Compressor cycle ?

Topic: Compressor cycle ? (Read 951 times) previous topic - next topic

Compressor cycle ?

January 07, 2017, 10:48:37 am

Trying to get Coach ready for Quartzite I put brakes and pins on coach and Changed types of antifreeze and trans service went to Synthetic from Dex-tron and had a little antifreeze leak and had sparks coming from starter. Pulled off cables off starter cleaned everything tightened everything and starter is good , lower hose tightened up and drove it yesterday for about 25 to 30 miles and the only thing I noticed was air gauge was cycling about every 5 or so minutes from 100 psi to 130 cutoff point is that to often? Raised up coach and heard no leaks but found rear air lines to rear spring brakes were loose about a 1/2 of turn on all 4 lines- 2 to spring brake- and 2 to brakes, I hate taking coach to anyone because no places around here seem to do a great job, so if you don't do it your self you have to check everything. When coach is aired up 130 psi it stays put but driving it drops and cycles a lot quicker, Is there anything that uses air driving down the road, Or holding off spring brake to drive the only thing that would use air if there was a leak?

Re: Compressor cycle ?

Reply #1 – January 07, 2017, 10:54:34 am

Driving brings your whole air suspension into play.

Re: Compressor cycle ?

Reply #2 – January 07, 2017, 10:59:59 am

5 minute recycle would be normal to me.

Re: Compressor cycle ?

Reply #3 – January 07, 2017, 11:00:24 am

Art that seems about normal,, I have never timed ours when driving but keep an eye on it just to make sure it stays up.and yes the spring brakes are held off with the air from the tanks . No air system is perfect they all leak at some point doing your own work is always good if you are able. Good catch o. The air lines.

Re: Compressor cycle ?

Reply #4 – January 07, 2017, 11:08:39 am

When air bags are up in drive mode and sitting there idling with spring brake on is stays put but driving it seems to loose air a lot quicker Does that hurt compressor to cycle like that? Compressor is always turning when engine is running is there difference when it's compressing air?

Re: Compressor cycle ?

Reply #5 – January 07, 2017, 11:12:27 am

There are two diaphragms in the spring brakes. Also a valve comes into play when brakes are released. Chock wheels and spray dish soap water mix on spring brake release exhaust port and around the relay valve for it.

Re: Compressor cycle ?

Reply #6 – January 07, 2017, 11:57:45 am

Driving will cause more frequent cycling of the compressor. A five minute cycle while underway is pretty normal to me. A plastic Hudson type sprayer filled with Pustefix (Amazon.com: Pustefix Premium Bubbles Refill 8.3 fl.0z.: Toys & Games), my favorite bubble solution, makes long lasting bubbles at any leak. Dish soap works too. The bubbles just are not as big and don't last long. This is available at most toy or party stores. Spray the brake cans, air bags, hoses, etc.

A leak in one air bag caused ours to cycle more often. After a couple of short camping trips, it got annoying so I changed out the bag.

As you probably know, never try to take a brake can apart without caging it. The spring can cause serious or even fatal injuries. View these videos before any DIY brake can work: http://www.youtube.com/results?search_query=caging+air+brakes

Pierce

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Re: Compressor cycle ?

Reply #7 – January 07, 2017, 11:58:20 am

Art, driving down the road moves the suspension, more rear than front, up and down all the time. Every up, triggers the ride height valve to dump air-bag air into the atmosphere and every down, moves air from brake tanks into air bags.

When brake tanks use up air, it is replaced from wet tank. When wet tank air pressure gets down to about 90psi the engine air compressor kicks on to fill wet tank, and turns off when wet tank is about 120psi.

Our dash rear air gauge shows this pressure moving down and then at a point it starts to move up. Repeats as necessary.

Smoother the road surface, the less the air pressure cycling. Also side by side movements create rear ride height valves adjustments.

Re: Compressor cycle ?

Reply #8 – January 07, 2017, 12:05:23 pm

The brake release diaphragm doesn't need caging. In California I can only buy new cans with the spring brake part sealed. Not consumer serviceable anymore. The one in this video is what you get buying new here now.

http://www.youtube.com/watch?v=ytSVUlInq0A

Re: Compressor cycle ?

Reply #9 – January 07, 2017, 01:49:33 pm

I replaced all 8 air bags a while ago and height never moves but drake cans are original, Al so spring does not hold real well

Re: Compressor cycle ?

Reply #10 – January 07, 2017, 01:54:43 pm

Brake cans are not that expensive. Especially if you factor in you might have a leaky diaphragm in one.

New 30/30 LS Air Brake Chamber long stroke w/ clevis | eBay

Re: Compressor cycle ?

Reply #11 – January 07, 2017, 02:23:27 pm

Five minutes is a short cycle on smooth roads without braking. Leaks

Re: Compressor cycle ?

