Scaffold Drive And Steering Unit

Abstract

Drive and steering attachments for application to and use with scaffold units of the type used in connection with construction and maintenance activities. A reversible drive motor associated with one scaffold support drive and steered wheel propels the scaffold and a motorized steering apparatus having an operative anchor that is fixed with respect to the scaffold unit moves the drive and steered wheel pivotally with respect to a vertically disposed axis of said scaffold for the directional control of said scaffold. The drive and steering motors are connected to a control panel that is movable to various elevated and/or remote locations. A power cord having a pivotally mounted and spring biased trailing arm is attached to the scaffold to prevent trapping of or damage to the power cord.

Parent Case Text

CROSS-REFERENCE TO RELATED APPLICATION

The present application is copending with respect to an earlier application of the same title filed Jan. 4, 1971, by this inventor and bearing Ser. No. 103,555, now U.S. Pat. No. 3,731,758. The subject matter and objectives of both applications are similar, but the developments represent separate inventions.

Description

BACKGROUND OF THE INVENTION

In connection with construction or maintenance operations, it is often advantageous for a workman to have a scaffold support so that he can work at high elevations with safety. Where ceilings or utilities are being installed or where lighting and heating systems are to be maintained, a rolling type scaffold is often used that may be conveniently moved to various work locations. Manipulation of the usual castor wheel supported scaffold generally requires an additional workman who can push and guide the scaffold and the workmen supported thereby to successive work stations. In order to avoid this obvious misuse of labor, others have previously devised scaffold propelling and steering systems that may be operated by a workman at his elevated work station. In general, the previous systems have been quite expensive. It is believed that the overall expense and the inconvenience of using and storing prior types of steering and drive apparatus have been detrimental to the widespread use of such systems. The present invention is intended to overcome shortcomings of the previous systems.

SUMMARY OF THE INVENTION

Briefly stated, the present invention provides attachments that may be applied to wheel supported scaffold units to propel the units and to steer the entire scaffold so that a single workman can move the scaffold and himself to successive work stations. Steering and drive functions are combined in a single attachment for application to one upright support of the scaffolding. The attachment itself provides an anchor component for fixed positioning with respect to the scaffold upright support, and the major drive and steering components pivot with respect to such anchor and support. Motive drive means interconnect the provided anchor and the pivoting components to steer the attachment, while drive power for moving the attachment and scaffold is applied to the wheel of such attachment. A power cord guide having a pivotally mounted spring biased trailing arm is attached to the scaffolding to prevent damage to the power cord.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an embodiment of the invention,

FIG. 2 is a side elevation showing a power cord guide,

FIG. 3 is a top plan view showing features of the present embodiment,

FIG. 4 is a front elevation of the present embodiment, and

FIG. 5 is a side elevation of such embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A preferred embodiment of the invention is shown in FIGS. 1-5. For this particular embodiment of the invention the drive and steering functions and operations are combined in a single attachment unit 70 that is applied to a single upright standard 77 of the scaffold unit 71. As in the mentioned previous application, this scaffold unit 71 is inclusive of end frames 72 and 73 joined together by cross braces 74. The upright standards 76 for the scaffold unit 71 and the standard 77 are all of the same type so that any particular scaffold unit is adapted for mating engagement in stacked arrangement with other scaffold units. The upright standard 77 to which the drive and steering unit 70 is applied is identical with all the remaining upright standards 76 and the drive and steering unit 70 could, accordingly, be affixed to any of the upright standards. While a single scaffold height is shown, the upper ends 78 of the upright standards are all adapted to receive the standards of mated scaffold units so that the entire scaffold system used on a maintenance or construction site could be two or more scaffold units high.

For convenience of usage the particular scaffold unit 71 illustrated is provided with pneumatic wheel supports. The wheel supports 81 applied to the upright standards 76 are all of the castor wheel type. These wheels, which may be of the type already used for the rolling support of construction scaffolds, usually have a socket or plug (not shown) adapted for mating engagement with the upright standards of the particular type of scaffold being used. The wheel supports 81 conventionally provide a thrust bearing 82 that facilitates turning movements of the wheels with respect to the associated standards 76. When used with a single attachment unit 70, the two rear wheels at the opposite end of the scaffold 71 should be locked or held in fixed straight-ahead position for best control of scaffold maneuvering operations. Pneumatic tires are used where the scaffold unit is to be used over rough floors or uneven terrain. The drive and steering unit attachment 70 applied to the upright standard 77 is of overall height corresponding to the height of the castor support wheels 81. Accordingly, such a unit 70 may be applied to any of the upright standards 76 in substitution for the castor wheel units 81.

