Pizza pans on long haul trucks
 

On my recent trip of 1,800 miles I saw lots of long haul trucks, about 10 of these had aero covers on the back two axles of the power unit (cab).

From what I saw as we passed the trucks (I know we were going to fast for FE) the caps looked like a manufactured product, with a hole for checking tire pressure.

The first one I saw turned my head as I went, cool large pizza pans like on my car :)

I only saw these on trucks in Texas, & Oklahoma none in Missouri, Illinois, Indiana or Michigan.

AT Dynamics makes some. They make trailer tails & side skirts as well. I don't know if Mooneyes makes them that big or not.

Don

Weather Spotter -

Did they have holes for the bolts? There was a trucker on this site who had some installed on his truck. His company did it. Unfortunately I can't find his posts right now.

CarloSW2

No bolt holes, looked very nicely done, with hole cut out for access to valve stems.

On the trip about 15% of trailers had side skirts, trucks with aero hub caps all had side skirts on the trailers.

This is what Schneider is using on their trucks...

http://ecomodder.com/forum/member-ba...wheel-caps.jpg

Press release... ;)

Deflecktor is the company who makes them... :D

They looked like the AT Dynamics ones.
I saw some schneider trucks but none of them had wheel covers.

Schneider only has put them on 1500 of their trucks...they've got a whole bunch of trucks... ;)

Some of the drivers are taking those wheel covers off cause they don't like the way they look... :(

I like the look of the sliver pizza pans, chrome would be better.

I saw some AirTabs on the backsides of a couple trucks a while back. Haven't seen the smooth wheels yet. XD

I saw some pans on Oak harbor trucks out in Washington

I don't think drivers are taking them off just because of looks. If your in a place with a lot of step hills the covers reduce brake cooling and thus braking. I can see these as being of use on the plains but in hilly or mountainous areas they could lead to run away trucks. Braking distance is bad enough on a semi under these conditions they don't want to make it worse.

I don't think the Schneider corporation would do anything that would jeopardize their drivers, vehicles, or the bottom line (clients' payload) by adding on items that would decrease the safety factor without intensive testing under all conditions that their vehicles would perform under. I know fer a fact that they tested this fer over a year before they agreed to install them on a bigger sample size. They did this exclusive of what the inventor/manufacturer of the Deflecktor claimed... ;)

I do know that the Deflecktor isn't lasting as long as one might want to believe. My brother (Schneider driver who got me the photos) found a bunch of them in a pile torn and tattered before they went with the bigger sample size. I wanted him to git me one of the beat up ones...but didn't really want to put his job at risk fer "unauthorized removal" of Schneider property... ;)

Weather Spotter -

This is not *the* one I was talking about, but it sounds close to what you saw :


CarloSW2

cfg83: those look just like what I saw. Some of the trucks though had holes for valve stem access, some did not.

Overall I like the look on the big rigs.

I would'nt want to put those on my car I like the look of the aluminum ones but I drive to much in the mountains and do not want the brakes to get that hot. I would have to duct air to them and that reduce the affects of the wheel covers. That is my theory anyways.

Probably a good theory, but if the pans are aluminum, and since aluminum is a very efficient heat conductor, maybe the heating problem would be not so bad.

My Porsche has Design 90 wheels, pressure cast with basically a pizza pan outer shape, but with vents at the rims. Cooling of brakes good. On a high speed ratrace through British Columbia some years back, about 30 of us went through rain and mist such that you could clearly see the wake and flow from each car. Despite identical car shape, the type of wheels made a huge difference in apparent air flow, with deep set spoke wheels being about the worst, and Design 90 and so-called "sewer lid" Porsche wheels the best. The deep dish spoked wheels threw out a lateral column of air which surely helped brake cooling, but utterly buggered flow along the sides of cars so equipped.

Mesilla Valley Transportation
I have seen these numerous times on semis in the Austin area.
We have mentioned them in another thread on the same topic, and the name of the trucking company is Masiila Valley trucking. I find it odd that they just cover two sets of wheels, but I'm sure there is a reason.
They use the disc covers with the hole that you spoke about.

that is the right trucking firm, the truck markings are the same.

The wheels on the drive axles are dished in so it's easy to put a cover on. The wheels on the front (steering) axles are dished out so it's a lot harder to put a cover on. It could still be done, but would stick out quite a bit.

I've driven 20,000 miles (mostly highway and backroads) through WV with my smooth wheels, and even when towing 1200 lbs + carrying another 500 I had no sign of brake fade. The trailer didn't have any brakes either. If you're worried about brake cooling, I feel the rotors still get plenty of air from the inside of the wheel.

