US2176724A - Brake shoe keylock - Google Patents

Description

Oct. 17, 1939. F E-FE 2,176,724

BRAKE SHOE KEYLOGK Filed Oct. 21, 1958 IlIgg/EN R. m L wimp up BY Ag ATTO YSf Patented Oct. 17, 1939 PATENT OFFICE BRAKE SHOE KEYLOGK Frederic Schaefer, Pittsburgh, Pa. 7 I Application October 21, 1938, Serial No. 236,229

8 Claims.

This invention relates to railway car brake rigging, and more particularly to brake heads and shoes. p

Railway brake shoes aredetachably connected to brake heads by means of keys that extend downwardly through vertically spaced lugs projecting from the head. Each shoe is provided with a pair of horizontally spaced lugs in which the ends of a substantially vertical hardened metal strap are embedded, and they project between the brake head lugs. The key extends between this strap and the shoe, whereby the shoe is attached to the head. Various types of keys have been proposed which are locked in position so that they will not accidentally permit the shoe to fall from the head. Nevertheless, a great many solid, onepiece, non-locking keys are still used, and such keys have a tendency to work upwardly out of place and occasionally release a brake shoe.

It is among the objects of this invention to provide means for looking a brake shoe key in position in a simple and inexpensive, yet effective, manner, and which is operative regardless of which end of the shoe is down.

The preferred embodiment of the invention is illustrated in the accompanying drawing in which Fig. 1 is a side view, partly broken away, of a brake head, shoe and key; Fig. 2 is a horizontal section taken on the line 11-11 of Fig. 1; Fig. 3 is a vertical section taken on the line IIIIII of Fig. 1; and Fig. 4 is an enlarged transverse section through the brake shoe strap.

Referring to Fig. 1 of the drawing, a brake head I is provided with a pair of forwardly projecting vertically spaced lugs 2 provided with the usual passages 3 therethrough for receiving a brake shoe key 4. This head supports a brake shoe 6 which has a pair of horizontally spaced lugs l projecting rearwardly between the brake head lugs. As is the usual practice, the outer ends of the shoe lugs are connected by a cross member or strap 8 of hardened steel, the ends of which are cast into the lugs (Fig. 3). The brake shoe key extends between this strap and the shoe whereby the shoe is detachably connected to the head.

Any type of key may be used, although this invention will generally have more utility with solid one-piece keys than with multiple leaf wedge lock keys. A conventional one-piece key is shown in the drawing. It tapers towards its lower end to form a wedge and is driven downwardly across strap 8 until the shoe is drawn up tightly against head lugs 2.

It is a feature of this invention that the head or shoe, or both, are provided with means for tightly gripping the key its upward movement that it is very unlikely that the key will work loose. Accordingly, the inner surface of the brake shoe strap is provided with a plurality of projections, preferably in the form of vertically spaced horizontal serrations ll that tend to dig into the adjoining surface of the key and prevent it from moving upwardly. To facilitate downward movement of the key across the serrations and at the same time to increase their resistance to upward movement of the key, the serrations that are in gripping engagement with the key should face downwardly; that is, the upper surface of each such serration is inclined but its lower surface is substantially perpendicular to the key (Fig. 4). As the key is both tapered and curved away from strap 8, they tightly engage each other only for substantially the upper half of the strap. Due to this and the face that brake shoes are reversible so that either end may be at the top, the serrations on the upper half of the strap face downwardly and those on the lower half face upwardly, as shown in Fig. 4. Consequently, the key is tightly engaged by downwardly facing serrations regardless of which end of the brake shoe is uppermost.

As a means of still further increasing resistance to upward movement of the key, or as an alternative means, one or both of brake head lugs 2 may likewise have their inner surfaces provided with projections or horizontal serrations for engaging the key. Ordinary cast brake head lugs are not hard enough to provide serrations of the desired hardness. Furthermore, it would be very difficult to cast the serrations into the lugs. Therefore, the body It of each lug is preferably provided with a hardened steel liner ll in one face of which the serrations ill have been cut (Figs. 1 and 2) This liner is cast onto a lug 2 when the head is cast, and preferably has laterally bent top and bottom portions that extend into recesses in the top and bottom of the lug body to aid in preventing the liner from being moved vertically by the brake shoe key. All of the serrations I8 face downwardly because the brake head is never put on bottom side up.

According to the provisions of the patent statutes, I have explained the principle and construction of my invention and have illustrated and described what I now consider to represent its best embodiments. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

so as tooffer such resistance to 1. In combination, a brake head having hollow lug members, a brake shoe provided with a strap member, and a smooth-surface brake shoe key for locking the shoe to the head, the inner surface of at least one of said members being provided with a plurality of relatively sharp projections for frictionally engaging the adjoining surface of said key.

2. In combination, a brake head having hollow lug members, a brake shoe provided with a strap member, and a smooth-surface brake shoe key for locking the shoe to the head, at least one of said members being provided with a plurality of sub- ;stantially horizontal serrations for engaging the adjoining surface of said key.

3. A brake shoe strap provided on its inner surface with a plurality of relatively sharp projections for frictionally engaging and gripping a smooth-face brake shoe key.

4. A brake shoe strap provided on its inner surface with a plurality of substantially horizontal serrations for engaging a smooth-face brake shoe key.

5. A brake shoe strap provided on its inner surface with a plurality of substantially horizontal serrations for engaging a brake shoe key, the serrations on the upper half of the strap facing downwardly, and those on the lower half of the strap facing upwardly.

6. A brake head having a pair of vertically spaced lugs provided with aligned passages for receiving a brake shoe key, the key-engaging surface of at least one of said lugs being provided with a plurality of relatively sharp projections for gripping the adjoining surface of the key.

'7. A brake head having a pair of vertically spaced lugs provided with aligned passages for receiving a brake shoe key, the key-engaging surface of at least one of said lugs being provided with a plurality of substantially horizontal serrations.

8. A brake head having a pair of vertically spaced lugs provided with aligned passages for receiving a brake shoe key, at least one of said lugs comprising a body member and a key-engaging hardened metal liner, said liner being provided with a plurality of substantially horizontal serrations.

. FREDERIC SCHAEFER.

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