGS. 35 and 36. This is particularly beneficial when multiple work platforms (300) are used next to one another. For instance, two work platforms (300) may be installed adjacent to one another thereby sharing a modular 10 mast (100, 200) such that only three modular masts are needed for the operation of two work platforms (300). This concept extends to job sites utilizing ten or more work platforms (300) to facilitate work on an entire face of a structure. Numerous alterations, modifications, and variations of the preferred embodiments disclosed herein will be apparent to those skilled in the art and they are all anticipated and 15 contemplated to be within the spirit and scope of the instant invention. For example, although specific embodiments have been described in detail, those with skill in the art will understand that the preceding embodiments and variations can be modified to incorporate various types of substitute and or additional or alternative materials, relative arrangement of elements, and dimensional configurations. Accordingly, even though only few variations of the present 20 invention are described herein, it is to be understood that the practice of such additional modifications and variations and the equivalents thereof, are within the spirit and scope of the invention as defined in the following claims. The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended WO 2007/005122 PCT/US2006/018936 to include any structure, material, or acts for performing the functions in combination with other claimed elements as specifically claimed. 26 WO 2007/005122 PCT/US2006/018936 INDUSTRIAL APPLICABILITY The self-erecting suspension platform answers a long felt need for a relatively safe work platform designed to be suspended between a plurality of modular masts. The self erecting suspension platform is used in the construction, maintenance, and cleaning of s structures. The platform has utility, among other uses, in construction of walls, to wash windows, or any number of other elevated tasks. The present invention discloses a work platform suspended between a sinistral modular mast and the dextral modular mast. The work platform has stabilizers that cooperate with the masts, redundant safety mechanisms to prevent unintentional descent of the platform, and is raised and lowered by a hoist system. 27