A clock movement is provided that contains a constant force device. In accordance with one implementation, the clock movement includes a spiral spring, and a train, having a first kinematic chain arranged to connect a main energy source to a first end of the spiral spring and a second kinematic chain for connecting a time base to a second end of the spiral spring. One of the first and second kinematic chains may contain an adjustment mobile comprising first and second members connected to each other by a friction such that a rotation of one member drives the other member during routine working of the clock movement. One of these members may include an adjustment member having at least one bearing surface arranged such that it is possible to act upon the latter so as to rotate the adjustment member without rotating the other member by dint of friction, in order to adjust the load state of the spiral spring.