Truck bed extension apparatus

An elongated plate, shaped to fit within a pick up truck bed, extends past the end of a opened tailgate on the truck. The plate serves to extend the usable length of the truck bed. The plate is supported at a front end by two stabilizer bars, telescoping adjustable tubular supports, which extend from the forward sides of the plate up to the inner lip of the truck bed. The rear of the plate is supported by an undercarriage which is attached to the bumper by a speed connection, which locks the undercarriage to the truck bumper.

BACKGROUND OF THE INVENTION 
This invention relates to apparatus for temporarily extending the size of 
the bed of a pick up truck, for carrying outsize loads. 
U.S. Pat. No. 4,993,088 to Chudik discloses a truck bed extension in the 
form of a flat platform which rides on rollers and rails within the bed of 
a standard truck. The extension is deployed by lowering the tailgate and 
rolling the extension on its rollers to the rear of the truck. A separate 
set of legs is provided to provide for mechanical support when extended. 
U.S. Pat. No. 2,788,137 to Harkness discloses a rearward extension for the 
trunk of a car or truck in the form of a roller supported tray which forms 
the rear floor of the truck bed or car trunk, and which can be rolled out 
and supported on legs to provide loading and unloading extension to the 
rear of the vehicle. 
U.S. Pat. No. 5,116,096 to Taylor discloses a load supporting outrigger for 
installation on a vehicle such as a truck. The outrigger comprises a frame 
attached to and supported by the tow ball in the rear bumper of the truck 
and further supported by a cable or the like extending from the rear of 
the outrigger to a vertical point of attachment on the rear corners of the 
truck. Please note FIGS. 3 through 5 for the construction of the under 
frame member which is the principle support of this device. While the 
device is shown as being attached to the tow hitch portion of the truck, 
this is a standard ball fitting and there is no rigid interconnect between 
the truck frame and the frame of the extension support. Bouncing of the 
outrigger is dampened by a rubber bushing or rigid support which extends 
up from the forward part of the outrigger, bearing on the lower tailgate 
of the vehicle so as to prevent relative vertical movement between the 
forward end of the outrigger and the rear of the vehicle. This structure 
is shown in some detail in FIG. 22. 
U.S. Pat. No. 4,856,840 to Hanley discloses a device for extending the bed 
of the truck. It comprises a particular folded metal shape at the forward 
end of a metal or aluminum plate. This shape catches as a lip between the 
lowered truck bed tailgate and the body of the truck, cantilevering 
support across the truck bed tailgate. 
U.S. Pat. No. 3,726,422 to Zelin discloses another form of sliding luggage 
rack, for extension from a stopped vehicle, and supported by external 
legs. 
U.S. Pat. No. 5,169,202 to Cupp and others discloses a work bench which may 
be attached to and become part of the tailgate of a truck. Note in FIG. 6 
that the work bench can be extended for load support when the truck is 
stopped. 
U.S. Pat. No. 3,877,714 to Black discloses a trailer attachment for pick-up 
trucks which extends load bed but does so as essentially a flat trailer 
supported by a rear wheel. It is connected at the forward end to a trailer 
hitch or the like on the vehicle. 
U.S. Pat. No. 2,468,579 to Vuori shows a truck load support. A truck is 
provided with an extending rear bumper secured by push pins to channeled 
frames underneath the truck. The bumper may be pulled out to support the 
tailgate in a first load bearing horizontal position or pulled out further 
to be in line with the bed of the truck forming an extended load support 
bracing long loads. Note: In this latter position, the device does not 
provide a continuous floor but is rather simply an extended load 
supporting beam located level with the bed of the truck, but some distance 
behind the rear of the truck tailgate. 
SUMMARY OF THE INVENTION 
The invention comprises a elongate flat plate, which may be rubber lined, 
shaped to fit within a pick up truck bed, and which extends from just 
behind the rear wheels of the truck to past the end of a opened tailgate 
on the truck. The plate serves to extend the usable length of the truck 
bed. The plate is stabilized in position at a front end by two stabilizer 
bars, telescoping adjustable compression resisting tubular supports, which 
extend from the forward sides of the plate up to the inner lip of the 
truck bed. These stabilizer bars are extended to impart a stabilizing 
force, against the plate and the truck bed lips, holding down the front of 
the plate against the truck bed. 
The rear of the plate is attached to the bumper by a unique speed 
connection. A support receiving box is attached to the rear bumper of the 
truck. This receiving box has external reinforcement, and is attached 
centrally to the bumper. The box has a flat, wide, tongue receiving 
opening, with a tapered entrance throat, to facilitate interconnection of 
the box and a undercarriage frame. Two locking screws, adjustable by 
T-handles, fit through the box to lock the undercarriage in place when 
inserted. 
