Patent Publication Number: US-6219943-B1

Title: Resilient mounting arrangement for moldboard

Description:
FIELD OF THE INVENTION 
     The present invention relates to devices that are useful for mounting moldboards onto vehicles and more particularly to devices that are useful for mounting moldboards used to remove material such as ice and snow from road surfaces and parking lots where obstructions may likely be encountered. 
     BACKGROUND AND SUMMARY OF THE INVENTION 
     Moldboards, such as are conventionally used for snow and ice removal, are well known in the art. Moldboards come in a wide variety of shapes and sizes depending upon the intended use. Some moldboards are relatively small and light and are intended to be mounted on a light domestic truck, i.e., a “pickup truck”. Other moldboards are of significantly larger size and weight and are intended for municipal or commercial use. These larger moldboards are typically mounted on large trucks which may also be used for spreading sand or salt. 
     A concern when using a moldboard to remove snow or ice is how to deal with obstructions occurring on the surface being plowed. Some surfaces are considerably rougher than others and may have numerous obstructions. Objects such as grates and manhole covers, rocks, curbs, etc., provide impediments to the removal of ice and snow and may damage the lower edge of the moldboard. In addition, if an obstruction is large enough, the obstruction may cause significant damage to the moldboard and may bring the vehicle used in the plowing operation to an abrupt halt which may result in injury to the vehicle operator. 
     Various arrangements have been provided along the bottom edge of a moldboard to deal with obstructions. These arrangements are commonly called “trip mechanisms” and are provided to avoid damage to the moldboard and to the vehicle carrying the moldboard. 
     A representative trip mechanism is described in U.S. Pat. No. 5,079,866, of Gene Farrell, which was issued on Jan. 14, 1992. In the &#39;866 patent, the trip mechanism has a hinged cutting edge along the bottom of the moldboard with two pivotally mounted linkage members and a trip return spring provided on each end of the moldboard to resiliently maintain the orientation of the cutting edge of the moldboard relative to the surface being plowed. If the cutting edge of the moldboard should encounter an obstruction, the pivotally mounted linkage members act on the plowshoe to cause the moldboard to raise and clear the obstruction. After the moldboard has passed beyond the obstruction, the trip return springs cause the cutting edge to return to its normal orientation and the moldboard returns to its initial position. 
     A trip mechanism such as is described in the &#39;866 patent or other trip mechanisms provided along the bottom edge of a moldboard used in snow removal provide significant protection against damage to the moldboard or to the surface being plowed. However, the need exists for different or for additional protection for moldboards and for the surfaces being plowed especially in the event that a moldboard should encounter an obstruction above the cutting edge. 
     Such different or additional protection against obstructions must be economical in design and construction as well as reliable in operation. Preferably, such protection for moldboards against obstructions will have relatively few moving parts and will be resistant to damage from rust or from low temperatures because of the environment in which such mechanism must function. 
     In view of the above background information, it is an object of the present invention to provide a mounting arrangement for a moldboard which provides protection against obstructions encountered during plowing. 
     A further object of the present invention is to provide a mounting arrangement for a moldboard providing an improved trip mechanism of high reliability and low complexity. 
     It is another object of the present invention to provide a mounting arrangement for a moldboard having an improved trip mechanism requiring low maintenance and which is suitable for use in a wet and cold environment. 
     An additional object of the present invention is to provide a mounting arrangement for a moldboard having an improved trip mechanism capable of preventing or significantly reducing damage to the moldboard or to the vehicle or to the operator when obstructions are encountered by the moldboard during plowing. 
     The above objects as well as other objects not specifically mentioned are accomplished by a mounting arrangement for a moldboard in accordance with the present invention. The mounting arrangement for a moldboard according to the present invention comprises truss means for connecting the moldboard to a vehicle and arm means for pivotally mounting the moldboard on the truss means. In addition, means are provided for resiliently connecting the arm means to the truss means. In the preferred embodiment of the present invention, the truss means includes a mounting member extending longitudinally along the moldboard, with the arm means including first and second arm members received at the ends of the mounting member. In addition, the means for resiliently connecting the arm means to the truss means preferably includes a urethane member provided at each of the first and second arm members between the arm members and the mounting member. Preferably, the mounting member is square in cross-section and hollow along the entire length of the mounting member to provide openings at each end of the mounting member with the urethane members being square in cross-section and configured to be snugly received within the openings in the mounting member. Preferably, each of the first and second arm members includes a shaft extending perpendicularly from said arm member with one of the urethane members being bound to the shaft of each of the arm members. In the preferred embodiment, a cam member is provided on each shaft to limit the extent of angular movement of the arm member and the moldboard about the mounting member. 
