Patent Publication Number: US-2013248619-A1

Title: Applicator boom tilt frame

Description:
RELATED APPLICATION 
     This is a continuation of Ser. No. 12/636,455, filed Dec. 11, 2009, entitled APPLICATOR BOOM TILT FRAME, which is hereby incorporated in its entirety by reference herein. 
    
    
     BACKGROUND 
     1. Field 
     The present invention relates generally to agricultural boom applicators. More specifically, embodiments of the present invention concern an applicator assembly with a tilt frame that permits tilting of an applicator boom. 
     2. Discussion of Prior Art 
     Boom applicators are used in agricultural applications to apply chemicals, such as pesticides, herbicides, or fertilizers, to a field. Prior art boom applicators include a boom assembly with a pair of booms that are supported by and extend laterally in opposite directions from a vehicle. The booms support equipment for discharging material at predetermined locations along the width of the boom assembly (e.g., a spray applicator that includes high pressure lines and nozzles mounted on the booms). Prior art boom applicators also include mechanisms that allow the boom assembly to tilt about a longitudinal axis (e.g., fore-and-aft axis) of the applicator and relative to the vehicle, particularly when traveling over uneven ground. 
     Prior art boom applicators are deficient and suffer from various undesirable limitations. For example, conventional boom applicators that permit tilting movement of the boom assembly are excessively heavy. The weight of prior art boom assemblies can cause damage to the booms or to another part of the applicator during conventional spraying operations, particularly when spraying is conducted over undulating terrain. Furthermore, conventional boom applicators generally support the boom assembly in a cantilevered configuration, with the weight of the booms located at an undesirable longitudinal distance from the vehicle. The conventional cantilevered support designs also promote a supporting structure that is unduly heavy. 
     SUMMARY 
     Embodiments of the present invention provide a tilting boom applicator that does not suffer from the problems and limitations of the prior art applicators set forth above. 
     A first aspect of the present invention concerns a tilting boom applicator that broadly includes a laterally-extending applicator boom, a lift, and a tilt frame. The lift supports the applicator boom and is operable to vertically shift the applicator boom. The lift includes a first lift arm and a second lift arm extending longitudinally relative to the applicator boom. The tilt frame interconnects the applicator boom and lift. The tilt frame includes a first frame section mounted to the first lift arm and a second frame section mounted to the applicator boom. The first and second frame sections are attached to each other at a frame pivot joint that defines a longitudinal tilt axis, with the frame pivot joint permitting tilting movement of the applicator boom relative to the lift about the longitudinal tilt axis. The second lift arm is directly attached to the second frame section and serves to limit movement of the applicator boom relative to the lift about a lateral pitch axis while permitting the tilting movement. 
     Other aspects and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments and the accompanying drawing figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
       Preferred embodiments of the invention are described in detail below with reference to the attached drawing figures, wherein: 
         FIG. 1  is a front perspective of a tilting boom sprayer constructed in accordance with a preferred embodiment of the present invention and broadly including a boom assembly, a lift assembly, and a tilt frame, and showing the lift assembly in an upper lift position; 
         FIG. 2  is a fragmentary front perspective of the tilting boom sprayer shown in  FIG. 1 , showing the base, upper lift arms, lower lift arms, and lift cylinders of the lift assembly, with the lift assembly in a lower lift position; 
         FIG. 3  is a fragmentary rear perspective of the tilting boom sprayer shown in  FIGS. 1 and 2 , showing the tilt frame positioned between and interconnecting the lift assembly and the boom assembly, with the lift assembly in the lower lift position; 
         FIG. 4  is an enlarged fragmentary front perspective of the lift assembly and tilt frame shown in  FIGS. 1-3 , showing a fixed section of the tilt frame attached to the upper lift arms and a swinging section of the tilt frame attached to the lower lift arms; 
         FIG. 5  is a fragmentary front elevation of the tilting boom sprayer shown in  FIGS. 1-3 , showing the fixed and swinging sections of the tilt frame in an untilted frame position, with the boom assembly in a corresponding untilted boom orientation; 
         FIG. 6  is a fragmentary front elevation of the tilting boom sprayer shown in  FIGS. 1-3  and  5 , showing the fixed and swinging sections of the tilt frame in a tilted frame position, with the boom assembly in a corresponding tilted boom orientation; 
