Lock and release mechanism for vertical adjustable deck in livestock trailers

A lock and release mechanism for vertically elevatable decks in a livestock trailer including a plurality of vertical rows of vertically spaced, pivotally mounted, locking pins located at a plurality of longitudinally spaced locations along each side of the livestock trailer. Each of the locking pins is connected to an operating arm extending radially from the axis of the pivotal locking pins. An operating rod is pivotally connected with the arms at each location for movement of all of the locking pins from a locking position to a released out of the way position by an operator at ground level. The lock and release mechanism of this invention enables livestock or other cargo to be sequentially loaded on decks at trailer floor level and sequentially raised. The deck locking pins automatically pivot out of the path of deck supporting hooks during elevation of a deck and return to a position to support the deck hooks when a loaded deck is lowered. This invention also enables the elevated decks to be lowered from a transport position to trailer floor level for unloading by elevating the decks off the pins and releasing the locking pins from a position externally of the trailer by a ground level operator utilizing a vertically elongated operating rod and spring assembly associated with the locking pins.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention generally relates to improvements in livestock 
trailers having vertically adjustable decks and more specifically includes 
a lock and release mechanism for the vertically adjustable decks which 
enables an operator to automatically lock vertically adjustable decks in 
their vertically elevated position and to effectively release the locking 
mechanism, all from a position on the ground exteriorly of the trailer. 
2. Description of the Prior Art 
Livestock trailers with multiple, vertically spaced decks are well known 
when it is desired to transport livestock having a relatively short 
vertical height. The decks are normally fixed permanently in position 
which requires elongated ramps to move the livestock onto the elevated 
decks. Alternatively, the decks are vertically adjustable and oriented at 
trailer floor level when loaded and moved to and locked in an elevated 
transport position. More specifically in movable deck trailers, the 
livestock or other cargo is placed on an uppermost deck at trailer floor 
level. The loaded deck is then elevated to a transport position and is 
locked in place by manually inserting locking pins, bolts or the like. The 
next highest vertically adjustable deck is then loaded with livestock or 
other cargo and elevated and locked in place. This procedure is repeated 
for each movable deck until the trailer is fully loaded. 
Usually, each trailer deck is supported at a plurality of longitudinally 
spaced points along each side of the trailer by removably inserting 
locking pins or bolts which requires an operator to obtain access to the 
vertically elevated points for manually manipulating the locking pins or 
bolts. Vertical access to the locking pins is usually accomplished by an 
operator climbing onto the side walls of the trailer at a plurality of 
locations to accomplish secure locking of the trailer decks in their 
transport position and subsequently releasing the trailer decks when 
unloading livestock or cargo in order for the trailer decks to be lowered. 
The locking and releasing operation is quite time consuming and subjects 
the operator to the possibility of injury when manually manipulating the 
locking pins or bolts and when climbing the side wall of the trailer. The 
danger of injury with these prior art systems is especially evident when 
considering that the loading and unloading of livestock is usually done 
outdoors in areas having supporting surfaces with various materials which 
can become attached to the shoes of an operator which introduces the 
possibility of injury to the operator especially during inclement weather. 
The following patents relate generally to this field of endeavor: 
______________________________________ 
375,764 1,774,140 
3,405,661 
384,913 2,099,774 
3,633,963 
777,732 2,129,438 
3,774,577 
1,558,224 2,529,893 
3,812,822 
1,591,033 2,970,861 
3,940,174 
______________________________________ 
The prior art requires the operator to manually place pins or bolts through 
the side wall of the trailer at each deck position while climbing up the 
side wall of the trailer to lock the adjustable decks into place and 
subsequentially release them which subjects the operator to the risk of 
slipping or falling from the trailer side. 
