Patent Grant
7228936
1. Field of the Invention
The present invention relates generally to mobile scaffolding. More specifically, the present invention concerns a mobile scaffolding brake that can be activated from the support platform and when activated generally prevents both rolling and swivelling of the caster wheel. The inventive brake provides a secure restraint of the scaffolding and enables a worker supported on the scaffolding platform to selectively prevent unsafe and inadvertent motion of the scaffolding while the worker is supported thereon.
2. Discussion of Prior Art
It is known in the art to utilize scaffolding to provide an elevated work platform to elevate a worker above a floor or ground surface to complete a task (e.g., painting, drywall finishing, etc.). The scaffolding utilized to provide the elevated work platform is often mobile scaffolding that can be quickly and easily moved from one working position to the next. For example, it is known in the art to support a scaffolding frame with one or more casters that enable the assembled scaffolding to be rolled along the floor or ground surface between working positions. However, it is desirable to prevent the scaffolding from moving when one or more workers are supported thereon.
It is known in the art to provide a scaffolding caster with a brake for selectively preventing the scaffolding from moving. These prior art caster brakes utilize a brake stop that engages the caster wheel and thereby prevents rolling rotation of the wheel. These prior art caster brakes typically include a two-piece housing, with the wheel supported by one of the housing pieces and the brake stop supported by the other. The housing pieces are pivotal relative to one another so that the wheel can be pivoted into contact with the brake stop. One of the housing pieces serves as a foot-activated handle for selectively causing the wheel to be pivoted into engagement with the brake stop. In this manner, the weight of the scaffolding supported by the caster works to maintain the locking engagement between the wheel and the stop.
These prior art caster brakes are problematic and have several undesirable limitations. Several of these problems have been described in Applicants' copending Application for U.S. patent Ser. No. 10/271,634, entitled MOBILE SCAFFOLDING BRAKE, filed Oct. 15, 2002 (hereinafter “the '634 Application”), which is hereby incorporated by reference herein. In addition to the problems identified in the '634 Application, the prior art caster brakes enable the scaffolding an undesirable range of motion when the brakes are activated. For example, when the prior art caster brakes are activated, the caster wheels are still enabled to pivotally rotate—i.e., to “swivel”—relative to the scaffolding frame. Swiveling of the caster wheels is problematic as the caster wheels can re-orient in the direction of an applied force, such as when a third party on the ground inadvertently bumps into the scaffolding, which undesirably allows the scaffold to move in the force direction. This problem is compounded by the common occurrence of only one of the caster wheels having the brake activated, therefore allowing the scaffolding to swing, for example, to pivot around the swiveling, single brake-activated caster wheel. In this regard, the prior art caster brakes are problematic in that each of the four brakes must be separately and manually activated. Such a requirement is undesirable to workers with limited time to complete a job, particularly where the consequences of not activating more than one caster brake could be severe.
The present invention provides an improved scaffolding brake that does not suffer from the problems and limitations of the prior art brakes detailed above. The inventive brake can be activated from the support platform and when activated generally prevents both rolling and swivelling of the caster wheel. The improved brake provides a more secure restraint of the scaffolding than the prior art caster brakes as well as enables a worker supported on the scaffolding platform to selectively prevent unsafe and inadvertent motion of the scaffolding while the worker is supported thereon. In a preferred embodiment, a plurality of caster wheels can be locked by activating a single actuator.
A first aspect of the invention concerns a mobile scaffold including a first frame vertically elongated between first and second ends, and a first caster. The first caster includes a first caster housing rotatably coupled to the frame adjacent the first end and a first wheel rotatably coupled to the caster housing. The scaffold includes a brake assembly connected to the frame. The brake assembly includes a first shiftable brake stop that is shiftable into and out of a braking position, wherein the stop engages the wheel and the brake assembly is spaced from the caster housing.
A second aspect of the invention concerns a mobile scaffold including a first frame vertically elongated between first and second ends and a first caster. The first caster includes a first caster housing rotatably coupled to the frame adjacent the first end and a first wheel rotatably coupled to the caster housing. The scaffold also includes a brake assembly connected to the frame. The brake assembly includes a first brake stop that presents an enclosed wall that defines an inner chamber. The stop is shiftable into and out of a braking position, wherein the stop engages the wheel and at least a portion of the caster housing is received within the inner chamber and spaced from the wall.
