Abstract:
An improved snow plow dolly having a low center of gravity for improved stability when supporting a snow plow, together with front and lateral support members to retain the snow plow in place during movement.

Description:
BACKGROUND OF THE INVENTION 
   1. Technical Field 
   The invention relates generally to the field of snow plow dollies. More specifically, the invention is directed to an improved snow plow dolly employing a simple yet sturdy construction that securely retains a snow plow thereon. 
   2. Description of Prior Art 
   Snow plow dollies are well known in the art. All disclose a support frame for supporting the snow plow blade and snow plow jack, and positioning means, typically wheels but also casters, for maneuvering the snow plow blade once it has been placed on the dolly and detached from the carrying vehicle. Many also disclose adjustment means for accommodating different height snow plow jacks. 
   Buttner, U.S. Pat. No. 3,941,400 (Mar. 2, 1976), “Plow Dolly”, discloses a triangular steel dolly supported by casters located directly beneath each corner. The snow plow blade is supported by a V-channel attached to the top of the shorter side. A horizontally and vertically adjustable snow plow jack support extends across the two remaining sides of the dolly. There are no lateral members to prevent sideways slippage of the snow plow blade or snow plow jack. 
   Pester, U.S. Pat. No. 4,821,435 (Apr. 18, 1989), “Snow Plow Alignment and Storage System”, discloses a triangular support frame with a caster located directly beneath each corner. At one corner is a snow plowjack support which is vertically adjustable by means of a screw jack. Notches to receive the lower edge of the plow blade are located at the other two corners. There are no lateral members to prevent sideways slippage of the snow plow blade or snow plow jack. 
   Iverson, et al., U.S. Pat. No. 5,524,917 (Jun. 11, 1996), “Lightweight Snowplow Dolly”, discloses a trapezoidal shaped snow plow dolly. Non-swiveling casters are mounted directly beneath each end of the front member, and a single swiveling caster is mounted directly beneath the center of the rear member. Two vertical guideposts extend upward from either end of the front member to prevent the snow plow blade from slipping off in a forward direction. There are no lateral members to prevent sideways slippage of the snow plow blade or snow plow jack. 
   Elia, U.S. Pat. No. 4,572,531 (Feb. 25, 1986), “Snow Plow Dolly”, discloses a T-shaped snow plow dolly constructed of square steel tubing. The cross piece is supported by two non-swiveling wheels. Two small blade rests are mounted near the ends of the cross piece to prevent the snow plow blade from sliding off in a forward direction. The base piece is supported by a swivel caster at one end and is bolted to the base piece after insertion into a receiving socket. A plow frame support, mounted at the distal end of the base piece, is vertically adjustable, utilizing bolts. The dolly may be disassembled for each of storage. There are no lateral or front members to prevent slippage of the snow plow blade or snow plow jack. 
   Langenback, et al., U.S. Pat. No. 5,335,923 (Aug. 9, 1994), “Snow Plow Dolly”, discloses a cross-shaped snow plow dolly, supported by a wheel at the end of each arm, the wheels located directly below the arms. An upturned C-channel supports the snow plow blade. A scissor jack supports the snow plow jack and permits height adjustments to facilitate adjusting the height of the snow plow jack. There are no lateral members to prevent slippage of the snow plow blade or snow plow jack. 
   Archambault, U.S. Pat. No. D503,838 (Apr. 5, 2005), “Dolly for Transporting A Plow”, discloses a T-shaped snow plow dolly having wheels located directly beneath the support structure. It also discloses a small trough for cradling the bottom edge of the snow plow blade. There are no lateral members to prevent slippage of the snow plow blade or snow plow jack. 
