Patent Publication Number: US-2007096412-A1

Title: Portable air compressor dolly with retractable handle

Description:
BACKGROUND OF THE INVENTION  
      The present invention relates generally to equipment dollies used with portable air compressors, and more particularly, to a handle for such a dolly configured for the support and movement of a portable air compressor, gas tank, or other similar heavy machinery to and from a jobsite.  
      Air compressors required for use with large pneumatically-powered tools on jobsites, such as power fastener drivers including roofing nailers or paint sparyers, can generally weigh as much as 70 pounds and are very difficult to move over long distances or rough terrain, such as commonly found at construction sites. Moving the compressor or gas tank is physically demanding to the workers.  
      Another problem with moving portable compressors and gas tanks is that they can be damaged, such as when they are dropped, or when they are carried by or on equipment not designed to bear the weight of the compressor. Further, particular care must be taken to prevent damage when transporting tanks containing compressed air, fuel, volatile gases or other contents.  
      To address this problem, a dolly can be used to transport compressors with a measure of maneuverability over difficult terrain. For added maneuverability, a handle is commonly provided and extends generally perpendicularly from the dolly platform to a height which is comfortable to the average user. This height is generally above the waist but below the shoulders of the user. However, when a conventional handle is added to the dolly, the height of the dolly is increased and the portable air compressor and the dolly are not easily stored in restricted spaces. On the other hand, if the height of the handle is decreased, it is difficult for the user to maneuver the dolly, particularly over difficult terrain.  
      Accordingly, there is a need for a dolly for an air compressor or the like with a handle that is storable in restricted spaces, yet is comfortable and maneuverable by the user.  
     SUMMARY OF THE INVENTION  
      The above-listed needs are met or exceeded by the present retractable handle on a dolly for a portable compressor, which has a handle assembly including at least one handle pole and a handle grip member. A clamp assembly secures the handle assembly onto a frame of the dolly. The clamp assembly includes a bearing portion configured for mounting the clamp assembly onto the frame, and a bushing portion for slidingly engaging the handle pole to permit the pole to extend and retract with respect to the clamp assembly.  
      A clamp assembly for use on a dolly having a frame and a retractable handle is also provided. The clamp assembly has a bearing portion having a contact surface configured for mounting the clamp assembly on the frame of the dolly. The clamp assembly also has a bushing portion having an opening configured for slidingly engaging the retractable handle with respect to the clamp assembly. A fastener recess is located between the contact surface of the bearing portion and the opening of the bushing portion. On an opposite wall of the bushing portion to the fastener recess is an access orifice.  
      Further, a method of attaching a bearing portion to a faceplate and a frame of a dolly for a portable compressor is provided. The method includes the steps of providing the bearing portion, which has a contact surface configured for receiving the frame and a fastener recess, and also providing the faceplate, which has a receiving portion configured for receiving the frame and a boss having an internally threaded portion. Additionally, an aperture on the frame is also provided. The boss is inserted into the aperture, and the fastener recess is also aligned with the aperture opposite the faceplate. The fastener is threaded through the fastener recess and into the aperture, and the internally threaded boss captures the fastener. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is an exploded front perspective view of a dolly, a faceplate, a handle, a plurality of clamp assemblies and a compressor (in phantom) of the present invention;  
       FIG. 2  is a top view of the dolly of  FIG. 1 ;  
       FIG. 3  is a front view of the dolly of  FIG. 1 ;  
       FIG. 4  is a right side view of the dolly of  FIG. 1 ;  
       FIG. 5  is a top view of the bearing of  FIG. 1 ;  
       FIG. 6  is a top view of the bearing of  FIG. 1  with a section view of a dolly arm and a partial top view of the faceplate;  
       FIG. 7  is a section view of the bearing along section A-A of  FIG. 6  with a fastener inserted and engaged with the faceplate, the dolly arm (in phantom), an assembly view of a handle pole, and a screwdriver inserted into the bearing (in phantom);  
       FIG. 8  is a top view of the faceplate of  FIG. 1 ;  
       FIG. 9  is a front view of the faceplate of  FIG. 1 ;  
       FIG. 10  is a right side view of the faceplate of  FIG. 1 ;  
       FIG. 11  is a rear view of the faceplate of  FIG. 1 ;  
       FIG. 12  is a top view of the handle of  FIG. 1 ;  
       FIG. 13  is a front view of the handle of  FIG. 1 ;  
       FIG. 14  is a schematic of a spring-clip lock of the handle of  FIG. 1 ;  
       FIG. 15  is a partial front view of the handle of  FIG. 1 ; and  
       FIG. 16  is a partial side view of the handle of  FIG. 1 . 