A third aspect of the invention concerns a mobile scaffold including a frame vertically elongated between first and second ends and a wheel coupled to the frame adjacent the first end. The wheel is rotatable about a central wheel axis and an upright axis, wherein the upright axis is substantially transverse to the central wheel axis. The scaffold also includes a brake assembly fixed to the frame. The assembly includes a brake stop that is shiftable into and out of a braking position, wherein the stop engages the wheel so that the wheel is generally prevented from rotating about the central wheel and upright axes.
A fourth aspect of the invention concerns a brake assembly for use with a mobile scaffold that includes a frame presenting upper and lower ends, and first and second wheels coupled to the frame near the lower end. The wheels are each rotatable about a first axis and a second axis that is substantially transverse to the first axis. The brake assembly includes a housing connectable to the frame, a first shiftable brake stop fixedly connected to the housing, and an actuator configured to cause the stop to shift into and out of a braking position. In the braking position, the stop engages the first wheel and prevents it from rotating about said first and second axes.
Other aspects and advantages of the present invention will be apparent from the following detailed description of the preferred embodiment and the accompanying drawing figures.
Several embodiments of the invention are described in detail below with reference to the attached drawing figures, wherein:
In more detail, each of the frames 12,14 is configured to elevate the platform 20 vertically above the floor or ground surface and support the platform 20 once elevated. The frames 12,14 are virtually identically configured, therefore, only the frame 12 will be described in detail with the understanding that the frame 14 is similarly constructed. The frame 12 includes a pair of spaced apart vertically extending support posts 34 and 36. Each of the posts 34,36 are generally tubular in configuration presenting a hollow, generally square shaped cross section. For purposes that will subsequently be described, a plurality of spaced apertures 38 are formed in each of the posts 34,36 and extend through the respective post 34,36 to form an axially aligned pin-receiving passageway. As further described below, the lower ends of each of the posts 34,36 include an end cap, such as the end cap 40 shown on the post 36 in
One exemplary frame is disclosed in U.S. Letters Pat. No. 6,471,003, issued Oct. 29, 2002, entitled UTILITY SCAFFOLDING HAVING SAFETY FEATURES (sharing a common inventor with the present application and hereinafter “the Wyse '003 patent”), which is hereby incorporated by reference herein as is necessary for a full and complete understanding of the present invention. However, the frame could be variously constructed and configured. For example, the frame need not utilize a tubular construction and need not be a ladder-type frame.
The platform 20 defines a generally flat work surface that is supported horizontally between the frames 12 and 14 on the cross beams 16,18 and is vertically adjustable between the upper and lower ends of the frames 12,14. Although not shown, the illustrated work surface 20 is preferably coupled to the beams 16,18 by a plurality of transverse pins and preferably includes rail pins and platform clips that can be pivoted into a locking position once the surface is placed on the beams 16,18 to prevent the surface 20 from dislodging from the transverse pins. Exemplary transverse pins, rail pins, and clips are disclosed in the Wyse '003 patent previously incorporated herein by reference. The illustrated beams 16,18 further each include a pair of corresponding bracket assemblies 48,50 and 52,54, respectively, that associate the corresponding beam 16,18 with each of the frames 12,14. The paired bracket assemblies 48,50 and 52,54 include assemblies that are mirror images of each other, but otherwise each of the assemblies 48,50,52,54 are virtually identically configured and therefore only the bracket assembly 48 will be described in detail with the understanding that the assemblies 50,52,54 are similarly constructed. The bracket assembly 48 includes a sleeve 56 slidably received on the post 34 of the frame 12. The sleeve 56 is generally C-shaped in cross section to define an open side configured to clear the rungs 46 as the sleeve slides relative to the frame 12. The sleeve 56 includes a plurality of apertures formed on the inside surface that are complementally spaced to match the spacing of the apertures 38 formed in the post 34 (not shown on the assembly 48, but see the bracket assembly 50). In this manner, the sleeve apertures are operable to axially align with the post apertures 38. In this regard, the bracket assembly 48 further includes a G-shaped pin 58 that is slidably received in the axially aligned apertures to retain the beam 16 and thus the platform 20 in a selected vertical position relative to the frame 12. The G-shaped pin 58 preferably slides in a pin guide 60 and is biased into the aligned holes by a spring (not shown). Although not shown, the bracket assembly 48 preferably includes an additional locking pin slidably received in a second set of axially aligned apertures to lock the beam 16 and thus the platform 20 in the selected vertical position. It is within the ambit of the present invention to utilize various alternative locking mechanisms and exemplary pin-type mechanisms are disclosed in the Wyse '003 patent previously incorporated herein.
