Motors are devices that produce motion due to the transfer of energy, but not of momentum, to the device. Recent advances in materials science have allowed the construction of motors where the motion is produced via changes in the shapes of solid objects.  In this talk, we consider motors where the shape change is a bend, rather than an elongation or contraction.  We analyze in detail the physical mechanisms which bring about the motion, and discuss the origins and path of the momentum current that is generated.  We present the results of numerical simulations, and compare these with experimental observations.  Some novel approaches to motor design will be discussed.