Heavy Haul Pusher Axles

I run heavy haul for a living. I typically do 120,000lbs on 6 axles or even 132,000lbs on 7. The truck I drive is a W900 with a drop axle in front of the drives. When Inrun the 7 axle loads, i use the the pusher on the truck as well as the terailer. The trailer im not worried about because the suspension leveler works to all airbags so pressure equals out on all axles when the drop axle is down. But on the tractor, the leveler only works to the drive axles and the pusher is adjusted manually. So naturally, increasing pusher axle prusher puts more weight on the drop axle tires and takes some off of the drive. Sadly, my pusher axle guage is broken. But as a general rule, im wondering what is a good balance between pusher in drive axle. Currently, when I haul up to 132,000 my drive suspenion gauge goes well over 100psi. That seems a bit much, but of course i have no clue what the pusher is doing. If increase pusher to try and reduce the drives, the truck rattles like crazy because of flat spots.

so obviously i need to fix both, but when i do get them fixed, what is a good balance on axle pressures?

 

I put the least amount of weight on my pusher as possible. Whatever weight my drives are over by, that’s all I put on the pusher. (Sometimes it’s only 2-3,000 pounds).

100psi sounds way over on your drives. I’d be getting that gauge fixed ASAP; in the meantime it’s probably a good idea to find a scale and check your axle weights.

Some DOT officers consider your drive and pusher axles as a group, and others separate them and want to see no more than 34,000LBS on your drives and your pusher under it’s legal rating.

-Not all pushers are rated for the same weight, you may want to find out what yours is rated for so you don’t exceed it.

 

Since you have a KW the factory installed lift Axel is a Watson Chalin you can go to there web site and look up the Axel you have and they have a chart that will list PSI verse Load on Axel, the model number on the Paccar products does not always match the models on the web site but the load rating is the same if you have a 20K lift Axel the the only difference I think they have is single tire vs dual tires.
On your truck the PSI on the air bags depends on the suspension on my trucks with the Neway ADZ 100 PSI is about 42K and for the super 10 in my Avatar is max load, when I drop the lift Axel with 80 PSI it picks up 8K pounds 3K off the steer and 5k off the drive.
after you have the lift Axel chart and figure out what the load vs PSI on you drives you can adjust the loads
Wright Weigh makes a gauge that will read out in pounds instead of PSI you can install in place of the PSI gauge on your drives they cost about 100$ and I have one that has been in a truck since 2002 and still is accurate.

 

oh wow nice. I forgot about those gauges you mentioned, I will have to keep that in mind. Yeah, I'm considering offering to buy this truck from my current employer if I can get financing approved. He might go for it, I don't know. There is plenty of work around here. The axle on this truck as I understand was not factory installed. It was an after thought and they shortened the fuel tanks to make room for the drop axle. It also has singles. and the air gauge and adjustment are on the out side mounted to the frame. It is a non steerable so I am assuming its rated at least 20K. I know some of them can be rated at 22k. If I had the truck, I would put larger diameter duals one it. I think the studs are long enough. I might also point out that it has a 231 inch wheel base from steer to drives. but hey, it's a KW 900 with a C15 625. I can't complain.

 

So I took another good look at the suspension on the truck I am driving and found out who the actual manufacturer is. Like I said in the previous post, the pusher axle was an after market installation. I found the tag on the axle and thus found the model make and part number. After a little bit of digging, I was able to locate information about this particular axle. So it is made by Silent Drive in Orange City, Iowa. It is a 20,000lb pusher axle. The links to the sale sheet and pressure load chart are down below.

Now if only I can find the same info about the factory suspension for the KW 900. If any one can help point me in the right direction that would be much appreciated. Thank you.


Sale Sheet: Non-Steer Lift Axle Air Suspension 20,000 lbs. | Heavy Duty Tag/Pusher (silentdrive.com)
Load pressure chart: SilentDrive-Catelog_2018MM.indd

 

Would you be willing to suggest that the main drive suspension is a Wataon Chalin as well? I know the pusher axle is a Silent Drive

 

you can call the parts department at any KW dealer and give them the year and last 6 numbers of the serial number and they can tell you
but if you post a couple pics we can probably identify it
there is usually a name of the brackets and that can get us to the right manufacturer
the model is a little harder
KW makes an AG series that is air ride but there is 2 models and i don’t know the difference by sight

 

There's probably at least half a dozen different factory air suspension models. Most are pretty easy to identify with a couple pictures of the hanger brackets and control arms. Door jamb sticker might have the suspension weight rating listed on it too.

 

The suspension weight rating is important to know but that doesn't help me identify the air pressure load. I will have to take a closer look at the truck to see who manufactured the main drive suspension.

 

I adjust mine as mentioned above.

Lightest possible that brakes don't lock up.
I beleive it was 30 or 32 psi.
The steers weighed 10,500.
I'm not driving that truck anymore.

But we don't do 120k on 7 axles. Since we only haul divisible.