Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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SPRING-BIA~T~l ) ~ATF, ~9~c~FMRLy
FIF T n OF TTTF. ~ON
The invention relates generally to gates and has particular
application to gate assemblies intended for scaffolds.
S BACT~GROUNT~ OF TTTF~ INVF,NTIOI~
Safety regulations require a gate assembly at any opening to an
elevated section of a scaffold. The gate assembly is normally required to open
only in a single direction, into the scaffold structure, and to close ~lltrm~ir~lly
to prevent falls. It will commonly include a gate of tubular frame . . ~"~ " .
10 and a post to which one side edge of the gate is hinged. Another post or
~U~ dl,l~, structure defines a stop that engages an opposite side edge of the
gate. The position of the stop determines whether the gate opens clockwise or
~ullL~l~,lo~ wis~ Fxposed coil springs are often extended horizontally
between the supporting post and the gate to bias the gate to a closed orientation
15 against the stop.
There are several shortcomings to such gates. The exposed
spring l,Ull~llU'_~ilJll is subject to damage and to catching. The gate also tends to
slam against the stop. When several workmen are climbing in succession
through the gate, there is a risk that the gate may strike a workman with
20 sufficient force injure him or knock him from the scaffold.
SUMMARY OF TTTF. INVF.~TION
In one aspect, the invention provides a g,,ate assembly
comprising a support structure and a gate including a tubular upright with upperand lower open ends. The support structure includes means supporting the
25 upright for relative rotation about a generally vertical rotational axis that extends
centrally through the upright. A mechanism is provided to urge the gate to an
adjustable rest position relative to the support structure. The mechanism ~L
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comprises upper and lower coil springs located within the upright in alignment
with the rotational axis. The lower end of the upper spring and the upper end ofthe lower spring are fl~ed to the tubular upright for rotation therewith about the
rotational axis. The mechanism also comprises upper and lower rotary
5 elements, which are preferably caps closing the tubular upright, that mount atthe upper and lower open ends of the tubular upright and rotate relative to the
tubular upright about the rotational axis. The upper rotary element engages the
upper end portion of the upper coil spring such that the spring end portion
rotates with the upper rotary element, and the lower rotary element engages the
10 lower end portion of the lower coil spring such that the spring end portion
rotates with the upper rotary element. The mechanism includes means that
separately and releasably secure each rotary element to the support structure toprevent rotation of the rotary elements, and ~ "ly the spring end
portions engaged by the rotary elements, with the tubular upright. The rotary
15 elements can be rotated to effectively adjust the torsional tension separately in
each spring. The rest position of the gate relative to the support structure canthus be set by rotating the rotary elements relative to the tubular upright and then
securing the rotary elements to the supporting structure.
The springs are preferably wound in a common direction (being
20 both left-hand or both right-hand springs). The inventor has observed that a
coil spring tends to have a directional bias. When the opposite ends of the
spring aue rotated relative to one another in a direction that tends to contract the
spring radially, the spring tends to resist rotation strongly. When rotated in an
opposite direction, the spring displays considerably less resistance to such
25 rotation. In a gate of the construction above, because a particular end of each
spring is held relatively stationary and the opposite end rotates with the gate,using springs wound in a common direction ensures that the gate's operation is
"bi-directional", substantially identical regardless whether it is opened
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clockwise or collnfp~ kwise.
A stop separate from the gate assembly will normally allow the
gate to open only in a single direction. The rest position of the gate relative to
the support will normally be set to coincide with the closure orientation of theS gate against the stop. The gate will ~,u~Ls~,~u~ ly tend to close reliably to its
position against the stop, but will not slam against the stop like the prior artgates described above.
Other aspects of tbe invention will be apparent from a
description below of a preferred C~lllbUI'- ' and will be more specifically
10 deflned in the appended claims.
