US 3467025 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
p 6, 1969 L. J. BRADT TOW TRUCK DISPATCH SYSTEM INVENTOR LYNN J. BRADT Filed April 20, 1967 ATTORNEY;
United States Patent 3,467,025 Patented Sept. 16, 1969 US. Cl. 104172 11 Claims ABSTRACT OF THE DISCLOSURE In a tow truck conveyor system, characterized by having a track in the floor, a closed loop roller chain has been provided at curves in the track for the purpose of supporting and reducing the friction of a drive chain as it negotiates the curve.
This invention relates to a tow truck dispatch system, and more particularly, to a novel conveyor arrangement for use in a tow truck dispatch system.
Heretofore, a plurality of small rollers have been provided at curved portions of the conveyors of tow truck dispatch systems. These devices using a plurality of small individually mounted rollers have not been entirely satisfactory. Thus, the use of such individual rollers presents problems of cleaning, increases maintenance, increases the cost of manufacture and installation, and has not been entirely reliable after substantial periods of use. Thus, after substantial periods of use it has been noted that some of the individual rollers are not even contacting the conveyor.
In accordance with the present invention, a roller chain is provided at the curved portion of a tow truck dispatch system. A wall is provided at the curved portion and having a radius of curvature corresponding to the curved portion. The roller chain is disposed between the curved wall and the conveyor and in rolling contact with each of them. It has been found that such a system is selfcleaning, is capable of use in higher speed systems, is simpler than devices proposed heretofore as well as being more reliable and more inexpensive. Also, the roller chain is moving in the same direction as the conveyor in addition to being in rolling contact therewith, thereby minimizing frictional forces at the curved portion of the dispatch system.
The present invention is applicable and adapted to be used between two straight portions of a dispatch system which are parallel to one another or at an angle with respect to one another less than 180. For purposes of illustration, the present invention will be described in connection with the curved portion extending between two straight portions which are perpendicular to one another. It will be apparent to those skilled in the art that the present invention is adapted to be utilized between curved or straight portions which are to be interconnected by another curved portion.
It is an object of the present invention to provide a novel tow truck dispatch system for moving vehicles along a reference surface and around curved portions of the system.
It is another object of the present invention to provide a guide means for a curved portion of a tow truck dispatch system which is simple, inexpensive, reliable, self-cleaning and capable of being used at high speeds.
It is another object of the present invention to provide a tow truck dispatch system having a curved portion which includes a movable back-up means adapted to be in rolling contact and moving in the same direction as a conveyor which is adapted to propel a tow truck along a reference surface.
Other objects will appear hereinafter.
For the purpose of illustrating the invention, there is shown in the drawings a form which is presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown.
FIGURE 1 is a plan view of a curved portion of a tow truck dispatch system, with a portion broken away for purposes of illustration.
FIGURE 2 is a transverse sectional view taken along the line 2-2 in FIGURE 1.
FIGURE 3 is a sectional view taken along the line 3-3 in FIGURE 1.
FIGURE 4 is a side elevation view of a portion of the roller chain.
Referring to the drawing in detail, wherein like numerals indicate like elements, there is shown in FIGURE 1 a portion of a tow truck dispatch system designated generally as 10.
The system 10 includes a reference surface 12. Surface 12 may be the floor or a ceiling in a building. For purposes of illustration, it will be assumed that the reference surface 12 is a floor. In the floor 12, there is provided a main slot having portions 14 and 16 interconnected by slot 15 in the curved portion 18.
The main slot portion 14 is defined by spaced horizontally disposed guide plates 20 and 22. Curved guide plates 24 and 26 define slot 15 at the curved portion 18. Only a portion of one of each of plates 24 and 26 are shown. Main slot portion 16 is defined by corresponding guide plates 28 and 30. A conveyor designated generally as 32 is provided below the main slot and supported on a base plate 34. Conveyor 32 is preferably of the type disclosed in copending application Ser. No. 405,951, now abandoned filed on Oct. 23, 1964, the disclosure of which is incorporated herein by reference.
As shown more clearly in FIGURE 2, the curved portion 18 is adapted to be factory assembled so that it can be rapidly and inexpensively installed. The plates 24 and 26 are supported from and removably connected to the base plate 34. Rigid upright backup walls 40 and 42 are provided on the base plate 34. Walls 40 and 42 are curved so as to correspond to the curvature of portion 18. Spacers 38 are welded to the walls 40 and 42 at spaced points therealong. Bolts 39 removably interconnect the plates 26 to the walls 4t] and 42. Plates 24 are removably connected to angle irons 41 on outside wall 36 by bolts 33. The height of walls 40 and 42 is greater than the height of the conveyor 32.
Clean-out boxes 43 and 45 are provided at the ends of curved portion 18 and located so that they overlap the straight portions 14 and 16 respectively. A wheel 44 mounted for rotation about a pin 46 is adjustably supported by a base plate 47 in box 45 spaced from plate 34. Adjacent one of the ends of the wall 40, there is provided an extension curved plate 48 connected to flange 50 on plate 47. Wheel 44 is adjustably coupled to the base plate 47 by nuts and bolts to facilitate adjustment and take-up of slack in chain 52. Wheel 44 lies in the same horizontal plane containing the walls 40 and 42.
