Reversible moldboard assembly

A moldboard assembly having a flexible moldboard sheet joined along its bottom edge to a scraper blade unit so that material passing over the blade is directed into contact with the sheet. Adjusting arms are secured to the top corners of the sheet and are independently positioned to contour the sheet to any desired shape whereby the flow of material through the assembly can be accurately controlled.

BACKGROUND OF THE INVENTION 
This invention relates to a moldboard assembly having a flexible moldboard 
sheet that is adjustable to change the contour of the moldboard to control 
the flow of material through the moldboard and the direction of discharge. 
Most conventional moldboards are formed from metal into a desired shape 
depending upon its intended use. In some cases the moldboard is involuted 
to provide a flared discharge at one end for casting snow to one side or 
the other of the propelling vehicle. When it is necessary to discharge to 
the opposite side of the vehicle, however, the contoured moldboard 
assembly must be replaced with one flared at the opposite end. Changing a 
moldboard assembly is a time consuming and often difficult task that is 
made even more difficult because of the accumulation of ice and snow 
within the component parts of the plow. Typically the truck is 
"deadheaded" or returned to the garage when a conversion is necessary so 
that the plow can be worked on indoors. 
A roll-over snow plow has been developed by the present assignee that 
permitted a moldboard, contoured for a right hand discharge, to be 
converted to a left hand discharge in a matter of seconds. The moldboard 
assembly in this piece of equipment has cutting edges running along the 
opposed lateral edges of the moldboard. A lifting mechanism is attached to 
the moldboard that lifts the moldboard, rotates it 180 degrees, and lowers 
it back into a plowing position when a conversion is needed. The operator 
does not have to leave the cab to make the changeover and no further 
adjustment to equipment is necessary. The rollover design has been found 
to be most useful in clearing large open areas such as parking lots and 
airport runways where wind is a factor or where the snow must be 
discharged into prescribed disposal areas. 
The rollover plow requires additional equipment to carry out the conversion 
maneuver and therefore is heavier and relatively more expensive when 
compared to a more conventional plow. 
Metal (steel) moldboards are heavy pieces of equipment and require a good 
deal of horsepower to propel. This, of course, results in higher fuel 
consumption. Snow also sticks or packs upon the working surface of the 
metal moldboard therein lowering the plow efficiency and again increasing 
fuel consumption. A lightweight plastic moldboard has been developed by 
the present assignee which, unlike a steel moldboard, does not have to be 
laboriously bent to a desired curvature during manufacture. The plastic 
moldboard is simply molded or otherwise formed into a sheet of desired 
dimensions and the sheet is then bolted upon a support frame. The plastic 
moldboard is not only lighter than its metal counterpart, but it also has 
a low coefficient of friction which prevents snow from sticking to its 
surface. The plastic moldboard has been proven to save up to thirty 
percent in fuel costs. However, once it is bolted to the frame, its shape 
cannot be altered. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to improve the 
efficiency of snow plows. 
It is another object of this invention to provide a moldboard assembly for 
a snowplow, the contour of which can be selectively changed to control the 
flow of snow through the assembly. 
It is a further object of the present invention to provide a snow plow that 
can be reversed to discharge snow from one side or the other by 
selectively changing the curved taper of the moldboard. 
Another object of the present invention is to reduce the amount of 
equipment required to convert a moldboard from a left hand discharge 
configuration to a right hand discharge configuration. 
These and other objects of the present invention are attained by securing 
the bottom edge of a flexible moldboard sheet to the top edge of a scraper 
blade unit, attaching an adjustable arm to each top corner of the sheet 
and independently positioning each of the arms to contour the sheet to a 
desired shape.

DETAILED DESCRIPTION OF THE INVENTION 
Referring now to the drawings, and in particular to FIGS. 1-3, there is 
shown a moldboard assembly, generally referenced 10, that is attached to 
the front of a truck 11 by means of a combination push frame and lifting 
conventional adjusting arm mechanism 12 of any suitable design. The 
moldboard assembly includes a trip blade unit 13 containing an elongated 
scraper blade 15, a flexible moldboard sheet 17 and a pair of spaced apart 
adjusting arms 19--19 that are attached to the back of the moldboard sheet 
at the top corners by ball and socket connectors 20--20. As will be 
explained in greater detail below, the shape of the flexible moldboard 
sheet can be varied through the use of the adjusting arms to control the 
movement of snow through the moldboard and thus permits an operator to 
deliver snow to either side of a vehicle without dismounting from the cab. 