         FIG. 7  is an exploded perspective of the tilt frame shown in  FIGS. 1-6 , showing the fixed and swinging sections and spring-and-damper assemblies of the tilt frame; 
         FIG. 8  is a fragmentary front perspective view of the tilting boom sprayer shown in  FIGS. 1-3  and  5 - 6 , showing the tilt frame and the lower lift arms pivotally attached to the tilt frame at ball pivot joints; 
         FIG. 9  is a fragmentary front elevation of the tilting boom sprayer shown in  FIGS. 1-8 , showing the tilt frame in the untilted frame position and partly showing the lower lift arms pivotally attached to the tilt frame; 
         FIG. 10  is a fragmentary cross section of the tilting boom sprayer taken along line  10 - 10  in  FIG. 9 ; 
         FIG. 11  is a fragmentary top view of the tilting boom sprayer shown in  FIGS. 1-10 , showing the tilt frame in the untilted frame position, and partly showing the lower lift arms pivotally attached to the tilt frame; 
         FIG. 12  is a front elevation of the tilt frame shown in  FIGS. 1-11 , showing the tilt frame in the tilted frame position; and 
         FIG. 13  is a cross section of the tilt frame taken along line  13 - 13  in  FIG. 10 . 
     
    
    
     The drawing figures do not limit the present invention to the specific embodiments disclosed and described herein. The drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the preferred embodiment. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Turning initially to  FIG. 1 , a tilting boom sprayer  20  is mounted on a vehicle (not shown) for applying material. In particular, the illustrated sprayer  20  is useful in agricultural spraying applications such as applying various material (e.g., liquid or dry chemicals) to a crop field. The sprayer  20  is preferably configured to be mounted to a self-propelled vehicle (e.g., a tractor or truck) for travel in a forward direction (indicated by the arrow in  FIG. 1 ) along longitudinal axis A 1  of the sprayer  20 . However, is also within the scope of the present invention where the sprayer  20  is mounted to a towed vehicle (e.g., a wheeled trailer). While the illustrated sprayer  20  is configured as a liquid spraying applicator it is also in the scope of the present invention where the sprayer  20  comprises another type of liquid applicator or comprises another type of applicator such as a granular chemical applicator. The tilting boom sprayer  20  broadly includes a sprayer boom assembly  22 , a sprayer lift assembly  24 , and a tilt frame  26 . As will be discussed further, the sprayer  20  is mounted such that the lift assembly  24  is preferably positioned forwardly of the boom assembly  22 , with the boom assembly  22  extending in a lateral direction. However, the principles of the present invention are applicable where the lift assembly  24  is positioned rearwardly of the boom assembly  22  (e.g., where the sprayer  20  is mounted to the front of a vehicle). 
     Turning to  FIGS. 1-3 , the illustrated boom assembly  22  serves to support pressurized sprayer equipment (not shown) including a plurality of pressure lines and nozzles. Pressurized spray nozzles are positioned at predetermined, laterally spaced locations (not shown) to provide a desired pattern of coverage. The boom assembly  22  broadly includes a central boom support frame  28  and booms  30  spaced on opposite sides of the support frame  28 . The illustrated support frame  28  preferably comprises a rigid weldment and includes lateral members  32 , 34 , 36  and upright end members  38  spaced adjacent opposite ends of the support frame  28 . The support frame  28  also includes a pair of upright connector members  40  spaced between the end members  38  and interconnecting the lateral members  32 , 34 , 36 . The connecter members  40  each comprise channel shaped sections that present an elongated slot and include upper, intermediate, and lower lugs  42 , 44 , 46  on opposite sides of the slot. The lugs  42 , 44 , 46  present corresponding openings, with the lugs  42 , 44 , 46  serving as attachment locations so that the support frame  28  can be removably attached to the tilt frame  26 . However, the principles of the present invention are equally applicable where the support frame  28  is alternatively configured for removable attachment to the tilt frame  26  and to support the booms  30 . 
     The booms  30  extend laterally from the support frame  28  and broadly include an upright post  48  and truss assembly  50 . The upright post  48  is elongated and presents upper and lower ends  52 , 54 . The upright post  48  is pivotally attached to the support frame  28  adjacent the ends  52 , 54  at upper and lower boom pivot joints  56 , 58 . As will be discussed, the illustrated boom pivot joints  56 , 58  permit pivotal movement of the booms  30  relative to the support frame  28  about respective vertical boom pivot axes. 