SUMMARY OF THE INVENTION 
The lock and release mechanism of this invention facilitates the loading 
and unloading of multiple vertically adjustable trailer decks with 
livestock or other cargo. More specifically, the instant lock and release 
mechanism includes a pivotal locking pin arrangement mounted on the side 
walls of the trailer that will automatically lock the deck or decks in 
elevated transport position and will enable the locking pins to be 
released by the operator at ground level when lowering the decks to 
trailer floor level. This enables the trailer decks to be sequentially 
locked automatically in an elevated transport position in a quick and easy 
operation and to be sequentially released from ground level to quickly 
enable the trailer decks to be lowered from an elevated transport position 
to trailer floor level position. This system therefore allows the operator 
to lock and unlock elevated decks of a livestock trailer, or the like, 
without having to scale the side walls of the trailer. 
The lock and release mechanism of the present invention includes a 
plurality of vertical rows of vertically spaced, pivotally mounted, 
locking pins located at a plurality of longitudinally spaced locations 
along each side of the livestock trailer. Each of the locking pins is 
designed to receive and support a deck supporting hook mounted on the side 
of the vertically adjustable trailer deck. An operating arm extends 
radially from the pivot axis of each pivotal locking pin, and an operating 
rod and spring assembly is associated with the arms. The operating rod and 
spring assembly acts to spring bias the locking pins to a locking position 
and to enable manual movement of the locking pins from a locking deck 
supporting position to a released out of the way position when the 
vertically adjustable decks have been lifted off of the locking pins a 
sufficient distance to enable them to pivot to the released position. 
The lock and release mechanism of this invention enables the livestock or 
other cargo to be loaded onto one, two or more decks at trailer floor 
level. The decks are then raised with the spring biased deck locking pins 
automatically pivoting out of the path of the deck supporting hooks as the 
hooks engage and pivot the pins upwardly as the upper deck passes upwardly 
past the pins. The pins engage and support the upper deck hooks when the 
decks are then lowered thereby securing the upper deck in a secure manner 
in a vertically elevated transport position. The arrangement of the 
operating arms and operating rod and spring assemblies allows the deck or 
decks below the upper deck in the transport position to be returned to 
floor level for loading additional livestock or other cargo. The lower 
deck or decks can then be sequentially elevated and locked in a similar 
manner at a spaced location or locations below the upper deck. 
This invention also enables the decks to be sequentially lowered from a 
transport position to trailer floor level for unloading the livestock or 
other cargo also from a position externally of the trailer by an operator. 
The lowermost deck is first elevated off of the locking pins for that deck 
and all locking pins below that deck are released to an out of the way 
position by the operator manipulating the elongated rod and spring 
assembly associated with the operating arms connected to each locking pin. 
The locking pins supporting any higher deck remain in supporting position. 
The lowermost deck can then be lowered to the trailer floor for unloading. 
After unloading, the lowermost deck can be raised to lift the next 
lowermost deck off its locking pins, and the sequence is repeated until 
all of the vertically adjustable decks have been sequentially lowered to 
the trailer floor level and unloaded. The rod and spring assemblies are 
preferably provided with a handle accessible to the operator standing on 
the ground surface alongside the trailer. 
When the trailer is outfitted with preferably two vertically adjustable 
decks, the release mechanism includes a sectional rod having a short upper 
segment and a longer lower segment. The upper segment is pivoted to the 
operating arm on an uppermost pin and includes a tension upper spring 
between the upper end of the upper segment and an upper portion of the 
trailer. The lower segment of the rod is pivotally connected to the 
operating arms of the lower pins, and a tension spring stronger than the 
upper spring connects the rods segments. This configuration allows the 
lower deck to be returned to trailer floor level by moving the lower rod 
segments downwardly which moves the lower locking pins to a released out 
of the way position. The lower deck can then be loaded and moved to a 
vertically elevated transport position below the upper deck. 
When unloading, the lower deck is elevated off the lowermost locking pins 
and the lower segment of the sectional rod is moved downwardly by 
stretching the lower spring thereby releasing the lowermost locking pins 
to enable the lower deck to be lowered to floor level for unloading. The 
lower deck is then elevated to engage and lift the upper deck from the 
uppermost locking pins. This movement enables the stronger lower spring to 
move the upper segment of the rod downwardly by overcoming the tension of 
the weaker upper spring thereby moving the uppermost locking pins to their 
released position. The upper deck can then be lowered to floor level for 
unloading. 
