For the manufacture of a heavy duty elastomeric having a stack of elastomeric and metal reinforcing layers interleaved with one another use is made of a mould sufficiently large to allow an elastomeric cover layer to be formed and cured simultaneous with compression and cure of the elastomeric layers. Relative transverse movement of the metal layers during compression is restricted by spacers which occupy in the mould a small part of the space that in the finished product is to be occupied by the cover layer. Subsequent to moulding and cure the spacers are removed and the resulting spaces in the part formed cover are filled.