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FIELD OF THE INVENTION
The present invention relates to a ladder assembly primarily for use in
conjunction with open trucks and vans.
Due to the increasing extent to which trucks and vans are utilized to
transport articles and goods from one location to another, the truck
industry has, in recent years, placed on the market a wide variety of
commercial vehicles with specifications to suit any type of transportation
requirement. In addition to such commercial vehicles, there has, in recent
years, been a steady increase in the popularity of home trailers and
converted vans for domestic use, particularly for camping and other
recreational purposes. Due to the nature of the construction of these vans
and trucks, the loading surface behind the driving area is usually
positioned at a not insignificant distance above ground level (usually at
least 3 feet), this distance depending in part, on the diameter of the
wheels of the vehicle. Accordingly, access to the loading surface from
ground level may require considerable effort, particularly in respect of a
large van or truck where the loading surface is more than three feet above
ground level.
Also, in view of the increasing extent to which trucks and trailers are
employed to transport loose material such as sand and gravel from one
location to another, there has been increasing concern recently regarding
the safety precautions which should be taken by the operators of loaded
trucks in order to minimize the possibility of the load either shifting
considerably or spilling out of the truck either when the truck is
travelling along the highway or, more particularly, when the truck is
involved in a road accident. Such spilling of the load onto the highway is
not only wasteful and time consuming for the operator of the truck but
also constitutes a serious hazard for other traffic on the highway in
particular that which is following immediately behind the truck.
In view of the above-mentioned risks and hazards, new regulations under the
Highway Traffic Acts of several countries are being evolved which require
that a tarpaulin, netting or some other material capable of confining the
load on a truck carrying, for example, sand, gravel, crushed stone, slag,
a sand-and-salt mixture, shredded scrap metal or garbage, is employed on
the truck whenever the truck is transporting the load from one location to
another.
A major consequence of such new regulations is that it is going to be
necessary for the operators of trucks and trailers carrying loads of loose
material to install and remove tarpaulins or nettings much more frequently
which means that the overall time taken both to prepare the truck for the
road and to unload the truck will be increased. In addition, tarpaulins in
particular are often heavy and inconvenient to handle especially when
being placed over loads in trucks which are long and high.
DESCRIPTION OF THE PRIOR ART
The problem of accessibility to the loading surface of a van or truck has
been overcome, in the past, by the use of a step ladder which is simply
inclined against the loding surface of the vehicle. However, the use of
step ladders in this way has several disadvantages, in particular the
possibility that the ladder will slip away from the loading surface while
the person is on the ladder, thereby causing personal injury. Furthermore,
such a separate step ladder has to be stored either in the goods area of
the van or truck or at some other location, which storing is inconvenient
and time-consuming.
Another arrangement which has been employed to facilitate access to the
loading surface of a truck or van is a hydraulically operated ramp
assembly which can be operated by a single person, either at ground level
or in the loading area of the van or truck. Although such hydraulic
systems have the advantage of ease of operability, they are subject to
break-down. They require regular maintanence to keep them in working order
and, furthermore, they are expensive to manufacture and install.
OBJECTS OF THE INVENTION
It is an object of the present invention to mitigate at least some of the
various disadvantages outlined above which are associated with the prior
systems. It is a further object of the present invention to provide ladder
assemblies which are not expensive to produce or install, are easily
manipulated by a single person, enable the ladder to be stored when it is
not in use, and are designed so that the ladder, when in use, cannot slip
away from the loading surface of the vehicle thereby inflicting injury to
the person on the ladder.
A still further object of the present invention is to provide a safety
ladder assembly which facilitates handling of tarpaulins or netting by the
operator of the truck.
Although the ladder assemblies of the present invention are primarily
designed for use in combination with open trucks and vans to facilitate
entry to and exit from the loading area thereof, it will be appreciated
that the present ladder assemblies can also be used, not only in, for
example, home trailers and railway carriages, but also in any other
situations (not necessarily mobile) where, from time to time, easy access
from a lower level to an upper level is desired (for example from the
living area of a house up to the attic).