Therefore, it is an object of the present invention to provide a lock and 
release mechanism for vertically adjustable decks in a livestock trailer 
which eliminates the use of manually installed pins or bolts, as well as 
the hazardous conditions encountered when an operator climbs along the 
side wall of a livestock trailer in order to insert and remove the locking 
pins or bolts. 
It is a further object of the present invention to provide a lock and 
release mechanism for vertically adjustable decks in a livestock trailer 
which enables a substantial time saving in the loading and positioning of 
the vertically adjustable decks and in the returning of the decks to the 
trailer floor level for unloading. 
It is another object of the present invention to provide a lock and release 
mechanism which includes a plurality of locking pins oriented in a 
vertical row in vertically spaced relation at a plurality of locations 
spaced longitudinally along each side of a livestock trailer with the 
locking pins being movable to enable the outwardly extending supporting 
hooks on the vertically adjustable decks to sequentially pass beyond the 
pins with the pins then being automatically moved into locking position to 
support the trailer deck hooks when the decks are lowered into engagement 
with the pins thereby automatically locking the vertically adjustable 
decks in vertically elevated transport position. 
A further object of the present invention is to provide a lock and release 
mechanism in accordance with the preceding object in which the locking 
pins are pivotally mounted for pivotal movement to a locking position 
extending across a guide channel for the deck supporting hooks with the 
locking pins being spring biased into locking position to enable pivotal 
movement of all or certain of the locking pins in one location by the use 
of an elongated operating rod and spring assembly connected to the pins in 
a unique manner. The operating rod and spring assembly preferably has a 
handle at a lower end thereof to enable the operator to grasp the handle 
and move the locking pins in that location to a released out of the way 
position by overcoming the spring bias on the pins which are below any 
pins supporting a deck when the vertically adjustable decks are lifted 
sequentially off of the locking pins a sufficient distance to enable the 
locking pins to swing out of the path of movement of the deck hooks. 
A still further object of the present invention is to provide a lock and 
release mechanism for vertically adjustable decks as described in the 
preceding objects in which each of the locking pins includes an operating 
arm extending radially from the pivot axis of each locking pin. Each 
operating arm is rigid with respect to its associated locking pin and 
preferably extends in a direction generally opposite from the locking pin 
in relation to the pivot axis. The operating rod and spring assembly is 
then associated with each of the arms for pivotal movement of each of the 
locking pins by an operator grasping the handle at the lower end of the 
operating rod and pulling it downwardly thereby enabling the locking pins 
to be released and moved to an out of the way position by an operator 
standing on the ground surface. The operating rod and spring assembly 
preferably engages a hook or latch in the downward position. 
Still another object of the present invention is to provide a lock and 
release mechanism for vertically adjustable decks in a livestock trailer 
as described in the preceding objects which enables effective loading of 
livestock or other cargo onto vertically adjustable decks at trailer floor 
level. The vertically spaced locking pins automatically pivot out of the 
path of the deck hooks and then pivot to a locked position for engagement 
with and supporting the deck hooks on an upper deck when it is lowered 
thereby securing the upper deck in a vertically elevated transport 
position. 
A still further object of the invention is to provide a livestock trailer 
having upper and lower vertically elevated decks with a lock and release 
mechanism by which the upper and lower decks can be supported in 
vertically spaced relation above the floor of the trailer to divide the 
interior of the trailer into three generally equal height spaces. 
Alternatively, the upper deck rests on the lower deck and both decks are 
elevated to a generally central position to divide the interior of the 
trailer into two generally equal height spaces. The lock and release 
mechanism as well as the elevating and lowering mechanism for the decks is 
capable of being operated from ground level thereby eliminating an 
operator climbing the side walls of the trailer to manually insert and 
remove lock pins or bolts. 