The single attachment unit 70 provides both drive and steering capability so that the entire scaffold 71 may be moved along random paths from one work position to another. A remote control unit 49 is provided which may be selectively attached to a cross bar 52 of scaffold unit 71 at a position adjacent a work platform 53. Control unit 49 is interconnected to the drive and steering unit 70 by a cable 84 which is of sufficient length so that the control unit 49 may be moved to higher elevations as the work platform is raised. Similarly the control unit 49 can be hand carried by workmen at the floor level when the scaffold is to be moved from one work site to another. A power cord 88 is also utilized to deliver power to the drive and steering attachment and specifically to a panel box 89 thereof. Since remote switching components may be positioned within the panel box 89, the cable 84 may be of small wire and still carry the signals for regulating the steering, driving and speed control operations of the drive and steering unit 70.

As in the mentioned previous application, separate drive and steering motors 87 and 91 are used. Drive motor 87 serves to revolve the wheel 92 while the steering motor 91 operates to move the wheel mount forks 96 pivotally with respect to the axis of its associated upright standard 77.

A beneficial arrangement of these components is more fully shown in FIGS. 3, 4 and 5. In these Figs. it will be noted that drive and steering unit 70 is adapted for attachment to its upright standard 77 when connector plug 97 is moved reciprocally into engagement in the hollow center 98 of the standard 77. Plug 97 is of size to be closely engaged by the standard 77 so that a proportionate load of the scaffold will be efficiently transmitted to the supporting wheel 92. When the attachment assembly is in its fully engaged position as shown in FIG. 5, the end of standard 77 will be passed through a center opening 99 (FIG. 3) in an anchor sprocket 101 to be engaged directly against a base plate 102. The base plate 102 is similar in construction to plates provided at each of the castor wheels 81. The base plate structure 102 and the forks 96 move rotatably one with respect to another, inasmuch as a thrust bearing 103 is interposed between such base plate and the supporting structure for the forks 96. The anchor sprocket 101, which is slightly raised above the base plate 102, is rigidly attached thereto by a plurality of spacers 104. A lock socket 106 is positioned above the anchor sprocket 101. A plurality of threaded lock pins 107 and 108 are engaged to the socket 106 for extension therewithin to engage the exterior walls of the standard 77. With this arrangement and with the standard 77 disposed about the plug 97 and extended through the anchor sprocket 101, the set screws 107 and 108 are turned inwardly to hold the anchor sprocket 101 and base plate 102 in fixed position with respect to the standard 77. With this arrangement the support wheel 92 is still free to move pivotally with respect to the standard 77 due to the interposed thrust bearing 103. In order to power turning movement of the support wheel 92 and its associated forks 96, a steering motor 91 is used. This steering motor 91 is mounted on an extension 116 of a base frame 114. The base frame 114 is itself rigidly attached to the wheel support forks 96 as by welding or similar fastening means. The steering motor 91 includes a gear reduction drive 111 so an increased torque force at slower speed will be delivered by the shaft 112 to a drive sprocket 113. A drive chain 117 interconnects the driving sprocket 113 and anchor sprocket 101. Tension adjustments may be made for drive chain 117, since the steering motor 91 is mounted on frame extension 116 by a plurality of adjustable mount bolts 118.

With the described arrangement, power from the steering motor 91 will cause rotation of drive sprocket 113, but since the anchor sprocket 101 cannot move with respect to the upright standard 77, the drive sprocket 113 will itself be caused to move orbitally about such anchor sprocket 101. As drive sprocket 113 and steering motor 91 are thus caused to move orbitally, the frame 114 will be moved in similar manner thus rotating the support forks 96 of the wheel 92. This arrangement, accordingly, provides for directional steering of the scaffold support wheel 92.

For the present apparatus the powered rotation of the support wheel 92 is attained in a manner similar to that described in the mentioned previous patent. A drive motor 87 is disposed on the base frame 114 and is held in position thereon by a mount bolt 119. A drive sprocket 121 on the shaft of jthe drive motor is connected by a chain 122 to a sprocket 123 on a jack shaft 124. As in the previous patent, the jack shaft has an output sprocket 131 that is connected to a driven sprocket 133 for rotating the axle 134 of drive and support wheel 92. Adjustable mounting bolts 136 are provided to move the jack shaft mount reciprocally with respect to the frame 114 to adjust the tension in the motor drive chain 122 and in the wheel drive chain 132. A drill motor as illustrated may be used for the drive motor 87. Inasmuch as such drill motor could already incorporate a gear reduction drive, a substantial torque force can be delivered to the wheel 92.

