Truck slides on slick surface

[jefrank]

Doesn't mean it IS wrong however...

I know, I was just trying to be funny

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[TMND]

The “mental gymnastics” you’re referring to here is kind of a moot point. This wasn’t a thread about a truck sliding down the hill, although thats likely what happened. This was about the OP believing there was a mechanical failure. Allowing it to keyword here, Roll.

 

[Runaway Tractor]

Are you sure.....

Yes. A video showing a truck sliding on ice seems to illustrate my point rather than negate it.

 

[Runaway Tractor]

Seems like a questionable design to double-lock the back wheels (awl plus parking brake) with nothing locking the front, but, hey, I'm a software guy, not a mechanical engineer.

You probably just don't realize it if you never needed to think about it. But this is what putting any 2wd or 4wd-in-2wd automatic transmission vehicle in park does. There is nothing different about the lightning vs any other pickup truck and most cars.

 

[Joe.....Montana]

Yes. A video showing a truck sliding on ice seems to illustrate my point rather than negate it.

Sorry....I should have put (Sarcasm)...afterwards...rawr...

 

[Henry Ford]

Yeah, this isn't a mystery. These simultaneous parking brake/parking pawl failures only seem to occur on icy hills.

In aviation there is a condition called "braking action nil" which is exactly what it sounds like; no braking action, your directional control is limited by whatever you can do with the engine(s). This is exactly what is happening in these "roll away" incidents. Braking action is nil and you don't have thrust to use. In the case of a truck sliding after parking I suppose it's more accurate to say two wheel braking action is nil since four wheel braking seems to still work.

 

[jefrank]

You probably just don't realize it if you never needed to think about it. But this is what putting any 2wd or 4wd-in-2wd automatic transmission vehicle in park does. There is nothing different about the lightning vs any other pickup truck and most cars.

I agree, but there is the fact that the Lightning automatically sets the parking brake when it's on an angle, which applies here. It's not unreasonable to think that action is setting brakes on more than one axle on a 4wd vehicle. It's a live and learn moment, for sure.

 

[Runaway Tractor]

I agree, but there is the fact that the Lightning automatically sets the parking brake when it's on an angle, which applies here. It's not unreasonable to think that action is setting brakes on more than one axle on a 4wd vehicle. It's a live and learn moment, for sure.

Is there any other vehicle that does that?? I don't know why anyone would have that expectation since that's not how the parking brake works on virtually any vehicle. This again is simply a matter of making assumptions that make no sense.

 

[Firn]

I agree, but there is the fact that the Lightning automatically sets the parking brake when it's on an angle, which applies here. It's not unreasonable to think that action is setting brakes on more than one axle on a 4wd vehicle. It's a live and learn moment, for sure.

The parking brake does not use the fluid system of the regular brakes, it uses a completely separate mechanical system. This is the norm with rear disk setups. The front brakes don't have the mechanical components needed to be engaged as a parking brake.

 

[jefrank]

The parking brake does not use the fluid system of the regular brakes, it uses a completely separate mechanical system. This is the norm with rear disk setups. The front brakes don't have the mechanical components needed to be engaged as a parking brake.

Aren't the Lightning's brakes disc all around?

Not trying to be argumentative, but want to understand why an electronically applied brake wouldn't have been applied to both axles on a vehicle that is significantly heavier than the average vehicle.

 

[jefrank]

Is there any other vehicle that does that?? I don't know why anyone would have that expectation since that's not how the parking brake works on virtually any vehicle. This again is simply a matter of making assumptions that make no sense.

Makes no sense to people who are gearheads, but most drivers are not that. It's an electronically applied brake, not a traditional emergency brake with a lever to mechanically engage the brake. The cost of applying that brake to both axles seems negligible given the overall cost of the vehicle and seems perfectly reasonable unless you only think in the past.

Still love my truck and have learned that I can't rely on the parking brake on a hill if there's snow, even if that snow doesn't rise to the level of being slippery to walk on. It's good I was able to learn that without the truck (or someone) being damaged.

 

[Firn]

Aren't the Lightning's brakes disc all around?

