Corner insulator for electric fences

A one-piece corner post insulator of high density polyethylene for electric fences includes a relatively rigid U-shaped body having a spring arm extending from the end of one leg of the body towards the end of the other leg thereof. The spring arm has a hooked end releasably engageable with a keeper formed on the said other leg. An appropriately located hole in the rigid body permits one end of an anchor wire to be threaded therethrough and the other end looped over the corner fence post. The electric fence wire can be pressed between the hooked end and the said other leg into the opening formed by the spring arm and rigid body, and then the hooked end snapped into engagement with the keeper so that the electric fence wire is held captive.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates generally to electric fence insulators, and pertains 
more particularly to an insulator for attachment to a corner post. 
2. Description of the Prior Art 
Corner post insulators for electric fences are, of course, not new. One 
extensively used corner post insulator employs a generally rectangular 
frame providing a relatively small entrance near one end via which the 
electric fence wire is inserted into the center of the frame. The 
entrance, when the insulator is in use, is closed by an oblong metal loop 
that is pivotally connected at one end to the plastic insulator adjacent 
one side of the entrance and releasably latched at its other end to the 
plastic insulator adjacent the other side of the entrance. While the metal 
loop effectively closes the entrance, being metal and therefore 
electrically conductive, it reduces appreciably the arcing distance 
between the electric fence wire and the wire attaching the insulator to 
the corner fence post. 
Another type of corner insulator with which we are familiar is a 
plural-grooved knob, the electric fence wire lying in one groove and the 
anchor wire in another groove extending perpendicularly to the first 
groove. The insulator, in this instance, is placed under compression 
rather than under tension as in the prior art insulator mentioned above. 
Here again, however, the arcing distance is relatively short, due to the 
proximity of the fence wire to the anchor wire, a situation which 
encourages arcing from the fence wire to that portion of the anchor wire 
nearest thereto. 
SUMMARY OF THE INVENTION 
Accordingly, an important object of the present invention is to provide a 
corner post insulator for electric fences that will assure a relatively 
long arcing distance. More specifically, an aim of the invention is to 
hold the electric fence wire at an appreciable distance from the anchor 
wire for a given size insulator, virtually the entire length of the 
insulator being made use of in providing a highly effective arc gap. 
Another object of the invention is to provide an all-plastic insulator 
devoid of any metal between the electric fence wire and the anchor wire, 
which would lessen the overall arcing distance between the electric fence 
wire and the anchor wire. Also, the invention has for an aim an insulator, 
lacking any metal, that will not rust. Thus, in addition to maintaining an 
effectively long arc gap, an insulator fabricated in accordance with the 
teachings of our invention will last indefinitely without deterioration. 
A further object is to provide a corner post insulator that can be easily 
and quickly installed without tools or implements. 
Still further, an object of the invention is to provide a corner post 
insulator of the foregoing character that permits the electric fence wire 
to be applied to the insulator after the insulator is attached to the 
corner post. 
Another object of the invention is to provide a corner post insulator that 
resists any inadvertent release of the fence wire, yet allowing the 
insulator to be readily pried open when it is desired to remove the 
electric fence wire from the insulator. 
Another object is to provide a tough and durable corner post insulator 
which can withstand the relatively large loads to which an insulator of 
this type is subjected by reason of it being located at a corner. In this 
regard, most electric fence insulators are only required to elevate the 
electric fence wire and hold the wire in a straight line, whereas a corner 
post insulator must change the wire's direction, usually at a right angle, 
so that the wire in this instance exerts a far greater pull or load on the 
insulator than where the electric fence wire is merely held at a desired 
height. 
The invention also has as an object the provision of an electric fence 
insulator for corner posts that can be readily and inexpensively molded in 
one piece, thereby obviating any time-consuming assembly of individual 
parts, as required with one of the prior art insulators hereinbefore 
alluded to. 
