US2067890A - Post driver - Google Patents

Description

Jan. 19, 1937.

G. L. COLLORD POST DRIVER Filed March 12, 1936 INVENTOR What ATTORN EYS Patented Jan. 19, 1937 UNITED STATES 1 Claim.

This invention relates to the driving of composite metallic posts, and relates particularly to an improvement upon the combination of my copending application, Serial No. 752,958, filed November 14, 1934.

In accordance with my previous invention I construct a one-piece, wholly metallic post. useful as a fence post, as a highway guard post, and

for various other purposes, by casting a shoe of iron about the lower region of a steel or wrought iron bar. As the post is so formed, it has above ground the tensile strength of the steel or wrought iron bar, and has below ground the resistance to corrosion of cast-iron. Desirably I utilize as the metal of which the shoe of my composite post is formed iron taken directly from a blast furnace, since such iron, comprising in excess of three per cent. graphitic carbon, and a lower sulphur content than that of cupol-a iron, possesses particularly high resistance to corrosion.

It should be herein explained that direct blast furnace iron, while highly fragile and readily susceptible to breakage under angularly delivered blows, has unusually high compressive strength, as well as unusually high resistance to corrosion. Because of the inherent fragility of the metal, however, it is of primary importance that, in driving a composite post which comprises a massive shoe cast from direct blast furnace iron, the driving blows be directly delivered and accurately distributed upon a relatively extended surface of the shoe arranged to receive them. The same is true in degree of cupola iron, although that metal possesses lesser resistance to corrosion, coupled with a lesser fragility under angularly delivered blows. The advantages attendant upon driving a post, rather than setting it in a prepared post hole, are obvious.

In my co-pending application, reference to which has been above made, I disclose the driving of a composite metallic post of the nature indicated by means of a co-operatively mounted hammer, which has a plane striking face adapted to co-operate with a plane upper face of the post shoe, and a tubular guide arranged to support the striking weight or hammer proper, and to embrace the bar of the post. While such combination is highly advantageous, it is open to criticism on two grounds. One undesirable effect resulting from the use of a hammer so constructed in conjunction with the composite metallic post is that the guide portion of the hammer which embraces the bar of the post, by its friction during driving, rubs from the post bar the paint, galvanizing, or the like protective coating which has (Cl. til-73) been applied to it. A less inevitable undesired effect is that in some instances there is a tendency for the shoe of the post to break away from the post bar in the region in which these elements are bonded by casting the shoe about the lower portion of the bar. When such latter effect is met, it is found to be caused by the jarring effect of the hammer blows at the line of bonding between the post elements.

I have invented a post and hammer combination, in which a corrosion resistant coating on the bar of the post is protected from the rubbing effect of the hammer during the operation of driving the post, and in which the hammer blows are delivered upon the upper b1ow-receiving face of the post shoe in a region spaced slightly from the line of bonding between the shoe and bar of the post. This I do by making the weight of the hammer and the hammer guide as separate elements, the guide being in the'form of a tubular element, dimensioned closely to embrace the bar of the post, and to rest upon the upper face of the post shoe; and the hammer being'in the form of a imple weight adapted to slide upon the guarding and guiding element as a track, and having a plane downwardly presented striking face for contact with the post shoe radially outward of the guarding and guiding element.

In the accompanying drawing Fig. I is a view, partly in elevation and partly in. vertical section, showing the composite post with the hammer assembly associated therewith for driving the post. Fig. II is a cross-sectional view through the post and hammer assembly, taken on the plane of the section line IIII of Fig. I. Fig. III is a crosssectional view through the assembly of the post and the guard and track element of the assembly, taken on the plane of the section line III-III of Fig. I, and showing additionally in phantom viewthe impending hammer weight. Fig. IV is a cross-sectional view through section line IVIV of Fig. I.

In the drawing reference numeral 1 designates the bar of the driven post, which bar is of a metal having relatively high tensile strength, such as steel or wrought iron, and which is protected against corrosion by a coating of paint, a galvanized coating, or the like protective coating. Cast about the lower region of bar l is a heavy, elongate, tapered shoe 2, which is shown as formed of vertically extended webs intersecting at right angles. Desirably the bar, which is shown as a T-section, has one or both of its webs perforate in the region in which the shoe embraces the bar. These perforations 3 conveniently provide for anchorage of the shoe to the bar during casting.

