Hydraulic expansion device

A hydraulic expansion device particularly suitable for the production of a hollow camshaft wherein individual camshaft elements are secured about the shaft at axially spaced apart radially outwardly expanded wall portions thereof, comprises a plurality of axially spaced apart hydraulic expansion elements 10, 12 interconnected by flexible hydraulic fluid conduit elements 14, 16, 18, 20. The conduit elements are connected to a pressurised hydraulic fluid source 22 whereby hydraulic fluid may be applied to axially spaced apart locations of the shaft by the expansion elements through a radially extending bore 40 in each element communicating at its radially inner end with an axial bore 28, communicating with a conduit element, and at its radially outer end with the radially outer surface of the expansion element intermediate a pair of sealing rings in recesses 36, 38. The flexibility of the interconnecting conduit elements enables the device to be used, whilst still permitting efficient sealing of each expansion element to the interior shaft wall, in shafts which have irregularities in their linearity. The expansion elements include pressure relief bores 42, 44. SONDA A BASE DE UN MEDIO DE PRESION PARA ENSANCHAR VARIOS TRAMOS LONGITUDINALES DE UN ARBOL HUECO, LA CUAL INCLUYE AL MENOS UN CANAL LONGITUDINAL PARA EL MEDIO DE PRESION Y RESPECTIVOS TALADROS RADIALES DE ALIMENTACION A CADA TRAMO LONGITUDINAL DEL ARBOL HUECO QUE SE HA DE ENSANCHAR, Y ELEMENTOS DE JUNTA QUE LIMITAN LA ACTUACION DEL MEDIO DE PRESION SOBRE DICHOS TRAMOS LONGITUDINALES. EL CUERPO DELA SONDA DE PRESION ESTA COMPUESTO DE TRAMOS LONGITUDINALES RIGIDOS, QUE ACOGEN A LAS JUNTAS, Y DE TRAMOS DE TUBO FLEXIBLE, DE MENOR DIAMETRO, QUE UNEN DICHOS TRAMOS RIGIDOS. EL INVENTO ES UTIL PARA FIJAR LEVAS, ENGRANAJES Y COJINETES SOBRE ARBOLES HUECOS DE MOTORES Y MAQUINAS.