BRIEF SUMMARY OF THE INVENTION
According to the present invention, there is provided a ladder assembly
comprising ladder storage means having an entrance at one end thereof, a
ladder slidable relative to the ladder storage means through the entrance
between a retracted storage position in the ladder storage means and an
extended operative position in which the ladder projects from the ladder
storage means, first retaining means for releasably retaining the ladder
in the storage position, second retaining means for retaining the ladder
relative to the ladder storage means when the ladder is in the operative
position.
BRIEF DESCRIPTION OF THE DRAWINGS
An embodiment of the present invention will be now described by way of
example, with reference to the accompanying drawings, in which:
FIG. 1 is a front elevational view of a ladder for use in a ladder assembly
embodying the present invention;
FIG. 2 is a cross-sectional view of one of the step portions of the ladder
shown in FIG. 1, the section being taken along the line A--A as indicated
in FIG. 1;
FIG. 3 is a plan view of the storage means of the ladder assembly showing,
in part, the ladder in the withdrawn position;
FIG. 4 is a side elevational view of the storage means shown in FIG. 3 with
the ladder removed;
FIG. 5 is a cross-sectional view of the storage means of FIG. 3 taken along
the line B--B shown in FIG. 3;
FIG. 6 is a slightly enlarged perspective view of the ladder retaining
means;
FIG. 7 is a perspective view showing the ladder assembly in position
beneath a loading surface of a truck with the ladder in the fully
withdrawn position;
FIG. 8 is a front elevational view of a ladder for use in a modified ladder
assembly embodying the present invention;
FIG. 9 is a front elevational view of the ladder assembly of FIG. 8 showing
the ladder in the upper position within the ladder storage means;
FIG. 10 is a side-elevational view of the assembly of FIG. 9 with the
safety cord shown in FIG. 9 removed;
FIG. 11 (which appears on the same sheet as FIG. 8) is a plan view of the
ladder storage means shown in FIG. 9 in the direction of arrow C with the
ladder removed for clarity;
FIG. 12 is a front elevational view of the ladder assembly showing the
ladder in the lower position;
FIG. 13 is a side elevational view of the assembly shown in FIG. 12; and
FIG. 14 is a perspective view showing a ladder assembly of the present
invention in position on a tailgate of a truck with the ladder in the
lower position.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIGS. 3, 4 and 5 of the drawings, the ladder assembly of the
present invention comprises a ladder storage means, generally referenced
1, having, at one end thereof, an entrance 2. The storage means 1 consists
of a pair of straight, spaced apart side members 3 having a U-shaped
cross-section, arranged parallel to each other. The side members 3 are
retained in this configuration by two pairs of spaced apart cross members
4, 4', extending at right angles to the longitudinal axis of each of the
side members 3. Each pair 4, 4', of cross members is mounted at each end
thereof to a vertical support plate 5 which is rigidly fixed to the side
members 3 by welding (not shown). It will be seen from FIG. 4 that the
longitudinal axis of each support plate 5 extends at right angles to the
longitudinal axis of the side members 3. Furthermore, as shown in FIG. 4,
the length of each support plate 5 is greater than the width of the side
members 3 so that neither the upper cross members 4 nor the lower cross
members 4' contact surfaces of the side members 3. It will also be
appreciated (see FIG. 4) that, for stability purposes, the support plates
5 are mounted on the side members 3 such that the lower cross members 4'
are nearer to the side members 3 than are the upper cross members 4 to the
side members 3.
