Note: Descriptions are shown in the official language in which they were submitted.
310
The invention relates to safety attachments for utility
vehicles such as industrial lift trucks and in particu]ar to
an overhead yuard for such vehicles.
Industrial lift trucks, tractors, and like utility
vehicles have been provided with overhead guards for protection
of the operator against falling objects. The,risk of injurv is
relativel~ high where a vehicle,is dischar~ing or receiving
material at an elevated point above the level of the operator
station of the vehicle. In recognition of the potential dangers
involved in such operations federal regulations where applicable
require the use of an overhead guard and prescribe minimum limits
of crush resistance for,the protective structure.
'In order to provide a high degree of head room for an
operator overhead guards have characteristically presented a
relatively high profile which has limited the ability of the
vehicle to operate in areas of low overhead clearance. Co~monly
encountered areas of limited overhead clearance include doorways
of semi-trailers and bulkhead passages in cargo ships. It is a
present practice to remove overhead guards from lift trucks
when the trucks are to be used in these or like areas of restricted
vertical clearance and to reinstall these units when a job has
been completed and the vehicle is to be used elsewhere. Even
under the most ideal conditions periodic removal and replacement
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of a guard requires nonproductive labor. Moreover, an operator
is exposed to risk during the period when a guard is deliberately
removed and whenever a guard is inadvertently not replaced.
According to the present invention there is provided an
overhead guard for an industrial vehicle for material handling
or the like having an operator station including a seat, the
guard protecting an operator seated in the seat from falling
objects. The guard includes a rigid metal frame as one component
generally surrounding the operator station, the frame including
rigid supporting elements at points forward and rearward of the
operator station and extending upwardly from the main body
of the vehicle to a zone generally above the operator station.
A rigid metal roof barrier is another component of the guard
supported by the frame and including a generally planar main
section substantially completely overlying the operator seat.
The roof barrier is shiftable on the frame between an extended
position for maximum head room and a retracted position for
maximum clearance of overhead structures. The roof barrier
main section maintains its overlying relationship with the
operator seat and is disposed in generally horizontal planes in
both of the positions. Means is provided on one of the components
for selectively maintaining the roof barrier at either of the
extended position or the retracted position. The rigid frame
and roof barrier are constructed and arranged on the vehicle
in such a manner that falling objects striking the roof
barrier are prevented from entering the operator station as a
result of the physical obstruction to such objects formed by
the roof barrier.
In a specific embodiment of the invention, the main frame
is constructed of elongated structural elements interconnected
in the manner of a space frame. The roof barrier is a generally
planar structure ~xtending substantially fully over and pro-
tecting substantially the full space enclosed by the frame
from vertical intrusion. The planar barrier, is shiftable from
the extended position spaced above the frame and the retracted
position immediately above the frame. The roof barrier may
be counterbalanced to facilitate manual positioning between
the extended and retracted positions and is guided by means
which permits it to be raised or lowered one half at a time
without binding or excessive friction.
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BRIEF DESCRIPTION OF TIIE DRAWINGS
Figure 1 is a perspec-tive view of an overhead nuard con-
structed in accordance with the invention and installed on a
typical utility vehicle.
Figure 2 is a perspective view on an enlarged scale of
the overhead guard.
Figure 3 is a fragmentary perspective view of a portion of
the guard showing certain constructional details thereof.
Figure 4 is a perspective view of a typica-l locking device
provided to lock a roof barrier of the guard in one of its positions.
Figure 5 is a fragmentary end view of the roof barrier in
an extended position on a supporting frame.
Figure 6 is a view similar to Figure 5 but showing the roof
barrier in a retracted position.
Figure 7 is a partial front elevational view schematically
illustrating the roof barrier in an intermediate position; and
Figure 8 is a view similar to Figure 7 schematically illus-
trating the roof barrier in a retracted position in solid line
and an extended position in phantom.
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llZ~i310
Figure 1 illustrates an overhead guard 10 mounted on a
utility vehicle in the form of a conventional industrial lift
truck 11 for material handling. The overhead guard comprises a
rigid frame 12 and a roof barrier 13 movably supported on the
frame.
The frame 12 is a weldment of square or rectangular steel
tubing including a set of four straight legs 14-17 intexconnected
by a set of four straight header bars 18-21. The legs 14-17 are
generally vertical although their upper ends may be tilted
inwardly towards opposite legs to achieve a degree of triangulation
for frame rigidity and for purposes of appearance.
In the illustrated arrangement the header bars 18-21 lie
in a common horizontal plane and define the boarder of an area
which has four sides in a manner of a rectangle or trapezoid.
The end faces of the header bars 18-21 are butt welded to res-
pective sides of the legs 14-17 adjacent end faces 22 of thelatter. ,
Rectangular or square flanges 23 are welded or otherwise fixed
to the lower ends of the legs 14-17 and are provided with holes
for convenient bolting to the vehicle 11. The upper end face 22
of each leg 14-17 is open to permit a roof barrier support pin
26 to telescope within the leg. The lower end of each support
pin 26 is resiliently supported on a compression spring 27 disposed
within the associated leg. In turn, a lower end of the spring
27 is supported by a cross-pin 28 or other suitable means within
the respective leg. An anti-friction ball transfer assembly 29
is fixed to the upper end of each support pin 26. The ball
transfer assemblies 29 are commercially availab]e units each
including a relatively large metal ball supported by a plurality
of smaller balls in a spherical socket. The horizontal area
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bounded by the header bars 18-21 extends substantially completely
over an opera~or stat.ion 31 of the vehicle 11 including an
operator seat 32 and steering wheel 33.
A roof barrier 13 includes a substantially planar cover
36 fabricated from steel plate having dimensions slightly larger
than the area bounded b~ -the frame header bars 18-21. A series
of holes 37 are cut in the plate 36 to provide overhead vision
from the operator station 31. Leading and trailing eages of
the cover plate 36 are bent downwardly to form stiffening flanges
38,39` respectively. A pair of elongated stirrups 41,42 are
welded or otherwise fixed to the underside of the cover plate 36.
Each stirrup 41,42 is U-shaped in cross section having vertical
sidewall portions 43,44 and an intermediate horizontal bight
portion 45. Outwardly directed horizontal flanges 47 integrally
formed with the sidewall portions 43,44 are in engagement with
the underside of the cover plate 36.
~s indicated most clearly in Figs. 3, 5 and 6, in assembly
the stirrups 41,42 wrap under respective side header bars 18,19
while the cover plate.is disposed over all of the header bars
18-21. The stirrups 41,42 have substantially the same length
as the side header bars 18,19. In the illustrated case the side
header bars 18,19 extending from the front to the back of the
guard 10 are somewhat longer than the front and rear header bars
20, 21. Under extreme service conditions the stirrups 41,42
are adapted to contribute to the strength of the relatively longer
side bars 18,19. The anti-friction support assemblies 29 bear
against the underside of the roof barrier plate 36 and allow the
springs to collectively support the weight of the roof barrier 13.
The roof barrier is vertically displaceable on the frame 12 between
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elevated and retracted positions indicated in Figs. S and 6
respectively. In the elevated position the bight portion 45 of
each stirrup channel 41,42 abuts an underside 49 of the related
header bar 18,19. In the retracted position the underside of the
cover plate 36 abuts or is immediately adjacent an upper side
51 of ~ach side header bar 18,19.
To maintain the roof barrier 13 in either of its positions
locking means in the form of toggle pin assemblies 53 are provided
on both of the s-tirrups 41,42. A typical toggle `pin assembly 53
is shown in Fig. 4 where a release position is indicated in solid
line and a locking position is indicated in phantom. The toggle
pin assemblies 53 which are individually bolted to U-shaped
brackets 5A on the stirrups 41,42 include a pin 56 slidably
disposed in a mounting block 57 and a set of levers 58,59 one
of which includes a manually manipulated handle 61. The pin
assemblies 53 are each aligned, at spaced centers 60, with a pair
of associated holes 63,64 in opposite stirrup sidewalls 43,44
through which a pin 56 is extended and retracted. The rearward
and forward hole centers 60 are vertically disposed on the stirrup
sidewalls 43,44 to permit the related pin assemblies 53 to maintain
the barrier 13 in its raised or extended position as indicated
in Fig. 5 with the stirrup bights 45 abutting or adjacent the
undersides 49 of the side header bars 18,19. The intermediate
pin centers 60 are arranged to permit the associated pin assemblies
53 to maintain the roof barrier in the lower position illustrated
in Fig. 6 with the underside of the cover plate 36 at or adjacent
upper sides 51 of the side header bars 18,19.
The extended or raised position indicated in phantom in
Fig. 8 may be considered the normal position of the roof barrier
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13. At this extended position ful.1 head clearance is provided
for the operator. In work environments where the truck 11
must be occasionally operated in areas of limited overhead
clearance such as through truck trailer doors or bulkhead openings
in the holds of ships and the like, the roof barrier 13 is
retracted to the full line position fo Fig. 8. The roof barrier
13 is manually moved between the extended and retracted positions
by withdrawing appropriate ones of the pins 56 and either man-
ually pulling the barrier 13 down against the force of the
springs 27 or allowing the springs to raise it. If desired,
hand grips may be provided on the cover plate 36 to facilitate
manual control. The counterbalancing springs 27 are dimensioned
to exert a force in the extended position at least as great as
the weight of the roof barrier 13. The stirrups 41,42 serve to
guide the roof barrier 13 vertically with respect to the frame 12
so that the extended and retracted barrier positions lie above
or below one another without significant horizontal displacement
relative to the vehicle 11. As suggested in Fig. 7, the roof
barrier 13 may be retracted or extended stepwise one-half at a
time.. Such stepwise extension or retraction reduces the maximum
effort required of the operator when manually adjustina the roof
barrier 13. The stirrups, 41,42 are dimensioned with respect to
the side header bars 18,19 to provide sufficient lateral clearance
indicated at 66 and the pins 56 are located to provide sufficient
vertical clearance indicated at 67 to permit this tilting of the
roof barrier 13 to one side or the other with respect to the frame
12.
By way of example, the illustrated guard 10 when mounted on
the vehicle 11 has a nominal height above ground of 81 inches
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when extended and is capable of retracting 4 inches from this
height in the retracted position. The disclosed guard assembly
10 is capable of protec-ting an operator from overhead falling
objects which would otherwise have a generally vertical trajectory
towards the operator station 31. The frame structure 12 which
generally surrounds the operator station 31 is capable of sus-
taining a blow of substantial energy without significant crushing.
While the pins 56 maintaining the barrier 13 in its upper or
extended position have limited strength as compared to the frame
12 failure of such pins under impact will result in a displacement
of the roof barrier limited to only that equivalent to the retract-
ed position. In this resulting position the frame 12 will be
loaded by direct engagement with the cover plate 36 and further
displacement of this plate is effectively,prevented. As shown,
the roof barrier and frame protect a relatively large area
surrounding the operator seat and steering wheel to afford a
high degree of protection from overhead falling objects.
Although a preferred embodiment of this invention is illus-
trated, it is to be understood that various modifications and
rearrangements of parts may be restored to without departing
from the scope of the invention disclosed and claimed herein.
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