It will be noted that the shoe 2 has its upper face 2a extended in a single plane perpendicular to the common axis of the bar I and shoe 2. Because of this structure blows squarely struck upon the face 20. are uniformly distributed parallel to the common axis of the bar and shoe, forming the longitudinal, and as mounted the vertical, axis of the post as a whole.

The hammer structure comprises as its primary element a weight 4, which is mounted concentrically about the lower portion of a relatively short tubular weight-carrying element 5. Adjacent the upper terminal of the tubular weightcarrying element are attached handles 6, by means of which the hammer structure proper may be lifted. Because of the mounting of the weight 4 on the tubular element 5, the hammer has a central longitudinal bore 1 therethrough. As shown, the weight and short tubular element of the hammer are formed as an integral casting with which the handles 6 have a screwthreaded engagement. The structure of the hammer proper may, however, be made by integration of its component parts in any suitable manner.

It will be observed that the under face of weight t is extended in a single plane perpendicular to the longitudinal axis of the hammer bore 1. As mounted to surround the bar I of the post, the hammer is therefore capable, in cooperation with the plane upper face 211 of the shoe, of delivering to the shoe driving impact uniformly distributed parallel to the longitudinal axis of the post.

The other element of the hammer assembly comprises a relatively elongate tube 8, which has an exterior diameter slightly shorter than the diameter of the hammer bore 1. In assembly, preparatory to driving the post, the elongate tube 8, is therefore positioned to surround the bar I throughout a substantial proportion of its height, and is permitted to rest upon the upper face 2a of the post shoe. It is of substantial advantage that the parts be so related in diameter that in assembly the tube 8 closely surrounds the web edges of the bar I.

As the hammer in assembly is mounted upon a post to be driven, the tube 8 forms therefore a track for traversing the hammer weight vertically to deliver post-driving blows upon the upper face of the shoe, and a guard protecting the bar of the post from friction as the hammer weight is raised and dropped. That is, with this tubular guard and track closely embracing the bar of the post, the hammer weight is at once accurately guided into a striking contact with the shoe perpendicular to the axis of the post and is kept out of physical contact with the post bar. As driven, the post thus has the protective coating on its upper, or bar, portion unimpaired, and is thus the longer able to withstand the corrosive effects of weathering. It may here specifically be noted that, if cast of direct blast furnace iron, the life of the post shoe is of indefinitely prolonged duration. This is so even though, in the natural use of the post, the shoe is exposed to intensive corrosion-promoting contact below and at the ground level.

The secondary effect of the guard and track element 8 is to shield the actual junction line between the post bar and the post shoe presented at the upper face of the shoe. By overlying this junction line, the guard and track element 8 spaces the delivery zone of the hammer blows a short distance radially outward from it upon the upwardly presented faces of the shoe webs. The hammer blows, therefore, create no tendency to cause at this line a separation between the bodies of dissimilar metals of which the bar and the shoe are composed.

It will be noted that the guard and track element 8 extends upwardly along the bar I such distance that the weight may be lifted through a relatively great proportion of the post height while remaining centered about the guard. In driving the post into ground which is penetrable with difiiculty, the weight may therefore be raised on the guard and track such distance as to acquire adequate acceleration when dropped.

I claim as my invention:

In hammer-driving assembly the combination of a metallic post comprising a bar element and an anchoring and ground-penetrating shoe embedding the lower terminal region of the bar element of the post and having an upwardly presented striking face extended radially from the bar together with a tubular guard element closely embracing the bar element of the post and resting upon the upwardly presented face of the post shoe, and a perforate hammer weight closely surrounding and traversable upon the said tubular guard element, said hammer weight having a downwardly presented striking face complementary tothe upwardly presented striking face of the post shoe; whereby in hammer-driving the composite post the tubular guard element both protects the post bar from friction in traversing movement of the hammer weight and spaces the hammer weight from the junction line between the post bar and the embedding body of the post shoe.

GEORGE L. COLLORD.

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