The sleeve 56 is fixed to the beam 16 by a block 56a and by a gusset 56b. In this manner, the beam 16, and thus the work surface 20 supported thereon, slides with the sleeve 56 relative to the frame 12. The block 56a is open on its upper end and includes means for securing attachment components in the block 56a (e.g., the illustrated block 56a is configured to receive a guard rail (not shown) and includes a pin-receiving aperture to removably secure the guard rail in the block 56a). The gusset 56b provides additional support to the beam 16 relative to the sleeve 56.
One exemplary platform is disclosed in the previously incorporated Wyse '003 patent. However, the platform could be variously constructed and configured, for example, the platform need not be adjustable, and could be fixedly supported along the frames, or on top of the frames. Additionally, as indicated above, the scaffolding could alternatively be some other form of support structure, such as a wheeled cart, or a mobile ladder, or the like. However, it is important that the support structure is mobile, for example including wheels that rollably support the structure on the ground.
In the illustrated scaffold 10, mobility is provided by the casters 22,24,26,28. The casters 22,24,26,28 are received at the lower ends of the frames 12,14 to provide rolling engagement with the ground. Each of the casters 22,24,26,28 are virtually identically configured, therefore, only the caster 22 will be further described in detail with the understanding that the casters 24,26,28 are similarly constructed. As illustrated in
The wheel 66 is a conventional caster wheel as is known in the art and is commercially available from a variety of OEMs. The illustrated wheel 66 rollingly rotates about a bolt shaft 66a coupled to the lower housing 64a. It will be appreciated that the shaft 66a defines the central wheel axis. In this regard, the wheel 66 both rolls relative to the ground about the central wheel axis, as well as swivels with the lower housing 64a about the upright stub axis 62. The wheel 66 is well suited for use with mobile scaffolding, however, the wheel width, diameter and configuration could vary based upon the anticipated use of the scaffold 10, and could include for example a roller ball type configuration or the like.
The illustrated mobile scaffolding 10 can be selectively prevented from moving relative to the ground by the brake assemblies 30,32 associated with the corresponding pairs of casters 22,24 and 26,28, respectively. As further detailed below, the improved and unique brake assemblies 30,32 are configured to prevent the rotation of the wheels, such as the wheel 66, about the central wheel and upright axes and further configured to be activated by the worker while elevated on the scaffold 10. Each of the brake assemblies 30,32 are virtually identically configured and therefore only the brake assembly 30 will be described in detail with the understanding that brake assembly 32 is similarly constructed. As shown in
More particularly, the illustrated brake housing 72 includes an upper support member 80, two lower support members 82,84 respectively associated with brake stop subassemblies 74,76, and transverse bars 86 interconnecting the lower support members 82,84. As best shown in
The lower support members 82,84 and the brake stop subassemblies 74,76 are virtually identically configured and therefore only lower support member 82 and brake stop subassembly 74 will be described in detail, with the understanding that lower support member 84 and brake stop subassembly 76 are similarly constructed. As perhaps best shown in
The brake housing 72 further includes a transverse bar 86 fixed to the lower support members 82,84 near their upper ends and extending generally orthogonally therebetween. The preferred bar 86 includes two longitudinal plates 116,118 and a plurality of cross-members 120 that interconnect the two plates 116,118. The proximal most cross-members 120a,120b to the brake stop subassemblies 74,76, each define a wire receiving opening for purposes that will be subsequently described herein. Finally, the preferred brake housing 72 is removably coupled to the frame 12, so that the brake assembly 30 can be easily added on, or coupled to existing scaffolding of various configurations. However, it is within the ambit of the present invention to utilize alternative configurations for the brake housing 72. For example, the housing 72 could be integrally formed with the scaffolding frame during the original manufacture thereof.
