Steering system for a multiple vehicle train

A steering system for a multiple vehicle train that is pulled by a prime mover. A series of connected adjacent leading and trailing vehicles each have a single axle mounted under a rear body portion and are equipped with a triangular linkage. The linkage is defined by three connections: a pivotal connection of the axle to a rear portion of the vehicle body; a pivotal connection between the bodies of the leading and trailing vehicles; and a fore and aft movable connection between the body of the trailing vehicle and a tongue that extends back from the axle. When the vehicle train is traveling straight ahead, the movable connection is in its forwardmost position and the three connection points are aligned in a straight line where the axle is disposed perpendicular to the direction of travel. When the prime mover turns to the right the movable connection moves back and the connection points form a triangle which acts to pivot the axle to the left of its perpendicular position causing the rear of the vehicle to closely track the path of the front of the vehicle. When a left turn is made the linkage acts to pivot the axle to the right causing the rear of the vehicle to closely track the front. The steering system allows a multiple vehicle train to maneuver through relatively narrow passageways since the vehicles closely follow the path of the prime mover.

CROSS-REFERENCE TO RELATED APPLICATIONS
 Not Applicable
 STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
 Not Applicable
 BACKGROUND OF THE INVENTION
 1. Field of the Invention
 This invention relates generally to the field of steering systems, and more
 particularly to a steering system for multiple vehicle trains.
 2. Description of the Related Art
 As can be seen by reference to the following U.S. Pat. Nos. 3,891,238;
 4,382,607; 4,484,758; 5,071,152; 5,163,698; and 5,477,937, the prior art
 is replete with myriad and diverse steering systems.
 While all of the aforementioned prior art constructions are more than
 adequate for the basic purpose and function for which they have been
 specifically designed, they are uniformly deficient with respect to their
 failure to provide a simple, efficient, and practical steering system for
 multiple vehicle trains.
 Maneuverability of multiple vehicle trains is a concern for example in
 farming applications where multiple vehicles, such as, for example, a
 train of multiple feed bunks, must be moved through narrow gates or around
 buildings or other obstructions.
 As a consequence of the foregoing situation, there has existed a
 longstanding need for a new and improved steering system and the provision
 of such a construction is a stated objective of the present invention.
 BRIEF SUMMARY OF THE INVENTION
 Briefly stated, the present invention provides a steering system for a
 multiple vehicle train that is pulled by a prime mover. A series of
 connected adjacent leading and trailing vehicles each have a single axle
 mounted under a rear body portion and are equipped with a triangular
 linkage. The linkage is defined by three connections: a pivotal connection
 of the axle to a rear portion of the vehicle body; a pivotal connection
 between the bodies of the leading and trailing vehicles; and a fore and
 aft movable connection between the body of the trailing vehicle and a
 tongue that extends back from the axle. When the vehicle train is
 traveling straight ahead, the movable connection is in its forwardmost
 position and the three connection points are aligned in a straight line
 where the axle is disposed perpendicular to the direction of travel. When
 the prime mover turns to the right, the movable connection moves back and
 the connection points form a triangle which acts to pivot the axle to the
 left of its perpendicular position, causing the rear of the vehicle to
 closely track the path of the front of the vehicle. When a left turn is
 made the linkage acts to pivot the axle to the right, causing the rear of
 the vehicle to closely track the front. The steering system allows a
 multiple vehicle train to maneuver through relatively narrow passageways
 since the vehicles closely follow the path of the prime mover.

DETAILED DESCRIPTION OF THE INVENTION
 As can be seen by reference to the drawings, and particularly to FIGS. 3,
 9, 10, 11, a steering system (10) that forms the basis of the present
 invention is utilized in each of the vehicles (11) attached in series and
 being pulled by the tractor or prime mover (1). FIGS. 1 and 2 illustrate
 that each successive leading and trailing vehicle closely follows the path
 of the prime mover (1) providing snake-like manueverability of the
 vehicles (11) as the vehicle train moves between and around obstacles such
 as fence posts (3) and trees (5).
