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I have 4 2010 CHU613.  MP8.  I have installed Tire Boss central tire inflation on all 4.  All 4 tractors are very slow to inflate the 8 tires up to highway speed pressures.  I have the same system on a sterling with 3406B and had them on Pete's with 3306's.  The mack/volvo setup is much slower.  It's all 4 units so I don't think I have bad compressors.  Are the volvo compressors typically lower CFM than the rest of the industry?  Could there be something choking flow or creating pressure in the plumbing?  Tire boss is plumbed dirrectly into the bottom (wet?) tank.   It looks like flow from the compressor goes to the air dryer and directly to that tank.   Is it a difference in the air dryer setup?   I have noticed that the tractors are slow to air up when we hook shop air to the governor on the firewall.    They air up but not like the other tractors we have..  All 4 CHU's are twins and all air up the same way.  There are no significant air leaks.  There are a couple at the firewall pass through connectors that we can't seem to completely eliminate but they are very minor.

Thanks!   

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My 95 rd takes forever to air up, but it's a triaxle so it has extra tanks. The compressor gets air from the turbo, so it may be a low cfm pump that relies on turbo boost to be high cfm.

How are your Pete and Sterling set up for compressor intake?

Edited by JoeH

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Is it just the tires that are slow or is the whole air system slow to reach operating pressure? do you vary your tire pressure often?

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I will check the sterling.  It’s C15.  I didn’t realize this.  Thought it took “atmosphere” psi air for intake.  

I’d say the whole systems are average.  Maybe a bit slower to fully build up than other tractors we’ve had.  Much slower to the tires and slower with shop air at the governer.  I haven’t been able to identify the compressor but they are single piston.  The tires are deflated to 25-35 lbs empty to loaded in the mud and pumped up to 95 lbs for the speed on the road  each load out of the field.  1 load/hr 24 hrs during harvest.  It’s the airing up slow with shop air that’s got me puzzled and not wanting to point at the onboard compressors.   

Edited by jwmcgregor
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Our shop compressor airs up to 150psi, shuts off, then kicks on again at like 115 psi. When you get down near 115 it takes a while to trigger it to pump back to 150. Tires hold a lot of volume. And if you're working in flat mud, you're not really winding your turbo like you can on hills...

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