     In an alternative embodiment, each of the shafts of the first and second arm members is square in cross section whereby pivoting of the arm members and the moldboard about the mounting member causes the urethane members to be compressed inside the mounting member when the moldboard encounters an obstruction. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The preferred embodiments of the present invention will be described in greater detail with reference to the accompanying drawings, wherein like members bear like reference numerals and wherein: 
     FIG. 1 is a pictorial view of a moldboard according to the present invention; 
     FIG. 2 is a side view of a mounting arrangement for a moldboard according to the present invention; 
     FIG. 3 is a view through the line  3 — 3  of FIG. 2; 
     FIG. 4 is a view through the line  4 — 4  of FIG. 2; 
     FIG. 5 is a view through the line  5 — 5  of FIG. 2; 
     FIG. 6 is a cross sectional view of an arm member and resilient member according to the present invention; and, 
     FIG. 7 is a cross sectional view of another embodiment according to the present invention. 
    
    
     DETAILED DESCRIPTION 
     A preferred embodiment of a mounting arrangement according to the present invention is shown the accompanying drawings. With reference to FIG. 1, a moldboard  100  of conventional design is carried by a truss  102 . The truss  102  is arranged to be removably mounted on the front of a truck or other suitable vehicle (not shown) through a bracket  104  in a suitable and conventional manner well known in the art. The truss  102  has a mounting member  106  which is formed from steel square tubing and which comprises a box beam, i.e., a member having a square cross-section, which is hollow along the length of the box beam. 
     The mounting member  106  is carried on the truss  102  by an A-frame member  108 . The mounting member  106  is pivotally attached to the A-frame member  108  at a mid-point of the mounting member  106  with a pair of hydraulic cylinders  110  provided on either side of the A-frame member  108 . The hydraulic cylinders  110  are provided to selectively orient the mounting member  106 , and therefore to selectively orient the moldboard  100 , with respect to the truss  102 . In this way, the angle that the moldboard makes with respect to the vehicle may be varied as desired. 
     In addition, the truss  102  includes an arrangement  112  to lift the moldboard  100  when desired. The arrangement  112  includes a support arm  114  which is pivotally attached to the truss  102 . The A-frame member  108  may be attached to the end of the support arm  114  by a chain  116 . In addition, the support arm  114  may be raised or lowered by a hydraulic cylinder  118  to raise or lower the A-frame member  108 , and thereby raise or lower the moldboard  100 . 
     If desired, the truss  102  may also include headlights  120  to illuminate the roadway in front of the moldboard  100 . 
     If desired, the cutting edge  124  of the moldboard may be made of a flexible or resilient material in order to minimize damage to the moldboard in the event that the cutting edge  124  should strike an obstruction during plowing. The cutting edge  124  may also be provided with a trip mechanism such as is described in U.S. Pat. No. 5,079,866, which is incorporated herein by reference. 
     The moldboard  100  includes a frame  126  which includes a series of curved support members  128 . The support members  128  are connected at their uppermost and lowermost portions to an upper cross member  130  and to a lower cross member  132 . Two additional support members  132  are provided adjacent the left and right sides of the moldboard  100  and are provided to connect the moldboard  100  to the truss  102 . 
     The additional support members  132  include a hole  134  which receives a bolt  136  positioned centrally within an end of the mounting member  106 . The additional support members  132  also include a series of holes  138  provided at about a midpoint of the frame  126 . A pair of arm members  140  formed of steel are carried by the mounting member  106  and the arm members in turn carry the moldboard  100 . The series of holes  138  permit the orientation of the moldboard with respect to the arm members  140  to be selectively adjusted. 
     With reference now to FIG. 2, the mounting member  106  includes a pair of A-frame pivot bearings  142  at a mid-point of the mounting member  106 . The mounting member is free to pivot about the pivot bearings  142  with respect to the A-frame member  108  (see FIG.  1 ). The mounting member  106  also includes a number of power angling bushings  144 . The hydraulic cylinders  110  are connected to the mounting member  106  through selected power angling bushings  144 . 
     The mounting member  106  is square in cross section with an opening  146  provided in a side wall of the mounting member  106  adjacent the vehicle to enable the hydraulic cylinders  110  to be connected to the power angling bushings  144 . 