     The truss assembly  50  comprises a pair of inboard and outboard truss frames  60 , 62  attached end to end and foldable relative to each other. However, it is also within the scope of the present invention where the truss assembly  50  is alternatively configured, e.g., where the truss assembly  50  comprises a single rigid frame. The truss assembly  50  is pivotally attached to the upright post  48  at a boom tilt joint  64  adjacent an inboard truss end. The illustrated boom tilt joint  64  is also preferably located adjacent the lower end  54  of upright post  48 . With the booms  30  in an unfolded operating position (see  FIG. 1 ), the illustrated booms  30  and support frame  28  preferably present a total boom width of the sprayer  20  (measured from one outboard end of one truss assembly  50  to the outboard end of the other truss assembly  50 ) that preferably ranges from about twenty (20) feet to about one hundred fifty (150) feet. More preferably, the boom width ranges from about fifty (50) feet to about one hundred (100) feet and, most preferably, the boom width is about ninety (90) feet. 
     The boom assembly  22  also includes a pair of boom tilt cylinders  66  each pivotally attached to a corresponding upright post  48  adjacent the upper end  52  and also attached pivotally to the corresponding truss frame  60  adjacent the inboard end of the truss assembly  50 . The illustrated cylinder  66  controls tilting movement of the truss assembly  50  relative to the support frame  28  about a generally horizontal axis. The boom assembly  22  further includes a boom pivot mechanism  67  that interconnects the booms  30  and the support frame  28 . The boom pivot mechanism  67  includes hydraulic cylinders  67   a , springs, and dampers mounted rearwardly of the support frame  28 , with cylinder pistons pivotally attached to corresponding inboard truss frames  60 . The hydraulic cylinders  67   a  of boom pivot mechanism  67  are operable to pivot the booms  30  relative to the support frame  28  about respective vertical boom pivot axes (see  FIG. 3 ). 
     Again, the illustrated booms  30  and support frame  28  are configured to support pressure lines and nozzles (not shown) at predetermined spaced locations along a lateral direction. However, it is within the ambit of the present invention where the booms  30  and support frame  28  are alternatively constructed to support the pressure lines and nozzles. In use, the booms  30  extend laterally during operation of the sprayer  20  and are shiftable relative to the support frame  28  about the vertical boom pivot axes. In particular, the pivot mechanism  67  can shift the booms  30  out of the unfolded operating position (see  FIG. 1 ) by pivoting the truss assemblies  50  forwardly into a folded storage position (not shown). In the folded storage position, the truss assemblies  50  extend substantially parallel to longitudinal axis A 1  of the sprayer  20 . Similarly, pivot mechanism  67  can shift the booms  30  rearwardly from the folded storage position into the unfolded operating position to permit use of the sprayer  20 . 
     Turning to  FIGS. 2-8 , the lift assembly  24  is operable to support and selectively position the boom assembly  22  relative to the ground (not shown) by shifting the boom assembly  22  along a vertical direction. The lift assembly broadly includes a base  68 , upper and lower lift arms  70 , 72 , braces  74 , and arm lift cylinders  76 . The base  68  is conventional and includes a pair of upright channel sections  78  and abase frame  80  that rigidly interconnects the upright channel sections  78 . Each channel section  78  presents a rearwardly facing slot  82  configured to receive upper and lower lift arms  70 , 72 . The channel section  78  also presents openings  84  that serve as arm attachment locations (see  FIGS. 2 and 3 ). Furthermore, the channel section  78  presents intermediate openings  86  spaced vertically between openings  84 , with the openings  86  configured for pivotal connection of the channel section  78  to corresponding arm lift cylinders  76  (see  FIG. 3 ). 
