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Lift Axle Question


jeffl1107
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Well I finally got all the stuff done on my truck except for one pressing issue that I need to get fixed. 97 RD688S Tri Axle Dump. The issue is my lift axle. It goes down in no time flat. But when I pull the (push/pull) valve, it takes almost 90 seconds before the lift tires start to come off the ground. With this being a Watson & Chalin non-steerable axle, that is no good. I have replaced most of the air lines to it, new push/pull valve and new quick release valves at every air bag. The only thing that I believe I have not replaced is the adjustable pressure regulator in the cab and the guage. I have adjusted the regulator in the cab anywhere from 20psi up to 85psi and it does not matter, still bleeds off the same. Someone told me there might be a screen in the system somewhere that is clogged up but I cannot figure out where that would be. Does anyone out there have any suggestions as to what might be causing this.

Thanks!

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Well I finally got all the stuff done on my truck except for one pressing issue that I need to get fixed. 97 RD688S Tri Axle Dump. The issue is my lift axle. It goes down in no time flat. But when I pull the (push/pull) valve, it takes almost 90 seconds before the lift tires start to come off the ground. With this being a Watson & Chalin non-steerable axle, that is no good. I have replaced most of the air lines to it, new push/pull valve and new quick release valves at every air bag. The only thing that I believe I have not replaced is the adjustable pressure regulator in the cab and the guage. I have adjusted the regulator in the cab anywhere from 20psi up to 85psi and it does not matter, still bleeds off the same. Someone told me there might be a screen in the system somewhere that is clogged up but I cannot figure out where that would be. Does anyone out there have any suggestions as to what might be causing this.

Thanks!

How's it going, I also run a tri up in Mass...What size tires do you have on the pusher ? I noticed when we had 385/65R22.5 on the pusher when fully raised it would only be about 1.5"-2" max off the ground, so we upsized the air lines & downsized the tires & it was much quicker...Hope this helps

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Hey Jeff, I run a rd688s out of NJ with a Watson Chalin with 425's on it and we had the same problem. It didn't have the valves on the air bags so my boss got the valves from Sanchez. Took us a while to figure out how to plumb them. By trial and error it works good now. Maybe the lines going into the valves are backwards? It wasn't hard to screw it up as there was no instructions and it depended on how the axle is set up.

Cheers, Rob

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Replace the regulator too, if you haven't already.

A few years ago I had a regulator go bad, it would work properly when the pressure was on (down) but would not let the air come back through when the push pull valve was moved to the up position, therefore the pressure was still held against the QR valve & bags even when the control was in the up position.

"If You Can't Shift It Smoothly, You Shouldn't Be Driving It"

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Hey Guys,

Big Mac - I am running 11R24.5 on their right now, no floats, Yet.

RFC - You may have something there but this is how the truck was plumbed when I bought it so I assumed it was correct. But, with how this guy took care of this truck, I would not doubt for one minute that something is F'd up on it.

HK Trucking - After speaking with the guy at the parts store and threw trial and error from what I already replaced, I think what you are saying is probably the case here. I just bought the whole in cab kit, regulator, push/pull valve and guage. It also came with new style quick release valves that the guy suggested I upgrade to as they release air faster than the old style on there now. Should not take long at all to re-plumb for the new style valves. Should take me an hour or two and then, god willing, it will work.

Already have several loads of crushed clam shells I will be delivering to the Port Norris area of Jersey starting on Tuesday. Cant wait to get this thing rolling.

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I have two lift axles and i used a quick release on the lift up and down bags. It makes it so much faster going up and down. A quyick release like the barking brake circuit uses.

That's how I do it too Glenn, on the new ones I set up where I work.

We use the electric over air solenoid valves connected to switches in the control console in the cab.

Switch on = release pressure on the up bags,pressure on the down bags.

Switch off = release pressure on the down bags, put pressure on the up bags. That way the default setting in case of an electrical failure is "axle up".

Regulator & gauge on the down pressure port of the solenoid valve to adjust axle weight, full system pressure to up bags to prevent axle bounce when raised.

QR valves on the frame just above the lift axle(s)to exhaust the pressure fast.

I've also seen some that use relay valves mounted near the axle to fill the bags more quickly.

"If You Can't Shift It Smoothly, You Shouldn't Be Driving It"

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Ok need your expertise one more time. I am about to bash my friggin head against the wall. I don't know if I am just a Dumb A**! or what.<br>

Ok, first, my setup has no electronics, totally manual. One non-steerable lift axle Watson & Chalin 25,000lb. I went out and purchased the new HLK NSI in cab kit for the axle. It came with the push pull valve, adjustable regulator to regulate how much air is in ride bags and the guage. Both Hendrickson and the Watson & Chalin had the same inlets on the bottom, just liked the ease of the Hendrickson push pull valve better.<br>

So, went to install it. All were color coded. There were no instruction that came with this kit. Guy printed me off some paper work and said that should be all I need, NOT! Put the line going from tank in the Green push in 3/8 inlet on bottom of kit. Put the Ride air bag line into the Red inlet. Put the lift bag line into the Blue inlet.<br> Here is where it all started to suck bad. Here is the site I found on line for the kit I bought, no where on that page, or any of the other setups, does it tell you what to do with the Yellow inlet which it says is the exhaust port. So started the truck up and it just spews air out of that inlet. But I don't know where to run that too. I also got two valves with the kit. One valve goes off the tank for a safety valve for the brakes. The other is the quick release valve. One IN port and Two OUT ports. The IN port is the Red line for the ride air bags. The other Two OUT ports goes to each of the two ride air bag fittings. So, where oh where does that yellow port suppose to get plumbed too??????????????????? I cannot figure it out. Please help before I have to go on major medication!

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Forgot to put this up for you to see. Use this link http://www.hendrickson-intl.com/pdfs/Auxiliary_PDFs/H605.pdf Scroll down to page 12 to the HLK NSI. That is exactly how I have the system plumbed. But no where on there, or any of the other setups does it show what to do with the Yellow Exhaust inlet. Somewhere I thought I might have read that it should go to the lift springs, but how would it if the blue line goes to that. I am dumified.

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"We use the electric over air solenoid valves connected to switches in the control console in the cab"

Herb, What do I need to ask for to get therse parts. I want to hook them up to drain the oil and water from my wet tank when I'm finally getting past these spandex 2 wheeling bastards that insist on riding on truck routes.

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"We use the electric over air solenoid valves connected to switches in the control console in the cab"

Herb, What do I need to ask for to get therse parts. I want to hook them up to drain the oil and water from my wet tank when I'm finally getting past these spandex 2 wheeling bastards that insist on riding on truck routes.

David, go to the Velvac site:

http://www.velvac.com/pdf/air.pdf

Scroll down to page 59, and find part # 320131, that's the valves we use.

Probably not a good idea to run all that water & air tank sludge through it though.

I hear ya on the 2 wheel morons!!!!

"If You Can't Shift It Smoothly, You Shouldn't Be Driving It"

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