GM, Navistar Considered Air Brakes For Silverado Medium Duty Truck
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General Motors and Navistar considered offering an air brake system on their Medium Duty Class 4, 5, and 6 trucks – the Chevrolet Silverado Medium Duty Chassis Cab Trucks and International CV, GM Authority exclusively uncovered thanks to insider sources familiar with future GM truck programs.
The air brake system was originally considered for the 2019 Chevrolet Silverado 6500HD, which currently is the range-topping model in the Silverado Medium Duty range. However, the duo ended up deciding against offering the feature on the vehicles for the time being. Instead, the feature will be reserved for the as-of-yet rumored but unconfirmed Class 7 truck that we have reported the duo to be exploring.
The current 2019 Chevrolet Silverado Medium Duty truck line comes with a hydraulic brake system with four-channel ABS from Bosch/Meritor/Wabco. However, the rumored Class 7 Silverado will likely include air brakes as exclusive equipment for the range-topping model.
For those not intricately familiar with the difference between hydraulic and air brakes, here’s a quick rundown: the vast majority of vehicles produced today are equipped with a hydraulic brake system, which uses brake fluid to squeeze brake drums or rotors with a friction material, like a brake pad or brake shoe. By comparison, air brakes use compressed air to transmit the braking force to the pad or shoe.
Air brakes are primarily used in large commercial vehicles, and are considered preferable to a hydraulic setup for such applications. Not only are air brakes less prone to overloading when slowing heavy-weight vehicles, but they are also more reliable and easier to service, especially as a large system. While brake fluid can leak out and drain away, air is abundant and ever-present, providing an inherent fail-safe. What’s more, an air brake system doesn’t require bleeding like a hydraulic system. For that reason, they would be perfect in a potential Class 7 truck from GM and Navistar.
The current Chevrolet Silverado Medium Duty truck line was developed in conjunction with Navistar, and includes the Silverado 4500HD (Class 4), Silverado 5500HD (Class 5), and Silverado 6500 HD (Class 6) models for GM, along with Navistar’s version – the International CV. The models were jointly developed by GM and Navistar, while Navistar handles production of both variants.
Last year, GM Authority exclusively reported that GM and Navistar were exploring a possible collaboration for a new Class 7 truck, which would sit at the top of the Chevrolet Silverado range with a Gross Vehicle Weight Rating (GVWR) between 26,000 and 33,000 pounds (11,794-14,969 kilos). Our intel told us that the new Class 7 truck will launch in 2022 and come with the new air brake system, among other exclusive features.
This latest rumor follows several other firsts reported by GM Authority, including that the Silverado Medium Duty truck line will receive a new gas engine option in the near future. This new engine will likely be variant of the 6.6L V8 L8T introduced in the 2020 Chevrolet Silverado HD and 2020 GMC Sierra HD. In May, we also reported that GM is looking to expand the Silverado Medium Duty line by adding a new 22.5-inch wheel option to create a dock-height version of the work truck.
We’ll keep our ears to the ground on this one. In the meantime, subscribe to GM Authority for more Silverado news, Chevrolet news, and 24/7 GM news coverage.
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In the current size classes I don’t think air is a big deal. You get better stopping power with hydraulic, Navistar did hydraulic brakes at one point actually (and it was best performing in the class) but had issues with their valving. That was during the pit of their slump with the maxforce motors so they didn’t have much appetite for trying to fix it, they just switched back to air. The real reason to need air is when you’re getting into those class 7 sizes and people are using them as day cab/yard tractors, need the air to supply the trailer brakes.
I’ve seen a couple of these new trucks on the road now (configured as rollbacks) and they looked really nice, like a traditional Chevy. Haven’t seen any of the Navistar flavored ones, I’m anxious to see one. In the pictures it looks more like it was designed as a Chevy first and then Navistar threw their vertical bar grill on it but hard to make a judgement from pictures.
“it looks more like it was designed as a Chevy first and then Navistar threw their vertical bar grill on it but hard to make a judgement from pictures.”
That’s exactly what happened. The cab is the last-gen Silverado HD cab… with a different grille for the Chevy model and a different grille still for the International CV.
Air brakes have traditionally been Class 7 and above, as you said… but from what we know, they were being considered for an ultra high duty Class 6 truck.
Some background on class 7 air brake tradition, with above 26k gvwr truck it is more difficult, but not impossible, to pass FMVSS 105 hydraulic braking standards, but below 26k gvwr 19.5″ or smaller wheels are more common and it is difficult to package FMVSS compliant air brakes in those wheel sizes. So the 26k ish range becomes a breakpoint for both wheel size and brake apply type.
What will be interesting to know about the potential air brake and larger wheel size is will Navistar/GM maintain the front wheel turn angles of the lighter gvwr’s, or need to reduce turn angles with the larger diameter tires. To maintain the lighter vehicle turn angles could mean wider front tread width and a hood assembly, basically to the 102″ federal limit.
Yes, since the 6500 is below 26,000#’s GVW, air brakes are not really necessary. One advantage to hydraulic brakes is that in many states driving an air brake equipped vehicle requires a commercial driver’s license, or at least a special endorsement. Even the 6500 HD does not require a special driver’s license here in California unless you are towing over 10,000#’s with it.
Commercial Driving license requirements between states, including Cali, are basically the same since following FMCSA guidelines became standard for interstate transportation.
Towing, when combined truck and trailer gvwr’s are over 26k, and the trailer is over 10k GVWR, a CDL A is required unless the towing unit is motorhome/recreational/transport of non business property.
Truck only, if the truck is over 26k gvwr, a CDL B or CDL A is required unless truck is motorhome/rec/non business property transport.
CDL B can be used for towing commercially if the towing truck is over 26k gvwr and the trailer gvwr is 10k or less.
For either CDL A or B license application, if the air brake written section and road test with air brake truck are not used and passed, air brake exemption is added to CDL. Air is no longer an endorsement, it is an exemption.
One could drive an air brake straight commercial truck that is 26k or less gvwr without either CDL A or B, but that is rare, it is more common to find non CDL drivers operating air brake motorhomes and rental trucks for personal moves where there are no endorsements required. I have a 75 year old friend which drives an air brake 60k gvwr Showhauler motorhome all over the country with no CDL, no air brake endorsement, no dot medical card, no trip permits/IRP/IFTA, no weigh station stops, and it is all legal.
On smaller trucks it would not be a good choice to use air,as I am sure that in most jurisdictions you would need a air brake addrossment on your licence—which the ordinary worker would not have.
Chevy does offer air brakes on the 6500 series LCF (Isuzu FTR), but that truck is basically a lighter duty version of a heavier truck sold in other parts of the world. Probably cost too much money to engineer hydraulic brakes into one version of a truck designed for air. I think air brakes pretty much require 22.5″ wheels for clearance, which the 6500 LCF has.
Still waiting for the pickup bed version of the truck and waiting to see if with the introduction of the 2020hd will the suspension change to match the capabilities of 35500lbs. Doesn’t make sense to spend money on these when a 3500 from the same brand will out perform