Abstract: A high efficiency positive Displacement Heat Machines, for applications such as engines with external heating, Internal Combustion Engines with reduced dirty emissions, heat pumps for ecology clear coolers or heaters, working with air from any source of mechanical energy, thermal processes with approximately constant pressure using an external High and Low Pressure Chambers (HPC and LPC that may be the Atmosphere) that are connecting to a Working Chamber (WC) correspondingly at the end of compression and expansion stages. The disclosed engines and heat pumps operate with displacing at least a part of the WF between said WC and HPC, without changing volume of the WC; with Pulse Pause Modulation of crankshaft speed; with remote expander for engine or compressor for heat pump. The expander or compressor are arranged without transferring mechanical work from another parts of the heat machine. The expander is used as power output from the engine, and the compressor is used as power input to the heat pump.