The undercarriage is the primary support for the extension plate. It is a 
string trapezoidal frame having a wide rear base and two sides tapering to 
a connection plate, which is sized to fit snugly within and against the 
support box. The plate support is connected by two vertical adjustable 
supports from its rear base up to the bottom rear of the extension plate. 
The adjustable supports hold the undercarriage a spaced distance below, 
and parallel to, the extension plate. This positioning of the 
undercarriage permits the extension plate to be slid into the truck bed, 
and, as the extension plate slides into the truck bed, the undercarriage 
tongue slides into the support box. This connection is then secured by 
tightening the T-handle screws; the weight of the extension plate and load 
then is supported by the extension plate against the truck bed in front, 
and by the bumper in the rear; the tailgate supports no weight. 
To aid in the movement of the extension plate into position, two outrigger 
wheels are fit to the plate near its center of balance; these outrigger 
wheels support the plate at the appropriate height of the truck bed to 
permit the plate to be held level and rolled into position. 
It is thus an object of the invention to disclose an extension plate for a 
pick up truck which is easily installed and removed, and which permits the 
transport of oversized loads. 
It is a further object of the invention to disclose an extension plate for 
a pick up truck which does not load the tailgate of the truck. 
It is a further object of the invention to disclose an extension for a pick 
up truck bed which can be easily installed by one person. 
It is a further object of the invention to disclose an extension plate for 
a pick up truck which is rigidly supported in position by a quick 
disconnect coupling to the bumper of the truck. 
It is a further object of the invention to disclose a quick engagement 
structure for securing the front end of a truck bed extension plate within 
a pick up truck. 
These and other objects of the invention may be seen from the detailed 
embodiment disclosed below.

DETAILED DESCRIPTION OF THE INVENTION 
The invention is best shown and described in conjunction with a pick up 
truck 2 bed 3, as the invention serves to temporarily extend the length of 
such a pick up truck bed 3 for occasional carrying of loads which would 
otherwise be oversize for the pick up truck 2. 
An extension plate 6 is formed as a flat plate 8, preferably metal, such as 
aluminum or steel for rigidity. Raised peripheral sides 10 provides 
stiffening to the plate 8, and the surface 12 of the plate 8 is patterned 
with a tread surface, as is used for metal surfaces, for additional 
friction. Optionally, the surface of the plate 8 may be coated with any 
common non skid material surfacing. An optional bottom coating 16 of 
rubber or plastic may be placed on the plate to prevent marring of the 
truck bed 3 finish. 
The extension plate 6 is formed with a narrow forward end 18, of a width 
and a length chosen to match the interior dimensions of a pick up truck 
bed 3. At a point 20 on the plate 6 corresponding to the location of the 
tail gate supports 22 on the truck 2, the extension plate 6 widens out; 
the outward curvature 24 of the sides 10 is chosen to clear the rear truck 
bed walls 35 and tailgate supports 22, and then to widen to a width 26 
substantially equal to the pick up truck exterior width 27. 
Near the forward end 28 of the plate 6, on each side, a securing notch 30 
or bolt hole is cut into the peripheral sides 10. Two telescoping 
stabilizer braces 32, one on each side of the plate 6, extend between the 
plate 6 and the upper lip 34 of the truck bed walls 35. 
Each telescoping stabilizer 32 comprises a cross bar 36 welded or otherwise 
securely affixed to an upper end of a first vertical tube 38. The cross 
bar 36 may be coated with a protective, non marring coating, any smooth 
rubber or plastic material, to protect the paint finish of the truck walls 
35. 
The first vertical tube 38 is telescoped into a lower tube 40, and secured 
to the lower tube 40 by a fixture means 42 which permits the combined 
length of the upper 38 and lower 40 tubes to be set and fixed. This 
fixture 42 may be a pattern of holes 44 in each of the upper 38 and lower 
tubes 40, with a through bolt 46 through a chosen pair of holes 44, or it 
may be a continually threaded section 48 of lower tube 40 with a matching 
threaded section 50, or it may be any form of rachet mechanism which may 
be jacked and locked into position. For ease of adjustment, a combination 
of the bolted holes 44 and the threaded section 48 provides quick coarse 
adjustment of the stabilizer 32 length, and fine adjustment of the length 
once installed. 
