Tire size affecting vehicle speed

[edgar c]

Recently experienced my vehicle catching up to and eventually bumping into the vehicle ahead at the dryer section of a conveyorized wash. The vehicles were sent in about 5 ft apart. At this wash my car always stops momentarily at the end of the conveyor, until the roller catches the back tire to push the car all the way through the dryer.

My first thought was catching up is impossible, but on further thought and watching the wash operate, I realized the roller and tire work together as the car go through. I have an older Honda with smaller tires than most modern cars, and think that since the tire is still in contact with the ground that it's size provide a different " gear ratio ".

Has anyone studied this? The wash company is deaf to my concerns.

 

[Axxlrod]

Impossible. It's a physics/science question. The chain moves all the vehicles on the conveyor at exactly the same speed. Different tires sizes does not change anything.

The only possible way for one vehicle to contact another inside a conveyorized car wash tunnel is if the car in front applies their brakes, thus stopping the car which causes the car behind to hit or the car behind puts their car in Drive and it drives forward into the car in front.

Both are caused by driver error.

 

[Earl Weiss]

The only possible way for one vehicle to contact another inside a conveyorized car wash tunnel is if the car in front applies their brakes, thus stopping the car which causes the car behind to hit or the car behind puts their car in Drive and it drives forward into the car in front.

Mostly true. Sounds like place is front wheel pull with safety roller spaced behind rear tire. At end roller touching front tire falls below and vehicle is motionless until roller catches up to rear wheel and starts pushing it. Conveyor speeds vary but you can figure 1 foot / sec for convenience so it roller is 2 feet behind rear wheel it will sit for 2 seconds and then contact rear wheel . Sure the roller can contact that rear wheel and give the vehicle a shove and if it has low rolling resistance and there is downhill exit cause it to roll forward more quickly but during that time the car in front will be long gone - excpt for those drivers who have the habit of applying the brake and then taking their sweet time to shift into drive,

 

[Axxlrod]

True, but that momentary pause after the front roller drops and the vehicle is stationary waiting for the safety roller to contact and push the rear tire will still not allow for a crash.

The only way for two vehicles to contact one another on a conveyor is if one driver makes an error, either by applying the brakes or shifting into Drive.

Also to note, many (most?) vehicles manufacturers require the brake pedal to be pushed in order to shift into Drive. Excluding manual transmissions of course.

 

[Earl Weiss]

Also to note, many (most?) vehicles manufacturers require the brake pedal to be pushed in order to shift into Drive. Excluding manual transmissions of course.

Park to drive usually requires depressing brake pedal. Not so much - Neutral to drive.

 

[Earl Weiss]

True, but that momentary pause after the front roller drops and the vehicle is stationary waiting for the safety roller to contact and push the rear tire will still not allow for a crash.

You are focusing on the lead car being stationary. I have seen at a fast line speed when the vehicle is stopped and then the roller travels a couple feet and impacts the stopped car it will roll ahead at a speed faster than that at which the conveyor is moving. Agreed that the overall speed is low any impact would be nominal.

 

[washnshine]

Never liked front wheel pull that relied on a catch up behind the rear wheel. If there is a front wheel pull installation, it should have enough conveyor length at the exit to fully get the car out of the wash and then a sign for the driver to “go”. I have only seen front wheel pulls installed where there is limited conveyor space at the entrance of the wash. If that is the case, it needs to be made up at the exit.

 

[Axxlrod]

Park to drive usually requires depressing brake pedal. Not so much - Neutral to drive.

All 3 of my cars require the brake to be pressed to shift into any gear, no matter what it is.

 

[JustaGuy]

All 3 of my cars require the brake to be pressed to shift into any gear, no matter what it is.

From Neutral to Drive? None of my automatic transmission vehicles have required the brake to be depressed to go from Neutral to Drive or vice versa. To take it out of Park, yes, but not Neutral. I think if you try it you'll find you don't need to.

 

[Axxlrod]

From Neutral to Drive? None of my automatic transmission vehicles have required the brake to be depressed to go from Neutral to Drive or vice versa. To take it out of Park, yes, but not Neutral. I think if you try it you'll find you don't need to.

Have two BMWs and a Tesla. None will let you shift from N to D without pressing the brake. It beeps at you and gives a warning to apply brakes to shift.

 

[JustaGuy]

Have two BMWs and a Tesla. None will let you shift from N to D without pressing the brake. It beeps at you and gives a warning to apply brakes to shift.

I guess some vehicles do, just none of the ones I've owned or driven. Not understanding the reason behind it, but appreciate the info nonetheless.

 

[Earl Weiss]

I guess some vehicles do, just none of the ones I've owned or driven. Not understanding the reason behind it, but appreciate the info nonetheless.

I think it's perhaps some new / newer vehicles that "Shift by Wire" rather than a mechanical linkage from the shifter to the transmission. I can see it being some engineers reason of safety but I can also see a downside beside the car wash environment.