Except for the possibility of entanglement of power or control cords or cables, the support wheel 92 could be freely rotated in excess of 360.degree.. Operation of the device at work sites has indicated, however, that even though full 360.degree. rotation is desired or required, some turning limitation should be imposed both to avoid destructive entanglement of the power and control cables and to eliminate other job site abuses. In order to limit steering rotation of the drive and steering wheel 92, microswitches are disposed within the panel box 89. Contact arms 137 for such microswitches are positioned beneath the box 89 in a position guarded by such box and also in position to be engaged by limit stops 138 mounted on the steering drive chain 117. When the arms 137 are engaged by the stops 138, power to the steering motor will be interrupted or reversed as desired. No turning movement in excess of that limited by the switch arms 137 and stops 138 can thereafter be made by the remote operation of control unit 49. In addition to the microswitches for such steering control the panel box 89 encloses remote switching components so that it is not necessary to deliver full motor voltage to the control box 49. A reduced operational control voltage may be transmitted by the control cable 84 to the control unit 49. A control circuit of reduced voltage is desirable where the work platform may be of substantial height or adjacent to electrical circuits of higher voltage or different phase than the power used for the steering and driving operations. In addition to enclosing any desired operational control circuits, the panel box 89 is of size and shape to provide an operative guard for the steering chain 117. The ends of the panel box 89 are, accordingly, positioned to cover the "pinch" areas of the drive sprocket 113 and of anchor sprocket 101. With this arrangement a separate chain guard is not required.

FIGS. 1 and 2 present an additional attachment for the scaffold unit 71 which has been found to be highly beneficial. A power cord guide 141 is shown in these Figs. The guide 141 is adapted for attachment to a lower cross bar 152 of the scaffold unit 71. A C clamp 142 of such attachment surrounds the cross bar 152 and a lock screw 153 is used to securely engage the attachment to the cross bar. A lower leg of the C frame provides a pivot 154 and a trailing arm 156 is connected thereby to the mounting clamp. The trailing arm has a terminal loop 157 through which the power cord 88 and any connector plugs 158 thereof may be extended. After the cord is threaded through the loop 157, it is engaged and held by a tie-down 159. The length of cord past the tie-down 159 can be regulated so that the segment 161 which delivers power to the attachment 70 will at all times be held out of contact with the supporting floor or at least in a non-interfering position with respect to all of the support wheels of the scaffold. The other end of the cord 162 which passes through the loop 157, however, will oftentimes be disposed on the supporting floor in a position where it can be run over by any of the support or drive wheels of the scaffold. Powered back and forward and other steered movements of the scaffold can trap such end 162 of the power cord 88 in a manner that would otherwise immobilize the scaffold unit. Such scaffold unit disabling entrapment of the power cord is avoided by the attachment 141, since free swinging movement of the trailing arm 156 is limited and controlled by a spring 163. This spring and the tension adjusting link chain 164 permit pivoting movement of the trailing arm 156. This pivoting movement to alternate positions as suggested in FIG. 1 is adequate to prevent the breakage of the power cord if the cord is trapped beneath any of the support wheels of the scaffold. After the cord is free from its entrapment, the trailing arm 156 will be returned by the spring 163 to its at-rest position as indicated by the full line representation of FIG. 2. Movement of the arm 156 from a trapped cord position to a free position is accomplished rapidly in a manner that serves to move the trapped cord from its previously trapped position. The arrangement of pivot attachment points is adjusted so that the maximum swinging motion for the arm 156 corresponds to that shown in alternate position in FIG. 1. With this type of limitation the arm 156 does not go past center, and the spring will accordingly always act to return it to a position as shown in the full line representation of FIGS. 1 and 2.

As more fully described in the previous patent, the remote control unit 49 shown in FIG. 1 will provide separate drive and starting controls. The toggle of the drive control may be moved to forward, neutral and reverse positions, while the toggle of the steering control is moved to left and right positions to control the direction of rotation for the wheel 92. In the present embodiment the single attachment unit 70 may be used at any of the upright standards of a scaffold in substitution for the support wheels thereof. Inasmuch as the attachment unit 70 provides its own anchor for steering operations, no modifications of the scaffold are required.

