Drive system, in particular for a self-propelled construction machine, in particular a soil compactor, comprising: - a drive unit comprising an internal combustion engine, - at least one hydraulic circuit (30, 34) with a hydraulic pump (32, 36) that can be driven by the drive unit, - a hydraulic-drive support unit having an open circuit with a hydraulic pump/motor assembly and at least one pressure fluid reservoir, wherein the hydraulic pump/motor assembly is or can be drivingly coupled with the drive unit or/and at least one hydraulic circuit (30, 34), and with a charge/discharge valve unit to selectively release/interrupt a flow connection between the hydraulic pump/motor assembly, and at least one pressure fluid reservoir at least in the flow direction from the pressure fluid reservoir to the hydraulic pump/motor assembly, wherein the hydraulic pump/motor assembly can be operated in a charging operating mode by the drive unit or/and at least one hydraulic circuit (30, 34) as a pump to charge at least one pressure fluid reservoir and can be operated in a drive support operating mode as a motor to provide a drive support torque for the hydraulic pump (32, 36) of at least one hydraulic circuit (30,34), wherein the hydraulic pump/motor assembly can be operated in a starting operating mode as a motor to start the drive unit, characterized in that the hydraulic drive support unit comprises in a bypass flow path bypassing the charge/discharge valve unit a starting valve unit to selectively release/interrupt a flow connection between at least one pressure fluid reservoir and the hydraulic pump/motor assembly at least in the flow direction from the pressure fluid reservoir to the hydraulic pump/motor assembly, and - in that in the bypass flow path in the flow path between the at least one pressure fluid reservoir and the starting valve unit or/and in the bypass flow path in the flow path between the starting valve unit and the hydraulic pump/motor assembly a flow restriction arrangement is provided. - a drive unit comprising an internal combustion engine, - at least one hydraulic circuit (30, 34) with a hydraulic pump (32, 36) that can be driven by the drive unit, - a hydraulic-drive support unit having an open circuit with a hydraulic pump/motor assembly and at least one pressure fluid reservoir, wherein the hydraulic pump/motor assembly is or can be drivingly coupled with the drive unit or/and at least one hydraulic circuit (30, 34), and with a charge/discharge valve unit to selectively release/interrupt a flow connection between the hydraulic pump/motor assembly, and at least one pressure fluid reservoir at least in the flow direction from the pressure fluid reservoir to the hydraulic pump/motor assembly, wherein the hydraulic pump/motor assembly can be operated in a charging operating mode by the drive unit or/and at least one hydraulic circuit (30, 34) as a pump to charge at least one pressure fluid reservoir and can be operated in a drive support operating mode as a motor to provide a drive support torque for the hydraulic pump (32, 36) of at least one hydraulic circuit (30,34), wherein the hydraulic pump/motor assembly can be operated in a starting operating mode as a motor to start the drive unit, characterized in that the hydraulic drive support unit comprises in a bypass flow path bypassing the charge/discharge valve unit a starting valve unit to selectively release/interrupt a flow connection between at least one pressure fluid reservoir and the hydraulic pump/motor assembly at least in the flow direction from the pressure fluid reservoir to the hydraulic pump/motor assembly, and wherein the hydraulic pump/motor assembly can be operated in a charging operating mode by the drive unit or/and at least one hydraulic circuit (30, 34) as a pump to charge at least one pressure fluid reservoir and can be operated in a drive support operating mode as a motor to provide a drive support torque for the hydraulic pump (32, 36) of at least one hydraulic circuit (30,34), wherein the hydraulic pump/motor assembly can be operated in a starting operating mode as a motor to start the drive unit, characterized in that the hydraulic drive support unit comprises in a bypass flow path bypassing the charge/discharge valve unit a starting valve unit to selectively release/interrupt a flow connection between at least one pressure fluid reservoir and the hydraulic pump/motor assembly at least in the flow direction from the pressure fluid reservoir to the hydraulic pump/motor assembly, and - in that in the bypass flow path in the flow path between the at least one pressure fluid reservoir and the starting valve unit or/and in the bypass flow path in the flow path between the starting valve unit and the hydraulic pump/motor assembly a flow restriction arrangement is provided.