Phone: 860-346-7421 ‎• 50 Silver St., Middletown, CT 06457

Remanufacturers of

Rotary Screw Compressors

Since 1977

Airend Rebuilding

machineCMS Airends include the installation of new bearing gaskets, seals, remetalizing and grinding of shafts and rotors, repair to the front and rear housings when necessary, and repair of the sealing strips and oil pump. On Ingersoll Rand, Sullair, Gardener Denver, and Compair encapsulated airends, we will provide new filters and separators. On direct drive units, we service the motor, clean winding, bakeout, and install new bearings and seals. Normal turnaround on our rebuilds is 3 - 5 working days for an average airend.

To see more of our finished work, please visit our gallery.

CMS rebuilds adhere to strict tolerances, use the highest standards to ensure quality, and are backed by a CMS warranty on equipment repaired and defects in materials replaced as well as workmanship for a period of twelve ( 12 ) months.


Rotory Screw Compressor Rebuilding Process

What Happens to Your Airend?

  • Your airend is off loaded and taken immediately to the disassembly area which contains mountingstand,overhead crane and oil pit for collecting waste oil.  All shipping documents are then forward to the office to be assigned a work order number, and a folder is generated for disassembly, teardown and spec sheets.  This folder follows the airend through the entire rebuilding process to ensure accurate documentation.
  • Once the airend is disassembled, damage and measurements are recorded, and pictures are taken identifying the problem areas.  A report is generated telling us the front and rear covers were damaged, the sealing strips are partially worn and the bearing journal on the rear is damaged.  The seal area on the unit has groves and a small area of the male rotor bore is out of round.
  • At this point a quote is written for the rebuild and submitted to the customer for approval.
  • The disassembled airend is then placed in one of the self-contained cleaning systems. 
  • Once we receive the OK and Purchase Order number from the customer, all parts that require work are brought to different areas of the shop and the repairs begin.  The front and rear covers will be metalized using the thermal ARC system, when finished depending on the size of the cover, its moved to either the 20” or 36” Blanchard grinder for finishing. 
  • The front male rotor bearing journal is mounted and turned on a lathe and will also be metalized and ground according to specs. 
  • The main bore area if damaged will be plated and bored on a vertical boring mill. 
  • Seal strips are built up and re-cut on a custom jig. 
  • Depending on the extent of the damage, the above work normally takes one to two days to complete. 
  • All components are then rewashed and taken to the assembly area, where all the bearings, seals, gaskets, and related materials needed to complete the assembly are pulled from inventory.
  • Before assemble takes place all the bearing pockets, bores, and alignments are rechecked.  The two rotors are then checked for proper balance and alignment
  • The bearings are removed from the boxes and re-measured for proper fit before installing.
  • To insure that the manufacturer’s specs are being met, the unit is continually measured and re-checked for accuracy 
  • Upon completion all open ports are plugged with plastic caps and the inlet taped.  The airend is now ready to be skid mounted and painted. 
  • As units enter the shipping area all necessary shipping documents and start-up procedures are attached to the unit, and trucking details are arranged. 
  • This whole process will normally take on the average 3 to 5 working days, depending on the MM size and degree of damage.  We have setup our shop so the work flows through on a orderly path to insure that all our inspection steps and quality controls are adhered too.

Airend Manufacturers Serviced By CMS

CMS is proud to service all of the following Manufacturers:

  • Atlas Copco
  • Bauer
  • Broomwade
  • Champion 
  • Compair 
  • Gardener Denver 
  • GHH 
  • Grimmer Schmidt 
  • Howden Tamrotor
  • Ingersoll Rand
  • Joy
  • Kaeser
  • Kellog-American
  • Leroy
  • Palatek
  • Quincy
  • Sullair
  • Sullivan
  • Worthington

CMS warrants all airend rebuilding for a period of twelve ( 12 ) months against defects in materials replaced and workmanship performed. 

Air/Portable Rotary Screw Rebuilds 

We are pleased to service the following rotary screw manufacturers:

  • Ingersoll Rand 
  • Atlas Copco 
  • Sullair 
  • Gardner Denver 
  • Joy 
  • Compair Leroi 
  • Kaeser 
  • Quincy 
  • Tamrotor 
  • GHH-Rand 
  • Rotaryaire 
  • Palatek 
  • Curtis 
  • Kobelco 

Blower/Vacuum Airend Rebuilds

We are pleased to service the following manufacturers.

  • Gardener Denver 
  • Sutorbuilt 
  • Duraflow 
  • Switzer 
  • Aerzener 
  • Robuschi 
  • Sihi 
  • Dresser Roots 
  • Tuthill 
  • MD Blower 
  • Kaeser 
  • Other MFG's

Gas/Refrigeration Airend Rebuilds

We are pleased to service the following manufacturers:

  • Gardener Denver 
  • Frick 
  • Leroi 
  • Ariel 
  • Tamrotor
  • Sullair 
  • Howden 
  • Kobelco 
  • Vilter 

Airend Installation Procedure

Proper Installation is critical to airend life.

  1. Motor Bearings: install new motor bearings, and inspect covers for wear. If the bearings are loose in the pockets, vibration will be transmitted to the front airend bearings and this will lead to premature failure. 
  2. Drain oil from the system and remove all oil piping, filter housings, sumps, and whatever else holds oil. Clean thoroughly all the components to remove all the old oil and particles. It is important to remove all the metal particles in the system. Most reinstalled airends fail because metal particles left in the machine clog the orifices.
  3. Steam clean oil coolers inside and out.
  4. Replace all filters in system and pre charge the oil lines and oil filter with fresh oil. This can be done with supplying outside air pressure to the sump and flowing through the coolers, oil filters and stop valves. Units with a stop valve will have to be pressurized to keep the valve open. Use a five ( 5 ) gallon container to capture any overflow. At this time you can also check how clean the system is. If any questions, please call.
  5. IMPORTANT: Coupling alignment and placement is critical to airend performance and longer life. Install the new coupling per the manufacturer's installation instructions. There should be a gap on insert type couplings and bolt-on couplings. Make sure that you are not forcing the coupling cushion in place. This will add additional load on the pilot and motor bearings which will cause premature failure. The coupling should be aligned to within .005 both ways.
  6. When installing the airend, cover the inlet to prevent any foreign material from entering the chamber.
  7. Before installing the inlet control, pour fresh oil down the inlet and turn by hand. This will prevent the airend from starting dry. On some units, they may seem stiff, this most likely is caused by the sealer getting on the rotors, it will clear once the unit starts. NOTE: it takes five to ten seconds for the unit to build pressure and force oil through the airend.
  8. Start unit and check for oil leaks and vibration. Let the unit run for about 15 minutes, shutdown and recheck all the oil ports and orifices to make sure there is no blockage.
  9. Restart and change oil filters after the first 50 HRS and then every 500 HRS there after.
  10. Use a good quality synthetic oil for longer life and a cleaner system.
  11. When the airend comes from the factory, they are designed to run within 100 degrees of ambient. If it is eighty degrees outside, the unit should be running at 180 degrees. If you are experiencing high temp., check the coolers, thermal bypass, and oil filter housing. Sometimes the bypass valve breaks apart and blocks the oil flow.
  12. Follow the manufacturers recommendations for all other related services.
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