Air Ends


Cronin Compressor Products LLC, in addition to supplying replacement parts and oil, offers a rebuild service for rotary screw air ends.  Efficiency is restored by holding tight tolerances and replacing the rotor sealing strips which few companies have the equipment or the expertise to do.

Our air end rebuilding service is approximately one third less than what you will pay an OEM.


Send the air end with all external piping removed.  The core is disassembled and the components completely boiled out in a Winona Van Norman parts cleaner.  All rotor and input shafts are measured for proper size.  If not to tolerance (+/- .0005″), shafts will be TIG welded with a high tensile, low heat, machinable rod and turned back to size.  The rotors are carefully examined and any profile damage or deep scratches in the rotors will be repaired.  If any portion of the rotor sealing strips have been scrubbed off during the failure they will be completely replaced.

The inlet and discharge bearing housings are checked for flatness and proper bore.  Any suspect castings are tested for heat cracks using a Magnaflux dye penetrant.  If either the bearing bores or gas seal annulus had sustained damage, they will be bored and bushed back to size.  Any substantial damage to the bearing housing faces or cylinder casing will be repaired.

Using special assembly fixtures to prevent bearing damage and state of the art SKF induction type bearing heaters, all bearings will be replaced using top of the line bronze caged bearings with proper internal clearance and preloads.  (Tapered roller bearing machines are fitted with top quality OEM type bearings.)  Rotor to housing clearances are set with OEM shims and checked manually.

A new OEM type shaft seal would be installed and the air end painted.  The unit will be spun on a test rig to check for vibration, noise, and leaks.  It will then be bolted to a skid for shipment.


Rebuilt air ends are warranted for one year.  The one year warranty is conditional upon customer chemically flushing out contaminated oil from the coolers and cleaning out the sump (all varnish, sludge, and metal contaminants must be completely removed), and installing new air, oil, and separator filter elements and oil before the rebuilt air end is installed.