These together with other objects and advantages which will become 
subsequently apparent reside in the details of construction and operation 
as more fully hereinafter described and claimed, reference being had to 
the accompanying drawings forming a part hereof, wherein like numerals 
refer to like parts throughout.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
In describing the preferred embodiment of the present invention as 
illustrated in the drawings, specific terminology will be resorted to for 
the sake of clarity. However, the invention is not intended to be limited 
to the specific embodiment illustrated and terms so selected; it being 
understood that each specific term includes all technical equivalents 
which operate in a similar manner to accomplish a similar purpose. 
Referring now specifically to the drawings, FIG. 1 illustrates a livestock 
trailer 20 incorporating usual frame structure 22 supported by tandem 
wheels 24 at the rear and a depending pin 26 at the front for connection 
to the fifth wheel of a tractor unit (not shown). The trailer is 
illustrated detached from the tractor unit and supported by the usually 
provided support members or landing gear 28 which can be manually lowered 
into engagement with a supporting surface 30. This portion of the 
livestock trailer is conventional as is the slotted or apertured side 
walls 32. The trailer 20 also includes a trailer floor 34 and roof 
structure 36 and two vertically adjustable decks 38 and 40. The adjustable 
decks are vertically movable from a position adjacent the trailer floor 34 
to an elevated transport position. As illustrated in FIG. 2, the upper 
deck 40, shown in broken line, has been elevated to an upper position. The 
lower deck 38 can be elevated to a lower position to divide the inside of 
the trailer into three generally equal height spaces or compartments for 
transporting livestock of short height, such as hogs. Alternatively, both 
decks can be simultaneously elevated while in contact with each other and 
be supported in a central position to divide the inside of the trailer 
into two generally equal height compartments for transporting taller 
livestock, such as cows. The number of vertically adjustable trailer decks 
may be varied depending upon the type and size of livestock or other cargo 
to be transported and the vertical height of the trailer. 
The loading procedure involves the lowering of both decks to the trailer 
floor position with the upper deck 40 then being loaded through access 
doors 44 at the rear of the trailer 20 with use of a horizontal ramp (not 
shown) in a conventional and well known manner. By using the vertically 
elevatable decks, the usual provision of stationary vertically spaced 
decks along with inclined chutes or ramps extending at a sharp angle to 
the plurality of vertically spaced stationary decks can be eliminated. The 
use of the plurality of vertically elevatable decks enables the decks to 
be loaded when they are at trailer floor position and then elevated to a 
transport position. Each deck also includes a foldable or collapsible gate 
or transverse wall 46 to compartmentalize the space above each deck when 
in its vertically elevated transport position in a manner well known in 
this art. 
Each side wall of the trailer 20 includes vertical frame or rail members 48 
at longitudinally spaced locations with the frame or rail members 
generally being of channel configuration with the open side of the channel 
facing inwardly as illustrated in FIG. 6. The decks 38 and 40 each include 
a series of outwardly extending support hooks 50 at longitudinally spaced 
locations along each of the side edges of the deck with each hook 
including a downwardly opening notch 52. The hooks 50 are positioned to 
extend into the channel-shaped frame members 48 and are guided by frame 
members 48 for vertical movement therein, as illustrated in FIGS. 5 and 6. 
Further, as illustrated in FIG. 8, each side edge of the adjustable decks 
38 and 40 includes an outwardly and upwardly inclined flange 54 having an 
upper edge terminating closely adjacent the side walls 32 of the trailer. 
This close proximity precludes livestock from having access to the space 
between the side edges of the decks and the side walls 32 of the trailer 
20. Also, each side wall 32 includes at least two vertical channel-shaped 
frame members 56, preferably adjacent certain of the frame members 48 such 
as the forwardmost and rearmost frame members, to receive a lift chain 58 
connected at its lower end to bracket 60 attached to each side edge of the 
lowermost deck 38. 
