The block is usually cast iron. Some manufacturers use welded rolled steel. In the block are assembled a set of parts (crankshaft, pistons, connecting rods, cylinder liners, suction and discharge valves, oil pump and other accessories) that form the internal part of the compressor. The base of the block forms the oil tank (Carter) and the crankcase covers and the cylinder heads are still part of the block.
The crankcase covers and the heads may be cooled by water or by the refrigerant fluid itself. In industrial compressors the shirts are separated from the block and made of special castings for this purpose.
