Background Art In general, a railway vehicle, which drives to its destination while truck wheels perform a rotational motion on a fixed track, needs a device for reaching the destination or controlling a speed of the truck restrictively, namely, a brake system. The brake system is to stop the truck on the destination by effectively controlling the speed of the truck. Types of the stop are divided into a stop by a normal speed control, a prompt emergent stop when unexpected incidents occur in front of the truck, and a stop for controlling the speed of the truck during curving.

In the brake system of the railway vehicle, when compressed air is applied to a braking tank, a number of link members and holder hangers transfer braking force to a brake shoe, and then, braking is carried out when there is friction between the brake shoe and the truck wheels.

A conventional brake shoe holder hanger described above is shown in FIGS. 1 and 2.

As shown in the drawings, the conventional brake shoe holder hanger 4 is a

component for supporting operation of the brake shoe during the braking action after braking-related devices are fixed to a truck frame end beam 1, and is connected between a hanger bracket 2 and a brake shoe 3 by a pin.

However, the brake shoe holder hanger 4 can perform only the rotational motion in a back and forth direction of the truck on the pins 5 of the hanger brackets 2 but is restricted in a lateral motion of the brake shoe holder hanger 4 because there is little interval between the hanger bracket 2 and the brake shoe holder hanger (single lever) connected with the brake shoe 3 by the pin 5.

When braking is performed during curving on a curved railway, which has lots of curved courses, there occurs a relatively horizontal displacement between the truck frame and the brake shoe due to centrifugal force of the truck in a state that the brake shoe is closely fixed to a wheel tread, and there occurs torsion stress around the hanger bracket because the horizontal displacement distorts the hanger bracket through the single lever 4.

The stress occurring by the torsion of the hanger bracket is three times as strong as stress occurring by vertical vibration of the braking relevant devices.

According to a theoretical analysis of the stress value, the stress exceeded 72% of allowable yield strength, and there was a crack when the stress was applied to a base metal part repeatedly.

Disclosure of Invention Accordingly, the present invention is directed to a torsion free brake shoe holder hanger for use in a truck of a railway vehicle that substantially obviates one or more problems due to limitations and disadvantages of the related art.

An object of the present invention is to provide a torsion free brake shoe holder hanger, whose center part is connected by a pin at right angels to pins connected to both ends of the brake shoe holder hanger without any change in a

hanger bracket connecting part and a brake shoe connecting part of the holder hanger so that a lower lever performs a relatively horizontal motion in relation to the hanger bracket, thereby absorbing horizontal strength by converting the horizontal displacement into a horizontal motion of the lower lever suitable for a position of a pin connection between an upper lever and the lower lever without transmission of the horizontal displacement to the hanger bracket.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a torsion free brake shoe holder hanger for use in a truck of a railway vehicle includes: an upper lever including an upper connecting section formed on the upper thereof and having a hanger connecting hole formed therethrough to be connected to a hanger bracket of a truck frame end beam by a pin, an insertion groove formed in the center of the lower end thereof, and a pair of connecting rings formed on both sides of the insertion groove and having an upper connecting hole formed therethrough, each upper connecting ring being placed at a state in which the upper connecting ring is located by 90 degrees with respect to the upper connecting section; a lower lever inserted between the connecting rings of the upper lever to be connected to the upper lever, and including a lower connecting ring formed on the upper end thereof and having a lower connecting hole formed therethrough, and a brake shoe connecting section formed on the lower end thereof and having a brake shoe connecting hole formed therethrough to be

connected to the brake shoe, the lower connecting ring being placed at a state in which the lower connecting ring is located by 90 degrees with respect to the lower connecting section; and a pin fit into the upper connecting holes of the upper lever and the lower connecting hole of the lower lever for rotational motion.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

Brief Description of the Drawings Further objects and advantages of the invention can be more fully understood from the following detailed description taken in conjunction with the accompanying drawings in which: FIG. 1 is a perspective view of a conventional brake shoe holder hanger; FIG. 2 is a view showing a state in which the conventional brake shoe holder hanger is installed; FIG. 3 is an exploded perspective view of a torsion free brake shoe holder hanger according to the present invention; FIG. 4 is an assembled perspective view of the torsion free brake shoe holder hanger according to the present invention; and FIG. 5 is a view showing a state in which the torsion free brake shoe holder hanger according to the present invention is installed.