Each lift chain 58 extends vertically in frame member 56 and has its upper 
end entrained over a sprocket 62 supported on a shaft 64 (see FIG. 12) 
positioned above a top wall 65 generally parallel to and vertically spaced 
below the roof 36 to form a longitudinal compartment above the floor 34 
and the vertically elevatable decks. The forwardmost sprocket 62, or all 
of the sprockets except for the last one if more than two lift chains are 
employed on each side, is a double sprocket with the inner sprocket 66 
supporting a movable chain 68 to which each lift chain 58 is attached as 
at 70 so that as the movable chain 68 moves toward the front of the 
trailer (to the right in FIGS. 1 and 9 ), it will pull lift chains 58 over 
the sprockets 62 to lift the lowermost deck 38. The rearmost lift chain 58 
is a continuation of movable chain 68 and is engaged with a single 
sprocket 66 aligned with the other inner sprockets 66 in order for chain 
68 to extend downwardly as a lift chain 58. 
A movable chain 68 is provided at each side of the trailer 20 above the top 
wall 65, and each movable chain 68 is preferably entrained over a movable 
sprocket 72 located toward the front of the trailer. The movable chain 68 
then preferably extends rearwardly as a stationary chain 74 above the 
movable chain 68 as illustrated in FIGS. 1 and 12, extending to the rear 
of the trailer where it is anchored to the trailer as at 76, as shown in 
FIGS. 1 and 9. Thus, as the movable sprockets 72 are moved longitudinally, 
the movable chain 68 and thus the lift chains 58 are moved a distance that 
is twice the distance of movement of the movable sprockets 72. The movable 
sprockets 72 are preferably connected by a cross member 78 to which the 
sprockets 72 are journaled. The cross member 78 then is preferably 
connected to a pair of piston rods 80 extending from a pair of 
longitudinally extending hydraulic cylinders 82. By extending and 
retracting the piston rods 80, the cross bar 78 and thus movable sprockets 
72 will move longitudinally, causing lift chains 58 to raise and lower 
decks 38 and 40. 
Rather than the sprockets 72 being interconnected by a transverse member 
78, the piston rods and cylinders may be moved to the outer corners of the 
trailer and connected directly to the movable sprockets 72. Alternatively, 
a single piston and cylinder arrangement may be connected to the cross 
member 78 or a flexible bridle structure may interconnect the movable 
sprockets 72 which will be slidably guided with the center of the bridle 
being connected to a single piston and cylinder assembly along the center 
line of the trailer. The portions of the movable chain 68 between the 
forward sprocket 62 and the rearmost sprocket 66 may be supported by 
slider supports 84, as shown in FIG. 1. Also, the stationary chain 74 may 
be provided with similar supports to retain it in spaced relation to the 
movable chain 68. The hydraulic cylinders are powered by a suitable 
hydraulic pump and electric motor assembly, such as assembly 86 provided 
with controls 88 positioned in a convenient location, such as preferably 
below frame 22 in a housing 90 adjacent the forward end of the trailer, so 
as to enable an operator to readily lift and lower the decks. 
When loading the trailer with both decks lowered to a position adjacent the 
trailer floor 34, the upper deck 40 is loaded with livestock or other 
cargo and both decks are elevated by retracting piston rods 80. During 
such elevation, the deck supporting hooks 50 will engage horizontally 
disposed, longitudinally extending locking pins 92. The pins 92 have one 
end rigidly mounted on a pivot pin 94 journaled in a cavity 96 in a 
mounting block 98 mounted on a wall of the channel-shaped frame 48, as by 
welding or the like. The free outer end of the pin 92 is supported on a 
horizontal ledge 100 formed in a vertical cavity 102 in a supporting block 
104 mounted in opposed spaced relation to the block 98. The block 104 is 
rigidly affixed to the opposite wall of the channel-shaped frame 48, also 
as by welding or the like, as illustrated in FIGS. 5 and 6. In this 
supported or locking position, the pin 92 can engage the downwardly facing 
notch 52 in the hook 50 as illustrated in FIG. 7 thereby supporting the 
elevated deck in a horizontal position on the frame members or support 
rails 48. However, when the decks move upwardly, the top edge of the hooks 
50 will engage the bottom surface of the pins 92 thus pivoting them 
upwardly into cavity 96 to enable the hooks 50 to pass upwardly beyond the 
pins 92 after which the pins 92 are biased to return to their horizontal 
position to support the hooks 50. 