The flexible moldboard is particularly well suited for use in clearing 
airport runways, large parking lots, highways or any open area where it is 
oftentimes necessary to move snow to either side of a vehicle, depending 
on the location of the snow disposal area or prevailing wind conditions. 
The flexible moldboard 17 is fabricated from a single sheet of any suitable 
high strength flexible material that is abrasion resistant and has high 
impact resistance. Preferably the moldboard sheet is constructed of any 
one of many plastics exhibiting these characteristics or blends thereof. 
Because snow will not stick to most plastics, the flow of snow through a 
plastic moldboard will be relatively constant for any configuration. The 
operator therefore can finely tune the moldboard much like an adjustable 
fluid nozzle to meet different snow conditions and/or to place the snow 
with refined accuracy into desired disposal area. 
As further illustrated in FIGS. 4-6, the moldboard assembly includes a 
rigid main support frame generally referenced 21 that is located behind 
the trip blade assembly and the previously noted flexible moldboard 
sheet. The frame contains a pair of spaced horizontal members 22 and 23 
that are joined by means of vertical aligned end ribs 24--24 and interior 
ribs 25--25. A lifting bracket 27 is welded to the frame so that it is 
centrally located therein. The bracket has an upper horizontally disposed 
cross member 28 containing a link 29 for attaching the moldboard assembly 
to the pusher frame and lifting assembly mounted upon the front of the 
vehicle 12 (FIG. 1). 
As best illustrated in FIG. 6, the scraper blade 15 is secured to 
horizontally disposed angle 31 which is rotatably supported upon a series 
of coaxially aligned shafts 32. The shafts, in turn, are supported on the 
main support frame within mounting lugs 30--30 (FIGS. 7 and 8). A series 
of torsion springs 33 are wound about the shaft and are arranged to act 
against the angle to bias the scraper blade in the normal plowing position 
as shown. In the event the blade moves against a rigid obstruction as it 
is being driven forward by the truck, the blade will turn under the shaft 
to permit the object to move thereunder. Once the object has passed under 
the assembly, the springs will quickly return the blade to a normal 
operative position. 
A deflector plate 34 is sandwiched between the blade 15 and angle 31. The 
plate extends upwardly beyond the top of the blade and is arranged to 
coact with a guide plate 35 to direct snow moving over the blade upwardly 
into contact with the flexible moldboard sheet 17. A backing member 37 is 
secured to upper frame member 22 as by welding and the upper section of 
the guide plate 35 is securely bolted along its length to the backing 
plate by means of uniformly spaced carriage bolts 38. The bottom skirt 39 
of the flexible moldboard sheet is clamped between the guide plate 35 and 
the backing member 37 and is securely held in place by the bolts which are 
arranged to pass through holes provided in the sheet. The entire lower 
edge of the rectangular moldboard sheet is thus held immobile in the top 
of the trip blade unit. The upper part of the flexible sheet is free to 
move so that it can be selectively shaped to most efficiently handle snow 
for prevailing weather and road conditions. 
The upper section of the flexible moldboard sheet is connected at the two 
rear top corners to the distal ends of movable adjusting arms 19--19 by 
means of universal connectors 20--20. FIGS. 9 and 10 show in greater 
detail the construction of one of the connectors. A base plate 40 is 
bolted to the back of the sheet at the corner by bolts 41--41. A pair of 
raised parallel tabs 42--42 depend upwardly from the base plate and a bolt 
43 is passed through the tabs and is secured in place by locknut 47. A 
cylindrical ball segment 44 is mounted on the stud portion of the bolt and 
is centered between the tabs by means of two centering bushings 45--45. 
Each adjusting arm 19 includes having a web 49 and a pair of opposed side 
walls 50--50 (FIG. 9). A cylindrical sleeve 52 is passed through holes 
provided in the sidewalls 50--50 of the adjusting arm and is welded to the 
sidewalls as shown. A ball seat 53 is affixed to the inner wall of the 
tube and mates in assembly with the ball segment to provide a universal 
joint between the arm and the top corner of the sheet. 
