Abstract: A high impact device, as for producing an impact of 1,000 foot pounds or more, includes a ram which is engageable by a pair of rotating flywheels. The ram may impact a tool, as of a chisel type adapted for demolition purposes, or having a enlarged head for percussion purposes, or other types or purposes. By terminating the engagement of the flywheels with the ram prior to its impact against a tool or similar object, the vibration normally associated with a demolition or percussion device is avoided. Such termination of engagement also reduces reverse shocks and conserves the energy of the rotating flywheels. In one embodiment, the flywheels are moved inwardly and outwardly of the ram through a linkage connected to a solenoid, with each flywheel supported between a pair of arms and alignment of the axis of each flywheel with the side of the corresponding ram being maintained by a torque tube extending between the arms.