Each locking pin 92 includes an operating arm 106 rigid with the pivot pin 
94 which extends radially from the pivot pin 94 in a direction generally 
opposite to the locking pin 92. By this arrangement, arcuate movement of 
arm 106 will cause pivotal movement of pivot pin 94 and corresponding 
arcuate movement of the locking pin 92 from a locking position against 
supporting ledge 100, as shown in FIG. 5, to a released vertical out of 
the way position within the cavity 96. An elongated, vertically disposed 
segmental operating rod and spring assembly, generally designated by the 
numeral 108, extends alongside the operating arms 106, as shown in FIG. 4. 
Each segmental operating rod and spring assembly 108 includes a lower rod 
segment 109 and an upper rod segment 110 with the upper rod segment being 
aligned with and shorter than the lower rod segment and spaced about 8 
inches above the lower rod segment. A tension coil spring 111 is connected 
to the upper end of the upper rod segment 110, extends upwardly therefrom 
and is connected to an upper portion of the trailer side wall or frame, or 
top wall 65, as at 112. The rod segments 109 and 110 are interconnected by 
a lower tension coil spring 113 which bridges the space between the rod 
segments. The upper coil tension spring 111 is sufficiently strong to move 
the entire operating rod and spring assembly 108 upwardly but is weaker 
than the lower tension coil spring 113. 
The upper rod segment 110 is pivotally connected to arm 106 on the 
uppermost locking pin 92 by a pivot pin 114. The lower rod segment 109 is 
connected to the central locking pin 92 by pivot pin 115 and to the 
lowermost locking pin 92 by pivot pin 116, as shown in FIG. 4. This 
structure enables all of the pivotal locking pins to be spring biased to a 
horizontal locking position, as shown in FIG. 7. This also enables all the 
locking pins 92 to be moved to a vertical released position out of the way 
of the supporting hooks 50 when the rod segments 109 and 110 are moved 
downwardly and enables the central and lowermost locking pins 92 to be 
moved to a vertical position when the uppermost locking pin is held in 
horizontal position by supporting engagement with a hook 50 on the 
elevated upper deck 40. The lower end of the lower rod segment 109 is 
preferably provided with a loop-type handle 117 which is oriented at an 
elevation to enable an operator standing on the ground to readily grasp 
the handle to pull the rod segments 109 and 110 downwardly against the 
bias of weaker coil spring 111. The loop handle 117 is designed to engage 
with a hook type latch 118, such as shown in FIGS. 10 and 11. The latch 
118 is rigid with a lateral rod 119 received in a hollow tube 120 on frame 
22. A compression spring 121 on rod 119 biases the latch 118 into latching 
engagement with the handle 117 to hold the rod and spring assembly 108 in 
a lowered position so that arms 106, pivot pins 94 and locking pins 92 are 
rotated (counter-clockwise as shown in FIG. 4) against biasing springs 111 
and 113. In this position, the pins 92 are retained in their vertical 
released out of the way position within cavities 96. 
With all of the decks positioned at trailer floor level and the operating 
rod and spring assembly 108 in an elevated position sustained by spring 
111, all of the locking pins 92 will be in a horizontal position supported 
by the pivot pin 94 and the ledge 100, as illustrated in FIG. 4. The upper 
deck 40 is then loaded and both decks are moved upwardly by retracting the 
piston rods 80 to move the lift chains 58 simultaneously upwardly. As the 
decks move upwardly, the upper edges of the hooks 50 will lift the locking 
pins 92 to pivot them to an upwardly extending position to enable the 
hooks 50 to pass upwardly beyond the pins 92. When the upper deck 40 
reaches a position with the hooks 50 thereon oriented slightly above the 
upper end of the uppermost locking pins 92, all of the locking pins 92 
will pivot to their locking position under the bias of springs 111 and 113 
so that the free end of each pin is engaged and supported by ledge 100. 