     Turning to  FIGS. 2-4 , upper lift arms  70  comprise elongated tubular beams and present fore ends  88  (see  FIGS. 2 and 3 ) and aft ends  90  (see  FIGS. 2 and 4 ). The upper lift arms  70  extend longitudinally and are spaced side by side. The arms  70  are rigidly connected by the tubular braces  74 , which extend laterally between the arms  70  and are spaced longitudinally between the fore and aft ends  88 , 90 . The illustrated braces  74  and upper lift arms  70  cooperatively form a rigid weldment. While the illustrated arms  70  preferably present a fixed length, it is also within the scope of the present invention where arms  70  have an adjustable length. The upper lift arms  70  also include lower lugs  92  positioned adjacent the aft end  90  and attached to a lower surface of the tubular beam (see  FIG. 4 ). The upper lift arms  70  are pivotally attached to the base  68  by inserting the fore ends  88  into corresponding slots  82  and inserting pins  94  through openings  84  in the channel section  78  and through corresponding openings in the fore end  88 , with the upper lift arms  70  and base  68  cooperatively forming upper base pivot joints  96 . 
     Turning to  FIGS. 2-4 , the arm lift cylinders  76  comprise conventional hydraulic cylinders and each broadly includes a cylinder housing  98  and piston  100 . The lift cylinders  76  are each attached to the corresponding upper lift arm  70  by attaching an aft end of the piston  100  to the lower lug  92  at a piston pivot joint  102  (see  FIG. 4 ). The cylinders  76  are also attached to the base  68  by attaching a fore end of the cylinder housing  98  within the corresponding slot  82  of the channel section  78 . The fore end of the cylinder housing  98  is attached by extending a pin  94  through intermediate opening  86  and through the fore end of the cylinder housing  98 , with the cylinder housing  98  and the base  68  cooperatively forming a cylinder pivot joint  104  (see  FIG. 2 ). 
     Thus, the cylinders  76  connect the upper lift arms  70  to the base  68 , and are operable to shift the upper lift arms  70  relative to the base  68 . As each cylinder  76  moves the piston  100  in and out of the cylinder housing  98  between extended and retracted cylinder configurations, the piston  100  causes corresponding vertical movement (i.e., downward movement and upward movement) of the upper lift arm  70  relative to the base  68 . Preferably, the illustrated cylinders  76  are configured to move the pistons  100  at the same time so that the upper lift arms  70  move with one another. 
     The lift assembly  24  also includes an elongated chock  105  pivotally mounted to the left-hand piston pivot joint  102  (see  FIG. 4 ). The chock  105  is positioned between the left-hand upper lift arm  70  and the cylinder  76  and is operable to pivot downwardly into engagement with an aft end of the cylinder housing  98  to selectively lock the cylinder  76  into the extended cylinder configuration. While the illustrated lift assembly  24  preferably includes a pair of cylinders  76  that cooperatively move the upper lift arms  70 , it is also within the scope of the present invention where an alternative number or configuration of cylinders are used to control movement of the upper lift arms  70 . Furthermore, it is also within the scope of the present invention where the lift assembly  24  includes a powered mechanism other than the illustrated hydraulic cylinder arrangement for lifting and lowering the lift arms  72 , 74 , the tilt frame  26 , and boom assembly  22 . 
     Turning again to  FIGS. 2-4 , lower lift arm  72  includes an elongated member  106  and oppositely spaced ball bearing assemblies  108  mounted to corresponding ends of the elongated member  106 . The illustrated lift arm  72  preferably presents a fixed length, but it is also within the ambit of the present invention where lift arm  72  has an adjustable length. The ball bearing assembly  108  includes a housing  110  with a cage (not shown), and a spherical sleeve  112  mounted in the housing  110  (see  FIG. 13 ). The lower lift arms  72  are pivotally attached to the base  68  at a lower base pivot joint  114  by inserting pins  94  through corresponding openings  84  and through an opening presented by the spherical sleeve  112 , with the lower base pivot joint  114  permitting relative pivotal movement between the lower lift arms  72  and base  68  about a lateral pitch axis and about a vertical arm pivot axis. In this manner, the lower base pivot joint  114  permits relative up and down pivotal movement of the lower lift arm  72  relative to the base  68  and also a limited amount of lateral pivotal movement of the lower lift arm  72  relative to the base  68 . 