DESCRTI~ON OF TTTF, DRAWINGS :
The invention will be better understood with reference to
drawings in which:
fig. 1 is a perspective view of a gate assembly embodying the
15 invention;
fig. 2 is a fragmented perspective view detailing connection of a
tubular upright of a gate gate to an upper bracket associated with a support post;
fig. 3 is a fr~gmPnf~fl, exploded view of the gate assembly;
fig. 4 is a fragmented view in partial vertical cross-section
20 detailing mounting of a spring assembly within the tubular upright;
fig. 5 is a view along the lines 5-5 of fig. 1;
fig. 6 is a view along the lines 6-6 of fig. 4; and,
figs. 7a and 7b are ~ ,,. ," " " 1 ~ plan views showing the gate assembly
uuu~ Lillg with a stop post to open only in a clockwise direction or counter
25 clockwise direction.
DESCl~ION OF PRF,FF,RRF,D FMRoDll\/rF~Ts
Reference is made to fig. I which illustrates a gate assembly 10
embodying the invention. The gate assembly 10 includes a suppon structure
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comprising a steel support post 12 and upper and lower U-channeled brackets
14, 16. The brackets 14, 16 are welded to the post 12 and reinforced with
upper and lower triangular webs 18, 20. A welded, tubular steel gate 22 is
mounted between the brackets 14. 16.
S The mounting of the gate 22 is apparent in figs. 3 and 4. The
gate 22 includes an upright 24 with upper and lower open ends 26, 28. The
upright's ends 26, 28 are received in a pair of vertically-aligned openings 30,
32 formed in the brackets 14, 16 and illustrated in phantom outline in fig. 3.
As apparent in fig. 4, the upright's upper end 26 is received within the opening30 in the upper bræket 14 terminating marginally short of the upper surfæe of
the bracket 14. The upright's lower end 28 is similarly received in the opening
32 of the lower bracket 16 (although not illustrated). Upper and lower end caps
34, 36 seat over the bracket openings 30, 32 and are bolted to the brackets 14,
16 to retain the gate 22 in such an orientation. This permits rotation of the gate
22 about a generally vertical axis 38 that extends centrally through the upright24.
Upper and lower coil springs 40, 42 are located within the
tubular upright 24, vertically aligned with the rotational axis 38. Each of the
springs 40, 42 is preferably formed of stainless steel wire. It might typically
have an outer diameter of I inch, a wire diameter of 1/8 inches, a pitch of about
5/8 inches, and a length of about 7 inches. Spring ~ should,
however, be selected æcording to the ~ U;~ llL~ of a particular gate. Both
springs 40, 42 are wound clockwise (when viewed from above each appears to
spiral downwardly in a clockwise direction as apparent in fig. 3 and particularly
fig. 6). This i~ ntif n ~tion of spring winding direction is entirely arbitrary, and
the important point to note is that both springs wind in the same direction. Theupper and lower end portions 44, 46 of the upper spring 40 are bent to extend
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across the diameter of the spring 40 to facilitate spring retention. This
~" ~ gf .. l l. ,1 is apparent in fig. 6, where the upper end portion 44 0f the upper
spring 40 can be seen.
The springs 40, 42 are secured to the support structure and to
S the tubular upright 24 to function essentially as torsion springs. Each spring 40
or 42 is retained within a pair of elongate vertical slots defined by the end caps
34, 36 and a shaft 52 located within the tubular upright 24. A first pair of upper
and lower slots 54, 56 (apparent in fig. 3) are intended to receive, ~ ,ly,
the upper and lower end portions 44, 46 of the upper spring 40. A second pair
of upper and lower slots 58, 60 are intended to receive, respectively, the upperand lower end portions 48, 50 the lower spring 42. The spacing and
configuration of the paired slots permits lengthwise extension and contraction of
the springs 40, 42. With respect to the upper spring 40, it will be noted in fig.
4 that its upper end portion 44 is normally located roughly rnid-way along the
slot 54, allowing for lengthwise extension and contraction without ~
from the slot 54. Although not illustrated, the upper end portion 44 of the
lower spring 42 is similarly onented relative to the slot 58 in which it is
received.
