Automatic recovery swing sign structure

A yieldable highway swing sign is described which swings out of the way when struck by farm equipment or other objects such as wet snow from snow plows. The sign has a torsion bar which returns the sign to its original position after being struck. The sign has notches in its hinges to maintain its original position. The notches resist any displacement forces by providing an inclined plane of 40.degree. which must be overcome before the sign is displaced in an arc pivoting around the torsion bar. The displacement of the sign is limited to a 90.degree. displacement from the original position by the configuration of the hinges and is helped by the increased torque created by the torsion bar as the sign swings further from its original position.

FIELD OF THE INVENTION 
This invention relates to yieldable structures. More particularly, this 
invention relates to yieldable swing sign structures which recover 
automatically. 
BACKGROUND OF THE INVENTION 
On vehicle roadways, particularly in areas where roadways are covered with 
snow for a part of the year, a continuing problem is the damage and 
destruction of highway signs and delineators situated at the side of the 
road for the guidance and warning of passing motorists. Of necessity such 
signs and delineators must be in close proximity to the roadway so that 
they can be readily observed by passing motorists. Because of their 
proximity to the edge of the road they are subject to damage by weed 
mowers, snow plows and occasionaily by automobiles. 
A specific example is where signs are located by narrow one-lane bridges 
along rural roads that have concrete railings or abutments on both sides. 
Highway department standards in some states require that one foot by three 
foot reflective markers be installed directly above these concrete 
abutments. Because various farm equipment is wider than the space between 
these markers, the markers many times are knocked down whenever the 
equipment goes over the bridges. Also, snow plows blast heavy snow against 
these markers causing the markers to become so bent or twisted that they 
are no longer readable by approaching motorists. In some areas as many as 
15 percent of all rural signs require repair each spring because of the 
damage inflicted during the winter. 
These problems have been around for many years and because of the expense 
of procuring, installing and replacing roadway markers, the need to solve 
these problems is great. The prior art teaches various solutions to these 
problems but because of various reasons, i.e., too costly, poor 
maintenance and impracticality, they have not been widely accepted. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, a new and improved yieldable 
structure is described. 
The yieldable structure comprises a yieldable member and a support member 
for supporting the yieldable member. The support member is substantially 
parallel to the yieldable member. The yieldable structure has a pivoting 
mechanism fixed to the support member and the yieldable member for 
pivoting the yieldable member. The pivoting mechanism has a pivotal axis 
about which the yieldable member pivots. The yieldable structure also has 
a positioning mechanism for positioning the yieldable member in a selected 
position in relationship to the support member. The yieldable structure 
has a pivot limiting mechanism for limiting the displacement of the 
yieldable member from the selected position in relationship to the support 
member. The yieldable structure has a torsion mechanism which coacts with 
the support member and the yieldable member for providing a force to 
resist displacement of the yieldable member from the selected position. 
The torsion mechanism coacts axially through the pivotal axis of the 
pivoting mechanism. A first portion of the torsion mechanism is 
substantially parallel to the yieldable member and the support member.

