US 3308584 A
Description (OCR text may contain errors)
March 14, 1967 w. G. GRAHAM HIGHWAY GUIDE POST Filed May 23, 1963 I NVE N TOR. William 6. Graham BY WWW villi/Effig United States Patent The present invention relates to a frangible highway guide post. Highway guide posts are placed in the highway shoulder along side of the usable roadway as an indication of the course of the roadway and to indicate the presence of culverts and obstructions beside the roadway and in the shoulder thereof. These posts are often in the form of a T bar having dimensions of about an inch and a half equal legs by seventy inches and weighing about twelve pounds. Such posts are driven into the ground a distance of two feet and an 8 X 24 or a 6" X 15" metal plate, or target board, with reflectors thereon is secured to the flat of the head of the T at and above the upper end of the post.
Automobiles frequently hit such posts at various speeds with resulting damage to both post and automobile. The degree of damage to the automobile is often very great as the automobile bends the post and rides over it, as the post is structurally rigid, heavy, and usually well anchored in the dense roadbed ballast. Often the post will deflect the automobile with the result that there is secondary, damage from the automobile hitting some other object.
In view of the above described construction of prior highway guide posts and their disadvantages, it is an object of the present invention to provide a guide post that when damaged may usually be repaired in the field and that usually will not damage an automobile that strikes it, even at high speed. A further object of the invention is that of reducing the cost of the original post as well as its repair.
A post constructed in accordance with the present invention may comprise, in addition to a reflector supporting plate, two lengths of iron tubing joined by a ball and socket fitting that is immobilized by readily sheared rivets. One of the lengths of about two feet is driven into the ground to about its upper end. This upper end is received in a hollow sleeve and held thereto by rivets. The upper end of this sleeve is spherically convex. The other length of tubing of about four feet is received in another hollow sleeve that has its free end spherically concave and dimensioned to mate with the spherical portion of the sleeve of the ground inserted tube. The two tube lengths are aligned and immobilized, one with respect to the other, by rivets inserted thru the sleeves transversely of the spherical surfaces. The above mentioned rivets may be metal and of the blind type that are set in place by pulling a swage, or expansion, pin therethru after insertion of the rivet in a hole thru the mating parts as described above. These rivets break comparatively easily when subject to shear loading. When an automobile hits one of the above described posts, the rivets holding the spherical surfaces together, are usually sheared before the upper length of the post is permanently bent. However, the shear load is usually sufiicient to cause the upper length to be thrown forward and downward directly to the ground, not backward and upward into the front portion of the automobile.
A post embodying the construction outlined above is hereinafter described in detail and illustrated in the accompanying drawings, in which:
FIGURE 1 is an elevational view of a post embodying the present invention.
FIGURE 2 is an enlargement over FIGURE 1 of a sectional elevational view of the post with parts thereof in extended relationship, and with most of the tubing broken away.
FIGURE 3 is a sectional view on the line 33 of FIGURE 2.
In the elevational view of FIGURE 1 of the complete post, aside from the target board 10 to which is secured three reflectors 11 and various rivets 12, the post consists of four parts. These parts are an aerial length of tubing 13 having at its lower end the socket half 14 of a ball and socket connector, and the ball half 15 of the connector at the upper end of a length of ground engaging tubing 16. Standard half inch steel pipe has been found satisfactory for the above tubing lengths.
The various parts of the device are secured together by means of rivets 12. These may all be of the same kind and size. One of these rivets is shown in elevation in FIGURE 2 where it is aligned for insertion in a rivet hole in the socket 14. Each rivet when manufactured and before being used has a tubular cylindrical stem 21 with a head flange 22 at one end. An expander pin has a shank 23 that extends thru the tubular stem 21 with each end of the shank enlarged. The end of the shank above the head flange 22 is in the form of a flat button 24, and the other end is in the form of a cone 25 that flares outward from the end of the shank. The diameters of the base of the cone 25 and of the flat button 24 are slightly greater than the inside diameter of the stem 21. To use the rivet, it is inserted by hand in an opening with a free fit, then force is applied between the flanged head end 22 and the shank button 24 to draw the cone 25 into and thru the stem 21 to cause its expansion and integration with the material forming the hole. Such a rivet is called a blind rivet as it is locked or swaged in place by access to only one end thereof.
The length of the aerial tubing part 13 is close to 46 inches, and that of the ground tubing part 16 is close to 23 inches. The length of the ground engaging tubing 16 is not critical except that it be long enough to anchor the stake well when driven into the ground to substantially the combined length of the tubing 16 and the ball half 15 of the connector. The combined length of the aerial tubing part 13 and its connector half 14, and the weight and positioning of the target board 10 are important and critical. This is so because the center of mass of the aerial assembly should be near or below that point on the post at which it will, in most instances, be impacted. If the center of mass is much above the point of impact, the aerial assembly will, upon impact by an automobile, move upward and back into the automobile or upward and forward instead of forward and downward to the ground. When the aerial assembly has a low center of mass, and it is impacted, it moves downward not only because of the low mass center, say a little above or below the impact point, but because of the resistance of the rivets that hold the connector halves together and because of the ball and socket construction which forces the socket 14 of the aerial post length to slide and pivot on the ball 15 even after the rivets are sheared.
