The brake shoe used on the vehicle is a brake part which is pressed into direct contact with a tread of a wheel or with a disk sliding surface to apply a braking power to the vehicle.
FIG. 13 is a typical drawing showing one example of a brake shoe of rolling stock.
In FIG. 13, a wheel 20 mounted on a bogie frame 23 is rotating on a rail surface 22. A brake shoe 21 for the wheel tread is mounted also on the bogie frame 23 through a holder 27. This brake shoe 21 for the wheel tread is pressed against the tread of the wheel 20 at the time of brake application to the vehicle.
FIG. 14 is a typical drawing showing another example of the brake shoe for the vehicle.
In FIG. 14, a disc 25 rotating together with the wheel 20 is mounted on an axle 24 which connects two wheels 20 placed on two rails. On either side of this disc 25 is provided a brake shoe 26 for the disc. When the brake is applied, the disc 25 rotating together with the axle 24 is held by a brake shoe 26 for the disc, thereby applying the brake to the vehicle.
The brake shoe 21 for the wheel tread (see FIG. 13) and the brake shoe 26 for the disc (see FIG. 14) are gradually worn to decrease in thickness t during brake application, and will require replacement for safety when worn away to specific limit thickness (wear limit value). In the event of abnormal brake application, the brake shoes will be subjected to abnormal wear. To check the wears described above, the prior-art technique has such a disadvantage that a checker goes around the vehicle which is at a stop to make visual checks of a worn condition of the brake shoes. Replacement of the brake shoe, when found necessary, will be carried out at this point of time.
Also the prior-art technique has such a problem that since the thickness and a worn condition of the brake shoes are detected by the above method, much time and work is required and the brake shoes are replaced at the time when the necessity of their replacement is found. The above-described method of brake shoe replacement, however, is not systematic and besides because the check is visually performed, it is difficult to properly control data concerning the thickness and worn condition of the brake shoes.