The shaft 52 serves as a spring-retaining structure within the
tubular upright 24. It has upper and lower end portions 62, 64 that are
stepped down in order to be received within the springs 40, 42. The upper
shaft end portion 62 defines the slot 56 that receives the lower end portion 46 of
the upper spring 40 (as apparent in fig. 4). The lower shaft end portion 64
similarly defines the slot 58 that receives the upper end portion 48 of the lower
spring 42. A sleeve 66 spaces the shaft 52 from the interior of the tubular
upright 24 and provides a measure of clearance for radial expansion of the
springs 40, 42 in response to gate rotation. The sleeve 66 might nlt~ Liv~ly be
formed as an integral part of the shaft 52. As apparent in fig. 5, a continuous
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passage (not indicated by reference numeral) extends through the upright 24,
sleeve 66 and shaft 52, and a rivet 67 extends through the passage to secure
these ~ for rotation together. The shaft 52 ~ u,u~llLly secures the
lower end portion 46 of the upper spring 40 and the upper end portion 48 of the
S lower spring 42 lo the uprighl 24 for rotation with the upright 24 about the
rotational axis 38.
The end caps 34, 36 secure the upper end portion 44 of the
upper spring 40 and the lower end portion 50 of the lower spring 42 to the
support and hold them against rotation with the tubular upright 24. The upper
end cap 34 is typical. It comprises a washer defining a head portion 68 that
seats against the upper surface of the upper bracket 14. It also includes a
generally cylindrical body portion 70 that is welded to the washer. The body
portion 70 is received in the open upper end 26 of the tubular upright 24. As
apparent in fig. 4, it defines the slot 54 that receives the upper end portion 44 of
the upper spring 40. The lower end cap 36 seats against the lower surfæe of
the lower bracket 16 and defines the slot 60 that receives the lower end portion50 of the lower coil spring 42. The upper end cap 34 is releasably attached to
the upper bracket 14 with a pair of socket bolts 72, 74.
Torsional tension in the springs 40, 42 can be adjusted by rotating the end caps34, 36. The term "torsional tension" should be understood as tension produced
by rotating one end portion of a spring relative to an opposite end portion. Thel~,L.Li~ between the upper end cap 34 and the upper end of the upper spring
40 is typical. The upper end cap 34 is of course shaped to rotate relative to the
upper open end 26 of the tubular upright 24. It is formed with two
~ ulllr~ lLidlly oriented slots 76, 78, as apparent in fig. 2. The upper bracket14 is formed with a pair of threaded holes (apparent in fig. 4, but not designated
with reference numerals) positioned to register with the slots 76, 78. The two
socket bolts 72, 74 are extended through the slots 76. 78 and threaded into the
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two holes of the upper bracket 14 to fix the cap 34 to the bracket 14 (as apparent
in fig. 4). To adjust tension in the upper spring 40, the two bolts 72, 74 are
loosened or removed, and the upper end cap 34 is rotated (rotating the upper
end portion 44 of the upper spring 40 relative to its lower end portion 46) either
5 to increase or decrease torsional tension. The two bolts 72, 74 are then
tightened to fix the cap 34 to the upper bracket 14. In place of the slots 76, 78,
a number of circumferentially-spaced circular clearance holes may be provided
in the cap 34, but slots 76, 78 are preferred because they permit relatively
continuous, rather than incremental, adjustment of spring tension and also
10 simplify assembly.
How iUlU~ C~ of the gdte assembly 10 are Ill~lura~ul~;d will
be readily apparent. Assembly is essentially as follows. The passage through
the tubular upright 24, spacing sleeve 66, and shaft 52 that is required to receive
the rivet 27 may be pre-drilled in the individual ~ l~o~ . The support
15 structure may be laid horizontally on a floor. The gate 22 is ~IU~Iit~ly
' ' ' SO that the upper and lower ends 26, 28 of the tubular upright 24
are received in the apertures 30, 32 of the upper and lower brackets 14, 16.
The shaft 52 and sleeve are inserted into the tubular upright 24 and positioned
so that the rivet 67 can then be inserted into the passage through the assembly of
the upright 24, shaft 52 and sleeve 66. The rivet 67 is then set. The spring 40
may then be inserted into the upper end 26 of the tubular upright 24 and its
lower end portion 46 engaged with the slot 56 of the shaft 52. The upper end
cap 34 may then be located against the upper bracket 30 with its slot 54 engagedwith the upper end portion 44 of the spring 40 and fixed to the upper bracket 30with the socket bolts 72, 74. The lower spring 42 and the lower end cap 36
may be similarly installed.
