GB573242A - Improvements in friction brakes - Google Patents

Abstract

573,242. Brakes. THORNTON, A. A. (Warner Electric Brake Manufacturing Co.). June 22, 1943, No. 10096. [Class 103 (i)] Brake mechanism comprises a main brake of the internal expanding type that is applied by the braking torque of an auxiliary brake of the same type applied in turn by an electromagnetically-applied disc brake, the main and auxiliary brake shoes being applied to axially spaced parts of a common drum which contains also the disc brake. The main brake comprises a pair of shoes 15, the ends 28 of which are normally held by springs 30 against arms 25 on an anchor member 18 bolted to the fixed closure plate 20 of the drum 11 carried by a vehicle wheel 9. Lateral movement of the shoes is prevented by lugs 21 thereon extending through brackets 22 on the member 18. The shoes are expanded by levers 73 pivoted at 74 to the anchor arms 25 and engaging by pins 78, brackets 29 on the shoes. The levers are operated by pins 77 on a member 40 rotatable on an extension 42 of the anchor member 18 and which carries arms 54 against the ends 54' of which the ends of the shoes 48 of the auxiliary brake are normally held by springs 58. The shoes 48 are applied by levers 60 pivoted at 62 to the arms 54 and engaging brackets 57 on the-shoes, by pins 66. The levers 60 are operated by pins 64 on a magnet ring 33 rotatably mounted on the member 40 and against which is normally lightly pressed an armature ring 34, by tangential plate springs 43 connecting the ring 34 to the drum 11. Thus when the winding of the ring 33 is energized the ring is turned by the armature 34 and applies the shoes 48 to the drum and the torque exerted in the shoes by the drum is transmitted by the member 40 to the levers 73 to apply the main shoes 15. The shoes of each pair anchor at diametricallyopposite ends when applied and are thus both self-energizing. The relative thickness and width of the linings of the two pairs of shoes is so arranged in relation to the relative pressure applied to them as to ensure that they wear down equally. The ring 33 is returned by springs 70 connected to it and the member 40 which is returned by springs 81.