Spring system

A method for controlling ride height of a rail vehicle, the vehicle having a spring system having a strut for arrangement between a dolly and a body of the rail vehicle comprising

• a non-resilient piston-in-cylinder unit with a cylinder and a piston displaceably received in the cylinder which bound a piston chamber, an abutment member and a space arranged adjacent an end region of the abutment member remote from the piston chamber so that the space is fluidly separated from the piston chamber, wherein the piston or the cylinder is connectable to the dolly and the other of the components is connectable to the body and
• one or more resilient springs which cushion the body with respect to the dolly and which are connected in series to the non-resilient piston-in-cylinder unit, the method comprising:
• (i) adjusting an amount of a hydraulic medium in the piston chamber to adjust a length of the strut via a hydraulic system in response to a vehicle operating parameter;
• wherein the hydraulic system is non-resilient such that suspension of the rail vehicle is not ensured by the piston-in-cylinder unit and also is not ensured by the hydraulic system in communication with it, and
• (ii) in response to the piston chamber or the hydraulic system becoming pressure-less or a pressure in the piston chamber or in the hydraulic system falling below a value, changing an end position of the piston in the cylinder with the abutment member by adjusting an amount of a hydraulic medium in the space to increase the ride height of the rail vehicle to an adequate minimum ride height.

A spring system comprising

• (i) a strut for arrangement between a dolly and a body of a rail vehicle, the strut comprising
• a non-resilient piston-in-cylinder unit with a cylinder and a piston displaceably received in the cylinder which bound a piston chamber, an abutment member, and a space arranged adjacent an end region of the abutment member remote from the piston chamber so that the space is fluidly separated from the piston chamber, wherein the piston or the cylinder is connectable to the dolly and the other of the components is connectable to the body and
• one or more resilient springs which cushion the body with respect to the dolly and which are connected in series to the non-resilient piston-in-cylinder unit,
• (ii) a hydraulic system which is in communication with the piston chamber, for varying an amount of a hydraulic medium in the piston chamber for adjusting a length of the strut, wherein the hydraulic system is non-resilient such that suspension of the rail vehicle is not ensured by the piston-in-cylinder unit and also is not ensured by the hydraulic system in communication with it,
• (iii) a hydraulic accumulator to supply high pressure hydraulic fluid to the space to change an end position of the piston in the cylinder to increase a height of the body of the rail vehicle to an adequate minimum ride height in response to the piston chamber of the hydraulic system being pressure-less or a pressure in the piston chamber or in the hydraulic system falling below a value, and
• (iv) a check valve arranged to permit a flow out of the hydraulic fluid from the hydraulic accumulator into the space and to suppress a flow out of the hydraulic fluid from the space into the hydraulic accumulator.