OAce b o e~a i i~embl~ l ~ bas becn ~ssomblod, ~si d in one
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or both springs 40, 42 may be adjusted to set the natural rest position of the gate
22 relative to the support structure. Most ,,~ will require the gate 22
and support structure to be substantially co-planar, when the gate 22 is in its
rest or closure orientation (as shown in solid outline in fig. 7a). To that end,
S the post 12 may be maintained in a vertical orientation. Eæh end cap 34 or 36
may be loosened from its respective bræket 14 or 16 and rotated until the rest
orientation of the gate 22 is substantially coplanar with the support post 12 and
brackets 14, 16. Each cap 34 or 36 is then fastened against rotation to the
brackets 14, 16. To install the gate assembly 10, the support post 12 may be
10 incorporated in a ,~JUVC~ iUll~l manner into the structure of a scaffold. If the
gate 22 is to assume an alternative closure orientation in a particular application,
spring tension may be adjusted on site to produce a different angular orientation
between the gate 22 and the support structure when the gate æ is in its rest
position.
Fig. 7a shows the gate assembly 10 cooperating with a stop post
80 such that the gate 22 opens only in a clockwise direction (as viewed from
above). Three positions are illustrated. The rest position of the gate 22
proximate to the stop post 80 is shown in solid outline at 82. A wide open
position ot the gate 22 relative to the support structure is shown in phantom
20 outline at 84. An in~rm~ position is shown at 86. In the process of
manually rotating the gate 22 to its wide-open position 84, the lower end
portion 46 of upper spring 40 is rotated clockwise relative to the spring's
stationary upper end portion 44. This causes the upper spring 40 to contræt
radially, strongly resisting opening of tbe gate and urging the gate 22 to its rest
25 position prox;mate to the stop post 80. The upper spring 40 sim~ n~ y
expands axially along the slot 54 of the upper end cap 34. In the lower spring
42, the spring's upper end portion 48 is rotated clockwise relative to the
spring's stationary lower end portion 50. The lower spring 42 ,. .,~c~ ly
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tends to expand radially and tends to contract axially along the slot 58. Its
resistance to the rotation of the gate 22 is relatively low. The magnitude of the
restoring torque urging the gate 22 to its rest position 82 is indicated with
curved arrows of different size proximate to the various gate positions of fig. 7a
5 (no exact depiction of magnitude being intended). It has a maximum value in
the wide open position 84, a reduced value at the i ~ ' ' position 86, and
substantially a zero value at the rest position 82 which is important to ensuring
that the gdte 22 does not slam against the stop post 80. As the gate 22 closes,
the radial and axial contraction and expansion of the springs 40, 42 is reversed
10 until they restore to a rest orientation.
In fig. 7b, the stop 80 is positioned to allow the gate 22 to open
only in a counter-clockwise direction. The operation of the springs 40, 42 is
essentially reversed, the lower spring 42 now being dominant. The upper end
portion 48 of the lower spring 42 is rotated counter-clockwise relative to the
15 spring's stationary lower end portion 50. The lower spring 48 ~ y
contracts radially, strongly resisting opening of the gate (and cimlllt~n/~o~ y
contracts axially). The upper spring 40 expands radially and contracts axially.
It should be noted that securing the end portions of the springs 40, 42 to the
support structure and to the tubular upright 24, as described, and using springs
20 40, 42 wound in a common direction ensures such bi-directional operation.
Several advantages should be noted. The spring-biased
mechanism for closing the gate 22 is compact and completely concealed within
the tubular upright 24. Damage and catching are prevented. Adjustment of
spring tension allows the rest position of the gate 22 to be set in a more precise
25 manner, ensuring that the torque on the gate 22 reaches a zero value proximate
to a stop, reducing slamming and potential injury to workers approaching the
gate 22 when opened. Use of springs 40, 42 wound in the same direction
ensures that the gate assembly 22 operates in a similar manner regardless of the
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direction in which the gate 22 is rotated. Permitting axial contraction and
elongation of the springs 40, 42 is expected to enhance the working life of the
springs 40, 42.
It ~ill be appreciated that a particular ~mh~ ~- of the
5 inventionhasbeendescribedandthat,.,...1;1;.~l;.,..~maybemadetherein
without departing from the spirit of the invention or necessarily departing f}om
the scope of the appended claims.
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