Electric drum brake

A duo-servo drum brake for a wheel of an automotive vehicle comprising:

• a brake drum for connection to the wheel;
• a backing plate for connection to the vehicle, the backing plate having an anchor at a first end;
• first and second brake shoes having means of mounting with the backing plate and having a pivotal mounting with respect to the anchor;
• a nonrotative nut mounted for linear motion with respect to the backing plate;
• a first apply lever pivotally mounted with respect to the nut and pivotally mounted with respect to the first brake shoe for imparting an actuation force to the first brake shoe and to receive an actuation force from the nut to effect both a service brake and a parking brake application,
• a second apply lever pivotally mounted with respect to the backing plate and also pivotally mounted with respect to the secondary brake shoe for imparting an actuation force to the second brake shoe to effect both a service brake and a parking brake application
• a generally fixed-length first strut for imparting an actuation force from the first lever to the second lever, the first strut having means of pivotal mounting with the first and second brake shoes, the first strut's pivotal mounting with the first brake shoe being on a line generally collinear with the pivotal mounting of the first apply lever with the nut and with the first shoe, and the pivotal mounting of the strut with respect to the second brake shoe being along a line collinear with the pivotal mounting of the second apply lever with the backing plate and with the second shoe;
• a second strut abuttingly engaged to the first and second shoes on an end of the first and second shoes opposite the anchor;
• a power screw threadably engaged with the nut for translating the nut;
• an electric motor torsionally associated with the power screw for turning the same;
• and
• means for preventing rotation of the power screw.