The IHT can transform hydraulic energy. This means that the output pressure can also be higher than the input pressure from the common pressure rail. A flow at a relative low pressure can be transformed to a smaller flow at a higher pressure. As the ingoing flow into the transformer must equal the output flow, there will be flow going from the transformer to the tank.
This possibility to go to a higher pressure offers the option to recuperate energy to the common pressure rail. For example when a forklift truck lowers a load, this energy represented by the load can be converted to the pressure rail, and stored in a hydraulic accumulator.