Best Mode for Carrying Out the Invention The present invention will now be described in detail in connection with preferred embodiments with reference to the accompanying drawings. For reference, like reference characters designate corresponding parts throughout

several views.

FIG. 3 is an exploded perspective view of a torsion free brake shoe holder hanger according to the present invention, FIG. 4 is an assembled perspective view of the torsion free brake shoe holder hanger according to the present invention, and FIG. 5 is a view showing a state that the torsion free brake shoe holder hanger according to the present invention is installed.

As shown in the drawings, the torsion free brake shoe holder hanger for use in a truck of a railway vehicle according to the present invention includes an upper lever 10 connected to a hanger bracket 2 of a truck frame end beam 1. The upper lever 10 includes an upper connecting section 12 formed on the upper thereof and having a hanger connecting hole 11 formed therethrough to be connected to the hanger bracket 2 of the truck frame end beam 1 by a pin, an insertion groove 13 formed in the center of the lower end thereof, and a pair of connecting rings 14 formed on both sides of the insertion groove 13. Each upper connecting ring 14 is integrally formed with the upper connecting section in such a manner as to be placed at a state in which the upper connecting ring 14 is located by 90 degrees with respect to the upper connecting section 12. The upper connecting ring 14 has an upper connecting hole 14 formed therethrough.

A lower lever 20 is inserted between the connecting rings 14 of the upper lever 10 to be connected to the upper lever 10. The lower lever 20 includes a lower connecting ring 22 formed on the upper end thereof and having a lower connecting hole 21, and a brake shoe connecting section 24 formed on the lower end thereof and having a brake shoe connecting hole 23 formed therethrough to be connected to the brake shoe 3. The lower connecting ring 22 is integrally formed with the lower connecting section 24 in such a manner as to be placed at a state in which the lower connecting ring 22 is located by 90 degrees with respect to the lower connecting section 24.

When a pin 30 is fit into the lower connecting hole 21 of the lower lever 20 and the upper connecting hole 15 of the upper lever 10, the upper lever 10 and the lower lever 20 are connected with each other to perform a relatively rotational motion.

Functions and effects of the present invention having the above structure will now be described as follows.

First, the upper connecting holes 15 of the upper connecting rings 14 of the upper lever 10 and the lower connecting hole 21 of the lower connecting ring 22 of the lower lever 20 are connected by the pin 30, and then, the upper connecting section 12 having the hanger connecting hole 11 is connected to the hanger bracket 2 of the truck frame 1 by a pin.

The brake shoe connecting section 24 having the brake shoe connecting hole 23 is connected to the brake shoe 3 by a pin to support the operation of the brake shoe.

In the above condition, a lateral displacement occurring when a truck brakes during curving to reach its destination or control a speed of the truck restrictively is changed into a horizontal displacement by the lower connecting ring 22 rotating in the lateral direction in relation to the upper connecting ring 14 connected with the lower lever 20 by the pin 30, and thereby, the present invention can prevent a crack from occurring in the truck frame around the hanger bracket due to torsion and improve a traveling safety of the truck.

The brake shoe holder hanger according to the present invention absorbs the horizontal displacement through the two-stage link structure, but it is also preferable that the brake shoe holder hanger has a chain structure.

Industrial Applicability

As described above, the brake shoe holder hanger according to the present invention can improve the traveling safety, extend life of the truck and reduce maintenance costs by preventing the crack from occurring in the truck frame around the hanger bracket due to the horizontal displacement occurring when the truck brakes during cornering, and reduce a size of the truck and reduce manufacturing costs by designing excessively designed parts for preventing cracks into the optimum size.

While the present invention has been described with reference to the particular illustrative embodiments, it is not to be restricted by the embodiments but only by the appended claims. It is to be appreciated that those skilled in the art can change or modify the embodiments without departing from the scope and spirit of the present invention.