     Turning to  FIGS. 4-13 , the tilt frame  26  serves to interconnect the lift assembly  24  and the boom assembly  22 . Furthermore, the tilt frame  26  permits relative tilting movement between the lift assembly  24  and the boom assembly  22  and dampens movement of the boom assembly  22  relative to the lift assembly  24 , as will be discussed in greater detail. The illustrated tilt frame  26  broadly includes a fixed section  116 , a swinging section  118  operable to tilt relative to the fixed section  116 , and spring-and-damper assemblies  119  extending between the sections  116 , 118 . 
     Turning to  FIGS. 7-13 , the fixed section  116  serves to interconnect aft ends  90  of the upper lift arms  70 . The fixed section  116  includes a tubular body  120  and opposite arm mounting brackets  122  rigidly attached to corresponding ends of the body  120 . The illustrated body  120  and brackets  122  preferably comprise a weldment, however it is also within the scope of the present invention where the fixed section  116  is alternatively constructed. The arm mounting brackets  122  each include pairs of adjacent upper arm lugs  124  that cooperatively present corresponding slots  126  and openings  128 . The mounting brackets  122  also include upper mounting pins  130  that are positioned outboard of the adjacent lug  124  to support the spring-and-damper assemblies  119 . The body  120  also presents a longitudinal opening  132  that is generally centered along the length of the body  120  and receives a bushing assembly  134  of the fixed section  116  along with a pin  136  (see  FIG. 10 ). 
     The illustrated bushing assembly  134  includes inner and outer metal sleeves  138 , 140  and an intermediate elastomeric sleeve  142  (see  FIG. 10 ). The illustrated elastomeric sleeve  142  preferably comprises an elastomeric compound (e.g., nitrile rubber) but could include other types of compounds without departing from the scope of the invention. The sleeves  138 , 140 , 142  are preferably joined to form a unitary assembly, with the elastomeric sleeve  142  permitting relative movement between the metal sleeves  138 , 140 . In particular, the elastomeric sleeve  142  is configured to permit relative off-axis movement between metal sleeves  138 , 140  about a lateral pitch axis PA, as will be discussed in greater detail (see  FIG. 10 ). It is also within the scope of the present invention wherein the bushing assembly  134  is alternatively constructed to provide relative movement between inner and outer metal sleeves  138 , 140 . For example, the bushing assembly  134  could include a ball joint to permit off-axis pivotal movement. 
     The fixed section  116  is attached to the upper lift arms  70  by inserting aft ends  90  into slots  126  of upper arm lugs  124 . The fixed section  116  is then pivotally attached by extending pins  144  through openings  128  and through corresponding openings in the aft ends  90 . Thus, the fixed section  116  and upper lift arms  70  cooperatively provide upper arm pivot joints  146  that permit relative pivotal movement between the fixed section  116  and the upper lift arm  70  about the lateral pitch axis PA (see  FIG. 10 ). However, it is also within the scope of the present invention where the fixed section  116  is alternatively constructed to interconnect the upper lift arms  70 . For example the fixed section  116  and upper lift arms  70  could be interconnected by more than two upper arm pivot joints  146 . The illustrated fixed section  116  is also preferably attached to the upper lift arms  70  so that the lift arms  70  restrict the fixed section  116  from swinging about the longitudinal axis A 1  relative to the lift assembly  24 . 
     Turning to  FIGS. 4-13 , the swinging section  118  is operable to be mounted pivotally to the fixed section  116 . The swinging section  118  broadly includes a weldment  148  and a hinge assembly  150  that serves to connect the weldment  148  to the fixed section  116 , as will be discussed. The weldment  148  includes a pair of upright members  152  and an elongated base member  154  that interconnects the upright members  152 . The weldment  148  also includes an offset brace  156  that extends laterally between the upright members  152  and is spaced between upper and lower ends of the upright members  152 . The offset brace  156  includes center segment  156   a  and end segments  156   b  that extend laterally between the upright members  152 . The offset brace  156  also includes gusset segments  156   c  that extend downwardly and outwardly from the center segment  156   a  to the base member  154 . 
