Instead of dissipating hydraulic energy the IHT transforms hydraulic energy. In the example shown in the figure throttling results in an energy loss of about one third of the input power. Conversely, transformation is in principle a reversible process with 100% efficiency. (In reality internal friction and leakage losses will result in somewhat lower efficiency).
In case of throttling the output flow equals the input flow. When transforming, the input power equals the output power. Therefore a pressure decrease will result in an increase of the flow. A third flow connection is added to the tank to fulfil this mass equation. The transformation can also move in the other direction: a low load pressure can be transformed to the common pressure rail level, with a smaller flow. This enables energy recuperation.