Boom, particularly a spreading boom for suspension on an outer frame of an agricultural tool, such as an agricultural vehicle

Abstract

A boom, particularly a spreading boom for suspension on an outer frame (1) of an agricultural tool and of the type in which the suspension device comprises spring suspension and shock absorbing devices in the form of a trapezoidal suspension with two substantially parallel beams of which one is connected to the outer frame (1). According to the invention the upper beam of the trapezoidal suspension is linked, each of the links (6, 7) being pivotally connected to the outer frame (1) and springs (12) being arranged on both sides of the linkage (20, 21), but on the other side of the center of suspension (8, 9). The individual spring (12) is arranged between one of said links (6, 7) and a separate beam fastened to the outer frame (1).

We claim: 
     
       1. A boom having a suspension device and an outer frame for use with an agricultural tool, such as an agricultural vehicle, wherein said outer frame is fastened to said agricultural tool and said suspension device comprises a suspension having springs and .Iadd.a .Iaddend.shock absorbing . .devices.!. .Iadd.device .Iaddend.in the form of a trapezoidal suspension with two substantially parallel beams, comprising an upper and lower beam, said upper beam being formed of links, said links being pivotally joined together near a center of said suspension and each link pivotally joined to said outer frame outwardly of said center, with said springs biasing said links at points outwardly of points of said pivotal joining of said links and said outer frame. 
     
     
       2. A boom according to claim 1, further comprising an elongated bar having a means for attaching said elongated bar to said outer frame, wherein said springs are disposed between said links and said elongated bar. 
     
     
       3. A boom according to claim 1, wherein said trapezoidal suspension device includes diagonal bars connecting said parallel beams and a .Iadd.second .Iaddend.shock absorbing device being mounted between one of said diagonal bars and said lower beam. .Iadd. 
     
     
       4.  Apparatus for mounting left and right side sprayer arms to an agricultural vehicle having a frame and a centerline, said arms being adapted for movement between an extended use position and a folded transport position, said apparatus comprising: a generally trapezoidal suspension linkage including,   a yoke extending generally horizontally to either side of said centerline;   an articulated linkage having left and right link arms pivotally mounted together at a location near said centerline and extending generally parallel to said yoke under normal conditions;   first and second side links inclined relative to the vertical, said side links having first ends pivotally connected respectively to said yoke on opposing sides of said centerline, and having second ends pivotally connected respectively to the outboard ends of said left and right link arms of said articulated linkage;   means for biasing said link arms of said articulate linkage to a normal position relative to said yoke;   first and second pivot mounting means for pivotally mounting said first and second link arms at locations intermediate their respective ends to said frame of said vehicle for rotation respectively about first and second horizontal axes located on opposite sides of said centerline; and   at least one shock absorber connected to said trapezoidal linkage to attenuate vertical oscillations of said linkage under use conditions;   whereby when force is applied in one vertical direction to one end of said yoke, said linkage arms are forced in counter rotation about said first and second pivot mounting means respectively to induce a similar vertical force applied in a similar direction to the other side of said yoke thereby to maintain said yoke in a substantially level position while said biasing means applies a restoring force to urge said trapezoidal suspension linkage to its normal arrangement. .Iaddend..Iadd.5. The apparatus of claim 4 wherein said yoke is a horizontal beam adapted for mounting to said frame and said articulated linkage is located above said yoke, said left and right link arms being pivotally connected together such that said arms may rotate about said first and second pivot mounting means respectively while having their adjacent ends pivotally connected together substantially on said center line. .Iaddend..Iadd.6. The apparatus of claim 5 wherein said first and second side links are inclined inwardly and upwardly from their respective pivotal connections to said yoke to their respective connections on said left and right link arms. .Iaddend..Iadd.7. The apparatus of claim 6 wherein said biasing means comprises first and second coil springs, each located respectively between said yoke and an associated one of said first and second link arms at a location outboard of a connection of said associated link arm to said frame such that a downward force on said yoke will cause said link arms to counter-rotate and thereby compress said first and second springs, said springs exerting respective forces to restore said link arms to their original positions, and said shock absorber acting to attenuate resulting vibrations. .Iaddend..Iadd.8. The apparatus of claim 7 further comprising a second shock absorber connected to said suspension linkage connected in said apparatus for attenuating non-vertical oscillations of said yoke. .Iaddend.