Referring to FIG. 3, a central spacer bar 6 extends parallel to the side
members 3 and is mounted at opposite ends thereof to the lower cross
members 4'. A cord securing block 7 provided with a hole 8, is mounted
substantially centrally of the spacer bar 6 on the underside thereof
approximately halfway between cross members 4'. The lower cross member 4'
nearer to the entrance 2 is provided with a U-shaped cord guide 9 through
which a first retaining means in the form of a cord 10 (see FIG. 5) can
pass. The cord 10 is secured to the block 7 by passing a hook 11 through
hole 8 and, with the other end of the cord passing through the guide 9,
hook 12 is hooked to ladder 19 when not in use and present in the storage
means 1. It will be noted that, to facilitate mounting the storage means
to the underside of a load-receiving surface of a truck or van, the end of
the spacer bar 6 nearest the entrance 2 curves downwardly at 13 to prevent
the steps from striking a flat surface causing them to stick. A
substantially U-shaped fixing means 14, which is of the same width as the
spacer bar 6 and which curves upwardly away from the side members 3, is
rigidly mounted adjacent the underside of the cross member 4 nearest the
entrance 2. It will be seen from FIG. 3 that the fixing means 14 is
positioned centrally of cross member 4 between the side members 3, and is
vertically above the spacer bar 6. The fixing means 14 also serves as a
guide for the steps in the ladder to prevent them from striking cross
member 4.
Referring to FIGS. 5 and 6, a pair of second ladder retaining means 15 are
provided on each of the side members 3 near to the entrance 2. The
retaining means 15 are substantially wedge-shaped abutments and are
mounted such that the slope of the wedge is downwardly inclined away from
the entrance. The retaining means 15 are mounted such that the distance
between the end of the side member 3, which are closed by walls 18, and
the vertical edge of the wedges is slightly larger than the diameter of
tubular cross member 26 (see FIG. 5) of ladder 19. In FIG. 6 a slightly
enlarged perspective view of the wedge 15 is shown prior to its
installation in a side member 3.
At the end of each side member 3 distant from the end having the ladder
retaining means 15 is provided ladder abutment means 16 of substantially
trapezoidal shape having an abutment face 17 inclined at substantially
45.degree. to the direction of movement of ladder 19 within the storage
means 1. The abutment means 16 is mounted to the side members 3 by means
of a nut and bolt combination 18.
Referring to FIG. 1, ladder 19 has a conventional frame including tubular
parallel spaced apart side members 20 with tubular rungs 21 extending at
right angles therebetween. In the particular embodiment shown in FIG. 1,
each rung, except rung 21' which is nearest ground level when the ladder
is in use, is provided with a substantially rectangular step block 22 of
length slightly less than the rung 21. Block 22 is rigidly fixed to one
leg of two elongated L-shaped members 23 by screws 24 (see FIG. 2). The
other legs of the L-shaped members 23 are separated from each other by a
distance which is substantially equal to the external diameter of the
tubular rung 21. As seen in FIG. 2, the L-shaped members 23 are welded to
the tubular rung 21 at an angle of approximately 30.degree. so that, in
use, when the ladder is inclined at approximately 60.degree. to the
horizontal, the upper surface of each block 22 is substantially
horizontal, thereby facilitating a person walking up or down the ladder.
To provide extra grip and drainage during wet weather, the upper surface
of each block 22 is provided with a plurality of longitudinally extending
channels 25.
At the end of the ladder opposite that which contacts ground level when the
ladder is in use, is provided tubular cross member 26 having opposed
lateral projections 27 which extend outside each side member 20. As seen
more clearly in FIG. 3, the projections 27 are slidably accommodated in
the U-shaped side members 3, which, in effect, act as a track for the
projections 27 as the ladder 19 is withdrawn from or retracted into the
storage means 1.
In use, the storage means 1, which has been assembled with the portions 27
of the ladder 19 contained in the side members 3, is mounted at the rear
of a truck 29 beneath the load-bearing surface 28 (see FIG. 7). When the
ladder is not in use, the projections 27 abut against the surface 17 of
abutment means 16 and the hook 12, fixed at an end of cord 10, is hooked
onto the end rung 21' to prevent the ladder sliding out of the storage
means 1 particularly while the vehicle is in motion.