    
    
     DETAILED DESCRIPTION  
      Now referring to  FIG. 1 , a dolly for a portable air compressor incorporating the features of the present invention is generally designated  10  and includes a frame generally designated  12 , a platform  14 , and at least one, but preferably two wheels  16  (shown in phantom). The platform  14  of the dolly is configured to receive a compressor tank  18  (shown in phantom). As is known in the art, the compressor tank  18  may be oriented on the platform  14  in a generally vertical or generally horizontal orientation. An exemplary dolly is disclosed in commonly owned U.S. patent Ser. No. 10/680,547, entitled “Dolly for Portable Air Compressor”, which is incorporated by reference herein.  
      Referring now to  FIGS. 1-4 , the dolly  10  will be described in more detail. Preferably integrally formed, or alternatively formed as separate members, the frame  12  has two legs  20  and an inverted “U”-shaped frame handle structure  22 . The frame handle structure  22  has arms  24  and a cross bar  26  which form the inverted “U” shape, although other shapes and configurations are contemplated. The arms  24  are spaced a distance apart to allow the compressor, gas tank, fuel tank or any other large article  18 , to occupy the space between the arms. The spacing distance may vary to suit the application.  
      In the preferred embodiment, the frame handle structure  22  is constructed of a single piece of strong, rigid and durable material such as tubular steel that is formed into a “U”-shape. In an alternate embodiment, the frame handle structure  22  is constructed of multiple components. Further, a protective coating may be applied to both the frame  12  and the frame handle structure  22 .  
      Referring now to  FIGS. 1 and 8 - 11 , extending from one arm  24  to the other arm is a faceplate  28 . While other durable materials are contemplated, the faceplate  28  is preferably die cast aluminum or injection molded plastic, and preferably has a marking portion  30  for displaying information about the compressor  18 , or any other information. The faceplate  28  may also serve to support portions of the compressor  18  when the dolly  10  is inclined backwards.  
      The faceplate  28  preferably has four receiving portions  32  for engaging the arms  24  of the frame handle structure  22  at four corresponding apertures  34 . While the preferred embodiment has four receiving portions  32  and four apertures  34 , it is appreciated that the number and arrangement may vary. The receiving portions  32  have a generally semi-circular contact surface  36  that is configured to receive the generally circular cross-sectional shape of the arms  24 . However, it is contemplated that other shapes of contact surfaces  36  and arms  24  may be used. Further, it is contemplated that individual receiving portions  32  can be used instead of a common faceplate  28  connecting the portions.  
      Turning now to  FIGS. 1 and 5 - 11 , the connection of the receiving portions  32  to the arms  24  of the frame handle structure  22  will be described. At each of the receiving portions  32 , the faceplate  28  has a primary boss  38  located generally centrally at the semi-circular shape and protruding therefrom. As seen in  FIG. 6 , the primary boss  38  is configured to be inserted into the aperture  34  of the arm  24  to self-locate the receiving portion  32  in position relative to the arm. Further, the semi-circular contact surface  36  is configured to contact the arm  24  of the frame  12  in a substantially flush engagement. The receiving portions  32  preferably also have at least one, but preferably a plurality of secondary bosses  39  at each end of the semi-circular contact portion  36 , as will be described in more detail, below.  
      A clamp assembly  40  forms a clamp with the receiving portion  32  around the arm  24 . In the preferred embodiment, when viewed from above ( FIG. 6 ), the clamp assembly  40  has a figure “8” shape, where a portion of the bottom ring of the “8” shape is removed, but is completed by the receiving portion  32 . The clamp assembly  40  includes a bearing portion  42  (open ring) and a bushing portion  44  (closed ring). In other embodiments, the bearing portion  42  may be a closed ring, or may be any other shape that permits it to act as a bearing. Similarly, the bushing portion  44  may be an open ring, or may be any other shape that permits it to act as a bushing.  
      Preferably, the bearing portion  42  has a generally semi-circular contact surface  45 , and a recess  46  located at each side of the contact surface. The bearing portion  42  preferably engages the faceplate  28 , preferably by receiving the secondary bosses  39  into the recesses  46  in a pressure fit, as seen in  FIG. 6 . In the preferred engaged position, the contact surface  36  of the faceplate  28  and the contact surface  45  of the bearing portion  42  concentrically encircle the arm  24 .  
      Additionally, as seen in  FIG. 7 , a threaded fastener  48  is introduced through a fastener recess  50  located between the contact surface  45  of the bearing portion  42  and the bushing portion  44 . The fastener recess  50  preferably includes a recessed seat  52  for seating the head  54  of the fastener to prevent protrusion into the bushing portion  44 . The fastener  48  extends into the aperture  34  of the arm  24 , and is captured in an inside surface  56  of the boss  38 . Located inside the aperture  34  of the arm  24 , the boss  38  is internally threaded to receive the threaded fastener  48 .  
