An energy recovering device for braking system of vehicles, wherein a vehicle comprises at least one wheel connected to propelling means of the vehicle and associated to a brake, the device comprising: - a support body (2, 22) anchorable to a fixed part of the vehicle, said support body being elongated along a longitudinal axis; - an energy storing elastic member (4, 24) housed into said support body (2, 22) and susceptible of turning from a first working position wherein it is unloaded to a second working position wherein it is at least partially loaded with a torque; - an interface member (5, 25) integral with said energy storing elastic member (4, 24) and associable to the vehicle brake, said interface member (5, 25) being susceptible of rotating around a first longitudinal axis for transmitting a torque to said storing member (4, 24) and allowing the transmission thereto of at least part of the energy produced during braking, promoting its turning from said first to said second working position; - a transmission member (6, 26) integral with said energy storing member (4, 24) and connectable to the propelling means of the vehicle for transmitting to this latter the energy stored by said elastic member (4, 24); - unidirectional releasing means (7, 27) of said elastic member (4, 24) designed for selectively avoiding the turning of said elastic member (4, 24) from said loaded second working position to said unloaded first position, said releasing means (7, 27) being at least partially disengageable in a selective manner by a vehicle user to allow the at least partial transmission of the stored energy from said elastic member (4, 24) to said transmission member (6, 26) as the brake is released; characterized in that said storing elastic member (4, 24) is a substantially longitudinal helical spring having a first longitudinal end (8, 28) integral with said interface member (5, 25) and a second end (9, 29) integral whit said transmission member (6, 26), said unidirectional releasing means (7, 27) comprising a kinematic motion adapted to mechanically connect said transmission element (6, 26) to said second end (9, 29) of said spring (4, 24). - a support body (2, 22) anchorable to a fixed part of the vehicle, said support body being elongated along a longitudinal axis; - an energy storing elastic member (4, 24) housed into said support body (2, 22) and susceptible of turning from a first working position wherein it is unloaded to a second working position wherein it is at least partially loaded with a torque; - an interface member (5, 25) integral with said energy storing elastic member (4, 24) and associable to the vehicle brake, said interface member (5, 25) being susceptible of rotating around a first longitudinal axis for transmitting a torque to said storing member (4, 24) and allowing the transmission thereto of at least part of the energy produced during braking, promoting its turning from said first to said second working position; - a transmission member (6, 26) integral with said energy storing member (4, 24) and connectable to the propelling means of the vehicle for transmitting to this latter the energy stored by said elastic member (4, 24); - unidirectional releasing means (7, 27) of said elastic member (4, 24) designed for selectively avoiding the turning of said elastic member (4, 24) from said loaded second working position to said unloaded first position, said releasing means (7, 27) being at least partially disengageable in a selective manner by a vehicle user to allow the at least partial transmission of the stored energy from said elastic member (4, 24) to said transmission member (6, 26) as the brake is released; characterized in that said storing elastic member (4, 24) is a substantially longitudinal helical spring having a first longitudinal end (8, 28) integral with said interface member (5, 25) and a second end (9, 29) integral whit said transmission member (6, 26), said unidirectional releasing means (7, 27) comprising a kinematic motion adapted to mechanically connect said transmission element (6, 26) to said second end (9, 29) of said spring (4, 24).