Both decks can then be lowered a slight distance until the hooks 50 of the 
upper deck 40 engage the uppermost locking pins 92 but the hooks 50 on the 
lower deck 38 miss the uppermost locking pins because they are spaced 
below the uppermost locking pins 92. The lower deck 38 is thus free to be 
lowered. Further, in this position the lower deck 38 is spaced above the 
next lower locking pins 92 a sufficient distance to enable the next lower 
locking pins to be pivoted to their vertical released position when the 
upper deck 40 is supported at its elevated position. Then, by moving the 
handle 117 and lower rod segment 109 downwardly, the lower spring 113 will 
be tensioned and elongated which pivots the lower arms 106, pivot pins 94 
and locking pins 92 counter-clockwise to move lower pins 92 to their 
vertical released position. Lower rod segment 109 can be secured in its 
lowered position by engaging latch 118 in handle 117. With this 
construction, all of the pins 92 below the uppermost pins, which are 
engaged by the hooks 50 on the upper deck 40, can be retracted to their 
released position. Thus, the lower deck 38 can be returned to the trailer 
floor position for loading. 
Once the lower deck 38 has been lowered, the operating handle 117 and lower 
rod segment 109 can be returned to their elevated positions, thus 
returning the lower pins to their horizontal supporting position. After 
the lower deck 38 is loaded, it is elevated until the hooks 50 on the 
loaded lower deck pass the lowermost set of locking pins by engaging the 
locking pins and moving them to a released position until the hooks 50 on 
the loaded lower deck pass upwardly to a position above the lowermost set 
of locking pins. At this time, the locking pins will automatically return 
to their locking position under the force of spring 113. The loaded lower 
deck 38 is then lowered until the hooks 50 on loaded lower deck engage the 
lowermost set of locking pins 92 in order to support the lower deck on the 
vertical frame members or rails 48. 
When unloading decks 38 and 40, the lower deck 38 is lifted off the 
lowermost set of pins 92 a sufficient distance to enable the pins 92 to 
pivot to their vertical released position. The handle 117 and lower rod 
segment 109 are pulled downwardly by stretching spring 113 thereby 
pivoting all of the pins 92 pivoted to lower rod segment 109 to a vertical 
released position. The handle 117 is latched in its downwardly displaced 
position and the lower deck 38 is lowered to trailer floor level and 
unloaded. The handle 117 is released and the lower deck 38 is elevated 
until it engages and lifts the upper deck 40 and hooks 50 off the 
uppermost set of pins 92 a distance sufficient to let the uppermost set of 
pins 92 to move to a vertical released position. During the vertical 
movement of the lower deck past the lowermost and central set of pins, the 
hooks 50 will lift the pins as the hooks pass upwardly. The lowermost and 
central set of pins 92 will return to their horizontal position as soon as 
the hooks pass due to the spring bias of spring 113. After the lower deck 
38 has lifted the upper deck 40 off the uppermost set of pins 92, the 
handle 117, lower rod segment 109, spring 113 and upper rod segment 110 
are pulled downwardly by handle 117 which stretches the upper weaker 
spring 111 thereby moving all of the arms 106 downwardly and pivoting all 
of the pins 92 to a vertical released position. The handle 117 is again 
latched in its lowered position and the decks 38 and 40 are lowered to 
trailer floor level and the upper deck 40 is unloaded. The handle 117 is 
then released and rod segments 109 and 110, the spring 113 and pins 92 
return to the position shown in FIG. 4 by spring 111. Alternatively, the 
handle 117 may remain in latched lowered position when the lower deck 38 
has been lowered so that it is only necessary to elevate the lower deck 38 
after it has been unloaded until it engages and lifts the upper deck 40 
which permits pins 92 to pivot to released position due to the bias of 
spring 113 overcoming the bias of spring 111. 
