Note: Descriptions are shown in the official language in which they were submitted.
Backgro_ncl of the lnvention
This invention relates to the construction oE a tiltable truck bed
and more particularly but not by way of limitation to a tail gate appara-
tus for opening and closing a tail gate on a dump truck.
Heretofore, a tail gate on a dump truck has been mounted
S adjacent the vertical side walls and horizontal bottom of a truck bed.
The tail gate is generally attached to the ends of the side walls and a~
the top thereof. The bottom portion of the tail gate is allowed to pivot
outwardly from the side walls and thé bottom of the truck bed. The
tail gate is prevented irom pivoting by various types of locking devices
10 which secure the lower portion of the tail gate to the side walls and the
bottom of the truck bed. When it is desired to unload the material from
the truck bed, the operator unlocks the tail gate and the bed is raised.
~s the bed is raised, the material urges the tail gate open and the
material slides outwardly through the gate- like opening between the tail
1~ gate and the rear o~ the truck bed. When the material is unloaded, the
bed is lowered and the tail gate is locked in position against the side
walls and the bottom of the truck bed.
There are prior art tail gates having various types of hinges and
locking devices. Also there are tail gates which are raised and lowered
20 using hydraulic rams. None of the prior art tail gates disclose a tail
gate apparatus which automatically raises and lowers without the use of
a power source or does not require a locking device to prevent the tail
gate from opening while the material is being transported.
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Summary__f the Invention
The subject invention is used on the truck bed of a dump truck
for transporting heavy bulk loads such as ensilage, or lighter loads such
as hay. The tail gate apparatus does not require a mechanical, electrical,
or hydraulic lifting mechanism for raising the tail gate. The apparatus is
automatically shoved open by the force of the material as the truck bed is
raised into an unloading position. The tail gate is lowered into a position
adjacent the truck bed by gravity when the material is unloaded.
The tail gate apparatus eliminates the need of a locking device
to hold the tail gate in position on the truck bed while the material is
being transported thereby reducing the time required in locking and unlocking
the tail gate when the material is loaded and unloaded.
The invention is adjustable for mounting on various widths and
lengths of truck beds. The apparatus is also adjustable so that the pivot
axis of the tail gate can be positioned at a predetermined distance from the
rear of the truck bed so that the tail gate can be raised and lowered auto-
matically according to the type of material hauled in the truck bed.
The invention is simple in design ye~ rugged in construction and
because no mechanical9 electrical or hydraulic lifting mechanisms are
required, the maintenance in maintaining the apparatus is kept at a minimum.
The invention provides a tail gate apparatus having an offset pivot
axis for automatically opening and closing a tail gate mounted at the rear
of a tiltable truck bed mounted on a dump truck, the truck bed havin~ a
vertical front wall and vertical side walls, the tail gate disposed adjacent
the ends of the side walls and the bottom of the truck bed when the bed is
in a horizontal position, the apparatus comprising:
a pair of elongated gate arms each attached at one end to an
opposite side of the tail gate, said gate arms extending forwardly toward
the front wall;
a pair of collars, said collars attached to the other end of said
gate arms;
a pair of mounting brackets mounted on top of the side wal]s, said
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mounting brackets positioned at a predetermined distance from the rear of
the truck bed; and
an elongated pivot arm mounted hori~ontally and parallel to the
width of the truck bed, said pivot arm slidably received through said
collars, the ends of said pivot arm attached to said mounting brackets;
the tail gate, said gate arms, and said collars pivoting about
a horizontal axis through the center of said pivot arm, the hori~ontal axis
offset and forward the rear of the truck bed so that the tail gate will open
and close automatically based on the angle of the unloading position of the
truck bed from the horizontal and the pressure applied against the tail gate
by the material heing unloaded from the truck bed.
The advantages and objects of the invention will become evident
from the following detailed description when read in conjunction with the
accompanying drawings which illustrate the preferred embodiments of ~he
invention.
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Brief Description of the ~rawings
~ igure 1 is a perspective view of the tail gate apparatus attached
to the rear of a truck bed in an unloading position on a dump truck.
Figure lA is a sectional view of the rear of the truck bed.
~ igure lB is a side view of a mounting plate and a collar o-f the
5 tail gate apparatus.
~ igure 2 is a side view of the dump truck with the tail gate
apparatus mounted thereon. The truck being in a transport position.
Plgure 3 is a side view of the dump truck with the truck bed
raised and the tail gate apparatus partially opened for unloading the
lO material therein.
