Try to turn the compressor by hand. It should be possible to turn it around. It should turn around smoothly, without any ‘hiccups’ (be sure to completely shut down the air compressor!). Check the isolation of the motor winding.
[pdf] Though the oil free type compressor design method is used for twin-screw steam compressor, the bearings and synchronous gears still need lubrication by pressured lubricating oil. If steam leaks into the l.
[pdf] Generally, of the two air compressor types available for hire, rental rates for portable models range from $45-$90/day or $100-$200/week. In contrast, a trailer-mounted compressor rental costs $75-$950/day or $220-$2,500/week.
[pdf] 
