leg of the respective spring member 36 the hole 36a in an outer leg of each of the spring member has an elongate rectangular shape and the ends of the pins 35 are compressed or upset to provide free end portions 35a of a generally corresponding elongate rectangular shape after insertion of pin 35 through spring member 36 the pin is rotated ninety degrees so that the longer dimension of its end portion 35a extends across the shorter dimension of hole 36a in the outer leg of the spring member further the end portion of each pin 35 rests in a groove in an outer leg of the respective spring member 36 after assembly with the longer dimension of the end portion extending lengthwise of the groove to prevent inadvertent rotation of the pin 35 to a releasing position as best shown in fig7 and 8 each pin 35 is provided with an enlarged head 35b larger than the corresponding hole in the brake support casting 28 the brake support casting 28 is also provided with a rotation preventing abutment 28g slotted at opposite arcuate ends with slots 28h and 28i the brake shoes 31 and 32 are also held in engagement with the respective pad portions 28a 28f by the disposition of arcuate end portions 31a and 32a of the brake shoe webs respectively in the slots 28h and 28i the brake shoes 31 and 32 are urged toward each other by tension spring 37 connecting one pair of adjacent arcuate ends and tension spring 38 connecting the opposite pair of adjacent arcuate ends of the brake shoe webs brake shoes 31 and 32 are held apart adjacent the spring 38 by the torque receiving abutment 28g and adjacent spring.