The lower tube 40 is supported on a base member 52 which attaches to the 
plate sides 10. Preferably base member 52 has an internal threading 50, 
engaging with a matching threaded section 48 on lower tube 40, to permit 
fine adjustment of the telescoping stabilizer 32 length so as to 
positively support the plate 6 down against the truck bed 3. A clevis 54 
is affixed to the base member 52; this clevis 54 is then fastened to a 
swivel hook 56. The swivel hook 56 is hooked into the notch 30 in the 
peripheral sides 10 of the plate 6. The cross bar 36 is placed under the 
lips 34 of the truck bed side wall 35, and the telescoping tubes 38, 40 
extended to extend the stabilizer 32 between the plate 6 and the truck bed 
side wall 35 lips 34. The base member 52 is then turned until the 
stabilizer 32 is maximally extended, holding the plate 6 forward end 28 
down into the truck bed 3. The stabilizer 32 does not twist or slip 
against the truck wall 35, as any slippage of the stabilizer 32 would 
require the cross bar 36 to tilt, and the cross bar 36 cannot be tilted 
against the upward force of the stabilizer 32 
At a rear end 60, the plate 6 is fastened to the truck 2 by a quick 
disconnect coupling comprising a box end 62, which usually remains 
fastened to the truck bumper 65, which couples to an undercarriage 64 
mounted to and under the plate 6. The plate 6 and undercarriage 64 are 
removable from the truck 2, being installed only when needed; the Box end 
62 usually remains affixed to the truck bumper 65. 
The box end 62 is a tongue receiving box 62 fixed to the truck bumper 65. 
It comprises a inverted metal angle section 66 with a horizontal side 68, 
extending horizontally across the top 70 of the truck rear bumper 65. A 
vertical side 72 extends down against the rear 74 of the bumper 65. This 
angle 66 is affixed to the bumper 65 by bolting or the like; preferably 
three through bolts 76, through the horizontal side 68 into the bumper 65. 
A top horizontal bar 78 is welded to the angle 66, extending to the rear of 
the angle 66, flush with the top of the angle 66 horizontal side 68. A 
lower horizontal bar 80 is fastened parallel to the top horizontal bar 78, 
extending to the rear of the vertical side 72, forming a tongue receiving 
slot 82, two downward angled bars 84, and two outwardly angled side bars 
86 are welded to and extend from the rear of the lower horizontal bar 80 
for a distance, forming a tapered entry 88 to the tongue receiving slot 
82. Four flat stiffener bars 90, equally spaced, are welded to the top of 
the angle 66 and the top bar 78, reinforcing the connection of top bar 78 
and angle 66. Four flat metal stiffener bars 92, also equally spaced, are 
welded to the lower bar 80 and the vertical side 72 of the angle 66, to 
reinforce the connection of the lower bar 80 and angle 66. 
Two high strength screw bolts 94 are vertically mounted in threaded 
couplings 96 in the top bar 78; these screw bolts 94 extend downward into 
the tongue receiving slot 82 when screwed down. T handles 96, large enough 
to be easily manipulated by hand, are fastened to the upper ends of each 
screw bolt 94. The lower ends 98 of the screw bolts are tapered. It should 
be noted that the height of stiffener bars 90 is limited so that there is 
easy side access to T handles 96 by hand. 
T handles 96 are provided for easy hand tightening of screw bolts 94 onto 
the tongue 114, as discussed below. It may be desirable for increased 
visibility of the truck license plate, to eliminate the T handles. In this 
case, screw bolts 94 would have an upper end in the form of a Hexagonal 
drive nut, adapted to be easily tightened and loosened by a long handle 
drive wrench of common design. T handles 96 are considered preferable, as 
no external tools are required to install or remove the invention from the 
truck with the embodiment described herein. 
The undercarriage 64 is formed of a cross beam 100 extending the width 26 
of the rear 60 of the plate 6. Cross beam 100 is preferably a hollow 
square cross section beam, extending from a first end 102 to a second end 
104. At two points 106, each set a distance in from each end 102, 104, 
inwardly angled beams 108 are welded to the cross beam 100, and extend to 
a forward point 110 to a short parallel front side 112 where a forward 
extending tongue 114 is mounted. 
Short front side 112 is formed of a short horizontal angle section 115 and 
a longer horizontal angle section 116 welded apex to apex. Tongue 114 is 
the forward extending side of short angle 115. It is a flat metal section, 
with chamfered corners 118. Tongue 114 has two counter sunk holes 117 of a 
diameter slightly smaller than box screw ends 98, but centered under the 
position of each box screw 94. The width of short angle section 115, and 
the length of tongue 114 is set to fit within the tongue receiving slot 82 
in the box 62. Two vertical metal stiffener bars 120 are welded to the 
longer angle section 116 to reinforce the angle face 122. The angled beams 
108 are welded to the longer angle section 116. The center of the angle 
face 122 is cut away to form a clearance opening 124, which provides 
visibility for the truck license plate when the invention is installed. 
At each of the cross beam ends 102, 104, outboard of the point of welding 
106 of the angled beams 108, an outer collar 126 is slid onto the cross 
beam 100. Collar 126 remains removable, in order to permit the 
undercarriage and plate to be separated for more compact packing and 
shipping. Collar 126 may be secured to cross beam ends 102, 104 during 
use, and a lock pin or lock screw will be sufficient. 
