Patent Publication Number: US-6981573-B2

Title: Scaffold lift system

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a lift system, and in particular to a lift system such as may be utilized for lowering and raising scaffolding. 
   2. Description of the Prior Art 
   Scaffolding is commonly used in the building industry where workers are erecting walls or working at an elevated position. Multiple story scaffolding systems are typically self supporting, such as tower scaffolding. For systems that are needed for raised elevations, but are not raised more than one or two stories above the ground, scaffolding may be supported by the building or structure being erected or worked on. 
   A common system for such lower level elevated applications has been a pump jack system. Pump jack systems normally include a pair of posts with each post including a pump jack connected thereto. The jacks support a platform for workers to stand on. Pump jacks typically are pedal operated to raise the platform on the posts and often utilize a hand operated crank to lower the platform. Both the crank and pedal are typically actuated by the worker standing on the platform. 
   Although such systems may be workable for certain applications, there are several drawbacks. The pump jack type systems require much exertion from the operator to raise or lower the pump jacks and scaffolding platform. In addition, the systems are complicated and require extra time for setting up and disassembly. Such systems have many moving parts and are not easily transported. Such systems are also difficult to use in inclement weather or at lower temperatures. 
   It can be seen then that a new and improved system is needed for lifting platforms and scaffolding systems. Such a system should provide for easy setup and take down as well as being easily transported. In addition, such a system should be easily operated by scaffolding users with minimal effort and provide for improved safety. The present invention addresses these as well as other problems associated with scaffolding lift systems. 
   SUMMARY OF THE INVENTION 
   The present invention is directed to a scaffolding lift system. The scaffolding system includes two vertical posts or poles that are engaged by and support a platform assembly configured for allowing workers to stand on or walk on while working. The platform preferably includes rails and a shelf for holding materials. In one embodiment, the platform may include a caddy and rails for providing for movement of the caddy along the platform. 
   The posts may include upper supports extending outward to engage the vertical surface of the wall for additional support. The posts also have a toothed track formed along one side for engagement by a complementary traveler device mounted to the platform assembly. The traveler device provides for lifting and lowering of the platform assembly along the post. The traveler device has a housing including rollers engaging opposite ends of the posts, along one side of the post along is formed the toothed track. A spur gear extends inward from the traveler device to engage the toothed track. Rotation of the spur gear lifts and lowers the traveler device, depending on the direction of rotation. The sprocket gear is driven by a worm type gear that includes an actuator engagement portion. The actuator engagement portion may be attached to a drill having a special fitting, such as a hex head to drive the worm gear. A crank may also be utilized for rotating the worm gear. The worm gear rotates several times for each rotation of the sprocket, thereby providing a mechanical advantage so that the platform assembly may be easily lowered and raised by one person, even when supporting workers and their gear. In addition, the drive train and gears provide a natural braking resistance so that the platform assembly does not accidentally slide down the posts under its own weight. In addition to the resistance and braking characteristics of the drive system, a separately operated foot brake also engages the toothed track and provides additional backup. The foot brake may be easily actuated and disengaged while the user&#39;s foot is also actuating the traveler device. The brake is typically spring loaded and configured to ride over the teeth when raised. 
   The present invention overcomes the drawbacks of the prior art and provides easy actuation, transport and assembly that is not provided for in the prior art. The present provides a safe scaffolding system that is reliable under all types of weather conditions and that does not require complicated machinery or an engine to run. 
   These features of novelty and various other advantages that characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings that form a further part hereof, and to the accompanying descriptive matter, in which there is illustrated and described a preferred embodiment of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Referring now to the drawings, wherein like reference numerals and letters indicate corresponding structure throughout the several views: 
       FIG. 1  shows a perspective view of a scaffolding system according to the principles of the present invention; 
       FIG. 2  shows a front elevational view of the scaffolding system of  FIG. 1 ; 
       FIG. 3  shows a top plan view of the scaffolding system of  FIG. 1 ; 
       FIG. 4  shows an end view of the scaffolding system of  FIG. 1 ; 
       FIG. 5  shows an end sectional view with of the scaffolding system taken along line  5 — 5  of  FIG. 2 ; 
       FIG. 6  shows a side partial sectional view of a first embodiment of a traveler device for the scaffolding system of  FIG. 1 ; 
       FIG. 7  shows a side sectional view of the traveler device of  FIG. 6  and rollers for the scaffolding system of  FIG. 1 ; 
       FIG. 8  shows an end partial sectional view of the traveler device of  FIG. 6 ; 
       FIG. 9  shows a top view of the traveler device of  FIG. 6 ; 
       FIG. 10  is an exploded perspective view of a second embodiment of a traveler device for the scaffolding system of  FIG. 1 ; and 
       FIG. 11  shows a side sectional view of the traveler device shown in  FIG. 10 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring now to the drawings and in particular to  FIGS. 1–5 , there is shown a scaffolding system, generally designated  20 , according to the principles of the present invention. The scaffolding system  20  includes a platform assembly  30  supported on a pair of poles or posts  22  with one disposed at each end of the platform assembly  30 . The posts  22  include wall supports  26  that are configured for positioning the system  20  relative to a wall and also provide additional support at the upper end of each post  22 . The platform assembly  30  includes a deck  32  configured for allowing workers to stand and walk on during use. Railings  34  extend around portions of the deck  32  and provide for additional safety and support. An upper shelf or ledge  36  is positioned above the deck  32  and on the opposite side of the post  22 . The shelf  36  is typically utilized for storing materials and supplies. 
