Abstract: A method is provided for recuperating potential energy during a lowering operation of a load, wherein a hydraulic system is adapted to lift and lower the load. In the method, at least two energy recuperation modes are provided, one of the modes is selected in response to a current operating state, and the hydraulic system is controlled according to the selected mode.

Abstract: An engine valve comprising a chromiferous steel and a protective surface layer (5) which consists of iron chrome oxide. A method for manufacture of an engine valve with a protective layer includes an engine component of a chromiferous steel which is heated (200) at a predetermined temperature for a predetermined time so that a layer (5) of iron chrome oxide is formed on the engine component's surface, and the engine component is then cooled (300) to room temperature.

Abstract: method is provided for recuperating potential energy during a lowering operation of a load, wherein a hydraulic system is adapted to lift and lower the load.

Abstract: A cooling system for a vehicle includes a first cooling circuit coupled to the vehicle engine for cooling the latter and a pump arranged in the first cooling circuit for pumping a coolant to the engine. The system further includes a second cooling circuit for cooling at least one other component in the vehicle, and an arrangement for coupling the second cooling circuit into the first cooling circuit in order to also supply the second cooling circuit with coolant from the pump. The cooling system further includes a line coupled from the first cooling circuit to the second cooling circuit bypassing the coupling means so that the second cooling circuit is supplied with coolant from the pump via the bypass line even when the coupling means is set to the disconnected position.