Gap and rotor alignment adjustment is released with using special tool, due to the highest efficiency of the air end and long lifetime of the unit is providing. The gaps adjustment are in certain ranges, which provides high efficiency.
If during compressor operation the gaps (for example, end gaps) will be adjust less than minimum value of the range, rotors heat, metal expands and it is a reason the rotor and housing contact. As rotation speed is high, shortly metal weld.
Then the screw unit can be just utilize. If the gaps are higher than maximum value of the range, efficiency decreases because of air-oil mixture leaks, as well as parameters of the cooling element and rotor lubricant are changed, that prevent to decrease the air end lifetime.