As shown in the elevational sectional view of FIGURE 2, each half of the connector is of similar construction except for the ball and socket conformation. The ball half 15 of the connector is in the form of a sleeve having an inside bore 31 from end to end of a diameter to receive the end portion of the ground length of tubing 16. Aligned holes 32 thru the sleeve and the tubing receive rivets 12 to secure the sleeve to the tubing. The thickness of the sleeve increases upwardly, and the upper end surface 34 of the sleeve is rounded convexly to a radius of about an inch with the center on the :axis of the sleeve about an inch from the upper end. Four equally spaced holes 35 are placed in and around the ball shaped surface 34 and thru the sleeve. The axis of each hole is substantially a radius of the curved surface 34 and at an angle of about 60 to the axis of the sleeve. The lower end of the ground engaging tubing 13 is cut transversely of the tube to leave an open end 36 for ease of insertion into the ground. It is to be noted that the upper end face 37 of the ground tube is free, and it is against this face 37 that blows are struck to drive the ground tube into the ground. To strike the upper end of the sleeve 15 would distort the rounded end surface 34 and would shear the rivets holding the tube and sleeve together. Further, as it is intended to make the sleeve of aluminum, driving on the sleeve would quickly and greatly distort it.
FIGURES 2 and 3 illustrate the construction of the socket half 14 f the connector. This part is, also, in the form of a sleeve having an inside bore 41 from end to end of a diameter to snugly receive the lower end portion of the aerial length of tubing 13. Aligned holes 42 thru the sleeve and the tubing 13 receive rivets 12 to secure the sleeve to the tube. The sleeve increases in thickness downwardly with an outward fiare 43 adjacent its lower end. The lower face 44 of this flare is rounded concavely to a radius to match that of the ball surface 34. Four equally spaced holes 45 are placed in, around, and thru the flare 43, as illustrated in FIGURE 3, and located so that when the connector is assembled with the aerial and ground tubes aligned and the ball and socket surfaces in contact, each one of the holes 35 in the ball surface will align with a separate one of the holes 45 in the socket surface 44 so that each pair of aligned holes may receive and have swaged therethru a rivet 12 so that the parts of the connector may be thereby secured together.
In FIGURES 1 and 2, a ground line 51 drawn relative to the post indicates the depth to which the ground length of tubing 16 is to be inserted in the ground. This ground line should be about at the lower edge of the ball surface 34. Thus there is no part of the ground parts of the post above ground sufiiciently to damage any part of an automobile that may strike the post. The rounded ball surface portion of the post is not likely to damage an automobile or its tires. The target board 10, or plate, may be a sheet of aluminum secured to the upper end portion of the aerial length 13 of the post by means of the rivets 12. When the post is impacted 'by an automobile, this board is easily separated from the tube length 13 with little damage to the board, and the board may be again easily fastened to the tube 13. If the board is bent, it is easily straightened. Also, if the tube 13 is slightly bent it is easily straightened, particularly more easily than if the post were made of a T -bar. When the post is impacted by an automobile, the rivets holding the connector halves together resist enough before shearing to start the aerial part pivoting at the ball and socket faces 34, 44. After the rivets shear, sliding of the ball and socket faces continues unt l fir t the W edge of h l e 43 contacts the ground and then the rest of the aerial part. If the aerial and ground parts were joined together at a plane, or flat surface, as the aerial part pivoted on the ground part, the aerial part would be accelerated axially upward to throw the part thru the air. This acceleration is not inherent in the present construction. Thus, there is little likelihood of the aerial part of the present device being thrown into the air upon impact.
Having described the construction, use, and operation of an embodiment of the present invention, I claim:
1. A ball and socket connector for a highway guide post, composed of two halves, each half having a spherical surface adapted to mate with and slide on the spherical surface of the other, each of said halves having holes formed therein that are transverse such surfaces, each hole in one half being aligned with a hole in the other half in pairs of holes, the inner one of said halves formed with an interior space, each of said pairs of holes extending radially of said surfaces and thru said halves from the exterior of the outer half to said interior space so that each such pair of holes forms a hole that is blind interiorly of said connector, and a frangible rivet extending thru each of said pair of holes to secure said halves together and to impede such sliding.
2. The combination of claim 1 in which said rivets are hollow blind rivets. V
3. The combination of claim 1 having therewith an aerial part in the form of a tube adapted to be in an upright position above the ground and to support a target board at its upper end, the female and outer one of said halves being in the form of a sleeve surrounding and secured to the lower end of said aerial tube, a ground engaging part in the form of a tube adapted to be a continuation of said :aerial tube and to be inserted in the ground for substantially its full length, and the other of said halves being in the form of a sleeve having such interior space as a uniform bore from end to end thereof and surrounding and secured to the upper end of said ground tube.
4. The combination of claim 3 in which said rivets are hollow blind rivets.
References Cited by the Examiner UNITED STATES PATENTS 79,141 6/1868 McFarlin 52-98 1,650,093 11/1927 Rank et al 941.S X 2,248,755 7/1941 Hathorn -452 FOREIGN PATENTS 48,496 3 1934 Denmark.
RICHARD W. COOKE, JR., Primary Examiner.