| 摘要 |
The invention relates to an internal shoe drum brake which comprises a back plate, two brake shoes, and shoe return springs biasing the shoes to brake release positions. An extensible strut has one end engaged by one of the brake shoes and has a rotary member with a ratchet teeth which may be rotated to extend the strut. The strut is rotatably mounted on a cross shaft to which a toggle lever is securely mounted for rotation therewith. The toggle lever extends through the back plate and has an operating arm, which is operatively connected to a parking brake lever mounted within a passenger compartment, disposed on an outside of the back plate and an actuating arm disposed on the inside of the back plate and engaged by the other brake shoe. An adjust lever which has a pawl engageable with the teeth of the rotary member is rotatably mounted on the cross shaft and biased in a rotational direction to cause the pawl to rotate the rotary member in a direction to extend the strut by means of a tension spring extending between the adjust lever and the strut. Stopper pin means is provided for transmitting the rotational movement of the adjust lever due to bias of the tension spring to the toggle lever to press the operating arm into engagement with the outside of the back plate thereby to press the cross shaft into engagement with the inside of the back plate whereby the strut is held in proper position even when the axial load applied to the strut is relieved of. |