   Reppen, U.S. Pat. No. 4,887,838 (Dec. 19, 1989), “Wheeled Carrier For A Snow Plow”, discloses a T-shaped support frame with generally trapezoidal supports extending beyond the short base of the carrier. The plow blade rests on resilient rub strips located on the side rails. A jackscrew projecting horizontally from front edge of the long base permits height adjustment of the rearward projecting snow plow jack support. The device folds up into a compact configuration for storage when not in use. The wheels are located directly beneath the support frame. There are no lateral or front members to prevent slippage of the snow plow blade or snow plow jack. 
   Petrell, Jr., U.S. Pat. No. 5,050,898 (Sep. 24, 1991), “Mobile Platform For A Snow Plow”, discloses a snow plow jack support adjustable on an angle to allow for different heights of attachment. Two tall guides allow the plow operator to position the plow in the proper location prior to dropping the plow onto the platform. This dolly places wheels directly below the snow plow jack support. It also has no lateral members for preventing a snow plow from sliding off. 
   The Internet also discloses several snow plow dollies having similar features as the patented devices described above. “Quickmount”, at http://www.quickmountplowcart.com (Feb. 17, 2006), discloses a T-shaped snow plow dolly with an integrated jack lift. There are no members for preventing forward or lateral slippage. “Snow Plow Carts”, at http://www.4qte.com/snowplow_carts.html (Feb. 17, 2006), discloses an H-shaped snow plow dolly having lateral channels to retain the snow plow blade and the snow plow jack. Wheels for positioning the device are located directly beneath the frame. “The Plow Buddy”, at http://www.assoc-elec-prod.com/PBBenefits.htm (Feb. 17, 2006), discloses a T-shaped snow plow dolly having an integral scissor jack for adjusting the height of the snow plow jack. It uses outriggers to raise the wheels and thus lower the frame, but has no lateral or front members to prevent slippage of the snow plow blade or snow plow jack. “Alan&#39;s Homegrown Plow Dollies”, at http://www.snowplowing-contractors.com/plow_dollies.html (Feb. 17, 2006), discloses a T-shaped snow plow dolly having parallel lateral support members. The snow plow blade support member comprises front and rear lips to prevent the snow plow blade front falling off either forward or rearward, but does not comprise any lateral supports to retain the snow plow blade in place if lateral forces are applied. There is a platform for supporting a snow plow jack, but no lateral supports therefore. The wheels are located directly beneath the support frame. 
   Many of the disclosed devices comprise complicated mechanisms for adjusting the height of the snow plow supports. While some of the prior art discloses various means for preventing forward slippage of the snow plow blade, none discloses lateral members for prevention of sideways slippage of the snow plow blade or the snow plow jack. Most position the wheels or casters directly beneath the frame, thereby providing a higher center of gravity and less stability during movement. None of the prior art discloses a simple, inexpensive snow plow dolly having a low center of gravity for stability and front and lateral support members for securing a snow plow thereon without risk of front or lateral slippage during movement. 
   It is therefore an objective of the present invention to provide a low cost, easy to manufacture snow plow dolly having a low center of gravity. 
   It is a further objective to provide a low cost, easy to manufacture snow plow dolly having front support members to prevent forward slippage of the snow plow blade. 
   It is yet a further objective to provide a low cost, easy to manufacture snow plow dolly having lateral support members to prevent sideways slippage of the snow plow blade. 
   It is yet a further objective to provide a low cost, easy to manufacture snow plow dolly having lateral support members to prevent sideways slippage of the snow plow jack. 
   Other objectives of the present invention will be readily apparent from the description that follows. 
   SUMMARY OF THE INVENTION 
   The invention comprises a snow plow support frame and a positioning means for moving same. The support frame is comprised of three support members formed as an isosceles triangle, with the base of the triangle directed forward and suitably adapted to support a snow plow blade, and the apex of the triangle directed rearward. A fourth support member runs from the apex of the triangle to the center of the base of the triangle; this fourth support member is suitably adapted to support a snow plow jack. In the preferred embodiment the snow plow blade support member comprises upwardly depending planar retaining members, one along the front and two at each end, to prevent the snow plow blade from slipping forward or laterally, and the snow plow jack support member comprises upwardly depending planar retaining members, one along each lateral edge, to prevent the snow plow jack from slipping laterally. 
