Anyone familiar with screw compressor air ends? Ingersoll Rand SSR screw question.

[SShep71]

I have a IR SSR7.5ep screw compressor at my shop. Lately the compressor is occasionally bogging down right before unloading. The compressor has 25000 hours on it, I was thinking of rebuilding the unloader valve and air end. I have some experience with rebuilding roots style blowers, and I am familiar with how the air end works, I just never tore into one before. Is there anyone here that has some experience with air end rebuilds that can attest to whether or not this can be done without a collection of specialty tools.

 

[john.k]

I worked for years with screw compressors,and vanes too....IR had a good name with vanes ,not so much with screws........anyhoo,usual indicator of worn bearings is noise......bogging down would be accompanied with over heating and noise /vibration.....so it seems to me maybe an unloading issue.........The sandblasters used to rerace (new bearings/seals) air ends at 16,000 hrs ,so yours is likely due.........By the way ,the bearing sets are super precision matched ,and like $10,000 a set a lot of years ago.

 

[Phil in Montana]

Change oil and filters and see how it works,in my book when a screw comp dies, scrap it and replace, not worth the rebuild and very costly to make a mistake...Phil

 

[kopcicle]

And last but not least

Look at the electrical connections. Over time the motor, contactor, relay, even the breaker panel can develop excessive resistance. It's a long shot but worth noting.

 

[atomarc]

I had several IR screws. While not sure of your situation I would make sure the belts are tight and sheaves and belts not misted with oil from the unloader. There is usually a small plastic muffler on the unloader that often becomes plugged with oil and gunk and that will make the snap-action unloading sluggish or even non functioning. Take a peek at those things before your planned rebuild.

Stuart

 

[dana gear]

Belt slippage at the upper end of pressure generation could seem like bogging, the serpentine belt can slip without the making much noise. generally, the belt will get hot and toss in time.
25000 hours on the air end is past its life cycle without a major rebuild. It may be far more cost effective to replace the unit
I/R tech support flat out SUCKS.

 

[atomarc]

Belt slippage at the upper end of pressure generation could seem like bogging, the serpentine belt can slip without the making much noise. generally, the belt will get hot and toss in time.
25000 hours on the air end is past its life cycle without a major rebuild. It may be far more cost effective to replace the unit
I/R tech support flat out SUCKS.

I could be all wet, but I think your hours/life cycle figure is way off the mark. The 15hp IR screw I mentioned above had regular oil and filter changes and when I left the facility, the hour meter was creeping up on 40,000 hours. This was on the original pump which ran 9 hours a day, 5 days a week.

As an aside...I used IR factory parts, but never used their 'tech support'. I used 'Stu's brain support' and that worked out pretty well!

Stuart

 

[john.k]

Belt driven compressors often develop wear of the profile of the motor pulley.....this causes slippage even with new belts.

 

[SShep71]

All good points, I am going to take it down next weekend and see what I find, I just want to make sure I have all the filters, coolant, and service parts before I do anything. I figure why not just service it now, it has been nearly 25hrs since the last service. Then I have to send out an oil sample for analysis. I was just hoping that someone here has some experience with rebuilding the actual air end. If things go bad and I find all kinds of damage I may have a Kaeser screw that I can put in, it is of course used and I need to put a new motor in it.

 

[dana gear]

I could be all wet, but I think your hours/life cycle figure is way off the mark. The 15hp IR screw I mentioned above had regular oil and filter changes and when I left the facility, the hour meter was creeping up on 40,000 hours. This was on the original pump which ran 9 hours a day, 5 days a week.

As an aside...I used IR factory parts, but never used their 'tech support'. I used 'Stu's brain support' and that worked out pretty well!

Stuart

We used to run I/R Unigy rotary screws, computer-controlled units, Brain support would not interface with the computer control, wish it did. Major piles of junk, We will NEVER use I/R again.
The serpentine pulleys do ware out and slip, very common on higher hour I/R screws. 40,000 hours on a I/R head is possible, miracles do happen.