Pigure 4 is a side view of the dump truck with the truck bed in
a completely raised position for unloading~the material therein.
F'igure 5 is similar to ~igure 2, but illustrates the tail gate
apparatus mounted at a difEerent predetermined distance from the rear
15 of the truck bed for hauling a different material therein.
i~igure 6 is similar to ~igure 3 with the truck bed in a raised
position for unloading the material therein.
~ igure 7 is similar to l~igure 4 with the truck bed in a completely
raised position and unloading the material therein.
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Detailecl Description o-f the Drawings
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In Pigure 1, the tail gate apparatus is designated by general
xefer-ence numeral 10. The apparatus 10 includes a pair of gate arms
12, a pair of hollow collars 14, a pair of mounting brackets 16, and a
pivot arm 18.
One end of the gate arms 12 is attached tO the sides of a tail
gate 20. The tail gate 20 pivots on the gate arms 12 which are attachecl
to the sides of the hollow collars 14. The ends of the pivot arm 18 are
slidably received through the hollow collars 14 and are attached to the
mounting brackets 16. The collars 14 pivot on the pivot arm 18 about
an axis X which extends along the length of the pivot arm 18 and through
the center thereof. The mounting brackets 16 are attached to the top
of vertical side walls 22 which are secured to a tiltable truck bed 24.
- ? ;~ A vertical front wall ~is attached to the ends of the side walls 22 and
the front of the bed 24. The bed 24 is raised and lowered on a dump
15 truck 26 having a power lift means such as a hydraulic ram or the like.
In Pigure 1, the truck bed 24 is shown in a raised or unloading
position for discharging a material 28 therein. The material 28 in this
example may be considered chopped hay or the like. The hay 28 being
a lighter material than a material such as ensilage which will be dis-
20 cussed under Figures 5 through 7. While materials such as hay andensilage will be discussed, it should be understood that various types
of materials other than agricultural products such as dirt, rock, or any
other type of bulk material may be haul~d in a dump truck using the
apparatus 10.
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In l~igure lA, a perspective view of the apparatus 10 is seen
mounted in the rear of the truck bed 24. In this view, the tail gate 20
is vertically disposed against the ends of the side walls 22 and the
bottom of the truck bed 24. In this position, the truck bed 24 is in its
5 normal horizontal transport position on the truck 26. The gate arms
12 are seen with bracing 30 and 32 for rigidly securing the gate arms
12 to the inside of the tail gate ~0. In this view, the collars 14 are
shown having outwardly extending collar arms 34 whi ch ~are bolted to
the ends of the gate arms 12.
~lso seen in this view is a hollow pivot arm sleeve 36 which
is used to divide the pivot arm 18. The ends of the divided pivot arm
18 are received in the sleeve 36 and secured therein. The sleeve 36
provides means for adjusting the length of the pivot arm 18 for adapt-
ing the apparatus 10 to truck beds having various widths. The pivot
15 arm 18 is mounted horizontally on the mounting brackets 16 and posi-
tioned parallel to the width of the truck bed 24.
In ~igure lB, a detailed view of the mounting bracket~and
collar 14 is illustrated. In this view, a cross section of the pivot arm
18 with pivot axis X through the center thereof can be seen received
20 through the hollow collar 14. Extending outwardly from the collar 14
is the collar arm 34 having a plurality of apertures 37 therein. The
end of the gate arm 12 includes a plurality of apertures 38. The aper-
tures 38 of the gate arm 12 are indexed with the apertures 37 of the
collar arm 34 and secured by bolts 39 so that the length of the elongated
25 gate arm 12 can be adjusted. Similarly the rnounting bracket 16 includes
plurality of apertures 40 therein. By indexing the apertures 40 with
apertures in ~lle sides al the side wall 22 and securing the bracket 16
thereto by bolts 41, the vertical hei~ht of the mounting plate 16 can be
adjusted thereby adjusting the height of the pivot axis X.