     In a moldboard mounting arrangement according to the prior art (not shown), the arm members  140  have a projection made from steel square tubing which extends at a right angle with respect to the arm member  140 . The projection is formed from a rigid box beam having a square configuration in cross-section with the projection sized so as to be snugly received within the ends of the mounting member  106 . In the prior art arrangement, the arm members  140  are slidingly received within the mounting member and cannot pivot or rotate with respect to the mounting member  106 . 
     According to the present invention, the arm members  140  are each provided with a resilient member  148  (see FIG.  6 ). The resilient member  148  has a square cross section and is sized so as to be snugly received within the opening provided at either end of the mounting member  106 . 
     The resilient member  148  enables the arm member  140  to pivot with respect to the mounting member  106 . The resilient member  148  preferably has sufficient rigidity to prevent the arm member (and therefore the moldboard) from pivoting about the mounting member  106  during normal operation of the plow in the absence of an obstruction. The flexibility of the resilient member  148  is measured in durometers and a suitable value depends upon the size and weight of the moldboard as well as the flexibility or resiliency desired for the resilient members  148 . For a typical moldboard of a light weight to medium weight construction, a durometer of about 330 pounds per linear inch is likely to be suitable, per arm. 
     In the preferred embodiment, the resilient member is connected to the arm member  140  through a shaft  150 . The shaft  150  is either integral with the arm member  140  or is welded to the arm member at one end of the shaft  150 . The shaft  150  has a sufficient diameter to enable the shaft to be provided with a threaded opening  152  extending through the arm member  140  to receive the bolt  136  (not shown in FIG. 6, but see FIG.  1 ). The bolt  136  passes through the lower hole provided in the additional support members  138  of the moldboard frame to connect the moldboard to the arm members. The shaft  150  is preferably centrally located in the resilient member  148  so that the shaft  150  is likewise centrally located in the end of the mounting member  106 . In this way, the arm member  140  and the moldboard  100  are arranged to pivot about the shaft  150 . 
     With reference now to FIG. 3, the arm member  140  has the first hole  152  provided in a lower portion of the arm member having a generally square configuration. The arm member  140  includes an upwardly extending portion provided with a second opening  154  which receives a second bolt (see also, FIG. 1) to connect the additional support member  138  to the arm member  140  through one of the series of holes provided in the additional support member at a mid-point of the moldboard  100 . 
     With reference to FIG. 4, the resilient member  148  is snugly received within the square opening provided in the end of the mounting member  106 . Because the resilient member  148  is securely bound to the surface of the shaft  156 , rotation of the shaft causes a deformation of the resilient member  148  inside the mounting member  106 . The extent to which the resilient member resists deformation determines the amount of force needed to rotate the arm member  140  about the shaft  156 . 
     With reference now to FIG. 5, to limit the angular range of motion of the arm member  140  about the shaft  156 , the shaft may be provided with a cam member  160 . The cam member  160  is fixed with respect to the shaft  150  and with respect to the arm member  140  such as by welding. The cam member  160  has four relatively flat surfaces  162  which contact the inside surface of the mounting member when the arm member  140  is in the rearwardmost position relative to the vehicle. The cam member  160  likewise has four additional relative flat surfaces  164  which abut the inside surface of the mounting member when the arm member  140  has moved sufficiently forward. In this way, the cam member  160  serves to limit the angular extent of movement of the arm member  140  and in turn limit the angular extent of movement of the moldboard  100  about the shaft  156 . 
     The cam member  160  may be welded in the valleys between the flat portions about the perimeter surface of the cam member in order to increase the strength of the cam member. 
     Preferably, the cam member prevents rotation of the moldboard about the shaft  150  to about 22.5 degrees and usually less than about 35 degrees of rotation in the event that the moldboard encounters an obstruction. 
     To adjust the ability of the resilient member to oppose a rotation of the moldboard about the shaft  150 , the length of the resilient member may be varied as well as the composition of the resilient member. For example, longer and therefore heavier moldboards likely require either longer resilient members  148  or resilient members of a material having a relatively higher durometer. 
     The mounting arrangement for a moldboard according to the present invention provides significant protection against damage to the moldboard or to the vehicle used for plowing and the vehicle operator (as well as to preventing damage to obstructions) in the event that the moldboard should encounter an obstruction during plowing. However, additional protection is provided when the mounting arrangement according to the present invention is used in conjunction with a conventional trip mechanism for a moldboard for objects and forces above the cutting trip edge. 