   In one embodiment the positioning means comprises at least two wheels, located at either end of the snow plow blade support member. In another embodiment the positioning means comprises casters instead of wheels. In the preferred embodiment a third wheel or caster is located at the apex of the triangle formed by the support members. In an alternative embodiment a skid may be located at the apex. The wheels may incorporate wheel locks to prevent movement of the snow plow dolly when movement is not desired. In the most preferred embodiment the wheels depend downward from lateral outriggers attached to the support frame at the corners of the triangle of the support frame, whereby the outriggers allow the support frame to be located below the tops of the wheels, thereby lowering the center of gravity of the device and making it more stable when positioning a snow plow. 
   Other features and advantages of the invention are described below. 

   
     DETAILED DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a top view of the snow plow dolly of the present invention, with wheels along the underside depicted in dotted line. 
       FIG. 2  is a side view of a portion of the positioning means of the present invention. 
       FIG. 3  is a perspective view of the present invention. 
       FIG. 4  is a side view of the present invention supporting a snow plow, with the bottom portion of the snow plow blade depicted in dotted line behind the second blade retention post and the second lateral support member deleted. 
       FIG. 5  is a front view of the present invention supporting a snow plow, with the bottom portion of the snow plow blade depicted in dotted line behind the blade retention front lip. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The improved snow plow dolly  1  of the present invention is intended to be used to support and position a standard snow plow  700 , when the snow plow  700  is detached from its carrying vehicle. The snow plow  700  must have at least a snow plow blade  710  and a snow plow jack  720 , with the snow plow jack  720  located along an axis substantially perpendicular with the plane of the snow plow blade  710 . See  FIG. 4 . The present invention comprises two principal components, each presenting an improvement over the prior art: the support frame  10  and the positioning means  600 . The support frame  10  is comprised of four subcomponents: the blade support member  100 , two lateral support members  200 , 300 , and the jack support member  400 . See  FIG. 1 . The four subcomponents should be made of a structurally sturdy and rigid material. The preferred material is steel. 
   The blade support member  100  is an elongate beam oriented substantially horizontally in a plane substantially parallel to the ground. See  FIGS. 1 and 5 . The blade support member  100  is intended to support the snow plow blade  710 , and thus is further oriented substantially parallel to the snow plow blade  710  and has a length greater than the width of a standard snow plow blade  710 . The blade support member  100  has a first end  110  and a second end  120  located opposite the first end  110 , and a central portion  160  located substantially equidistant between the first end  110  and the second end  120 . The blade support member  100  has a top surface  130  facing away from the ground, upon which the snow plow blade  710  is rested. There are two edges  140 , 150  running along the longitudinal axis of the blade support member  100 : the leading edge  140  and the trailing edge  150 , with both edges  140 , 150  running from the first end  110  to the second end  120  of the blade support member  100 . The trailing edge  150  is located parallel to and interior to the leading edge  140 . See  FIG. 1 . 
   The first lateral support member  200  and the second lateral support member  300  are each elongate beams oriented substantially horizontally in the same plane as the blade support member  100 . See  FIG. 1 . Each has a front end  210 , 310  and a back end  220 , 320 . The front end  210  of the first lateral support member  200  is fixedly attached to the first end  110  of the blade support member  100  at an acute first angle to the blade support member  100 . The front end  310  of the second lateral support member  300  is fixedly attached to the second end  120  of the blade support member  100  at an acute second angle to the blade support member  100 , with the second angle being substantially equivalent to the first angle. The back ends  220 , 320  of the first and second lateral support members  200 , 300  are fixedly attached to each other, thereby causing the blade support member  100  and the first and second lateral support members  200 , 300  to form a substantially isosceles triangle. See  FIG. 1 . The blade support member  100  and the first and second lateral support members  200 , 300  are fixedly attached to each other by any suitable means known in the art, for example by welds or by the use of fasteners, such as bolts. 