As shown in FIGS. 5,6 and 7,8, the brake stop subassembly 74 is shiftably coupled to the lower support member 82 and is shiftable between a braking position as shown in
The preferred cylindrical collar 122 presents an endless wall 128 having a lower wheel engaging surface 130 and defining an inside diameter and a height (see
As shown in
For reasons subsequently described herein, one of the intermediate plates 136,138 also includes an actuator engaging member 144. More preferably, the member 144 is mounted on the interior frame plate 140, as shown in
The plurality of rollers 126, shown as four in the illustrated embodiment, is provided to present rolling engagement between the lower support member 82 and the brake stop subassembly 74. The rollers 126 are rotatably coupled to the sleeve 124 via roller pins 152 and nuts 154. The illustrated rollers 126 are removably coupled the sleeve 124. The rollers 126 are fastened near the upper and lower edges of the contact plates 126,128 and are vertically centered within the sleeve gaps. Finally, as shown in
Turning to the actuation of the illustrated brake assembly 30, and perhaps as best shown in
The lever 162 is pivotal from the release position, as shown in phantom in
In addition to the plunger 174, the illustrated connection subassembly 158 includes a floater prong 178 connected to the plunger 174 adjacent the lower end, and first and second cables 180,182 adjustably fastened to the floater prong 178 (see
The bushing block 176 is fastened against the upper surface of the uppermost support prong 104 by a bushing block nut 192 that bears against the lower surface of prong 104. The bushing block 174, uppermost prong 104, and bushing block nut 192 define coaxially aligned central openings that snugly receive the plunger 174. The floater prong 178 also defines a central opening, and is fixedly connected to the plunger 174 by an externally threaded bolt 194 that extends through the floater prong opening and is threadably received within a tapped axial hole (not shown) defined by the lower end of the plunger 174.
As shown in
The lowermost upper support prong 106 also defines a pair of wire receiving openings that are configured to initially receive the portions of the first and second cables wires 184,186, but not the first and second cable sheaths 188,190. The lowermost prong 106 stops the sheaths 188,190 when the cables 180,182 are drawn upwardly towards their braking position, so that the wires 184,186 are able to slidably translate therein. It is appreciated that this configuration reduces the weight of operation and facilitates the actuation of the braking assembly 30. Alternatively, lubricant (i.e, light grease, heavy oil, plastic lining, etc.) can be interposed between the wires 184,186 and sheaths 188,190 so as to reduce static and kinetic friction therebetween.
The actuator 78 includes virtually identical means for interconnecting to and biasing brake stop subassemblies 74,76. As such, only the interconnection of the first cable 180 to brake stop subassembly 74 and the first biasing element 160 will be further described herein, with the understanding that the interconnection of the second cable 182 to brake stop subassembly 76 and the second biasing element (not shown) are similar. As shown in
The preferred brake stop subassembly 74 is biased towards the braking position by the biasing element 160. The biasing element 160 is oriented such that the direction of the biasing vector is parallel to the linear motion of the shiftable collar 122. In this arrangement, the magnitude of the biasing vector must additionally be overcome, when shifting the brake stop subassembly 74 from the braking position shown in
The upper end of the pneumatic cylinder 200 is removably connected to the transverse bar 86 by a pin fastener 204 (see
As previously indicated, the configuration of the brake assembly 32 is virtually identical that of the brake assembly 30 described in detail above. Although the dual brake assemblies 30,32 are preferred to provide a brake stop for each of the casters 22–28, the scaffolding 10 could include a single brake assembly (with stops on only two caster wheels) or a single stop on any one of the caster wheels. Additionally, it is within the ambit of the present invention to utilize various alternative configurations for the brake assemblies 30,32. Although preferred, the brake assemblies do not need to enable activation by the worker while elevated on the platform 20, and if a top-activated brake assembly is utilized, it could incorporate various alternative linkages to activate the brake stop below. Furthermore, if one activator is used for a pair of brake stops, the brake stops could be linked in a variety of alternative ways. The brake stop(s) could be variously configured as well and, for example, need not include the cylindrical collar spaced from the caster housing. However, it is important that the brake stop(s) is configured to generally prevent both rolling and swiveling rotation of the caster wheel.