     With reference now to FIG. 7, an alternative embodiment is disclosed in which the arm member  140  is provided with a square shaft  150 ′. The square shaft  150 ′ is welded to the arm member  140  and is oriented so that the corners of the square shaft are adjacent the flat interior surfaces of the mounting member  106  when the arm member  140  is in the rearwardmost position. When the arm member  140  rotates forwardly (such as when the moldboard  100  encounters an obstruction), the flat exterior surfaces of the square shaft  150 ′ compress the resilient member  148 ′ against the inside surfaces of the mounting member  106 . In this way, the resistance of the resilient member to being compressed prevents the moldboard  100  from rotating forward about the central axis of the square shaft  150 ′. As in the embodiment of FIG. 3, the moldboard is connected to the arm member  140  through a bolt  136  which is threadably received by the arm member  140  and by the square shaft  150 ′. If desired, the arm member  140  of FIG. 7 having a square shaft  150 ′ may also have a cam member  160  (not shown) which operates as described in connection with the embodiment of FIG.  5 . 
     The square shaft  150 ′ may be solid, if desired, or may be hollow depending upon the weight of the moldboard and the thickness of the walls of the square shaft  150 ′. 
     The resilient member  148  may be formed of any number of materials readily apparent to one skilled in the art with a suitable material being Adiprene LF 1860A (Adiprene is a trademark of Uniroyal Chemical Company, Inc. of Middlebury, Conn.). Another suitable material is Adiprene LF 1800A. Both Adiprene LF 1800A and Adiprene LF 1860A may be cured with MBCA (4,4′-methylene-bis-(o-chloroaniline)) (MBCA Activator M is available from Miki Sangyo USA, Inc. and MBCA Bis Amine A is available from Omni Spec. Corporation-formerly Palmer Davis Sieka). In addition, when the Adiprene is being cured in a mold, it is preferable (or necessary) to use a mold release such as Mold Release S236 available from Stoner. If the shaft  150  (or the square shaft  150 ′) is to properly bind to the urethane, the surface of the shaft must be prepared. Suitable preparation involves a grit blasting of the shaft using G40 or G50 steel or aluminum oxide 60 mesh at 80-100 p.s.i. In addition, Adiprene Primer Chemlock AP213 or AP218 available from Hughson Chemicals, Division of Lord Corporation, Erie Pa. may be used to facilitate the attachment of the urethane to the shaft. 
     A suitable process for bonding liquid cast Adiprene to metal surfaces includes the following steps: 
     1. Degrease metal surfaces with suitable solvent to reduce contamination of grit. 
     2. Grit blast metal surfaces to be bonded with G40 or G60 steel grit or aluminum oxide-60 mesh at 80-100 p.s.i. air pressure. 
     3. Degrease metal with solvents; toluene, methyl ethyl ketone, trichloroethylene or perchloroethylene. (Avoid using fast evaporating solvents which may cause moisture condensation on the metal surfaces and result in poor adhesion.) Prepare surfaces just before application of the primer to prevent rusting and contamination. Care should be taken in the selection and application of mold releases to avoid contamination from mold releases on the surfaces intended to be bound to the Adiprene. 
     4. Apply one or more primer coats and allow to dry. 
     5. Preheat metal part and mold to about 212 degrees Fahrenheit before casting. 
     6. Cast mixture of Adiprene prepolymer and crosslinking agent and cure according to manufacturer&#39;s instructions. 
     In operation, a moldboard mounted on a vehicle using the mounting arrangement according to the present invention may be used for plowing material such as ice and snow from a road or other surface. In the event that the moldboard should encounter an obstruction, the resilient material provided about the shaft of the arm members permits the moldboard to pivot forward about 22.5 degrees and preferably less than about 35 degrees to permit the moldboard to pass over the obstruction. In this way, the damage to the moldboard, to the vehicle carrying and moldboard and, most importantly to the operator of the vehicle, from encountering the obstruction is either prevented or significantly reduced. 
     The principles, preferred embodiments and mode of operation of the present invention have been described in the foregoing specification. However, the invention which is intended to be protected is not to be construed as limited to the particular embodiments disclosed. The embodiments are therefore to be regarded as illustrative rather than as restrictive. Variations and changes may be made without departing from the spirit of the present invention. Accordingly, it is expressly intended that all such equivalents, variations and changes which fall within the spirit and scope of the present invention as defined in the claims be embraced thereby.