When access to the load-bearing surface 28 is desired, the hook 12 is
disengaged from the rung 21' and the ladder is withdrawn, conveniently by
gripping the rung 21', from the storage means 1 until the projections 27
slide up the inclined surfaces of the wedges 15 and drop into the space
between the wedges and the end walls 18 of the side members 3, which act
as stops to prevent complete withdrawal of the ladder from the ladder
storage means. The ladder is then placed into contact with the ground so
that it is inclined towards the load-bearing surface 28 to facilitate
entry thereto. The wedge-shaped members 15 not only prevent the
projections 27 from progressing back into the storage means 1, but also
serve to prevent twisting of the ladder which may cause the ladder to
become disengaged from the storage means 1. When the ladder 19 is no
longer required, the cross member 26 is lifted so that the projections 27
pass over and down the inclined portions of the wedge members 15 and,
again by holding the end rung 21', the ladder can be readily manually
pushed back into the storage means until the projections 27 abut against
the surfaces 17. Finally, as a safety precaution, the hook 12 is hooked
onto rung 21' to hold the ladder in position in the storage means.
Since the above-described embodiment of the present invention is primarily
a safety device, the storage means and the ladder are generally fabricated
from steel to withstand not only an individual's weight but also the
severe conditions which the assembly will be subjected to under a truck.
If the ladder assembly is to be employed for domestic purposes, it may be
possible to employ a resilient low density metal, such as aluminum,
instead of steel.
As indicated briefly above, it is possible for the ladder assemblies of the
present embodiment to be employed in any situation where access from a
lower level to an upper level is desired. Examples of such instances are
entry into a railway carriage from ground level, entry into a caravan or
home trailer, or access to an attic space from a lower level.
Although the length of the ladder 19 is, in part, determined by the
distance between the upper and lower levels, it has been found that, for
open trucks and vans, a suitable overall length is about 48 inches and the
length of the cross member 26, including the both portions 27 is about 18
inches. In this case, the overall length of the storage means 1 is about
49 inches and the overall width is about 181/2 inches.
Referring to FIGS. 9 to 13 of the drawings, the modified ladder assembly
illustrated therein comprises a ladder storage means, generally referenced
101, having, at one end thereon, an entrance 102. The storage means 101
consists of a pair of straight spaced apart side members 103 having a
U-shaped cross-section arranged parallel to each other. The side members
103 are retained in this configuration by two parallel spaced apart
cross-members 104, 104' extending between the side members 103 at right
angles to the longitudinal axis of each of the side members 103, and by a
plurality of parallel equally spaced apart step means 105 extending
between the side members 103. In the particular embodiment shown in the
drawings, the step means 105 each have an L-shaped cross-section, one leg
of the L being firmly mounted to the side members 103 and the other leg
providing the step.
As can be readily seen from FIG. 10, the cross-members 104, 104' are
mounted at opposite ends of the side members 103 and on opposite faces of
the side members 103 to the step means 105.
Referring to FIG. 8, ladder 106 has a conventional frame including tubular
parallel spaced apart side members 107 and tubular spaced apart parallel
rungs 108 extending at right angles therebetween. At the upper end of the
ladder 106 is provided tubular cross-member 109 having portions 110 which
extend outside each side member 107. As can be seen clearly in FIGS. 9 and
12, the portions 110 are accommodated in the U-shaped side members 103
which, in effect, act as a guide or track for the portions 110 as the
ladder 106 is withdrawn from or retracted into the storage means 101.
Referring to FIGS. 12 and 13, a pair of ladder retaining means 111 in the
form of support brackets are provided inside the side members 103 at a
position such that when the ladder is in its lower position (as shown in
FIG. 12), the tubular cross-member 109 and the rung 108 which is nearest
to cross-member 109 are in register with the two lower step means 105,
105' as shown in FIG. 12. The exact position at which the ladder retaining
means 111 is mounted inside the side members 103 can be very readily
determined by a person skilled in the art having regard in particular to
the diameter of the tubular cross-member 109. The retaining means 111,
which are formed from a piece of angle iron, are L-shaped in cross-section
with one leg of the L being trapezoidal in shape and the other leg
extending at right angles from the shorter parallel side of the trapezium.