A telescoping vertical support 128 extends from the outer collar 126 
upwards to the plate. An angle attaching section 130 is fit to the top of 
the telescoping support 128, and is bolted to the plate sides 10. This 
telescoping support 128 is preferably two telescoping tubes 130, adjusted 
for vertical height by a provided pattern of holes 132, with a securing 
pin 134 or bolt through a pair of holes 132 to set the vertical height of 
the support 128. Alternatively, the tubes 130 may be adjusted by a 
threaded collar, so that the tubes may be screwed together to adjust 
height, or a ratchet or similar length adjusting mechanism. The vertical 
supports 128 are adjusted to bring the height of the undercarriage tongue 
114 level with the box tongue receiving slot 82 when the plate is 6 
horizontal and resting smoothly on the bottom of the truck bed 3. Once so 
adjusted, the vertical support 128 does not have to be readjusted for a 
particular truck unless the undercarriage 64 is removed. However, the 
vertical support 128 is made separable, and is the point at which the 
undercarriage 64 is removed from the plate 6, if this should be desirable 
for storage. 
To aid in moving the plate 6 into engagement with a pick up truck 2, and in 
removing the plate 6 from the pickup truck 2, two retractable outrigger 
wheels 140 are mounted to the sides of the plate 6 at the point of balance 
142 of the assembled plate 6 and undercarriage 64. The height of these 
wheels 140 is adjustable so that, when the plate 6 is balanced on the 
wheels 140, both the plate 6 and the undercarriage tongue 114 are level 
and positioned to slide easily on to the truck bed 3 and into the box 
tongue receiving slot 82 respectively. The design of such outrigger wheels 
are common, and a height adjustable wheel mechanism such as is used on 
boat trailers and the like is suitable. The wheels 140 are fastened 
preferably to the sides 10 of the plate 6 by two U-bolts 144, although any 
suitable method of affixing can be used, such as a welded coupling. 
Further, the outrigger wheels 140, since they are used only to mount and 
dismount the plate 6, may be removable if desired. 
In use, when it is necessary to extend the length of a truck bed 
temporarily the assembled plate 6 and undercarriage 64 is balanced on the 
outrigger wheels 140, and rolled up to the rear of the truck bed 3. The 
truck tailgate is lowered and the plate 6 slid forward. The undercarriage 
tongue 114 slides into the tongue receiving slot 82, aided by the tapered 
entry 88. The plate 6 slides onto the truck bed 3 floor. The stabilizers 
32 are then installed, by hooking the clevis hook 56 into the plate lip 
notches 30. The stabilizers 32 are then extended upward until the cross 
bar 36 is snugly fit under the truck sidewall lips 34. The threaded 
coupling 50 is then adjusted to snug down the forward end 18 of the plate 
6; and the box vertical screws 94 are run down firmly upon the tongue 114, 
securing it in the slot 82. The box screws 94 tapered ends 98 fit into the 
tongue chamfered slots 117, bringing the tongue 114 into a tight fit 
within the slot 82. At this point the plate 6 is firmly mounted onto the 
truck 2, and forms a rigidly affixed extension of the truck bed 3. The 
outrigger wheels 104 are raised free of the ground level. The oversize 
cargo can then be loaded and transported. 
Visibility of the truck license plate is assured by the cut away opening 
124 in the undercarriage. In addition it is considered desirable to 
provide reflectors 150 on the sides and rear edge near the rear 60 of the 
plate 8. The entire extension plate 6 is generally below the truck rear 
lights, which are customarily mounted in the side walls 35 above the level 
of the extension plate 6. Thus use of the invention leaves safety 
visibility of the truck unimpaired. 
When it is desired to return the truck to its usual configuration, the 
outrigger wheels 104 are positioned to support the plate 6. The 
stabilizers 32 are then collapsed to bring the cross bar free of the truck 
side walls, and the hook or clevis is freed from the plate sides 10. The 
vertical screws 94 in the box are unscrewed, raining the screws 94 free of 
the tongue 114. The plate and undercarriage 64 are then rolled back free 
from the truck on the outrigger wheels 104, and the truck is restored to 
its usual configuration. 
It can thus be seen that the invention is of an improved extension 
structure, with a single plate extending beyond the length of the truck 
bed, and of a particular support for locking this extension plate to the 
truck to form a rigid extension of the truck bed. While a particular 
embodiment for the plate and the telescoping structures has been 
described, within the scope of the invention many variations in the 
detailed design of the telescoping structures and of the plate surface 
design are possible, and all are contemplated as included within the scope 
of the invention.