   The jack support member  400  is an elongate beam oriented substantially horizontally in the same plane as the blade support member  100  and the first and second lateral support members  200 , 300 . It has a front end  410 , a back end  420 , a first edge  440  running from the front end  410  to the back end  420 , and a second edge  450  running from the front end  410  to the back end  420  opposite the first edge  440 . The front end  410  of the jack support member  400  is fixedly attached to the central portion  160  of the blade support member  100  along the trailing edge  150  of the blade support member  100 , with the jack support member  400  oriented substantially perpendicular to the blade support member  100 . The back end  420  of the jack support member  400  is fixedly attached to the back end  220  of the first lateral support member  200  and the back end  320  of the second lateral support member  300 . See  FIG. 1 . The jack support member  400  is fixedly attached to the blade support member  100  and to the lateral support members  200 , 300  by any suitable means known in the art, for example by welds or by the use of fasteners, such as bolts. 
   The jack support member  400  has a top surface  430  located between the first and second edges  440 , 450  and facing away from the ground, upon which the snow plow jack  720  is rested. The jack support member  400  is further comprised of a first jack retaining wall  460  and a second jack retaining wall  470 . The first and second jack retaining walls  460 , 470  are substantially planar and each depends upward in a substantially vertical orientation, running along the first and second edges  440 , 450  of the jack support member  400 , respectively, with the second jack retaining wall  470  substantially parallel to the first jack retaining wall  460 . The first and second jack retaining walls  460 , 470  and the top surface  430  of the jack support member  400  form a jack support channel  480 , into which the snow plow jack  720  is placed. See  FIGS. 3 and 4 . 
   Configured as such, the support frame  10  of the present invention is suitably adapted to securely support a snow plow  700 , with the snow plow blade  710  positioned on the top surface  130  of the blade support member  100  and the snow plow jack  720  positioned within the jack support channel  480  of the jack support member  400 . See  FIGS. 4 and 5 . The first and second jack retaining walls  460 , 470  of the jack support member  400  minimize lateral movement of the snow plow jack  720  and retain the snow plow jack  720  within the jack support channel  480 , preventing the snow plow  700  from falling off the snow plow dolly  1 . See  FIG. 4 . The jack support channel  480  represents a significant improvement over the prior art, which discloses jack support surfaces only, with no means for laterally securing a snow plow jack  720 . While the substantial weight of a snow plow  700  will likely serve to retain it onto a snow plow dolly  1  when the snow plow dolly  1  is at rest, movement of the snow plow dolly  1  may cause lateral forces to shift the snow plow jack  720 , as would vibrations resulting from positioning the snow plow dolly  1  over uneven surfaces, or even inadvertent contact with the snow plow  700 . The jack support channel  480  of the present invention overcomes these shortcomings of the prior art. 
