In the promo video, why does the air suspension squat while towing?

[aadams1278]

In the truck pull video shown at the delivery event, the Cybertruck and Rivian are squatting at the back end while the front end is pretty high. The rest of the trucks with traditional suspension don’t seem to do this. It was my understanding, and according to Elon, the air suspension is supposed to be better than spring suspension for towing heavy loads because it can auto level regardless of the weight.

So why are the air suspension trucks low at the rear in this video? I can only think of two reasons. Either the weight is too much for the air suspension to handle, or there is some benefit to this stance for the truck pull.

If the weight is too much for the air suspension and it’s essentially bottoming out, I would think it would be better to just lower the front suspension as well to keep it relatively flat.

If there’s some benefit to it, I don’t understand the physics behind that.
Any ideas?

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[SlightlySinged]

Look how low the attachment point is on the sled. At that angle, when you're accelerating it will pull the rear and down, and make the front lift.

 

[Alpine]

Physics

 

[aadams1278]

And the air suspension can't or doesn't try to compensate for it once it starts moving?

 

[Rutrow]

Tractor pull rules govern the maximum height for the hitch, since pulling upward on the front of the sled is considered cheating. I don't know if Tesla was just making sure they abided by the rules of the tractor sled owner, I'm sure they could've done it at whatever height they wanted since they hired the sled, but had they towed from too high a point I'm sure there'd've been naysayers citing the rules and accusing Tesla of cheating.

Rule #7 in the pdf below is about typical.

https://assets.ctfassets.net/vqgxde...2a5a94407bf8ea/VTP_Rules_Regulations_2023.pdf

 

[lowtek]

All trucks will squat in the back under load from a trailer. The air shocks can only do so much.

In a real towing scenerio, depending on the weight of the trailer, you would usually use a weight distribution hitch. These hitches essentially push upwards at the hitch point leveling both the truck and the trailer distributing the load evenly. They make a huge difference in feel and prevent the "tail wagging the dog" resulting in a much safer experience and night and day towing dynamics.

 

[charliemagpie]

If testing, CT was perhaps towing its maximum 11,000lb limit.

The CT is rated to tow say 50% above its own weight, If the tow is 6000lb I reckon it is borderline if you need WDH. I have read both sides of the reasoning.

Regardless, If the front is lifting, safety is compromised. A Google search will explain weight distribution hitches.

 

[Rutrow]

If testing, CT was perhaps towing its maximum 11,000lb limit.

The CT is rated to tow say 50% above its own weight, If the tow is 6000lb I reckon it is borderline if you need WDH. I have read both sides of the reasoning.

Regardless, If the front is lifting, safety is compromised. A Google search will explain weight distribution hitches.

Tractor pull sleds like the one used in the delivery event presentation are WAAAAAAAY above 11,000 lbs. Depending on how much weight is added for different class competitions, can weight up to 60,000 lbs, AND have a plow attached to front to ensure that the sled always wins.

 

[aadams1278]

Thanks for the replies. To clarify, I’m familiar with what a weight distribution hitch is, and I’m not planning to tow super heavy weights. The thing that is new and interesting to me about Cybertruck is the air suspension, especially as it relates to towing. I’m aware this demonstration isn’t a real world scenario, but it made me think there may be more to the air suspension I still don’t understand. Such as I did kindof think air suspension may eliminate or reduce the need for a weight distribution hitch.

 

[SSonnentag]

If the weight is too much for the air suspension and it’s essentially bottoming out, I would think it would be better to just lower the front suspension as well to keep it relatively flat.

When towing a 35,000 lb sled that is actively digging into the ground, it wouldn't matter what the suspension settings were on, the results would be the same: full squat in the rear and full extension in the front.

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