The simplicity of installation and usage adds measurably to the on-site user benefits. With this type of scaffold unit a single workman may install plumbing, electrical or heating utilities or suspended ceilings or lighting systems. Similarly, the scaffold may be used for the maintenance of such systems as in the replacement of fluorescent lights, etc. A stock of parts may be carried to the upper supporting deck 53 and thereafter a plurality of operations can be accomplished before a workman would have to come down.

When not in use, the attachment unit 70 may be conveniently removed to prevent undesired use of the scaffold or theft of this major component.

Claims

I claim:

1. A drive and steering attachment for scaffolding type supports having upright standards that in scaffolding usage may be mateably engaged one above another when multi-stages are to be used and wherein each of said upright standards are further adapted to receive separate supporting wheel attachments when increased mobility is advantageous comprising a plurality of separable and separate wheel attachments for said support with a wheel attachment for each upright standard, wheels for each said attachment, frame components for each attachment, wheel axles on said frame components for the rotative support of said wheels, means for separately and selectively engaging each of said wheel attachments with the upright standards of said supports, means facilitating the rotative movement of a first one of said frame components with respect to the vertically disposed axis of its associated upright standard to provide a castor type mounting therefor, an anchor element in non-moving relationship with respect to said associated upright standard, motive drive means interconnecting said anchor element and said first frame component to provide a steerable castor wheel attachment whereby said first frame component and its associated wheel may be rotated to alternate radially directed positions with respect to the axis of its associated upright standard and said support, a mount adjacent said same first frame component and its wheel attachment, a motor drive unit on said mount and interconnected to the wheel of said first frame component and attachment to power rotative movement of said wheel about its axle, and power control apparatus interconnected to said motive drive means and said motor drive unit whereby an operator may conveniently steer and drive said support unit.

2. The combination as set forth in claim 1 and further comprising at least one additional castor wheel type attachment for the support of said scaffolding.

3. The combination as set forth in claim 2 wherein said additional castor wheel attachment is rotatable to alternate radial positions independently of the movement pattern for said steerable castor wheel attachment and the motive drive means associated therewith.

4. The combination as set forth in claim 1 wherein said steerable castor wheel attachment is rotatable to full circle radial positions.

5. The combination set forth in claim 1 wherein said anchor element is disposed at the upright standard for said steerable castor wheel attachment.

6. The combination set forth in claim 5 wherein said anchor element is concentrically disposed with respect to the axis of the upright standard for said steerable castor wheel attachment.

7. The combination set forth in claim 6 wherein the motive drive means interconnected to said anchor element moves orbitally about said anchor element to steer said steerable castor wheel attachment.

8. The combination of claim 5 wherein said power control apparatus is inclusive of a panel box disposed on the said first frame component.

9. The combination set forth in claim 8 and additionally comprising a flexible type power transmission element interconnecting said motive drive means and the anchor of said steerable castor wheel attachment.

10. The combination set forth in claim 9 and additionally comprising a limit stop component disposed for engagement by said power transmission element to limit the steering rotation of said steerable castor wheel attachment.

11. The combination set forth in claim 10 wherein said panel box is positioned as a guard for the said limit stop and the pinch areas for said flexible type power transmission element.

12. The combination set forth in claim 1 and further comprising a power cord for trailed disposition from said drive and steering attachment, a power cord guide for attachment to said scaffold support, a trailing arm for said guide, a pivot mount for said arm, a fastener for engaging said cord to said trailing arm, and an elastic element for biasing said trailing arm to a first trailing position with movement away therefrom resiliently deforming said elastic element whereby said cord is freed from entrapment by the scaffold support wheels as said trailing arm returns to said first position.

13. In wheel mounted mobile apparatus to be powered from a fixed electrical power outlet and, accordingly, utilizing a power cord, a power cord guide attachment for use on said mobile apparatus, comprising mounting means for securing said guide attachment to said mobile apparatus for movement therewith, a trailing arm for said guide attachment, a pivot on said mounting means for rotatably holding one end of said trailing arm, a fastener at a free end of said trailing arm for engaging said cord to the trailing arm, an elastic element for biasing said trailing arm to a first trailing position directed away from the wheels of said apparatus with movement away from said first position due to forces applied by said power cord resiliently deforming said elastic element whereby the cord is freed from entrapment by any wheels of said apparatus by the return forces of said elastic element that tend to return the free end of said trailing arm toward said first position and, accordingly, away from any cord entrapping wheel.

14. The combination as set forth in claim 13 and further comprising tension adjusting means for regulating the forces exerted by said elastic element.