     The weldment  148  further includes lower arm lugs  158  positioned adjacent to ends of the lateral base member  154 , with the lower arm lugs  158  projecting forwardly of the lateral base member  154 . The weldment  148  further includes upper and lower pairs of boom lugs  160 , 162  positioned adjacent to corresponding ends of the upright member  152  and projecting rearwardly from the upright member  152  (see  FIG. 10 ). Yet further, the weldment  148  includes pairs of side lugs  164  that support lower mounting pins  166 . The mounting pins  166  are positioned outboard of the upright members  152  to support the spring-and-damper assemblies  119 . The weldment  148  also includes guide plates  168  attached adjacent corresponding upper ends of the upright members  152  and positioned forwardly of adjacent upper boom lugs  160 . As will be discussed in greater detail, the illustrated guide plates  168  present horizontal and vertical guide surfaces configured to engage the fixed section  116  during relative tilting movement between the sections  116 , 118 . 
     Turning to  FIG. 2 , the swinging section  118  is removably attached to the boom assembly  22  by connecting lugs  44 , 46  of connector members  40  to corresponding upper and lower boom lugs  160 , 162 . In particular, the boom support frame  28  is positioned rearwardly of swinging section  118  with lugs  160 , 162  extending into the slots presented by the connector members  40 . Pins  170  are removably inserted through adjacent openings in corresponding lugs  44 , 46  and lugs  160 , 162  to preferably provide a rigid connection between the swinging section  118  and boom support frame  28 . However, the swinging section  118  could be alternatively attached to the support frame  28  without departing from the scope of the present invention. 
     Turning again to  FIGS. 4-13 , the hinge assembly  150  connects the fixed section  116  and the weldment  148  so that the swinging section  118  is generally positioned below and hangs from the fixed section  116 . While the illustrated relationship between sections  116 , 118  could be switched, it is preferable that one of the sections  116 , 118  is generally above or below the other section  116 , 118  to minimize the fore and aft extent of the tilt frame  26 . The hinge assembly  150  includes a pair of hinge plates  172 , upper bushings  174 , 176 , lower bushings  178 , and lower fasteners  180  (see  FIGS. 7 and 10 ). The hinge plates  172  are generally L-shaped and each present a pair of integral plate segments  182  that extend from an upper end  184  of the plate  172  to respective lower ends  186  of the plate  172  (see  FIGS. 7 and 9 ). The hinge plates  172  also present upper and lower holes  188 , 190  adjacent corresponding ends  184 , 186 , with the upper holes  188  receiving respective upper bushings  174 , 176  (see  FIGS. 7 and 10 ). 
     The hinge plates  172  are attached to the tubular body  120  and the offset brace  156  on respective fore and aft sides thereof. The lower ends  186  are attached to the offset brace  156  by inserting lower bushings  178  into corresponding holes in the offset brace  156  and securing the lower ends  186  with lower fasteners  180 . The upper end  184  is attached to the tubular body  120  by inserting upper bushings  174 , 176  into corresponding upper holes  188 , and inserting the pin  136  through the bushings  174 , 176  and the bushing assembly  134 , with the pin  136  being secured by a fastener  192  that extends through transverse holes in the bushing  174  and pin  136 . In this manner, the sections  116 , 118  cooperatively form a frame pivot joint  194  that defines a longitudinal frame pivot axis A 2  extending along the longitudinal sprayer axis A 1 . The frame pivot joint  194  permits the swinging section  118  to pivot relative to the fixed section  116  about the longitudinal frame pivot axis A 2 . Preferably, the frame pivot joint  194  comprises the only direct pivotal connection between sections  116 , 118 , but the tilt frame  26  could be constructed to provide an alternative connection between sections  116 , 118  (e.g., a four-bar linkage) without departing from the scope of the present invention. As will be discussed further, the frame pivot joint  194 , via the bushing assembly  134 , permits a limited amount of relative pivotal movement between the sections  116 , 118  and between the lift assembly  24  and boom assembly  22  about the lateral pitch axis PA. 
     The fixed and swinging sections  116 , 118  are preferably constructed so as to be compactly positioned relative to one another, particularly along the longitudinal direction. The illustrated sections  116 , 118  are preferably constructed so that the swinging section  118  is located below and hangs from the fixed section  116 . More preferably, the tilt frame  26  is devoid of any part of the fixed section  116  extending below the hinge assembly  150  to provide this relative positioning of the sections  116 , 118  and to allow a predetermined amount of swinging movement between sections  116 , 118 . However, the principles of the present invention are applicable where the sections  116 , 118  are alternatively configured to provide a compact tilt frame construction. 