      To capture the fastener  48  in the boss  38 , the fastener is preferably introduced through an access orifice  58  located in the bushing portion  44  on a wall  57  opposite to and aligned with the fastener recess  50 . For ease of insertion, the access orifice  58  is preferably in registry with the recessed seat  52 . When the fastener  48  is located in the fastener recess  50 , a screwdriver or other tool  59  (shown in phantom) is inserted through the access orifice  58  to thread the fastener until the head  54  is seated in the recessed seat  52 . In this configuration, the receiving portion  32  and the bearing portion  42  are attached to each other, and the clamp assembly  40  is anchored to the frame handle structure  22 .  
      Referring now to FIGS.  1 ,  5 - 7  and  12 - 14 , the handle assembly  60  extends from the clamp assembly  40  and has generally parallel alignment with the frame handle structure  22 . The handle assembly  60  includes at least one, but preferably two handle poles  62  and at least one handle grip member  64  extending between the poles to form a general “U”-shape.  
      Disposed inside an opening  66  in the bushing portion  44  of the clamp assembly  40 , the handle assembly  60  is configured to slidingly extend and retract with respect to the frame  12 . In a retracted position, the handle poles  62  are slid downward in the opening  66  towards the platform  14  of the frame  12 , and generally parallel with and adjacent to the arms  24 . The handle assembly  60  is fully retracted when the handle grip member  64  engages the bushing portion  44  of an upper clamp assembly  40 A. Alternatively, it is contemplated that a stop can be located on the pole  62 . In the retracted position, the overall height of the dolly is decreased, making storage of the portable air compressor feasible in restricted spaces.  
      In an extended position, the handle poles  62  are slid upward away in the opening  66  from the platform  14  of the frame  12 . The handle poles  62  are extendable to a height that is comfortable to the user, generally somewhere between waist and shoulder height of the user. A flared end  68  is provided on the poles  62  to prevent the poles from pulling out of the bushing portion  44 . The flared end  68  is sized to be larger than the opening  66  to prevent pole pull-out, however other stops may be incorporated.  
      To hold the handle poles  62  in an extended position relative to the clamp assembly  40 , at least one spring-loaded button  70  is located on the pole. A spring  72  located inside the handle pole  62  biases the button  70  to protrude from an inside surface  74  to an outside surface  76  of the pole. In this way, the button  70  forms a stop to impede the sliding motion of the handle pole  62  within the opening  66  by engaging an upper surface of the bushing portion  44  on the uppermost clamp assembly  40 A.  
      To retract the handle pole  62 , the user overcomes the bias of the spring  72  by pressing the button  70  and selectively sliding the pole within the opening  66 . While the preferred embodiment has one spring-loaded button  70  on each pole  62 , it is contemplated that a plurality of buttons can be located on the poles for varying lengths of extension and retraction. Further, other means of selectively locking the poles  62  into varying lengths of extension and retraction are contemplated.  
      The clamp assembly  40  is disposed in spaced relationship on the arms  24 . Further, the clamp assembly  40  is designed and constructed of suitable materials to support the static and dynamic loading of the compressor and dolly without major deformation of the clamp assembly during use. Further, the contouring and removal of portions of the clamp assembly  40  not necessary for maintaining the requisite strength of the assembly, such as removal portion  77 , reduces the amount of material used, thus lessening costs. Further, the bearing portion  42  and the bushing portion  44  are preferably integrally formed to create the clamp assembly  40 , however it is contemplated that the portions may be formed in components and attached to each other.  
      It is preferable that the contact surface  45  of the bearing portion  42  and the opening  66  of the bushing portion  44  are configured to receive members, preferably the frame handle structure  22  and the handle poles  62 , respectively, which are substantially parallel. Additionally, while the bushing portion  44  is preferably an enclosed sleeve, it is contemplated that the bushing portion can be an open sleeve, a notch-in-groove arrangement with the pole, or any other arrangement which permits the sliding engagement of the pole.  
      Turning now to  FIGS. 1 and 12 - 16 , the handle grip member  64  is attached to the poles  62  to form the handle assembly  60 . The handle grip member  64  includes a hand receiving portion  78  for receiving the hands of the user, and a pole-engaging portion  80  for engaging the poles  62 . The pole-engaging portion  80  is sized and shaped to be slightly smaller than the inside dimensions of the pole  62 . In this way, the pole-engaging portion  80  is configured to be pressure-fit inside the pole  62 ′. Further, a nut  82 , or similar mechanical receiving structure, is captured or located in the pole-engaging portion  80 .  
      When the pole-engaging portion  80  is assembled onto the pole  62 , the nut  82  is moved into registry with an upper aperture  84  on the pole. Subsequently, an upper fastener  86  is inserted into the upper aperture  84  and received in the captured nut  82 , as seen in  FIG. 15 . The engagement of the handle grip member  64  and the pole  62  is not only strong, but it also saves material, thus lowering cost, and minimizes the outside appearance of fasteners on the handle assembly  60 .  
      While particular embodiments of the present portable air compressor dolly with retractable handle have been shown and described, it will be appreciated by those in the art that changes and modifications may be made thereto without departing from the invention in its broader aspects and as set forth in the following claims.