With the brake drum and wheel hub installed on the axle the service brake band is mounted around the circumference of the brake drum.  The brake shoe actuation mechanism (silver colored hardware) is shown at the center left of the photo.  As the foot brake pedal is depressed an actuating bolt rotates (just like the handbrake) to move a short lever arm counterclockwise.  Attached to the lever arm is one end of the service brake band.  The other end of the service brake band is fixed and doesn't move.  Just as was done for the handbrake a series of rods and shafts transmit the motion of the foot brake's pedal to the actuating mechanism (of both rear wheel service brakes) such that the brake shoe is pulled tight against the exterior of the brake drum.

In the photograph above the front of the car is to the left.  This means that when the car is moving in the forward direction the drum rotates counterclockwise.  The actuation of the service brake shoe also pulls the brake shoe in a counterclockwise direction.  The drum and shoe rotating in the same direction assists in the braking motion as the tendency is for the friction between the brake shoe lining and the drum to assist in pulling the brake shoe tighter.  The same principals apply to the right wheel with the exception that the rotation of the drum, and the tightening of the service brake shoe, are both clockwise instead of counterclockwise as is the case with the left wheel.

When backing up the left wheel's brake drum is turning clockwise while the brake shoe still wants to be pulled counterclockwise to tighten against the brake drum.  The result is that when the car is moving in the reverse direction, and the service brake is applied, it requires more effort on the brake pedal to stop the car.  The result is that while stopping the car when it is moving in the forward direction is marginal at best, there's only a marginal ability to stop the car when it is moving in the reverse direction!