   The second principal component of the present invention is the positioning means  600 . See  FIGS. 2 and 3 . In one embodiment the positioning means  600  comprises a first wheel  610 , located at the junction of the first end  110  of the blade support member  100  and the front end  210  of the first lateral support member  200 , and a second wheel  620 , located at the junction of the second end  120  of the blade support member  100  and the front end  310  of the second lateral support member  300 . See  FIGS. 1 ,  3 , and  5 . The first and second wheel  610 , 620  may pivot 360°, providing increased maneuverability to the present invention. Alternatively, first and second casters may be used in place of wheels. In the most preferred embodiment the support frame  10  comprises first and second outriggers  510 , 520  to support the positioning means  600 . See  FIG. 3 . The first outrigger  510  is located at the junction of the first end  110  of the blade support member  100  and the front end  210  of the first lateral support member  200 , is substantially planar and oriented substantially horizontally. The second outrigger  520  is located at the junction of the second end  120  of the blade support member  100  and the front end  310  of the second lateral support member  300 , and is also substantially planar and oriented substantially horizontally. The first wheel  610  is attached to the first outrigger  510  such that the first wheel  610  depends downward from the first outrigger  510  to the extent that one portion of the first wheel  610  is at an elevation above the front end  210  of the first lateral support member  200  while another portion of the first wheel  610  is at an elevation below the front end  210  of the first lateral support member  200 . The second wheel  620  is attached to the second outrigger  520  in a like manner. See  FIGS. 3 and 5 . If casters are used, they are attached to the outriggers  510 , 520  in the same manner. As such, the support frame  10  of the present invention rides lower to the ground than snow plow dollies of the prior art, which place wheels beneath the support frame. This lowering of the support frame  10  in the present invention results in a lower center of gravity of the snow plow  700  when it is placed on the support frame  10 , providing greater stability when positioning the snow plow dolly  1 . Further increasing the security of the present invention, the first wheel  610  may comprise a first wheel lock  612 , suitably adapted to prevent the first wheel  610  from rolling. The second wheel  620  may also comprise a second wheel lock  622 . See  FIG. 3 . 
   In the preferred embodiment the positioning means  600  further comprises a third wheel  630 , located at the junction of the back end  220  of the first lateral support member  200  and the back end  320  of the second lateral support member  300 . See  FIG. 3 . The third wheel  630  may pivot 360°. A third caster may be substituted for the third wheel  630 , or even a skid. A third outrigger  530  may be attached to a rear support post  500  located at the junction of the back ends  220 , 320  of the first and second lateral support members  200 , 300 . The rear support post  500  is substantially planar and depends upward in a substantially vertical orientation. The third outrigger  530  is substantially planar and oriented substantially horizontally. See  FIG. 3 . The third wheel  630  is attached to the third outrigger  530  in a like manner as the first and second wheels  610 , 620  are attached to the first and second outriggers  510 , 520 , respectively. If a third caster is used instead of a third wheel  630 , it is attached to the third outrigger  530  in the same manner. The third wheel  630  may comprise a third wheel lock  632 . See  FIG. 3 . 
   Other embodiments of the present invention provide additional security when the snow plow  700  is placed on the snow plow dolly  1 . In one embodiment, the blade support member  100  of the support frame  10  further comprises a blade retention front lip  170 . See  FIGS. 3 and 5 . The blade retention front lip  170  is substantially planar and depends upward in a substantially vertical orientation, running along the leading edge  140  of the blade support member  100  from the first end  110  of the blade support member  100  to the second end  120  of the blade support member  100 . The blade retention front lip  170  serves to prevent the snow plow blade  710  from moving forward off the blade support member  100 . In another embodiment the blade support member  100  further comprises a first blade retention post  180  and a second blade retention post  190 . See  FIGS. 1 and 3 . The first blade retention post  180  is substantially planar and depends upward in a substantially vertical orientation. It is located at the first end  110  of the blade support member  100  and oriented substantially perpendicular to the blade retention front lip  170 . The second blade retention post  190  is configured in a like manner and located at the second end  120  of the blade support member  100 . The first and second blade retention posts  180 , 190  prevent the snow plow blade  710  from shifting laterally off the blade support member  100 . The first and second blade retention posts  180 , 190  may also comprise front flanges  182 , 192 , which form right angles with the first and second blade retention posts  180 , 190 , thereby adding strength to the connection of the first and second blade retention posts  180 , 190  to the blade retention front lip  170 . See  FIGS. 1 and 3 . In another embodiment the first and second lateral support members  200 , 300  further comprise side flanges  230 , 330 , with each side flange  230 , 330  created by forming a right angle in the respective lateral support members  200 , 300 . See  FIG. 3 . The side flanges  230 , 330  depend upward in a substantially vertical orientation. The side flanges  230 , 330  increase the strength of the respective lateral support members  200 , 300 . 
   Other embodiments not specifically set forth herein are also within the scope of the following claims.