For a better understanding of the present invention, together with other 
and further objects, advantages and capabilities thereof, reference is 
made to the following disclosure and appended claims in connection with 
the above-described drawing. 
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
As shown in FIG. 1 is an illustration of a yieldable structure 10 employed 
for supporting a highway sign. The structure 10 comprises a yieldable 
member 20 and a support member 30 for supporting the yieldable member 20. 
The yieldable member 20 is a frame with a highway sign 40 attached. The 
support member 30 is substantially vertical and elongated and the 
yieldable member 20 is substantially parallel to the support member 30. 
The structure 10 has two pivoting mechanisms 50. The pivoting mechanism 50 
has two parts, a first "L" shaped portion 51 having a first opening 84 and 
a second "L" shaped portion 52 having a second opening 85 shown in FIGS. 
2, 3, 4c and 4d. The first "L" shaped portion 51 is fixed to the yieldable 
member 20 and coacts with the second "L" shaped portion 52. The second "L" 
shaped portion 52 is fixed to the support member 30 and coacts with the 
first "L" shaped portion 51 as shown in FIGS. 2 and 3. The combination of 
the first "L" shaped pivot member 51 coacting with the second "L" shaped 
pivot member 52 comprise the pivoting mechanism 50. The pivoting mechanism 
50 has a pivotal axis 60 shown in FIG. 3. The first "L" shaped pivot 
member 51 and the second "L" shaped portion 52 shown in FIG. 3 have the 
same pivotal axis 60 as the pivoting mechanism 50. 
The first "L" shaped pivot member 51 and the second "L" shaped pivot member 
52 have bearings 63 and 64 through which a torsion bar 70 passes as 
illustrated in FIG. 3. The torsion bar 70 acts like a hinge pin for the 
pivot mechanism 50 as well as resisting a radial displacement of the 
yieldable member 20 and resisting an axial displacement of the yieldable 
member 20 in relation to the support member 30. The first "L" shaped pivot 
member 51 and the second "L" shaped member 52 have positioning notches 54, 
55, 56 and 57 shown in FIG. 3. FIGS. 4a, 4b and 4c illustrate the 
positioning notches 54 and 56 of the first "L" shaped pivot member 51. The 
first "L" shaped pivot member 51 shown in FIG. 4c is the same as the 
second "L" shaped pivot member 52 illustrated in FIG. 4d. The notches 54, 
55, 56 and 57 all are made to impose an angle .alpha. of 40.degree. from 
the horizontal plane of the pivot members 51 and 52. Shown in FIG. 4b are 
the notches 54 and 56 illustrating the 40.degree. angle. The coacting of 
notches 54 and 56 with notches 55 and 57 respectively determine a selected 
position which the yieldable member 20 has with respect to the support 
member 30, illustrated in FIG. 5. Whenever a force, having a horizontal 
vector great enough, is applied to the yieldable member 20, the notches 54 
and 56 lift out of notches 55 and 57 respectively shown in FIG. 3 by 
sliding along an inclined plane having the 40.degree. angle .alpha. shown 
in FIG. 4b. Once the notches 54 and 56 are lifted out of notches 55 and 57 
the yieldable member 20 is free to be displaced carrying the highway sign 
40 attached thereto in an arc pivoting about the torsion bar 70 which 
passes through the pivotal axis 60 of the pivot mechanism 50 shown in FIG. 
3. The torsion bar 70 resists the displacement force with a torsion force 
of its own. The torsion force increases the greater the displacement 
distance from the original selected position. The yieldable member 20 can 
be displaced through an arc up to but not exceeding a pre-determined 
position, such as 90.degree., from the selected position if sufficient 
force is applied. Rotation limiting mechanism 58 and 59, shown in FIG. 5 
and 6, limit the displacement of the yieldable member 20. One of the 
rotation limiting mechanisms 58 located on one side of the first "L" 
shaped pivot member 51 coacts with one of the rotation limiting mechanisms 
59 located on the inside face of the second "L" shaped pivot member 52 
when the yieldable member 20 traverses an arc of 90.degree. from the 
selection position; thereby, preventing the yieldable member 20 from 
proceeding past the 90.degree. position in respect to its original 
selected position. Once the force which displaced the yieldable member 20 
has been removed or reduced sufficiently for the resisting torsion force 
of the torsion bar 70 to overcome the displacement force the yieldable 
member 20 will be returned to its original selected position by the 
resisting torsion force of the torsion bar 70. The resisting torsion force 
decreases as the yieldable member 20 comes closer to its original selected 
position and reduces to zero once the yieldable member 20 reaches the 
selected position. 
The pivoting mechanism 50 may have shear pin apertures 80 and 81 located in 
the first "L" shaped pivot member 51 and shear pin apertures 82 and 83 
located in the second "L" shaped pivot member 52 to provide an alternative 
means for increasing the resistance to initial displacement of the 
yieldable member 20. This is accomplished by placing shear pins in the 
apertures 80 and 81 aligned with apertures 82 and 83. Shear pins of 
different shear forces can be utilized to permit design variations. 
The torsion bar 70 has a first portion 71 which is substantially parallel 
to the support member 30 and the yieldable member 20 as illustrated in 
FIG. 2. The torsion bar 70 has a second portion 72 and a third portion 73, 
shown in FIG. 2, which are substantially perpendicular to the first 
portion 71, the yieldable member 20 and the support member 30. This 
configuration imparts a general "S" shape to the torsion bar 70. The 
second portion 72 coacts with the support member 30 and the third portion 
73 coacts with the yieldable member 20 shown in FIG. 2 so whenever the 
yieldable member 20 is displaced from the selected position a torque is 
created in the torsion bar 70 which provides the torsion force to resist 
the displacement of the yieldable member 20. The general "S" shape of the 
torsion bar 70 also resists any axial displacement of the yieldable member 
20 from the support member 30 by the coacting of the second portion 72 
with the support member 30 and the coacting of the third portion 73 with 
the yieldable member 20. The resistance to an axial displacement helps 
maintain the engagement of notches 54 and 56 with corresponding notches 55 
and 57. The length of torsion bar 70 can be changed to increase or 
decrease the torque required depending upon the design, the size, and 
weight of the yieldable member 20. As shown in FIG. 7 and 8, different 
highway signs may require more than one torsion bar. Shown in FIG. 7 is a 
second embodiment of a yieldable structure 12 having a support member 32, 
a yieldable member 22, two torsion mechanisms 72, two pivoting mechanisms 
102 and a highway sign 42. Shown in FIG. 8 is a third embodiment of a 
yieldable structure 11, having a support member 31, a yieldable member 21, 
three torsion mechanisms 71, three pivoting mechanisms 101 and a highway 
sign 41. By changing the number of torsion bars and, or the length of the 
bars, a great variety of designs and variables may be incorporated into 
the same basic support member, yieldable member and pivoting mechanisms. 
In accordance with the invention the yieldable structure can also be used 
to make horizontally supported signs as shown in FIG. 9. Illustrated in 
FIG. 9 is a horizontal structure 13 having a horizontal support member 33, 
a horizontal yieldable member 23, two torsion mechanisms 73, two pivoting 
mechanisms 103 and a sign 43. It can also be used to make yieldable mail 
box supports, yieldable display signs, swing gates, or any application 
where a supported frame is displaced in an arc about a vertical or 
horizontal support member by a force having a horizontal vector. FIG. 10a 
illustrates an example of how the instant invention can be used to make a 
swing gate 14 having a support member 34, a yieldable member 24, a torsion 
mechanism 74 and a pivoting mechanism 104 as shown in FIG. 10b. 
While there has been shown and described what is at present considered the 
preferred embodiment of the invention, it will be obvious to those skilled 
in the art that various changes and modifications may be made therein 
without departing from the scope of the invention as defined by the 
appended claims.