The retaining means 111 are mounted by means of a nut and bolt 112 such
that the leg extending at right angles from the shorter parallel side of
the trapezium is normal to the longitudinal axis of the storage means 101.
As can be clearly seen from FIG. 10, the leg of the retaining means 111
which is trapezoidal in shape is inclined such that the sloping face of
the trapezium is parallel to the longitudinal axis of the side member 103.
Referring again to FIG. 9, the ladder storage means 101 is provided with
ladder support means 113, for example metal support posts having a
cross-sectional area which is smaller than the internal cross-sectional
area of the tubular side members 107 of the ladder 106 and having a length
which is greater than the leg of the step means 105' which is fixed to the
side members 103. The support means 113 are rigidly fixed (for example by
welding) to the lowest step means 105' such that the support means 113
protrude above the level of the step of the step means 105'. Furthermore,
as can be seen from FIG. 9, the support means 113 are spaced apart by a
distance which is approximately equal to the distance between the centers
of the tubular side members 107 of the ladder 106.
According to a preferred feature of the assemblies of the present
invention, a flexible safety cord 114 is provided (see FIG. 9) which is
provided at each end with a hook means 115 which is adapted to be received
in a hole 116 of a plate 117 mounted on each of the side members 103. As
can be seen in FIG. 9, when the ladder is in the upper position, and the
tubular side members 107 are placed over the support means 113, the
flexible safety cord 114 is positioned over the lowest rung of the ladder
so that if the ladder becomes disengaged from the support means 113 and
moves out of the storage means 101, the rung next to the lowest rung of
the ladder comes into engagement with the cord 114 and further movement of
the ladder out of the storage means is thereby prevented.
In order to facilitate mounting of the storage means 101 to a tailgate of a
dump truck or dump trailer, mounting means 118 are provided at the four
corners of the storage means. The mounting means 118 are generally
brackets which are mounted to the side members 103 by a nut and bolt 119
(see FIG. 9). Mounting means 118 are provided with a hole 120 through
which can be passed a bolt for mounting at a suitable point on the
tailgate of a truck 121 as shown in FIG. 14.
In use, the storage means 101 is generally mounted substantially vertically
to the tailgate of a truck as shown in FIG. 14. When the ladder 106 is not
in use, the tubular side members 107 are placed over the protruding
portions of the support means 113 (usually metal rods) and the bottom of
each side member 107 of the ladder abuts against a portion of the step
portion of the lowest step means 105'. For safety, the flexible safety
cord 114 is placed in position as shown in FIG. 9. When access of the
upper regions of the truck is desired, in particular when a tarpaulin or
netting is being installed or removed from the truck, the flexible safety
cord 114 is removed, the ladder 106 is is lifted upwards to disengage from
the rods 113 and then withdrawn vertically downwards from the storage
means 101 until the portions 110 engage with the retaining means 112. FIG.
14 shows the instance where the ladder is in the lower position. When the
ladder 106 is no longer required, the operator moves the ladder back into
the storage means 101 and places the ends of the tubular side members 107
over the rods 113. Finally, the flexible safety cord 114 is placed in
position as shown in FIG. 9.
Since the assemblies of the present invention are primarily designed to be
installed and employed outdoors on vehicles, the storage means and ladder
are generally fabricated from steel to withstand not only an individual's
weight but also the severe conditions which the assembly will be subjected
to on the truck.
Although the above description of the modified ladder assembly has been
made with reference to dump trucks and dump trailers, it will be
appreciated that it is possible for the ladder assemblies of the present
invention to be employed in any situation where access from a lower level
to an upper level is desired, for example, access to the roof of a railway
carriage or home trailer, or access to an attic space from a lower level.
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