Briefly, our invention contemplates a one-piece corner post insulator of 
high density polyethylene which contains no metal parts. The insulator 
comprises a generally U-shaped rigid body composed of a substantially 
straight shank and two legs. A spring arm, also of polyethylene, is 
integral with one leg and extends toward the other leg, the spring arm 
having a hooked end which is engageable with a keeper formed on the second 
leg. Actually, the hooked end has a pair of inwardly directed jaw elements 
thereon and the keeper constitutes a pair of dog elements formed by a 
transverse groove on the second leg. The second leg is rounded so that the 
jaw elements are first cammed outwardly and then snap into the transverse 
groove to latch the spring arm closed. A web associated with the two jaw 
elements is received in a slot between the two dog elements to prevent the 
hooked end of the spring arm from shifting laterally when the spring arm 
is latched. A thumb lug on the spring arm facilitates the latching by the 
user. The leg to which the spring arm is connected has a notch of fairly 
small radius into which the fence wire moves during use. A hole through 
the U-shaped body remote from the notch permits the anchor wire to be 
threaded therethrough at one end and attached at its other end to the 
fence post. Consequently, a relatively long arcing distance between the 
fence wire and anchor wire is assured when following the teachings of our 
invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring first to FIG. 1 of the drawings, a section of a typical electric 
fence has been denoted generally by the reference numeral 10. Included in 
the fence 10 is a wooden post 12 having an electric fence insulator 14 
attached thereto. The insulator 14 can be of various constructions, and, 
not being a corner post insulator, plays no role in the practicing of our 
invention. Further included in the fence 10 is an electric fence wire 16. 
The electric fence 10 additionally includes a corner wooden post 18 having 
an anchor wire 20 engaged therewith. 
Describing now our corner post insulator, the insulator exemplifying our 
invention has been indicated generally by the reference numeral 22. It can 
be explained at the outset that the insulator 22 is of one-piece 
construction, being completely of plastic and more specifically of high 
density polyethylene. The corner post insulator 22 comprises a rigid 
U-shaped body 24 which includes an elongated shank 26 and a pair of legs 
28 and 30. The leg 30 is curved, having a fairly short radius notch at 32 
for the accommodation of the fence wire 16 during use. 
Extending in a cantilever fashion from the free end of the leg 30 is a 
spring arm 34 which includes a resilient shank 36. Actually, the shank 36 
is relatively rigid where it connects with the leg 30 by there being an 
underlying gusset or reinforcing portion 38. Consequently, the spring arm 
34 is relatively rigid adjacent its juncture with the leg 30 but is 
resilient by reason of the relatively thin shank 36 which has a lesser 
cross section than the cross section of any portion of the body 24. 
Continuing with the description of the spring arm 34, it is to be observed 
that it has a hook end at 40. More specifically, the hook end 40 is 
composed of a pair of inwardly directed jaw elements 42 and 44 having a 
web 46 for a purpose soon to be made manifest, the web extending upwardly 
from the adjacent ends of the jaw elements 42, 44 to the underside of the 
shank 36. Also, it will be discerned that a thumb lug 48 is formed 
integrally with the spring arm 34 being located adjacent the hook end 40. 
At this time attention is called to the special configuration of the leg 28 
which functions as a keeper 49 for the hook end 40. It will be seen that 
the free end of the leg 28 is rounded at 50. Extending across the leg 28 
adjacent the rounded end 50 is a transverse groove 52 which forms a pair 
of dogs 54 and 56, the ends of which are separated slightly by a slot at 
58. 
Where the leg 28 is joined to the rigid shank 26 of the U-shaped body 24 
there is a hole 60 through which the anchor wire 20 is threaded. The other 
end of the anchor wire 20 is looped over the corner post 18, as can be 
seen in FIG. 1. 
Having presented the foregoing description, the manner in which our corner 
post insulator 22 is used should be readily understood. However, in order 
to appreciate fully the benefits to be gained by employing a corner post 
insulator constructed in accordance with the teachings of our invention, a 
brief description of the manner in which it is installed will be 
presented. Assuming that the electric fence wire 16 has been engaged with 
the insulator 14 on the post 12, then the farmer or rancher will attach 
the anchor wire 20 to the corner post 18. This can be done by forming a 
loop that is simply placed over the upper end of the corner post 18. Then, 
he inserts the anchor wire 20 through the hole 60 in the U-shaped body 24. 
