Breakaway connector

A breakaway bolt (10) formed from a shaft (12) having a first end (14), a second end (16), and a breakaway shank (18). The breakaway segment is formed from laterally projecting and circumscribing flanges (22 and 24) that reduce in diameter to form cones (26 and 28) that intersect at a midpoint intersection (30) to create a preformed stress point that will break when the first end (14) or second end (16) is subjected to a predetermined lateral load. A breakaway spacer (32) formed in accordance with the present invention form a shaft (34) to have a first end (36) and a second end (38) that are connected by a breakaway shank (40). A first flange (44) and second flange (46) project laterally outward from and circumscribe the shaft (34) to form shoulders (48 and 50) and cones (52 and 54) that intersect at a midpoint intersection (56) to form a preformed stress point that allows the spacer (32) to break in any direction when subjected to a predetermined lateral load.

TECHNICAL FIELD 
The present invention pertains to connectors and, more particularly, to a 
connector for securing a support member to an anchor member and that will 
break in any direction only at a preformed stress point when subjected to 
a predetermined lateral load. 
BACKGROUND OF THE INVENTION 
Existing highway signs, fences, lights, and guardrails frequently utilize a 
two-part support post. For instance, in the installation of road signs, a 
stub post is first placed in the ground with one end projecting four to 
eight inches above the ground. A flange is formed on or slipped over and 
attached to the projecting end of the stub post. The signpost has a 
corresponding flange that is then bolted to the stub post flange. If it 
becomes necessary to change the signpost, a new signpost can be quickly 
bolted to the stub post. When a signpost is subjected to a strong lateral 
load, e.g., the impact of a motor vehicle, the shear force will cause the 
bolts to fail, allowing the signpost to break from the stub post. One 
drawback of this type of installation is that the stub post and flange are 
frequently damaged or destroyed if the bolts are over-torqued when they 
are installed. This necessitates digging out and replacement of the stub 
post. 
One proposed method for overcoming this drawback utilizes a concrete anchor 
placed into the ground and having bolt inserts cemented in place. Bolts 
that are designed to break when subjected to a predetermined amount of 
torque are placed through the signpost flange and threaded into the 
insert. This method has several disadvantages. First, because 
overtightening of the bolts will cause them to fail, installation must be 
accomplished by crews trained on proper torquing procedures. In addition, 
special torquing tools must be used to properly install the bolts. 
Furthermore, the bolt inserts tend to fill with water, dirt, adn other 
foreign matter, complicating the reinstallation of a damaged signpost. 
Finally, existing slip-based stub posts cannot be easily converted to this 
method because of the requirement that a concrete anchor be used. 
SUMMARY OF THE INVENTION 
The present invention is directed to a breakaway connector for attaching a 
support member to an anchor member. The connector comprises a first end 
adapted to be attached to a support member, such as a signpost, and a 
second end adapted to be attached to an anchor member, such as a 
slip-based stub post. The connector further comprises a shank positioned 
between and connected to said first end and said second end, said shank 
having a preformed stress point such that when said connector is subjected 
to a predetermined lateral load, the connector will break only at said 
preformed stress point. 
In accordance with another aspect of the present invention, the shank has a 
predetermined outside diameter and the stress point comprises a portion of 
the shank having a reduced diameter. Preferably, the stress point 
comprises a V-shaped groove formed in the shank. 
As will be readily appreciated from the foregoing description, the present 
invention provides a breakaway connector that will fracture at a desired 
fracture point in any direction when subjected to a predetermined lateral 
load. The connector is easily installed using standard tools. Present 
slip-based posts can be easily converted to the breakaway bolt or spacer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring initially to FIG. 1, a breakaway bolt 10 is formed from a 
machined shaft 12 having a first end 14, a second end 16, and a breakaway 
shank 18 located between the first end 14 and the second end 16. The shaft 
may also be formed by a casting process, using either iron or brass 
material. Threads 20 are machined down the first and second ends 14 and 16 
a suitable distance to accommodate various thicknesses of flange plates 
through which the bolt 10 will be inserted. Two flanges 22 and 24 are 
formed to project substantially perpendicularly outward from the shaft 12 
to circumscribe the shaft 12 at the intersection with the breakaway shank 
18. The breakaway shank 18 tapers gradually downward in diameter from the 
flanges 22 and 24 to form cones 26 and 28 that intersect at a midpoint 30 
in the shank 18. 