An endless roller chain 52 extends around the wheel 44, curved plate 48, and is in rolling contact with the walls 40 and 42 are shown more clearly in FIGURES 2 and 3. The height of the roller chain 52 is slightly less than the height of the walls 40 and 42. As shown more clearly in FIGURE 4, the roller chain 52 includes spaced rollers 58 interconnected by an upper link 54 and a lower link 56. The rollers of the chain 52 adjacent to the rollers 58 in FIGURE 4, are interconnected by an upper link 54' and a lower link 56. Links 56 are removable provided with wear links 57. The height of the rollers 58 is greater than one-half the height of the roller chain 52. The pitch for the rollers on the chain 52, that is the distance between the axis of rotation of adjacent rollers 58, is less than the length of a side face 60 on various links of the conveyor 32. This relationship is shown more clearly in FIGURE 1. Thus, the side face 60 of various links of the conveyor 32 are preferably in contact with two adjacent rollers 58 most of the time. It is theoretically impossible to have side faces of the links in contact with two rollers at all times because of the angular change of the links as they move around curved portion 18.
A removable cover 59 is provided for box 45. A similar cover is provided for box 43. A curved plate 61 is provided in box 45 as an extension to wall 42. The radius of plate 61 is the same as for plate 48. A- similar plate 62 is provided in box 43 at the other end of wall 42. A wheel 64 is rotatably supported in box 63 spaced from the bottom thereof. It will be noticed that wheels 44 and 64 rotate about axes located alongside portions 16 and 14 respectively. Wear plates 64 and 66 are provided for conveyor 32 and chain 52 respectively.
The operation of the system is as follows:
A tow pin on a load carrying vehicle will project through the main slots 14, 15 and 16 for driving contact with driving links of the conveyor 32. The tow pin is adapted to be supported in an upright position at the front end of a tow truck such as that in Patent 2,619,370. The conveyor 32 will engage the lower end of the tow pin and propel the tow truck along the main slot of the dispatch system 10. The means for propelling or dragging the conveyor 32 is not shown and may be conventional.
As the links of the conveyor 32 enter the curved portion 18, their side faces 60 engage at least one end preferably two of the rollers 58 on the chains 52. Such contact between the moving conveyor 32 and the rollers 58 causes the rollers 58 to rotate about their axes. The rollers 58 are in intimate frictional contact with the wall 40 and therefore move along the wall 40 as a result of the rotation imparted thereto by the conveyor 32. This causes the chain 52 to move along wall 40, around wheel 44, along wall 42, and around wheel 64.
The side face 60 of the various links of the conveyor 32 may be perfectly straight. Since the support for each side face 60 of the links of the conveyor 32 is in the form of rotating movable rollers 58 which are in frictional contact with wall 42, the chain 52 will walk itself along the wall 40 and will be self-cleaning. The entire curved portion of the conveyor and system may be prefabricated at the factory and shipped to the point of installation. Minimum adjustment is required at the point of installation. The opportunity for foreign matter to become lodged in the chain and cause the same to jam is minimized by the fact that the rollers 58 are in rolling contact with spaced substantially parallel vertical surfaces of walls 40 and 42 and the wheels 44 and 64 are spaced from the bottom or floor of the boxes 43 and 45. It will be noted that chain 52 and wall 40' provide support for conveyor 32 before, during and after the curved portion 18.
Since chain 52 is a roller chain, elements 44 and 64 need not be wheels. That is, one or both of elements 44 and 64 may be a ring-shaped member which is stationary.
The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof.
It is claimed:
1. In a tow truck dispatch system comprising a reference surface having a main slot through which a tow pin on a vehicle may extend for contact with a conveyor, said slot having first and second sections connected by a curved section, a roller chain alongside the main slot at said curved section, a rigid curved back-up wall at said curved section, the curvature of said back-up wall and the curved section being substantially identical, said chain having rollers in rolling contact with a surface of said wall and side faces of link members on said conveyor, and said rollers being rotatable about a vertical axis, whereby said conveyor may cause said chain to walk along said wall and frictional contact is reduced.
2. A system in accordance with claim 1 wherein the pitch of said roller chain is less than the length of side faces of said link members.
3. A system in accordance with claim 2 wherein said chain is an endless chain extending around curved members positioned adjacent the respective ends of the curved section.
4. A system in accordance with claim 1 wherein said rollers have a height which is at least greater than onehalf the height of said link members.
5. A system in accordance with claim 1 wherein said chain is an endless chain, said chain extending around a rotatable wheel positioned in a clean-out box adjacent one end of said curved section.
6. A system in accordance with claim 1 wherein said chain is an endless chain, said chain extending around terminal members in clean-out boxes, each box being positioned adjacent one end of said curved section and one end of one of said first and second sections, said boxes having a debris accumulation space below the plane of the terminal members.
7. In a system in accordance with claim 1 including a second curved wall, said chain being in rolling engagement with a vertical surface on said second curved wall, said first curved wall being positioned between said second curved wall and the conveyor.
8. In a system in accordance with claim 7 wherein said curved section, chain, and walls are a prefabricated unit.
9. In a system in accordance with claim 1 wherein said wall has a curved end adjacent one of said sections, the radius of said curved end being less than one-fourth the radius of said curved wall.
10. In a conveyor comprising a track guide member, a conveyor chain guided by said member, said member having a curved portion, a back-up wall at the curved portion, an endless movable back-up chain having rollers, said rollers rollingly contacting said conveyor chain and wall, said rollers being between said conveyor chain and wa 11. In a conveyor in accordance with claim 10 wherein the pitch of the back-up chain is less than the length of links of the conveyor chain, and said rollers transmitting forces from the conveyor chain directly to said wall.
References Cited UNITED STATES PATENTS 1,407,673 2/1922 Roe 104172 ARTHUR L. LA POINT, Primary Examiner DANIEL F. WORTH III, Assistant Examiner US, Cl. X .R, 104-l89, 197