The insulator 22 is now in readiness for receiving the electric fence wire 
16. As can be understood from FIG. 4, when the hook end 40 is unlatched 
from the keeper 49, that is, the jaw elements 42, 44 disengaged from the 
dog elements 54, 56, the electric fence wire can be easily inserted into 
the opening 62 formed by the U-shaped body and the spring arm 34. Due to 
the resiliency of the spring arm 34, it will normally bear against the 
rounded end 50 on the leg 28. A slight pressure from the fence wire 16, 
however, will flex the hook end 40 of the spring arm 34 away from the 
rounded end 50 to permit the electric fence wire to pass into the opening 
62 defined by the body 24 and arm 34. After being received in the opening 
62, it can be seen from FIG. 1 that the electric fence wire 16 is received 
in the curved notch 32. 
With the electric fence wire engaging the leg 30, more specifically the 
curved notch 32 formed on this leg where it is integrally connected to the 
rigid shank 26, the hook end 40 on the spring arm 34 is ready to be 
latched into engagement with the keeper 49 on the leg 28. All that the 
farmer or rancher need do is to grasp the insulator 22 in the fashion 
appearing in FIG. 4. More specifically, he places his hand 64, shown in 
phantom outline, so that his thumb engages the lug 48. He then firmly 
presses the hook end 40 of the spring arm 34 downwardly so that the jaw 
elements 42 and 44 cam against the rounded end 50 of the leg 28. Owing to 
the resiliency of the shank 36, the pressure being applied by the farmer 
or rancher causes the jaw elements 42, 44 to bear forcibly against the 
rounded end 50 with the consequence that the shank 36 flexes sufficiently 
to permit the jaw elements 42, 44 to enter into the transverse groove 52. 
Once received in the groove 52, the jaw elements 42, 44 cannot be 
unlatched or dislodged readily from their engagement with the dog elements 
54, 56 and the spring arm 34 is retained in a latched condition so that 
there is no likelihood of the electric fence wire 16 becoming detached 
from the insulator 22. 
Close inspection of FIG. 3 will indicate that once the hooked end 40 has 
been engaged with the leg 28, as explained above, the web 46, which 
engages in the slot 58, prevents any lateral shifting to either side, 
thereby further assuring retention of the wire 16. Consequently, even if 
relatively large deflective forces are applied to the insulator 22, the 
spring arm 34 cannot be deflected to either side which would permit the 
electric fence wire to become detached. 
As perhaps best appreciated from FIG. 2, should the farmer or rancher wish 
to remove the electric fence wire 16, all that need be done is to insert a 
suitable implement, such as a screwdriver, between the rounded end 50 and 
the underside of the resilient shank 36, and then pry the shank 36 in a 
direction away from the leg 28. A sufficient amount of prying force will 
cause the jaw elements 42, 44 to ride out of the transverse groove 52 past 
the dog elements 54, 56. This causes the insulator 22 to assume once again 
the condition in which it appears in FIG. 4. The electric fence wire 16 
can then be slid between the rounded end 50 of the leg 28 and the jaw 
elements 42, 44 so that the wire 16 is completely removed from the 
insulator 22. 
Although dimensions are not critical to a practicing of our invention, 
nonetheless it should be appreciated that the greatest possible distance 
is maintained between the electric fence wire 16 and the anchor wire 20. 
Also, it will be recognized that no metal parts exist between the electric 
fence wire 16 and anchor wire 20. Consequently, the insulator 22 can be 
less than two inches when measured from the leg 30 to the hook end 40. 
While the distance between the electric fence wire 16 and the anchor wire 
20 is somewhat less than the overall length of the insulator 22, 
nonetheless the distance is quite appreciable and is more than adequate 
for the voltages normally used to energize present-day electric fences.