The flanges 22 and 24 provide bearing surfaces for plates, flanges, etc. to 
which the bolt 10 is fastened. The cones 26 and 28 provide circumscribing 
angled surfaces that permit bending and breaking of the bolt 10 in any 
direction. Breaking of the bolt 10 is designed to occur at a predetermined 
point. In this case, the sharp line formed by the intersection of the 
cones 26 and 28 at the midpoint 30 creates a preformed stress point that, 
combined with the narrowed diameter of the shaft at this point, 
facilitates breaking of the bolt at the midpoint 30 when subjected to a 
predetermined lateral load. 
The present invention may also be embodied in the configuration of a 
breakaway spacer 32 shown in FIG. 2. The spacer 32 is preferably machined 
from a shaft 34 to have a first end 36, a second end 38, and a breakaway 
shank 40 formed between the first end 36 and the second end 38. An 
internal axial bore 42 is formed in the first and second ends 36 and 38 
and is threaded to receive a bolt or other similar fastener. The breakaway 
shank 40 is formed to have first and second flanges 44 and 46 projecting 
laterally outward form the circumscribing the shaft 34 to form shoulders 
48 and 50. The diameter of the breakaway shank 40 decreases from a maximum 
diameter at the outside edges of the flanges 44 and 46 to form cone-shaped 
surfaces 52 and 54 that intersect at a midpoint intersection 56. The 
midpoint intersection 56 forms a stress point that, along with the 
narrowed diameter, facilitates breaking of the spacer 32 in any direction 
when subjected to a predetermined lateral load. 
Both the breakaway bolt 10 and the breakaway spacer 32 may be constructed 
of cast iron, steel, aluminum, plastic, or other materials suitable for 
the desired application. Furthermore, the breakaway bolt 10 or spacer 23 
can be galvanized to meet federal highway standards. The predetermined 
lateral load required to break the bolts can be calculated from the 
thickness of the midpoint intersection and the type of material used to 
construct the bolt 10 or spacer 32. Ideally, these connectors will be 
strong enough to resist breaking from the wind and normal maintenance 
while yielding to a strong lateral load, such as the load generated by the 
impact of a vehicle. 
FIG. 3 illustrates one application of the present invention wherein both 
breakaway bolts 60 and breakaway spacers 62 are used on a post-and-stub 
connection 58. A pole 64 and pole stub 66, which can be part of a sign, 
fence, or other structure needed to be supported above the ground, are 
attached to a stub post 68 and stub flange 70. In a new installation, the 
stub post 68 is firmly placed in the ground 72 to project upward no more 
than two inches to provide a clearance for any low-profile vehicle that 
may run over it. When breakaway bolts are used, the bolts 60 are placed in 
openings in the stub flange 70 so that the bolt flanges 74 bear against 
the stub flange 70. When the spacers 62 are used, the spacer flanges 78 
are placed on the stub flange 70 and firmly affixed thereto with bolt 
fasteners 76. 
The pole flange 66 is then brought into position over the stub flange 70 
and placed on the bolts 60 or the spacers 62. When the bolts 60 are used, 
the pole flange 66 has openings that allow the pole flange 66 to be placed 
over the threaded shaft 80 and rest on the bolt flanges 74. Nuts 82 are 
then threaded over the shafts 80 to hold the pole flange 66 in engagement 
with the stub flange 70. Alternativley, the spacers 62 could be used as a 
substitute for one or more of the bolts 60, in which case a bolt 76 would 
pass through the pole flange 66 and into the spacer 62 to hold the pole 
flange 66 to the spacer 62. 
With the present invention, failure would occur only at the preformed 
stress points or midpoint intersections 56 of either the breakaway bolts 
60 or the breakaway spacers 62 when the pole is subjected to a 
predetermined lateral load. Should this occur the stub pole 68 would 
remain in the ground 72 with the lower half of the bolt 60 or spacer 62 in 
place. Replacement or repair would simply be accomplished by removing and 
replacing the bolt 60 or spacer 62. As is evident from the foregoing 
description, the system requires no special tools or training by 
maintenance personnel. In addition, it enables existing slip-based posts 
to be upgraded very easily at a minimal cost. 
It is to be understood that, while a preferred embodiment of the present 
invention has been illustrated and described, various changes can be made 
therein without departing from the spirit and scope of the invention. For 
instance, the breakaway bolts 10 may be threaded directly into bolt 
inserts held in the ground or in a cement anchor. In addition, the 
cone-shaped breakaway segment 18 may have other configurations. 
Consequently, the invention is to be liimited only by the scope of the 
claims which follow.