Mechanism for regulating an average angular speed in a horological movement, comprising: - an oscillator, - an escape wheel for interacting with the oscillator according to an operation repeating a cycle, and - an intermediate device (9, 23, 24; 9, 123, 24; 9, 223, 24; 300) for putting the oscillator and the escape wheel in interaction in such a way that a quantity of energy is transmitted from the escape wheel to the oscillator at each cycle and that a frequency of the oscillator regulates an average speed of rotation of the escape wheel, the intermediate device (9, 23, 24; 9, 123, 24; 9, 223, 24; 300) comprising elastic means arranged to store substantially entirely, through elastic deformation, the said quantity of energy, the intermediate device (9, 23, 24; 9, 123, 24; 9, 223, 24; 300) being configured so that its elastic means provide at each cycle substantially the same quantity of energy to the oscillator, the intermediate device (9, 23, 24; 9, 123, 24; 9, 223, 24; 300) comprising a pallet fork (23; 123; 223) for putting the oscillator and the escape wheel in interaction, the pallet fork (23; 123; 223) comprising two pallets which are an entry pallet and an exit pallet for being alternatively engaged with the escape wheel, each pallet (45, 46) including an active profile (47, 50) for being travelled from the upstream to the downstream by teeth of the escape wheel, each active profile (47, 50) including a straining ramp configured to be pushed back in the direction opposite to the escape wheel by each tooth when this tooth moves along this straining ramp downstream, characterized in that a fork provided to exchange thrusts with the oscillator is rigidly connected to the two pallets (45, 46) and forms part of the pallet fork (23; 123; 223), the pallet fork (23; 123; 223) being able to rock between a first position, in which the entry pallet is able to co-operate with the escape wheel, and a second position, in which the exit pallet is able to co-operate with the escape wheel, the elastic means tending to bring back the pallet fork (23; 123; 223) toward the first position when this pallet fork (23; 123; 223) is located between this first position and an intermediate position of unstable equilibrium, the elastic means tending to bring back the pallet fork (23; 123; 223) towards the second position when this pallet fork (23; 123; 223) is located between this second position and the intermediate position of unstable equilibrium, in that each active profile (47, 50) includes a locking surface, at least one portion of which is for blocking temporarily each tooth downstream, and in that, at each pallet (45, 46), the straining ramp is disposed upstream from the locking surface in a manner that, before stopping any tooth among said teeth downstream, each pallet (45, 46) is pushed back by this tooth. - an oscillator, - an escape wheel for interacting with the oscillator according to an operation repeating a cycle, and - an intermediate device (9, 23, 24; 9, 123, 24; 9, 223, 24; 300) for putting the oscillator and the escape wheel in interaction in such a way that a quantity of energy is transmitted from the escape wheel to the oscillator at each cycle and that a frequency of the oscillator regulates an average speed of rotation of the escape wheel,