A portable pressure transducer for driving exchangeable hydraulic tools, having - a gas or air pressure driven pneumatic unit, - a hydraulic unit connected to the pneumatic unit, - a coupling unit for immovably and releasably connecting the hydraulic tool to the hydraulic unit, wherein the pneumatic unit, the hydraulic unit and the coupling unit are integrated into a one-piece mobile handling unit, characterized in that the coupling unit has a spherical catch mechanism, wherein - a locking element fixing, which is configured as a twistable locking ring and which can be adjusted between the opening position and the closing position by twisting the locking ring, and a coupling ring are arranged coaxially, - there is configured between an inner side of the locking ring and an outer side of the coupling ring a cavity which is configured to receive a locking element which is configured as a spherical latching body and which can be adjusted between an unlocking position and a locking position, - the coupling ring has an opening having a smaller diameter compared to the spherical latching body, - the locking ring has a recess in order to receive at least in sections the spherical latching body, and - the locking element fixing in the closed position fixes the locking element in the locking position and in the opening position the locking element can be adjusted between the unlocking position and the locking position, wherein the locking ring, the spherical latching body and the coupling ring are matched to one another such that - in the closing position the spherical latching body is arranged in sections in the opening and projects from an inner side of the coupling ring and is secured by the locking ring in this locking position, and in the opening position the spherical latching body can be moved into the unlocking position. - a gas or air pressure driven pneumatic unit, - a hydraulic unit connected to the pneumatic unit, - a coupling unit for immovably and releasably connecting the hydraulic tool to the hydraulic unit, - a locking element fixing, which is configured as a twistable locking ring and which can be adjusted between the opening position and the closing position by twisting the locking ring, and a coupling ring are arranged coaxially, - there is configured between an inner side of the locking ring and an outer side of the coupling ring a cavity which is configured to receive a locking element which is configured as a spherical latching body and which can be adjusted between an unlocking position and a locking position, - the coupling ring has an opening having a smaller diameter compared to the spherical latching body, - the locking ring has a recess in order to receive at least in sections the spherical latching body, and - the locking element fixing in the closed position fixes the locking element in the locking position and in the opening position the locking element can be adjusted between the unlocking position and the locking position, - in the closing position the spherical latching body is arranged in sections in the opening and projects from an inner side of the coupling ring and is secured by the locking ring in this locking position, and