A cylindrical spacer bar 60 (FIG. 11) is welded at each end to the inside 
tab of each universal connector. As illustrated in FIGS. 1-3, the bar 60 
is slidably retained within a pair of slide units 62--62 affixed to the 
upper back part of the sheet by any suitable means. Each slide unit 
includes a cylindrical bushing 63 that encompasses the bar and permits it 
to move freely along the back of the sheet. The bar serves to maintain a 
uniform spacing between the top corners of the sheet as the moldboard 
contour is being changed. As will become evident from the disclosure 
below, the adjusting arms are permitted to turn independently in separate 
vertical planes to roll the sheet forwardly over the top of the blade 
unit. By maintaining the spacing between the top corners constant, the 
front surface of the sheet which is presented to the snow will always be 
arcuate in form regardless of the adjusting arm positions. 
As shown in FIG. 1 an elongated stiffening beam 65 is bolted on the back of 
the moldboard sheet along the top edge thereof which keeps the top edge of 
the sheet in parallel alignment with the spacer bar 60 at all times. 
Diagonal cut outs 67--67 are provided at each top corner of the sheet to 
prevent the corners form extending downwardly below the lower margins of 
the moldboard when the sheet is rolled forward into the two extreme 
positions shown in FIGS. 1 and 2. 
Referring once again to FIGS. 6, 7 and 8, the proximal or lower end of each 
adjusting arm is contained within a movable bracket generally depicted at 
70. The bracket includes a pair of vertical sidewalls 71--71 that are held 
in spaced relationship by a horizontal webs 72 and 73. The webs, in 
assembly, are superimposed over an upper horizontal flange 74 and a lower 
horizontal flange 75 which are securely welded to the main frame. A pivot 
pin 77 having an expanded head 78 is passed downwardly through the 
superimposed members and is retained in assembly by a cotter pin 79. A 
vertical tube 80 is mounted between the flanges which surrounds the body 
of the pivot pin 77. A tie bolt 82, which is arranged to pass through both 
horizontal sleeve 83 and the bottom section of the bracket, is bolted in 
place to hold the lower portion of the sidewalls in spaced apart 
alignment. 
Accordingly, the bracket is secured to the main frame of the moldboard 
assembly by horizontal pivot pin 77 which permits the bracket to swing in 
a horizontal plane about the pin. 
The proximal or lower end of each adjusting arm 19 passes between the upper 
sections of the bracket sidewalls and is secured therebetween by a 
threaded horizontally disposed hinge pin 85. A spacer sleeve 87 passes 
through the sidewalls 50--50 of arm 19 and seats against the opposing 
sidewalls of the bracket. The threaded end of the hinge pin is secured in 
place by means of a lock nut 89. Adjusting arm 19 is thus adapted to pivot 
in either a horizontal or a vertical plane. As will become apparent from 
the disclosure below, this freedom to move in two planes allows each 
adjusting arm to independently position one top corner of the moldboard 
sheet in an infinite number of positions within the movable range of the 
arm. 
As shown in FIG. 7, a double acting hydraulic cylinder 90 is pivotally 
mounted in the lower part of each bracket 70 upon sleeve 83. A 
reciprocating rod 91 extends from the top of the cylinder body 92 and is 
connected between ears 93--93 carried in the lower part of the movable arm 
19 by means of a horizontally disposed pin 95. By extending or retracting 
the rod 91, the arm can be turned about horizontal hinge pin 85 thus 
permitting the attached top corner of the moldboard sheet to be 
selectively positioned. A pair of ports 97 and 98 are provided in the 
cylinder body by which hydraulic hoses 99--99 (FIG. 4) are connected. 
Fluid is pumped from a reservoir to either side of a power piston (not 
shown) housed within the cylinder body. The activity of each power 
cylinder is controlled by the operator from the cab of the vehicle using 
suitable hydraulic controls (not shown). By simply extending and 
retracting the cylinder rods, the entire contour of the flexible moldboard 
can be selectively changed to direct snow form one side of the vehicle to 
the other. In addition, the shape of the moldboard can be finely adjusted 
or tuned to more efficiently handle snow under a wide range of conditions. 
Snow passing through the assembly will not adhere to the sheet so that 
once an adjustment is made, the flow path of the material will remain 
constant as long as the snow condition remains unchanged. 
While this invention has been explained with reference to the structure 
disclosed herein, it is not confined to the details as set forth and this 
application is intended to cover any modifications and changes as may come 
within the scope of the following claims.