 It should be understood that while the steering system (10) of the present
 invention is shown and described particularly with reference to the use of
 the steering system (10) on a train of feed bunks, this is but one
 practical application of the steering system (10) of the present
 invention. Thus, the identification of feed bunks as the vehicles (11) to
 which the steering system (10) has been adapted are included in this
 specification only for the purpose of providing an enabling disclosure and
 for disclosing the inventor's best mode for practicing the invention at
 the time the application was filed. Therefore, it should be readily
 appreciated that the steering system (10) of the present invention may be
 adapted to any other types of single axle or double axle vehicles (11),
 such as wagons, implements, etc. that may need to be connected in series
 to be towed behind a prime mover. Thus, the scope of the present invention
 should not be considered limited to the particular application shown and
 discussed herein.
 Turning now to a particular embodiment and application of the steering
 system (10) of the present invention, as most clearly shown in FIGS. 3-5,
 each of the feed bunks (11) include a body (12) having a top peripheral
 rim (14) with connection plates (16) extending from the front and rear.
 The front section of the underside of the body (12) carries a pair of
 spaced brackets (18), and the rear section of the underside of the body
 (12) carries an axle mounting plate (20). Ground wheels (22) are mounted
 on a single axle (24) and a forwardly extending elongated tongue (26) is
 operably attached to the axle (24) and extends normal thereto. A bar (28)
 having a stop (30) at the rear is slidably engaged in the brackets (18)
 for aligned fore and aft movement with respect to the body (12). As best
 illustrated in FIGS. 9-11, the axle (24) of the leading vehicle is
 pivotally attached at a first connection (40), the leading vehicle is
 pivotally attached to the trailing vehicle at a second connection (50),
 and the tongue (26) is pivotally attached to the sliding bar (28) at a
 third connection (60). The three pivotal connections (40, 50, 60) and
 their relation to the operation of the steering system (10) of the present
 invention are discussed in further detail later.
 A hitch attachment and end stand (70) is provided for attachment of the
 forwardmost feed bunk (11) to the prime mover (1) as illustrated in FIGS.
 7 and 8. The hitch attachment (70) includes an end stand having a pair of
 legs (72) with upper hooked ends (74) that attach to opposing sides of the
 feed bunk rim (14). Bracing (78) extending forward of the ground engaging
 feet (76) of each leg (72) supports a pin (80) that engages an opening in
 the plate (16), and supports a pivotally attached clevis (90) for
 attachment to the prime mover (1). The hitch attachment and end stand (70)
 may be easily and conveniently removed from the feed bunk as needed, such
 as to add another feed bunk to the front of the vehicle train. The end
 stand (70) is then easily and conveniently attached to the forward most
 feed bunk of the train. When the feed bunks have been towed to the desired
 location, the prime mover (1) is simply un-hitched from the end stand
 (70), which then acts to support the forward end of the bunk (11) in a
 substantially horizontal position.
 The novel operation of the steering system (10) of the present invention
 allowing for the snake-like manueverability of the vehicles (11) will be
 readily appreciated in the following description of the operation of the
 steering system.
 Operation of the Steering System
 As mentioned previously, and as best illustrated in FIGS. 9-11, the axle
 (24) of the leading vehicle is pivotally attached at a first connection
 (40), the leading vehicle is pivotally attached to the trailing vehicle at
 a second connection (50), and the tongue (26) is pivotally attached to the
 sliding bar (28) at a third connection (60).
