Envelopes are tight fitting sleeves inside which the built tyre casing is kept during the curing operation. The envelopes ensure uniform application of pressure on the tread during the curing operation. The loading of built casing into tight fitting envelopes is a physically demanding job manually. Hence envelope expanders are used to ease the task. The envelope is loaded on the table and is stretched by the pneumatic claws. The Built casing is loaded above it by the lifting arrangement. The Casing is centred and lowered on to the stretched envelope. The jaws are released to allow the envelope return to its normal shape. The enveloped casing is then loaded into the curing Chamber.