   The platform assembly  30  may also include a caddy  38  slidably mounted on rails  40  that may also form a portion of the railing  34 . A mounting portion  42  supports the platform assembly  30  and includes a first embodiment of a traveler device  50  shown in  FIGS. 6–9  or a second embodiment of a traveler device  150  shown in  FIGS. 10–11 , which engages the associated post  22 , as further explained below. 
   Referring now to  FIGS. 6–9 , each of the lift devices  50  travels vertically along its associated post  22 . The lift device  50  includes a gear housing  58  attached to a roller housing  60 . The roller housing  60  is configured to extend around the posts  22  and receive rollers  70  and  72  that engage opposite ends of the generally oval posts  22 . The rollers  70  are typically made of a plastic or other material and are spaced apart, as shown in  FIG. 7 , to provide added engagement security. The rollers  70  include an arcing contour that substantially matches the corresponding outer surface of the associated post  22 . The rollers  70  of each traveler device  50  engage the associated post  22  at different heights, as shown in  FIG. 7 , for improved support and alignment. 
   As shown in  FIG. 9 , on one side of the post  22  is formed the track  24  having teeth disposed there along that engage complementary teeth on a gear on the traveler assembly, as shown most clearly in  FIG. 6 . A spur type gear  54  has teeth that mate to the teeth of the track  24 . Therefore, as the gear  54  is rotated, the lift device  50  moves up and down the posts  22 . The gear  54  is actuated by a worm gear  52  positioned at the side of the gear  54  opposite the posts  22 . The worm type gear  52  engages the sprocket type gear  54  and rotation of the worm gear  52  actuates the spur  54 . The spur gear  54  does not rotate as often as the worm gear  52 , so that a mechanical advantage is provided. The worm gear  52  includes a driver engagement  56 . The driver engagement  56  is configured to couple to a tool, such as a power drill or a hand crank. In this manner, a cordless drill, such as is often utilized for tasks performed on the scaffolding assembly  20 , may be placed on the engagement portion  56  and the scaffolding may be easily raised or lowered with mechanical advantage provided through the gear drive train. The housing  58  is angled for easier access and actuation of the driver engagement  56  by a worker with either a crank or drill. 
   Referring again to  FIG. 1 , as a safety precaution, a brake  80  mounts to the platform assembly  30  and also engages the teeth of the track  24 . The brake  80  is easily operated with the users foot and is spring loaded to prevent accidental uncoupling. The brake  80  acts as a secondary safety device as the gears  52  and  54  have sufficient resistance that the platform assembly  30  cannot accidentally drop or slip under its own weight, or when loaded. 
   In use, the brake  80  is disengaged from each of the posts  22  and the actuator, such as a drill or hand crank, is attached to the driver engagement portion  56  of the worm gear  52 . The drills are rotated in the same direction to either raise or lower each of the lift devices  50 , thereby raising or lowering the platform assembly  30  relative to the posts  22 . It can also be appreciated that the lift devices  50  may be operated independently so long as the devices are moved only a short distance at a time and alternated. The brake  80  is also configured to ride over the tracks  24  on the way up so that the brake  80  need not be disengaged in order to raise the platform, only to lower the platform assembly  20 , thereby acting as a ratchet device. 
   Referring now to  FIGS. 10 and 11 , a second embodiment of the traveler device  150  is shown. The traveler device  150  operates in a similar manner to the traveler device  50 , but includes additional gears to provide a greater mechanical advantage for applications in which a different gear ratio is needed. The traveler device  150  mounts in a similar manner and engages the teeth of the track  24  in the same manner as the traveler device  50 . The traveler device  150  includes a housing  158  retaining a drive train for the traveler device  150 . A planetary spur type gear  154  has exterior teeth  164  that mate to the teeth of the track  24 . The traveler device  150  is driven by a worm gear  152  receiving an input from a driver with an engagement portion  156 . The driver engagement  156  is configured to couple to a tool, such as a power drill or hand crank. The drive engagement  156  is directly mounted to a worm gear  152  that rotates with the driver. The worm gear  152  engages a spur gear  166  coaxially mounted to a second set of spur gears  160 . The spur gears  160  are shown as three gears formed out of thin material, but may also be a single monolithic gear. Rotation of the worm gear  152  drives the spur gear  166  and the gears  160 . The gear  160  engages interior teeth  162  of the planetary type spur gear  154  while exterior teeth  164  engage the track  24 . Therefore, as the worm gear  152  is rotated, it drives the gear  154  moving the traveler device  150  and therefore, the scaffolding  20  up and down. It can be appreciated that the traveler device  150  provides a reduction between the rotation of the worm gear  152  through the gear train  166 ,  160  and  154 . The traveler device also provides a further reduction and greater mechanical advantage so that less power is needed for input and provide for easier lifting and lowering of the entire scaffolding system and greater capacity with less power. 
   It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.