In ~igure 2, a side view of the truck 26 with tiltable bed 2a~ is
illustrated wherein the tiltable bed 24 is in a normal horizontal trans-
port position and carrying the chopped hay material 28. In this view,
the axis X of the pivot arm 18 can be seen as a point and offset from
the top of the tail gate 20 and forward therefrom. The pivot arm 18
with axis X is mounted a distance L between a vertical line B drawn
through the rear of the truck bed 24 and a vertical line A drawn through
the center of the pivot arm 18. The tail gate 20 is pivoted about the
axis X of the pivot arm 18 via the gate arm 12 and collar 14. The
weight of the tail gate 20 in combination with the distance L produce
a moment force urging the tail gate 20 downward in a clockwise direc-
tion toward a position directly below the pivot axis X. This moment
force holds the tail gate 20 against the ends of the side walls 22 and
the bottom of the truck bed 24. The moment force is a product of the
distance L ancl the weight of the tail gate 20. The predetermined
distance L will vary depending on the type of material hauled in the
truck bed 24 and the force the material applies against the sides of
the tail gate 20. Since the weight of the tail gate 20 is constant, the
distance L must be great enough to prevent the material from raising
the tail gate 20 in a counter clockwiæe direction while the material is
2 5 being transported in the truck 26 .
3~
In ~igure 3, the truck bed 24 has been raised from a horizontal
position and the material 28 has begun to slide downwardly urgingthe
tail gate 20 outwardly in a counter clockwise direction. A~ the truck
bed 24 is raised, the pivot axis X moves toward the vertical line B.
5 The distance between line A and line B is illustrated as distance M
which is substantially less than the distance L in l~igure 2. The
moment force of the weight of the tail gate 20 and the distance M is
substantially less than the moment force of the distance L and the weight
of the tail gate 20. Therefore, the weight af the material 28 has begun
lO to overcome the moment force thereby rotating the tail gate 20 out-
wardly in a counter clockwise direction so that ~he material 28 has
automatically begun to unload from the rear of the truck bed 24.
In ~igure 4, the truck bed 24 is in a completely raised position
and the pivot axis X has now moved on the opposite side of the vertical
15 line B a distance N. In this position, the tail gate 20 would ordinarily
be floating vertically and directly below the pivot axis X. But in this
view, the tail gate 20 is extended outwardly due to the material 28
flowing through the gate-like opening at the rear of the truck bed 24.
In F~igure 5, a similar side view of the truck 26 shown in
20 l~igure 2, is illustrated except ~n this view the truck 26 is transporting
a heavier material 44 such as ensilage. Because ensilage is heavier
than the chopped hay 28, the weight of the ensilage against the inside
of the tail gate 20 is greater. Therefore, the forces tending to urge
the tail gate 20 in a counter clockwise direction are greater, and the
25 offset axis X must be readjusted so that the pivot arm 18 is posi~ioned
. .
a predetermined distance R between vertical lines A and B which is
greater than the distance L shown in ~igure 2. By adjusting the length
of the gate arrns 12 as discussed under l~igure lB and moving the
rnounting brackets 16 forward on the sides of the side walls. 22, the
5 distance L in ~igure 2 is increased to a distance R. The product of
the distance R and the weight 20 of the tail gate produces- a moment
force great enough to overcome the forces produced by the weight of
the material 44 against the inside of the tail gate 20 thereby preventing
the tail gate 20 -from opening while the material is being transported.
In .l~igure 6, the truck bed 24 is raised and the pivot axis X
moves toward the vertical line B. In this view, the distance between
lines A and B is S. The product of the distance S and the weight of
the tail gate 20 is now less than the moment force of the product of
the distance R and the weight O:e the tail gate 20 illustrated in :F igure S.
15 In l~igure 6, the force of the material 44 now in a tilted position has
now begun to overcome the moment force and the tail gate 20 is urged
outwardly in a counter clockwise direction automatically opening the ~.
tail gate 20.
In ~igure 7, the truck bed 24 is in a completely raised position
20 and the pivot axis X has now moved past the vertical line B a distance
T and the tail gate 20 is floating freely except for the material 44
which is being discharged between the rear of the truck bed 24 and the
inside of the tail gate 20.
As discussed in ~igures 2 through 7, the use of an offset axis X
25 through a horizontal pivot arm 18 for pivoting a tail gate 20 thereon
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provides a tail gate assembly 10 which automatically raises and lowers
in hauling various types of materials in a truck bed. The predetermined
distance being the horizontal distance between a vertical line through
the rear of the truck bed and a vertical line tlirough the horizoncal
pivot axis X of the pivot arm 18. The predetermined distance being
greater for heavier materials for producing a greater moment force
to offset the forces of the mate:rial t~nding to open the tail gate 20
while it is being transported. When lighter materials such as chopped
hay are transported, the predetermined distance is less since the
force of the hay against the wall gate 20 is less.
- Changes may be made in the construction and arrangement
of the parts or elements of the embodiment as disclosed herein
without departing from the spirit or scope of the invention as defined
in the following claims.
I CLAIM:
