Note: Descriptions are shown in the official language in which they were submitted.
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"HANDRAIL HINGE"
Field of the Invention
[0001] The present invention relates to hinges for handrails, such as
handrails used outside the cabs of mobile equipment. The invention has
been developed for use in handrails primarily within the mining industry, but
is considered to have wider application.
Background to the Invention
[0002] Many mining operations require the use of elevated platforms. These
can be in fixed plant, or can be in mobile equipment, such as outside the
cabs of diggers, loaders and the like.
[0003] To ensure workplace safety, these platforms are generally
surrounded by handrails, to prevent a worker from falling from the platform.
[0004] In some instances, it is necessary for the handrail to be lowerable or
removable, to permit ready access to the platform when desired. To this
end, it is known to use hinged handrails which are moveable between an
upright position and a lowered position.
[0005] Such hinged handrails require hinges which can be securely locked
in the upright position, as a safety precaution, yet which can be quickly and
easily moved into the lowered position when required. The hinges should be
sturdy, damage resistant, and also long-lasting in dusty and potentially wet
and even corrosive conditions.
[0006] It is also desirable that the hinge can be operated without the risk of
entrapment of a worker's fingers.
[0007] The present invention seeks to provide a handrail hinge suitable for
this purpose.
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Summary of the Invention
[0008] According to one aspect of the present invention there is provided a
hinge for a handrail, the hinge including a first handrail portion and a
second
handrail portion, the first handrail portion including a receiving portion and
the second handrail portion including an engaging portion arranged to be
received in the receiving portion, the first handrail portion having a
longitudinal axis which defines an axial direction, the second handrail
portion
being moveable relative to the first hand rail portion between a first
position
and a second position, and the second position and a third position; the
second handrail portion being oriented in the axial direction in both the
first
and second positions, the second position being axially spaced from the first
position, and the second handrail portion being rotated relative to the first
handrail portion in the third position.
[0009] Preferably, the second handrail portion is constrained to move in the
axial direction between the first and second positions.
[0010] In a preferred embodiment the receiving portion includes a
positioning slot, the positioning slot having an axially aligned first portion
and
a generally circular second portion, the engaging portion having a
positioning projection arranged to locate within the positioning slot, the
positioning projection being sized and shaped such that it is restricted from
rotating relative to the positioning slot when located in the first portion of
the
positioning slot, and is free to rotate relative to the positioning slot when
located in the second portion of the positioning slot.
[0011] The positioning projection may have parallel side walls. The
positioning projection may have arcuate end walls. In one embodiment, the
end walls may be symmetrical. In an alternative embodiment, at least one
end wall may be eccentric.
[0012] It will be appreciated that in an alternative embodiment the
positioning slot may be located within the engaging portion and the
positioning projection within the receiving portion.
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[0013] It is preferred that the hinge includes two positioning slots and
associated positioning projections, one diametrically spaced from the other.
[0014] The receiving portion may include a guiding slot, the guiding slot
extending axially from an outer edge of the receiving portion. The engaging
portion may have a guiding projection which locates within the guiding slot in
the first position, and outside the guiding slot in the second and third
positions.
[0015] It will be appreciated that in an alternative embodiment the guiding
slot may be located within the engaging portion and the guiding projection
within the receiving portion.
[0016] It is preferred that the hinge includes two guiding slots and
associated guiding projections, one diametrically spaced from the other.
[0017] The receiving portion and the engaging portion may each be
generally cylindrical in shape, with the receiving portion having a larger
diameter than the engaging portion to allow the engaging portion to locate
inside the receiving portion when in the first position.
Brief Description of the Drawings
[0018] It will be convenient to further describe the invention with reference
to preferred embodiments of the present invention. Other embodiments are
possible, and consequently the particularity of the following discussion is
not
to be understood as superseding the generality of the preceding description
of the invention. In the drawings:
[0019] Figure 1 is a perspective of a handrail hinge in accordance with a
first embodiment of the present invention, shown in a first position;
[0020] Figure 2 is a perspective of the handrail hinge of Figure 1, shown in
a second position;
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[0021] Figure 3 is a perspective of the handrail hinge of Figure 1, shown in
a third position;
[0022] Figure 4 is a perspective of a receiving portion from a handrail hinge
in accordance with a second embodiment of the present invention;
[0023] Figure 5 is a cross sectional view through the receiving portion of
Figure 4; and
[0024] Figure 6 is an end view of a positioning projection for use in
connection with the receiving portion of Figure 4.
Detailed Description of Preferred Embodiments
[0025] Referring to Figures 1 to 3, there is shown a handrail hinge 10
located within a handrail stanchion. The handrail stanchion has a fixed lower
portion 12 and a moveable upper portion 14.
[0026] The lower portion 12 has an upper end 16, which acts as a first
handrail portion of the hinge 10. The upper end 16 terminates in a receiving
portion 18, which is a generally open cylindrical portion axially aligned with
the lower portion 12, having a diameter greater than that of the remainder of
the lower portion 12.
[0027] The receiving portion 18 has a side wall 20 which extends about
240 about the circumference, leaving a gap 22 of about 120 .
[0028] The receiving portion 18 has two positioning slots 24, diametrically
spaced from each other and equidistant from the gap 22. Each of the
positioning slots 24 has a first portion 26, which extends in an axial
direction
from a lower end 28 to an upper end, and a generally circular second portion
30 which is located at the upper end of the first portion 26.
[0029] The axial length of the first portion 26 is about equal to the diameter
of the second portion 30. The width of the first portion 26 is about one third
of the diameter of the second portion 30.
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[0030] The receiving portion 18 has two guiding slots 32, each one axially
aligned with a respective first portion 26 of a positioning slot 24. Each
guiding slot 32 extends from an upper axial end 34 of the receiving portion
18 towards the corresponding positioning slot 24.
[0031] Each guiding slot 32 has a rear wall 36, and a front wall 38. The rear
wall 36 is of full height; that is, it extends to the upper axial end 34 of
the
receiving portion 18. The length of the rear wall 36 is about equal to that of
the first portion 26 of the positioning slot 24. The front wall 38, facing
towards the gap 22, has a height about two thirds that of the rear wall 36.
The front wall 38 terminates in a rounded edge 40, which curves towards the
gap 22.
[0032] The upper portion 14 of the handrail stanchion has a lower end 46,
which acts as a second handrail portion of the hinge 10. The lower end 46
terminates in an engaging portion 48, which is a generally cylindrical portion
axially aligned with the upper portion 14, having a diameter less than that of
the remainder of the upper portion 14.
[0033] The engaging portion 48 has two positioning projections 50,
diametrically spaced from each other. The positioning projections 50 are
generally rectangular in shape, with semicircular ends (that is, a geometrical
stadium). More generally, the positioning projections can be described as
having parallel side walls and arcuate end walls. The positioning projections
50 are similar in size and shape to the first portions 26 of the positioning
slots 24.
[0034] The engaging portion 48 has two guiding projections 52,
diametrically spaced from each other and axially aligned with the positioning
projections 50. The guiding projections 52 are located axially internally of
the
positioning projections 50. The guiding projections 52 are generally circular,
and are arranged to locate within the guiding slots 32.
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[0035] The hinge 10 is assembled by locating the engaging portion 48
within the receiving portion 18, with the positioning projections 50 located
within the positioning slots 24. Once assembled, the hinge 10 is moveable
between three positions.
[0036] In the first position, as shown in Figure 1, the upper portion 14 of
the
stanchion is axially aligned with the lower portion 12. This represents a
closed, 'locked' configuration of the hinge 10.
[0037] In this first position the positioning projections 50 are located
within
the first portions 26 of the positioning slots 24, and the guiding projections
52 are located within the guiding slots 32. In this position, the upper
portion
14 is restricted from rotational movement relative to the lower portion 12. It
is
free to move in only one direction: axially upwards.
[0038] Movement of the upper portion 14 in the upwards axial direction
leads to the second position, as shown in Figure 2. This position represents
an intermediate configuration of the hinge 10.
[0039] In this position the positioning projections 50 are located within the
second portions 30 of the positioning slot 24, and the guiding projections 52
are located above the front walls 38 of the guiding slots 32. From this
position, the upper portion 14 can move in one of two ways: axially back to
the first position, or rotationally about an axis defined by the second
portions
30 of the positioning slots 24.
[0040] Rotation of the upper portion 14 from the second position leads to
the third position, as shown in Figure 3. This position represents a lowered
configuration of the hinge 10.
[0041] It will be appreciated that rotation can only occur in one direction;
that is, with engaging portion 48 moving within the gap 22 of the receiving
portion 18, and the guiding projections 52 moving across the front walls 38
of the guiding slots 32 into an unconstrained location. The second portions
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30 of the positioning slots 24 act as a bearing within which the rounded outer
ends of the positioning projections 50 can rotate.
[0042] The hinge can be readily returned to its locked configuration by
rotating the upper portion 14 back to the intermediate configuration, and
then lowering the upper portion in an axial direction.
[0043] Figures 4 to 6 show a second embodiment of the handrail hinge 10,
with a receiving portion 18 which has been created with smoother edges
ready for production. The receiving portion 18 has positioning slots 24 which
have longer first portions 26 than those shown in the first embodiment. It
will
be appreciated that this translates into a longer axial 'stroke' during
movement of the hinge from the first position to the second position.
[0044] The positioning projection 50 designed for use in this embodiment is
shown in cross section in Figure 6. The positioning projection 50 has two
parallel side walls 60, and an arcuate upper end wall 62, similar to that of
the
first embodiment. The positioning projection 50 of this embodiment has an
eccentric arcuate lower end wall 64, having a radius of curvature less than
that of the upper end wall 62 (and that of the second portion 30 of the
positioning slots 24).
[0045] It will be appreciated that this arrangement reduces the degree of
contact between the positioning projection 50 and the second portion 30 of
its associated positioning slot 24 during movement from the second position
to the third position of the hinge 10. This reduction in contact corresponds
to
a reduction in friction, making the movement easier to achieve.
[0046] Modifications and variations as would be apparent to a skilled
addressee are deemed to be within the scope of the present invention.