Reply #12 – January 07, 2017, 02:45:22 pm

Quote from: Caflashbob – January 07, 2017, 02:23:27 pm

Five minutes is a short cycle on smooth roads without braking. Leaks

Disagree. 5 Minute cycle is fine in my book. When driving my coach it cycles about that or sooner. All depends on the road and how much the suspension adjusting is required. My previous coach worked similar.

Re: Compressor cycle ?

Reply #13 – January 07, 2017, 05:47:15 pm

Quote from: Caflashbob – January 07, 2017, 02:23:27 pm

Five minutes is a short cycle on smooth roads without braking. Leaks

Agree with this. Also, there is dead-band in the height adjusting valves. They don't dump or add air until a certain amount of movement occurs.

If I'm on the highway with cruise on, my compressor won't cycle unless I use the brakes. My dash gauges don't move.

Re: Compressor cycle ?

Reply #14 – January 07, 2017, 06:08:56 pm

Don't worry. OK to drive.

Re: Compressor cycle ?

Reply #15 – January 07, 2017, 09:07:24 pm

Krush my gauges do not move either unless something asks for air.

My mechanic fixed my leaks and I replaced the D2 valve with a 110/130 unit. Keeping the pressure higher normally makes the brakes work better

Re: Compressor cycle ?

Reply #16 – January 08, 2017, 10:02:05 am

Do you more info on D2 valve replacement pictures and part # on 110/130 valve pictures of where valve is?

Re: Compressor cycle ?

Reply #17 – January 08, 2017, 10:23:47 am

Most D2 governors are adjustable, and can be set to a range of 110-130, if desired.

BENDIX D-2 GOVERNOR MANUAL Pdf Download.

Mechanics Hub Toolbox | Adjusting a Bendix Air Governor

Re: Compressor cycle ?

Reply #18 – January 08, 2017, 10:39:40 am

Is this the governor on top of compressor?

Re: Compressor cycle ?

Reply #19 – January 08, 2017, 10:44:40 am

Quote from: prevostart – January 08, 2017, 10:39:40 am

Is this the governor on top of compressor?

Yes.

Re: Compressor cycle ?

Reply #20 – January 08, 2017, 11:23:38 am

Quote

drove it yesterday for about 25 to 30 miles and the only thing I noticed was air gauge was cycling about every 5 or so minutes from 100 psi to 130 cutoff point is that to often?

@Art,

What Chuck said. The governor is adjustable. Looks like yours has already been adjusted higher if you're seeing 130psi on the gauge.

Quick Edit: Most governor's (in Foretravels) are adjustable

With a 5 minute recycle I think you do have a small leak but in my book that is acceptable leak down. Nothing to worry about right now but it would be on my project list. Every leak eliminated is a good thing. As the late Dave M says DWMYH!

see ya
ken

Re: Compressor cycle ?

Reply #21 – January 08, 2017, 11:25:46 am

Sounds like I could adjust it but being 20 plus years old I should replace it? How does it work? large line on bottom of compressor that is supply line and 2 smaller lines to gov, does gov hold valves closed and open? High side good low side under 100 psi when it cycles.

Re: Compressor cycle ?

Reply #22 – January 08, 2017, 11:33:03 am

Edited your pic to point out governor and adjustment location.

Unscrew adjustment plastic cover and use exposed screw to adjust pressure. In for more pressure out for less. (someone please correct me if I have the in/out backwards)

see ya
ken

Re: Compressor cycle ?

Reply #23 – January 08, 2017, 11:35:40 am

Quote from: prevostart – January 08, 2017, 11:25:46 am

Sounds like I could adjust it but being 20 plus years old I should replace it? How does it work? large line on bottom of compressor that is supply line and 2 smaller lines to gov, does gov hold valves closed and open? High side good low side under 100 psi when it cycles.

It sounds like it is working correctly so no need to replace. Not a bad idea to carry a spare. They are inexpensive. $15 to $20 bucks at NAPA.

see ya
ken

Re: Compressor cycle ?

Reply #24 – January 08, 2017, 12:13:35 pm

Quote from: kenhat – January 08, 2017, 11:33:03 am

In for more pressure out for less. (someone please correct me if I have the in/out backwards)

Sadly, the adjustment is not intuitive.

Excerpt from Bendix manual linked in my post (above):

A. Remove the top cover from the governor.
B. Loosen the adjusting screw locknut.
C. To raise the pressure settings, turn the adjusting screw counter-clockwise. To lower the pressure settings, turn the adjusting screw clockwise.
Note: Be careful not to overadjust. Each 1/4 turn of the adjusting screw raises or lowers the pressure setting approximately 4psi.
D. When proper adjustment is obtained, tighten the adjusting screw locknut and replace the cover.
Note: The pressure range between cut-in and cut-out is not adjustable.

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