In operation, once the mobile scaffold 10 is erected as described above, the upper support member 80 can be vertically adjusted by disengaging the lock bolts 98,102 from the post 36. The upper support member 80 is vertically spaced between the platform 20 and upper end of the scaffold 10, so as to enable the worker supported on the scaffolding 10 to shift the brake stop subassemblies 74,76 into and out of the braking position. The worker selectively prevents the movement of the scaffold 10 by pivoting the lever 162 in the clockwise direction and shifting the brake stop subassemblies 74,76 until the braking position is achieved. To enable movement, the worker pivots the lever 162 in the counter-clockwise direction until the released position is achieved. The brake stop subassemblies 74,76 can be vertically adjusted by loosening the locking bolts 114, vertically adjusting the conjoined subassemblies 74,76, and reinserting the locking bolts 114 to engage the lower support members 82,84. Finally, to maintain proper function of the brake assembly 30, the actuator 78 can be adjusted by loosening the clamps 196, manually adjusting the cable wires 184,186, and refastening the clamps 196.
As indicated above, the brake assemblies could be alternatively configured. One such suitable alternative brake assembly configuration is shown in the mobile scaffolding 300 illustrated in
As shown in
In more detail, the collars 318,320 are each virtually identical in configuration to the collar 122 described in detail above. Similarly, the sleeves 322,324 are each similar in configuration to the sleeve 124 detailed above. However, the sleeve 124 is configured for use with the rollers 126 whereas the sleeve 324 (as well as the sleeve 322) is associated with the spacers 326 to facilitate smooth shifting of the brake subassembly 312 into and out of the braking position. The spacers 326 are preferably formed of plastic or the like and are supported between the sleeve 324 and the corresponding sleeve of the lower housing 306 in any suitable manner, such as by rivets or the like.
As shown in
The biasing elements 338,340 are each similar to the biasing element 160 detailed above. However, the cylinders are coupled to the prongs of the corresponding sleeves 322,324, respectively, and the devises are coupled to the corresponding bars 332,334, respectively. When the handle subassembly 310 is placed in the braking position (as shown in
As indicated above, the linkage subassembly could be variously configured. One such suitable alternative linkage configuration is shown in the mobile scaffolding 400 illustrated in
The collars 422,424 are each virtually identical in configuration to the collar 120 described in detail above. Similarly, the sleeves 426,428 are each similar in configuration to the sleeves 322,324 detailed above. However, the sleeves 426,428 each include an inner linkage-receiving box 426a and 428a, respectively, in place of the biasing element-receiving prongs. The linkage subassembly 430 presents a simplified configuration relative to the linkage subassembly 328 detailed above and does not include any biasing elements. The linkage subassembly 430 includes a plunger bar 432 pivotally coupled to the bottom of the plunger 406 at one end and pivotally coupled to the box 426a at its other end. Between its ends, the plunger bar 432 is rotatably coupled between the transverse bars 418,420 by a bolt. One end of a linkage bar 434 is pivotally coupled between the ends of the plunger bar 432 and pivotally coupled to the other box 428a at its opposite end. Between its ends, the linkage bar 434 is rotatably coupled between the transverse bars 418,420 by a bolt. In this manner, the plunger 406 is pulled upwardly with the handle subassembly to place the brake assembly 402 in its braking position as shown in
The preferred forms of the invention and mode of operation described above are to be used as illustration only, and should not be utilized in a limiting sense in interpreting the scope of the present invention. Obvious modifications to the exemplary embodiments, as hereinabove set forth, could be readily made by those skilled in the art without departing from the spirit of the present invention.
The inventors hereby state their intent to rely on the Doctrine of Equivalents to determine and assess the reasonably fair scope of the present invention as pertains to any apparatus not materially departing from but outside the literal scope of the invention as set forth in the following claims.
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| Number | Date | Country | |
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| 20060027423 A1 | Feb 2006 | US |