As illustrated in FIG. 4, the three sets of pins 92 are generally spaced so 
that when the decks 38 and 40 are supported on the lowermost and uppermost 
sets of pins, each of the three compartments formed by the trailer floor 
34 and decks 38 and 40 is approximately 1/3 the height of the trailer. 
This enables livestock that is relatively short in height, such as hogs, 
to occupy each of the compartments by being supported on the trailer floor 
34 and the decks 38 and 40. 
When livestock that are relatively tall in height, such as cattle, are to 
be transported, the livestock can be loaded onto the upper deck 40 when 
both decks are in their lowered position adjacent the floor 34 of the 
trailer. Both decks 38 and 40 are elevated with handle 117 released until 
both decks pass upwardly to a position just above the central set of pins 
92. As the hooks 50 engage the pins 92, the pins 92 will pivot upwardly to 
permit passage of the hooks 50 and immediately return to horizontal 
locking position due to bias of spring 111. After both decks have been 
elevated above the central set of pins, the decks may be lowered so that 
the lower deck 38 is supported from the central pins 92 and the upper deck 
40 rests on the lower deck. This arrangement divides the trailer into two 
compartments each of which is generally 1/2 the height of the trailer so 
that taller livestock may occupy the upper deck 40 and the trailer floor 
34. 
To unload the trailer when livestock or cargo occupy the trailer floor 34 
and the upper deck 40 supported by the lower deck 38 and central set of 
pins 92, the trailer floor 34 is unloaded first. Then the lower deck 38 is 
moved upwardly which also lifts upper deck 40 to a position so that the 
central pins 92 can pivot upwardly to a vertical released position. The 
handle 117 is lowered and latched in its lowered position. Lowering of 
handle 117 moves rod segments 109 and 110, spring 113 and arms 106 
downwardly stretching spring 111 thereby moving all of the pins 92 to 
vertical released positions. The lower deck 38 and upper deck 40 supported 
thereon can then be lowered to trailer floor level for unloading the 
livestock or cargo therefrom. The handle 117 is released and all of the 
pins 92 return to their horizontal position in readiness to repeat the 
loading process. 
Various other arrangements of vertically movable decks and locking pins can 
be employed with the structure of this invention which enables the 
vertically elevatable trailer decks to be loaded at trailer floor level 
and elevated to a desired elevation. More specifically, the locking 
function of the decks in their elevated position and their subsequent deck 
releasing function and lowering of the elevatable decks is totally 
controlled by an operator at ground level. Accordingly, the present 
invention eliminates hazardous conditions encountered by operators 
climbing up the trailer side walls, using an external ladder or entering 
the interior of the trailer to insert or secure locking pins or bolts 
below vertically elevatable decks for locking the decks in a vertically 
elevated transport position, and subsequentially removing the locking pins 
or bolts to enable the decks to be moved to trailer floor level. 
Further, the operation of the operating rod and spring assembly, the 
automatic locking of the decks in elevated positions and sequential 
loading, elevation and locking of the decks and sequential unloading of 
the decks by releasing the pins and lowering to trailer floor level for 
unloading, greatly reduces the time required to load and unload a 
multi-deck livestock trailer. In addition, this invention which 
facilitates loading of multiple vertically spaced decks at trailer floor 
level is advantageous in transporting hogs which have been bred to produce 
relatively high lean meat product. Such hogs are known as "stress 
positive" and in many instances subjecting such hogs to negative stress 
such as climbing long or steep inclined ramps, which is usually 
accompanied by prodding, shouting and general confusion, will produce 
harmful effects on their meat product such as discolorization. 
The foregoing is considered as illustrative only of the principles of the 
invention since numerous modifications and changes will readily occur to 
those skilled in the art. For example, the present invention could be 
adapted for more than two elevatable decks, if desired. Further, other 
mechanism for moving the locking pins to their vertical released position 
and for rasing and lowering the vertically moving decks could be adopted 
without departing from the principals of the present invention. Therefore, 
it is not desired to limit the invention to the exact construction and 
operation shown and described, and, accordingly, all suitable 
modifications and equivalents may be resorted to, falling within the scope 
of the invention.