     Turning to  FIGS. 7-13 , the spring-and-damper assembly  119  is conventional and includes a coil spring  195  and a damper  196 . Each coil spring  195  and damper  196  present upper and lower ends that are attached to corresponding upper and lower mounting pins  130 , 166  of the tilt frame  26 . In the usual manner, the spring-and-damper assemblies  119  cooperatively dampen and control relative movement between the sections  116 , 118 . 
     During relative pivotal movement between the sections  116 , 118  about the frame pivot axis A 2 , the sections  116 , 118  present adjacent surfaces that slide relative to one another. The fixed section  116  includes a pair of pads  197  attached to the aft side of respective arm mounting brackets  122  (see  FIG. 10 ). The pads  197  present rearwardly-facing surfaces located alongside respective vertical guide surfaces  198  of guide plates  168 , with the pads  197  and guide plates  168  restricting excessive off-axis pivotal movement between the sections  116 , 118  (see  FIGS. 7 and 10 ). 
     The fixed section  116  also includes a pair of flexible stops  200  attached to underneath surfaces of respective arm mounting brackets  122 , and the stops  200  are located below the lugs  124 . The stops  200  are positioned above corresponding horizontal guide surfaces  202  of guide plates  168 , with the stops  200  and guide plates  168  restricting relative pivotal movement between the sections  116 , 118  about the frame pivot axis A 2 . In particular, the sections  116 , 118  are operable to pivot relative to one another into and out of an aligned frame position (see  FIGS. 5 and 9 ). The sections  116 , 118  can pivot out of the aligned frame position and into a tilted frame position (see  FIGS. 6 and 12 ), with the swinging section  118  operable to pivot relative to fixed section  116  through a tilt angle α measured relative to the aligned frame position (see  FIGS. 9 and 12 ). The maximum amount of tilt angle α (i.e., the angle beyond which additional tilting movement would cause damage to the tilt frame  26 ) for the illustrated tilt frame  26  preferably ranges from about one (1) degree to about ten (10) degrees. More preferably, the maximum amount of tilt angle α ranges from about two (2) degrees to about five (5) degrees and, most preferably, is about three (3) degrees. Because the swinging section  118  is rigidly attached to the support frame  28 , the boom assembly  22  is configured to shift between an untilted boom orientation associated with the aligned frame position (see  FIG. 5 ) and a tilted boom orientation associated with the tilted frame position (see  FIG. 6 ). 
     The swinging section  118  is connected directly to the lift assembly  24  by lower lift arms  72  to restrict relative pivotal movement between the sections  116 , 118  about the lateral pitch axis PA. The aft ends of lower lift arms  72  are pivotally attached to the swinging section  118  by inserting the aft ball bearing assemblies  108  between lower arm lugs  158  and inserting a pin  204  through each spherical sleeve  112  and through bushings  206  received by openings in the lower arm lugs  158  (see  FIG. 13 ). Thus, the lower lift arms  72 , lower arm lugs  158 , bushings  206 , and pins  204  cooperatively provide lower arm pivot joints  208  that each permit relative pivotal movement between the lower lift arms  72  and swinging section  118  about a lateral pitch axis, and also about a vertical arm pivot axis. 
     The illustrated base  68 , lift arms  70 , 72  and tilt frame  26  are preferably interconnected in a four-bar linkage configuration that allows the lift assembly  24  to shift the tilt frame  26  and boom assembly  22  along a vertical direction relative to the ground. In particular, the lift arms  70 , 72  are preferably configured to move between upper and lower lift positions (see  FIGS. 1 and 2 ) while maintaining the tilt frame  26  and the boom assembly  22  in a generally upright orientation. 
     With the sections  116 , 118  connected to each other, the illustrated tilt frame  26  is constructed to be compactly positioned relative to the arm pivot joints  146 , 208  along the longitudinal direction. In particular, the offset brace  156  is constructed to locate the frame pivot joint  194  so that the boom lugs  160 , 162  are positioned as far as possible in the forward direction relative to the arm pivot joints  146 , 208 . Consequently, the illustrated tilt frame  26  locates weight of the boom assembly  22  closely to the lift assembly  24 . In the illustrated embodiment, the arm pivot joints  146 , 208  cooperatively define an upright plane P, with the frame pivot joint  194  extending fore and aft of the plane P. However, it is also within the ambit of the present invention where the tilt frame  26  is alternatively configured to compactly position the boom assembly  22  relative to the lift assembly  24  (e.g., where fixed section  116  is positioned below swinging section  118 ). 
