2.2 Working System
Ambient air, which must be free from exhaust fumes, is drawn through the intake filter and inlet valve
into the 1st stage cylinder, where it is pre-compressed.
A portion of the compression heat is dissipated through the valve head, piston, cylinder, crankcase and
lubricating oil to the cooling airflow. The larger portion remains in the compressed air and cooled down
in the following intercooler to a few degrees above ambient temperature. The air is then passed on to
the next stages, where it is compressed in the same way. The after cooler cools the air to 10
o
C above
ambient temperature at the maximum.
Operating temperatures are:
inlet nipples of suction valves approximately 15
o
- 20
o
C above ambient temperature (hand warm);
outlet nipples of pressure valves and valve heads approximately 90
o
- 105
o
C.
Each stage incorporates an independent preset safety relief valve.
The intake air always contains a certain amount of humidity depending on the weather. During
compression and the consequent cooling down, this humidity largely condensates and forms the
condensate together with small particles of lubricating oil. This condensate is a milky fluid and
precipitates in the separators.
2.3 Technical details of the compressor Block
2.3.1 Crankcase, crankshaft, piston, cylinder
The crankcase is made of light alloy; the bearing cover is sealed by means of an O-ring. The crank-
shaft, connecting rods and piston pins all incorporate roller bearings and grooved ball bearings. The
connecting rods are mounted on the single throw of the crankshaft.
The pistons of the 1st and 2nd stage are made of light alloy and incorporate piston rings.
The 3rd stage piston is a free-floating piston with piston rings. The free-floating piston is driven by a
guide piston, the lateral surface of which is flattened to improve the lubrication of the free piston. The
cylinders are made of cast iron.
2.3.2 Valve heads, valves, intercoolers, separators, filters
The valves are screwed into the well-ribbed valve heads. Valves are arranged side by side and can be
removed by a valve key.
Maintenance of the pressure valves can be carried out from outside, the suction valves can only be
removed after removal of the valve heads. Torque for tightening the valve head screws of the 3rd
stage: start with 1 kpm (7ft.-lb), finish with 2,2 kpm (16 ft.-lb) ensure yourself that piston is down into the
cylinder.
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