US2068015A - Brake head - Google Patents

Description

Jan. 19, 1937. H. E. GANNETT BRAKE HEAD Filed Oct. 27, 1933 Patented Jan. 19, 1937.

, .UNITED STATES PATENT OFFICE 1 Claim.

My invention relates to a method of treating wear receiving surfaces of a friction encountering cast ferrous metal object and more particularly the shoe encountering lugs and the hanger receiving sockets of a brake head whereby such portions of the head will be materially hardened above the normal hardness, in order that the head will be capable of withstanding the constant chatter or frictional action of the brake shoe and of the hangers usually employed for properly suspending the heads in place.

The brake heads are usually of cast malleable iron while the shoes are made of harder metal, with the result that the constant vibration or up and down movement of the shoe during car operation and brake application causes the headlugs soon to become excessively worn which necessitates renewal of the worn portions or replacement of the entire head.

This, of course, also results in car service loss and in increased expense due to defective brake conditions.

The object of my invention, preferably, is to merely treat those surfaces of the head which are subject to wear receiving contact so as not to destroy the more or less tough characteristic of malleable iron; the method of treatment being such that the depth of hardness may be readily controlled.

The invention will be readily comprehended from the detailed description of the particular embodiment disclosed in the accompanying drawing, wherein:

Figure 1 is a side elevation of a brake head with portions of the lugs on the forward face shown in section to disclose the treated surfaces.

Figure 2 is a front elevation of the head shown in Figure 1.

Figure 3 is a detail sectional view taken substantially on the line 3-3 of Figure 1, as viewed by the arrows.

In order to exemplify my invention, I have chosen a well known standard type of brake head Ill, the forward face whereof is shown provided with forwardly presented brake shoe contacting lugs; the upper and lower ends of the head being shown with the laterally spaced lugs I I, H at the top and lugs l2, l2 at the lower end; while the intermediate portion of the front face is provided with the vertically spaced lugs l3 and I l.

The head illustrated is of what is known as a top hung type, having a hanger receiving socket l5.

The lugs l3 and U! are spaced sufliciently apart in order to receive the lug on the rear side of the shoe (not shown) therebetween; the lug l4 supporting the shoe-lug and thus holding the shoe in place.

The lugs l3 and I l, like the interposed shoelug, are provided with vertical slots extending through the lugs and adapted to receive the usual Wedge-key (not shown) whereby the shoe is locked in place against the forward side of the head.

The brake heads are usually of malleable iron and are made with more or less tolerance between the lugs to permit easy application or reception of the shoe lug therebetween.

As the shoes are of harder metal than that of the heads, the constant vibration or up and down movement of the shoe during car operation and brake application causes the head lug It, in particular, to soon become excessively worn beyond the permissible latitude and point of safety.

At the same time, the more or less constant swinging movement or play between the head and. the hanger (not shown) also causes the hanger receiving socket l5 to become so worn as to allow the head to drop down too far, or cause the head to break.

My invention contemplates subjecting the shoe encountering surfaces of the lugs on the head and also the hanger receiving sockets of the heads to a method of controllable heating, preferably a resistance heating, whereby the preselected portions of the head will be hardened without affecting the major portion of the head.

A preferred method of treating the head consists in subjecting the malleable iron head or rather the lugs and hanger receiving socket to the action of an electric carbon arc whereby the malleable iron is practically returned to the consistency, in hardness, of white cast iron.

That is to say, by passing a sufficiently heavy electric current through the preselected sections, a very hard wear resisting surface is provided.

In practice, the head is grounded and the carbon of an electric torch is then momentarily placed in contact with the surface to be treated, causing a concentrated heating of these surfaces; the carbon being moved across the face of the surfaces for a comparatively brief period. This movement of the carbon arc of the electric torch across the head lugs causes the outer surfaces of the lugs to be given a hardness as indicated at l6, known to be in excess of 500 Brinell; the carbon being also momentarily brought into contact with the upper wear receiving'wall of the hanger socket l5, as indicated at l! in Figures 1 and 3.

The depth of hardness is controlled by the length of time the arc is maintained and played upon the surface; it being preferable in brake heads to merely harden the surface as disclosed in the drawing so as not to subject the head to easy breakage.

The method of passing a sufiiciently heavy electric current merely through the sections desired to be hardened is found more desirable and more easily controlled.

My improved treatment is intended more particularly to new brake heads and to heads which are not worn to a point below the limit of wear brakehead provided with integral brake shoe engaging and supporting lugs, the shoe contacting surfaces of said lugs being recarbonized and given a substantially White cast iron consistency.

HOMER E. GANNETT.

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