Besides, F1 cars use these (and paint wheels on the covers). And I imagine there braking needs are a bit more than ours.

When I taped up the holes in my wheels, I just removed the dust covers from the front discs. Then again, I haven't done any mountain driving since I did.

Brake fading due to overheating is a very real problem and is well documented. F1 cars recently started using Carbon Carbon brake rotors which don't require as much cooling. Unless you have tens of thousands of dollars to spend on a custom set for your street car your not going to get a set. Its pretty much the same story for semi trucks.

They do fade if over heated, but If you drive right they need not be used much. How many times are trucks in stop and go traffic (that they use brakes not just engine break)?

ummmmmm stop and go traffic isn't the problem. Its decent down long steep hills. That is why they have run away truck ramps. Even with these run away truck ramps its not always possible for a truck to use these ramps due to traffic and carnage ensues.

Good point about the hills, I would think that over 95% of the time the trucks are not in the hills and the better aero is the best choice. When in the hills, take them off.

I was about to say that cars can get away with the covered wheels, even when towing in mountains. I've never had brake fade on mine.

Then I realized there is a 7% grade for 13 miles about 45 miles away I drive regularly. Everyday the weigh station wasn't open it was almost guaranteed a truck would have the brakes on fire by the bottom of the hill. You could always smell it way before you could see the smoke coming from the thing. Luckily there were never any accidents as there is a reverse incline right before the bottom.

Cross country trucks have lots of hills to contend with. I know, it is harder for the flatland native to consider.

I don't see truckers climbing in and out to R&R hubcaps.

Good points, all.

Maybe have lightweight removable covers for use on cross country trips, lower speeds and more frequent braking around town compromising the need for such covers except on the open highway.

And, maybe duct some of the undercar air that would othewise drag on the front wheels directly to the brakes, so wheels are faired and brakes stay cooler.

( Actually I meant the rear set on the trailer. I can understand if they don't own the trailer, and just swap out trailers, but this company actually owns the trailers, yet they don't cover the rear set - just the rear set on the rig.)

It would make it more complicated but they could add a pneumatic arm for the attachment point and a temp sensor on/by the brakes. When the temp hits X the pneumatic arm pops out leaving a gap, if the under side is designed correctly it could actually direct air into the wheels to cool and create some extra drag.

They would then stay open for a preset time after the temp drops.

Brake calipers are often made of cast iron. Maybe aluminum (much lighter and an excellent heat conductor) calipers with cast fins (like a motorcycle engine) would keep the brakes cool enough when pizza pan wheel covers are used.

Otherwise, ventilation holes or slots out at the edges where the wheel lip would make turbulence anyway, would add little or no drag while keeping the brakes sufficiently cool.

Aluminum melts at too low a temperature. I supposes one could have nitinol actuators to open vents but expenses pile up quickly when one considers this as an option.

So, the aluminum engine on my BMW motorcycle and the one in my Porsche car, and the head in my BMW car are all gonna melt? One would think this would have already happened, since these vehicles have a collective total of nearly half a million miles, over the past 25 years.

There really ain't much for alum brake rotors and drums out there... and the temps those engine components see vs brake rotors/drums really don't compare, especially when the loadings are considered i.e. the exhaust port in an alum head doesn't have to do much more than not fall apart but an alum rotor or rotor/hub better retain almost ALL of it's structural integrity even at high temps.

Sorry for bringing back an old thread, but I missed the party the first time around. Putting smooth covers on the outer dual on a big rig has no effect on brake drum temps. There is a 2 inch gap between the inner and outer tires and any air comming from the outer rim would get pushed out the rear by the air comming from the front of the tractor. The drums are recessed in the inner rim, protruding inward from the rim area to catch cooling air. I have seen front scoops in place of backing plates to duct more air flow toward the drums on some trucks.

Current truck mech, JB.

And they're open on the backside, too.

Big rigs shouldn't be using the air brakes when going down grades anyway. That's what engine and exhaust brakes are for. Besides, there isn't a whole lot of cooling coming through the outer wheels anyway and the drums are huge, most heat should dissipate inside the inner wheel.
pavementinteractive.org/images/2/25/2_axle_configuration.jpg

I had a set on a Peterbilt 372 I used to own. They looked cool, spun aluminum and all, but there didn't seem to be a noticeable increase in economy. That truck did pretty darned well, though, being the most aerodynamic cabover in the industry (at the time, at least).

There are already aluminium drum brakes for commercial vehicles:
Materials - Truck & Bus Engineering Online

did any of the trucks (in Texas) look like these?

Mesilla Valley Transportation