 The connections (40), (50), and (60) define a triangular linkage best
 illustrated by reference to FIGS. 3, 10 and 11. The first leg of the
 triangle is the fixed horizontal distance between the vertical axes of
 connection (40) and connection (50). The second leg is the fixed
 horizontal distance between the vertical axes of connection (40) and
 connection (60), which in the embodiment shown is the length of the tongue
 (26). The third leg is the variable horizontal distance between the
 vertical axes of connection (50) and connection (60). The third connection
 (60) is preferably located rearwardly of connection (50) by a horizontal
 distance of about twelve inches when the vehicles are in line as shown in
 FIG. 9. However, it is to be understood that the relative position of the
 connections (40), (50) and (60) may be modified for other vehicles to
 provide appropriate clearances and range of motion of the axle (24) and
 adjacent vehicles (11). For example, the greater the horizontal distance
 between the second and third connections (50, 60) the sharper (i.e.
 smaller radius of curvature) the vehicles (11) will be able to turn,
 assuming there is also enough clearance between adjacent ends of the
 vehicles (11). Likewise, as the horizontal distance between the second and
 third connections (50, 60) decreases the larger will be the radius of
 curvature.
 In the preferred embodiment of the steering system (10) for the feed bunks
 (11) illustrated in the drawings, when the vehicles (11) are traveling in
 a substantially straight line (FIG. 9), the three connections (40, 50, 60)
 are substantially aligned along the longitudinal axis of the vehicle
 train. As the prime mover (1) makes a turn (see FIGS. 1 and 2), the
 forward end of the forwardmost vehicle (11), pivotally attached to the
 prime mover (1), will be pulled in the direction of the turn. For example,
 upon a right turn as illustrated in FIG. 10, the leading vehicle (11a)
 will pivot about the vertical axis of the second connection (50) while the
 trailing vehicle (11b) will continue along a substantially straight line
 of travel until the transverse pulling force of the leading vehicle (11a)
 causes the forward end of the trailing vehicle (11b) to be pulled to
 follow the leading vehicle (11a) (i.e. to the right). As the forward end
 of the leading vehicle (11a) turns, the axle (24) at the rear of the
 leading vehicle (11a) will tend to rotate in the opposite direction about
 the vertical axis of the first connection (40) (i.e. to the left in FIG.
 10). This is so because one end of the fixed-length tongue (26) is
 attached substantially perpendicular to the pivotal axle (24) and the
 other end of the tongue (26) is pinned at connection (60) to the sliding
 bar (28), which can only move fore and aft along the longitudinal axis of
 the vehicle (11).
 As the leading vehicle (11a) continues to turn, the tongue (26) forces the
 sliding bar (28) rearwardly as indicated by arrow (61) (FIG. 10). This is
 so because, as the leading vehicle (11a) begins to turn, the horizontal
 distance between any point on the leading vehicle (11a) and any point on
 the trailing vehicle (11b) correspondingly decreases. However, because the
 length of the tongue (26) is fixed, as the leading vehicle (11a) turns,
 the sliding bar (28) must move rearwardly to accommodate the fixed length
 of the tongue (26) as the horizontal distance between the leading and
 trailing bunks (11a, 11b) decreases. As the vehicles (11) straighten out
 from the turn (see FIG. 9), the third connection (60) will move forward
 until it returns to its forwardmost position as indicated in dashed lines
 in FIG. 10. FIG. 11 shows the operation of the steering system (10) when
 the vehicles are turning to the left.
 It should be appreciated that on the rearmost trailing vehicle (11) the
 tongue (26) will not be connected to a slide bar (28). Thus, if the tongue
 (26) is not secured in some manner, the axle (24) on the rearmost trailing
 vehicle would be free to pivot uncontrolled. To prevent this, FIG. 6
 illustrates one method of securing the rearmost axle (24) by reversing or
 flipping or rotating the axle assembly such that the tongue (26) on the
 rearmost trailing vehicle (11) is pointed forward and is then secured to a
 tongue bracket (19) attached to the underside of the body (12). Obviously,
 there are many other means of securing the axle (24) of the rearmost
 vehicle, such as by inserting locking pins in the axle mounting plate (20)
 to prevent the axle from rotating about connection (40).
 Therefore, although only an exemplary embodiment of the invention has been
 described in detail above, those skilled in the art will readily
 appreciate that many modifications are possible without materially
 departing from the novel teachings and advantages of this invention.
 Accordingly, all such modifications are intended to be included within the
 scope of this invention as defined in the following claims.