Not trying to be argumentative, but want to understand why an electronically applied brake wouldn't have been applied to both axles on a vehicle that is significantly heavier than the average vehicle.

The electromechanical brake is an entire second set of components. These are all pieces in addition to the system used brake the vehicle during normal driving. Some systems will use the same brake pads, but others incorporate an entire separate braking system inside the rotor of the disk brake. COULD Ford have applied a mechanical awl in the front motor too? Sure. But that's extra parts and extra cost when the normal way of doing business has been fine for decades.

There really isn't a need for a better parking brake, and big trucks and F350s have been using this system for years, and they are as heavy, if not more heavy, than the lightning. All it does is make sure the wheels can spin, and it has accomplished that job.

In the end this wasn't because the parking brake was insufficient, it was because the surface parked on was insufficient.

 

[Runaway Tractor]

The parking brake on virtually every vehicle is only applied to one axle, virtually always the back. It is not part of the hydraulic system. It is a physical cable that pulls on a lever that compresses the brake cylinders. Usually that cable is pulled by a lever or foot pedal. One some vehicles, including the lightning, it is done with an electric over mechanical device that pulls it for you.

This is how every vehicle out there works since before any of us were born. So yes it would be very strange if this applied to the front wheels as well. The problem is the user(s) not knowing how the brake works and thinking the lightning is something special or unique in that regard. It is not. It is nothing new or different.

As has been said many times, wheels on ice will slide. It doesn't matter what braking system you use. You can weld the rotors to the axle housing and it will still slide down the hill. Just like humans with shoes on ice. And anything else on ice.

 

[Wattsgas]

This would be great information for people living in these climates. Since in our case, the truck rolled back into the street in the direction that it came from vs sliding straight across to the neighbors driveway where they part their car at the very edge of the street . During the second episode when I was in half in the cab on the shotgun side, I felt it rolling. As we know from watching all the CSI shows eye witness recall is flawed, but traumatic memory gets embedded .

We had snow in the Northwest just last week. I parked the truck on a incline with snow. The truck slid down the driveway, about 4 feet until the snow formed a wheel chock. I attached a couple of pictures that I took. I was doing a trash run for the inlaws. Would not have believed it if i didn't see it.

 

[Effonefiddy Lightning]

Yesterday I returned from the grocery store and parked my son’s truck in the usual spot and plugged it in. By the time I got back in front of the vehicle to get groceries out of the passenger side the truck began rolling back into the street. The charger pulled out of the port (connector is damaged and needs to be replaced). My son who is recovering from major surgery and limited on activity came into the garage and guided me to park again (we have had snow so wanted to make sure I was completely on a clear spot). I again put the truck in park, turned on the parking brake, vehicle was powered off. I walked around and got two bags of groceries with no problem, but when I went back to get the rest, as I was 1/2 way in the door bending to pick up stuff from the floor board, the truck again began to roll trapping me between the door and the vehicle. I was able to grab the overhead handle and step up on the running board as it rolled back into the street.
I had the dealership come and get the car. My son uses a different service department since the one at his dealership is inefficient, but that is further away. They may get to look at the truck by tomorrow. They don’t see any sensors off, but because I was honest, the sales manager said maybe it is my inexperience driving the vehicle or that it had a low tire pressure light last week, or the severe weather, all that sort of BS when a car guy talks to a woman. I grew up driving a split axle cattle truck so know how to drive and especially park.
Had I slipped (it was raining but hadn’t started to ice over yet) I would have been at least run over by the front wheel.
I am going to try and alert everyone because the service manager said he hadn’t seen any thing on any forum but I saw here that there have been recalls and some issue with wiring on the rear axle or something.
A vehicle in park with a parking brake activated should stay parked.
Regardless of the repair I am ordering an airline bumper or something like that and now refer to the vehicle as Christine (for you Steven King fans).

Great, another problem with our oh, so awesome Lightnings. Best truck ever they say. Legacy manufacturing better than those $h!t start ups. My driveway is sloped, I hope it doesn't run over some poor kid riding his/her bike.

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