We improved and upgraded the apparatus that Fillers, Moonan, and Tschoegl used several years ago to investigate the influence of pressure and temperature on the mechanical properties of time dependent polymeric materials. The new apparatus can measure the volume and the shear relaxation moduli of solid polymer specimens, subjected to a combination of temperatures from -60 to + 110 degreesC, and pressures from atmospheric to 360 MPa. The paper demonstrates the capabilities of the new apparatus from the scientific as well as engineering stand point. Shear relaxation measurements on poly(vinyl acetate) (PVAc), natural rubber, styrene-butadiene rubber, and ethylene-propylene-diene-monomer rubber are also presented. For PVAc we present also bulk creep compliance, coefficient of thermal expansion, and the bulk modulus.