check it out - new equipment

I trust theory over marketing materials. If something does not seem to jive with the physics, then I want to see experimental proof before I'll commit my hard-earned dollars.

I'd be interested in the details. Payback being tire cost? tolls? mpg? Was this a new trailer or the modification to one already in service?

 

Do you really know how to do all the math you posted....?

 

I don't pull a reefer or a dry van and I didn't stay at a holiday inn last night....

But I do have a lift axle...or three.

I run local so this doesn't apply to most of you but I save around $20 a day by lifting the front of the closed trailer tandems on fuel.

Doesn't sound like much but it adds up over time. Not counting tires and brakes.

These are real world numbers...In my world. My last trailer was exactly the same trailer I have now without a front lift. This is on a triple spread hopper with closed tandems. I go to the same places all the time so the calculations were easy. I traded trailers for a few reasons but one was I didn't think to put the lift on the last one. To add it would have voided my warranty on my supension. They use 1/4" tubing on the suspension instead of 3/16" and add extra bracing. The valves are normally open instead of closed in case you loose power to the valves. There are also pressure set quick exhausts on the axle that stays down in case you forget to put your axle down. Mine isn't automatic.

 

If anyone with a lift axle wants to do some experimenting, we could quantify exactly how big of a difference it makes. Would just need to weigh your truck & trailer and then use a logger (plenty of free ones on android play store) to record speed/time for 10 coast-downs with axle up and 10 with it down...

Algebra? Of course. A few years ago I could have done the differential equations to derive that formula from scratch, but now I drive truck instead...







Sorry for the hijack RC

 

There was a member here Roxanne or Marmon something.. Who installed a couple shut off valves on two airbags then drove onto a 4x4 and used a ratchet strap or two to hold axle up in air .. Supposedly dot was ok with that . Only issue I see is abs sensor would probably go off

 

She is banned...

http://www.thetruckersreport.com/truckingindustryforum/members/85052-autocar/

 

I wonder if having an axle lifted affects stopping distance.

 

Brand new Triaxle grain trailer, Round trip of 760 km (sorry about the metric, but it's what I'm used to)
On an Out n back basis..

My mistake for putting payback period as Time based, When It's clearly a distance based Figure.(But was merely stating in My operation it took 3 years for the extra investment in the Lift axle to be recouped in Fuel & tyre savings (Tolls not applicable).

It also depends on wether you calculate tyre savings On the Trailer alone or over the entire truck trailer Combination. As this makes large difference in the final tyre cost savings.
The Fuel saving whilst measurable weren't significant but this was attributed to the terrain & high proportion of secondary Roads. (had to transverse a Mountain range.)
I'm sure if the terrain was flatter and included More freeway running the fuel saving would be far higher than....

Did I learn from the exercise ? yes.. (because if you can't measure it you can't control It..)

Would I spec another trailer with a lift Axle?? Not for that particular job!
For A different job with flatter terrain & lager percentage of freeway running?? maybe..

Another issue we have with lift axles,
IS;
Compliance with your rear overhang & Kingpin to centre of Axle group measurement..
But as I'm not conversant with your laws regarding those issues. I'll let you guys thrash that one out..

Sorry for the Hijack Rollin............

 

Just a few remarks:

RC: You do have to admit it's an interesting hijack LOL. With the cost of a new refrigerator at about 2x what you paid for yours, that's not in my immediate future. On the other hand, I have given some serious thought to doing a manual lift with some air line work and some ratchet straps. We do a lot of 500-700 mile hauls, which would be long enough to merit the effort to lift/lower the axle without an automated rig. Although I'm thinking that would be even less fun if it were pouring down rain or the axles were encased in ice.

DY: Diffy-Q was one of the reasons I elected to graduate with BA at the end instead of an S. I got thru the math, but the lab work was killing me. What appealed to me more than writing software, was being in charge of a bunch of smarter people that could do that, and get it done on time LOL.

magoo: Most trailers with tandems only have the abs sensors on one axle, usually the rear. Lift the front and abs is still on duty.

LR: I would expect stopping to be improved. With the same weight on half the tires, more traction and more braking before they skid.

HC: Great write up on your lift exp. I might be a little off, but I think the line haul you quoted was just over 500 miles in American LOL. Interesting remark about overhang and kingpin to axle length. One would definitely need to reset their "markers" to make sure the lifted assembly remains legal. In my case, the rear axle would be on the ground so couldn't slide back as far as with both down. Overhang wouldn't be a problem, but a light load out to the doors needing that axle farther back, maybe. Anyhow, what you described is sort of what I would expect. Not enough savings that I'd be stacking up hundred dollar bills on my desk each week, but really only seeing it at the end of the month or quarter when there's a little more cash left in the accounts after bills are paid than usual.

Along that train of thought, I wanted to share my experience with incremental savings like this and why it's really important to not dismiss as trivial. We tend to look at these improvements as a part of the whole. That is, what is the percentage it reduces my operating cost for example. What's more meaningful to me, and actually is how it appears in my bank account, is to consider it as "found profit."

For round numbers, consider a savings of $200 on $20,000 revenue. Wow, only a crummy 1%! Let's say it cost you $15,000 to run the loads to produce that $20k. Now it's still looking weak at 1.3%. But look at the profit side of the equation. $200 on $5,000 profit is 4%. So it's a lot less trivial than meets the eye. Do a few things like that, and it starts to add up to real money. In 2014, I have managed to accomplish a few of these things in 2014 and gone from barely getting by, to now being able to make a substantial investment toward more improvement. In other words, these incremental savings have momentum. Achieve a couple and it gives you the needed breathing room to go after more.

Obviously on something like this with a substantial cost up front, you have to consider payback period. On the other hand, if I do it for $200 worth of air parts and straps plus more hassle to work it, the payback gets a whole lot shorter.