     The lower arm pivot joints  208  permit relative up and down pivotal movement of the lower lift arm  72  relative to the swinging section  118  about the respective vertical arm pivot axes. Moreover, the lower base pivot joints  114  both permit rotation about respective vertical arm pivot axes so that the lower lift arms  72  can swing side-to-side with the swinging section  118 . During relative swinging movement between the sections  116 , 118 , the lower lift arms  72  remain connected to the swinging section  118  and restrict off-axis pivotal movement of the swinging section  118  about the lateral pitch axis PA. However, because the lower lift arms  72  present a fixed arm length, the lower lift arms  72  urge the swinging section  118  to pivot slightly about the lateral pitch axis PA during swinging movement. The illustrated bushing assembly  134  has been found to provide sufficient “give” between the sections  116 , 118  of the tilt frame  26  so that the lower lift arms  72  can remain attached to the section  118  through the disclosed range of swinging movement. 
     It has also been found that the illustrated connection of lower lift arms  72  to swinging section  118  further permits the compact, vertical arrangement of sections  116 , 118  relative to each other. In particular, the fixed section  116  and hinge assembly  150  are preferably spaced above the lower arm pivot joints  208  to provide the illustrated configuration of sections  116 , 118  and also permit attachment of the lower lift arms  72  to the section  118 . However, the sections  116 , 118  and lower lift arms  72  could be alternatively configured to permit swinging movement of section  118 . 
     The lift assembly  24  and tilt frame  26  are configured to support the boom assembly  22  during travel over undulating terrain. During spraying operations, the vehicle and sprayer  20  commonly travel at elevated speeds over undulating terrain, which could cause sudden and sometimes undesirable rolling movement (i.e., movement about the longitudinal axis A 1 ) of the vehicle and sprayer  20 . It has been found that the weight of the booms  30  and the distribution of boom weight relative to the longitudinal axis A 1  applies extensive loads within the boom assembly  22  and lift assembly  24 , particularly when the sprayer  20  is exposed to rolling movement. As the boom assembly  22  swings about the longitudinal axis A 1  in response to rolling movement, the swinging section  118  moves with the boom assembly  22  and swings relative to the fixed section  116 . The spring-and-damper assemblies  119  of the tilt frame  26  serve to dampen the swinging movement and isolate the lift assembly  24  from some movement of the boom assembly  22 . The sections  116 , 118  are also constructed to limit relative swinging movement so that the sections  116 , 118  do not exceed the maximum value of tilt angle α. As a result, the sections  116 , 118  limit the maximum vertical displacement of the booms  30  due to swinging of the boom assembly  22  and thereby prevent damage to the booms  30  (e.g., from inadvertent contact between the boom  30  and the ground). 
     In operation, the tilting boom sprayer  20  is carried by a vehicle and the booms  30  are shiftable between the storage position (not shown) and the operating position. With the booms  30  in the operating position, the vertical position of the boom assembly  22  is also adjustable by moving the lift arms  70 , 72  of the lift assembly  24  up and down. Thus, the boom assembly  22  and the spray nozzles (not shown) can be precisely located relative to the ground (not shown) to control sprayer coverage. During spraying operation, the sprayer  20  can travel over undulating terrain. The illustrated tilt frame  26  permits the boom assembly  22  to swing about the longitudinal axis relative to the lift assembly  24  when exposed to rolling vehicle movement. The tilt frame  26  also dampens rolling movement of the boom assembly  22  relative to the lift assembly  24 . As a result, the tilt frame  26  restricts the sprayer  20  from becoming damaged when traveling over undulating terrain. 
     The preferred forms of the invention described above are to be used as illustration only, and should not be utilized in a limiting sense in interpreting the scope of the present invention. Obvious modifications to the exemplary embodiments, as hereinabove set forth, could be readily made by those skilled in the art without departing from the spirit of the present invention. 
     The inventors hereby state their intent to rely on the Doctrine of Equivalents to determine and assess the reasonably fair scope of the present invention as pertains to any apparatus not materially departing from but outside the literal scope of the invention as set forth in the following claims.