stop car at 30mph in 100ft.

c64
Evil Senior Member

Posts: 3,440

stop car at 30mph in 100ft. Jun 28, 2015 13:19:00 GMT

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Post by c64 on Jun 28, 2015 13:19:00 GMT

Jun 28, 2015 9:04:44 GMT silverdragon said:

This was when the brake balance regulator blew up the moment I had stepped on the brake pedal pulling into a left turn lane...

Ouch.....

One thing I miss from my days owning a Lada was that it had Dual Circuit brakes.

I dont understand the bit on selecting "P", I presume thats "Park", of course, but, what does that do?...
As you know, I aint a fan of Automatic transmission in smaller vehicles.

I am a fan of automatic in Trucks... I have been driving a few recently where its too bloody easy to change gear, and not miss a cog....
Except I cant persuade one of them to "block change", even though I dont need all the gears, it will insist I use them sequentially.

For instance, solo, or Bobtail, a more usual gear change to 30mph is 2,4, then high-ratio 2.

Any car has to have two independent parking brake systems. For a manual transmission you can pull the hand brake and keep the transmission in gear. If the hand brake cable snaps, the car can't pick up speed rolling away due to the engine.

An automatic transmission can only be kept in gear when the engine is running. So they have to have an additional park brake system. Usually, it is a latch locking the shaft on the output side of the gearbox. To prevent cracking the gearbox when a parked car is hit by another car, this latch is fragile. When you put a moving car in "P", the latch will snap in half instantly and the park brake is gone.

Some cars used a brake belt instead. This is tightened by the transmission selector. This belt can brake the car but usually it burns out quickly at higher speeds. The first Audi 80 has a very durable belt which can survive braking from high speeds. The problem is that when parked on a very steep hill, the plain brake belt can slip slowly making the car roll away like a manual car parked with a gear in. When the belt is not well adjusted, the car can pick up speed so the system isn't that good.

Modern cars which use a brake belt have knobs on the belt which catch holes on the shaft. If the forces become too great, the knobs pop out. So the braking effect at high speeds is negligible. But when parked, the car is held in place much more secure and still tolerates being bumped.

c64
Evil Senior Member

Posts: 3,440

stop car at 30mph in 100ft. Jul 24, 2015 9:08:05 GMT

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Post by c64 on Jul 24, 2015 9:08:05 GMT

Jun 5, 2015 7:00:47 GMT silverdragon said:

If you have seen the show "what could possibly go wrong", you have seen the idea.

In that show, they tried several things, like Parachutes, Air-brakes, a log under the tyres, and chucking the anchor (A REAL anchor) out the back....

Of course they failed.

But I appreciated the entertainment.....

So, can you stop a car at 30mph in 100ft without using conventional brakes?..
Their proposal was what can you do if the brakes fail.

Their parachute idea, fail, because even when Adam tried using a chute, full sized chute, as a anti-chase technique, it didnt exactly slow him down "That" much did it?...
Drag races use chutes to skew away speed so their conventional brakes can work, ..
I suggest Chutes only work effectively above a certain speed.

Air brakes?.. the ones they tried were not strong enough, wooden flaps that just blew backwards.
Again, useless above a certain speed?...

An Anchor.
On tarmac, useless, its not going to dig in is it?..

Friction.... they tried a heavy sledge, that may have worked better is they had put a rubber base on it to get traction?...

What other methods could have been used?

This was recently aired here in Germany. Naturally, I went to a friend and showed him the video. This guy could be one of "the Stig" from Top Gear. It's the guy who had taught me how to race drive cars.
He said that this is very simple and did it with an unmodified car at 80kph (~50kph as seen on the show is too slow). Just some fancy work on the steering wheel and the car spins 90° around which makes it brake hard by skidding sideways. It was slightly more than the ~30 meters from the show but it worked well and he was a lot faster after all. He was just unable to keep a straight line all the way but that wouldn't be impossible, just unlikely to do that every time.

silverdragon
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Busters Stunt Double, .. because "Life" is something that happens when your planning something else.

Posts: 19,452

stop car at 30mph in 100ft. Aug 12, 2015 8:14:06 GMT

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Post by silverdragon on Aug 12, 2015 8:14:06 GMT

This was recently aired here in Germany. Naturally, I went to a friend and showed him the video. This guy could be one of "the Stig" from Top Gear. It's the guy who had taught me how to race drive cars.
He said that this is very simple and did it with an unmodified car at 80kph (~50kph as seen on the show is too slow). Just some fancy work on the steering wheel and the car spins 90° around which makes it brake hard by skidding sideways. It was slightly more than the ~30 meters from the show but it worked well and he was a lot faster after all. He was just unable to keep a straight line all the way but that wouldn't be impossible, just unlikely to do that every time.

Say you dont have the room to swing round.
Say its my own road.
No one yet, even some twonka in a not-s-smart, has managed a 3pt turn on this street, its that narrow.
In fact, one neighbour has a motorcycle, and not even HE can turn round in the street...

And then you have Mr Average who cant drive as well as say we can, Would he even THINK of swinging the wheel ?

Hell some of them would even miss an escape lane on a steep hill.

I have experience of a van damaged by emergency braking by a good friend who used a long stone wall at the side of the road to friction-drag down to scrub some speed off when the brakes cooked.
Yep, it ruined the side of the van, but he lost enough speed to manage the VERY tight hairpin at the end of the wall?....

How did the brakes cook?... bad servicing by the owners.
Those brakes should have been replaced, but were not.
The van did 200,000 mile in three years on the same set of brakes....
We dont work for that firm any more.

-x-clacks-GNU Terry Pratchett----Release the Clan Mac Feegle, awae hame ye scunners.[p]Most of my Job is avoiding Stupid. ...You cant Fix Stupid. Especially when you turn Left at Hammerhead.

c64
Evil Senior Member

Posts: 3,440

stop car at 30mph in 100ft. Aug 12, 2015 20:06:23 GMT

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Post by c64 on Aug 12, 2015 20:06:23 GMT

Aug 12, 2015 8:14:06 GMT silverdragon said:

This was recently aired here in Germany. Naturally, I went to a friend and showed him the video. This guy could be one of "the Stig" from Top Gear. It's the guy who had taught me how to race drive cars.
He said that this is very simple and did it with an unmodified car at 80kph (~50kph as seen on the show is too slow). Just some fancy work on the steering wheel and the car spins 90° around which makes it brake hard by skidding sideways. It was slightly more than the ~30 meters from the show but it worked well and he was a lot faster after all. He was just unable to keep a straight line all the way but that wouldn't be impossible, just unlikely to do that every time.

Say you dont have the room to swing round.
Say its my own road.
No one yet, even some twonka in a not-s-smart, has managed a 3pt turn on this street, its that narrow.
In fact, one neighbour has a motorcycle, and not even HE can turn round in the street...

And then you have Mr Average who cant drive as well as say we can, Would he even THINK of swinging the wheel ?

Hell some of them would even miss an escape lane on a steep hill.

I have experience of a van damaged by emergency braking by a good friend who used a long stone wall at the side of the road to friction-drag down to scrub some speed off when the brakes cooked.
Yep, it ruined the side of the van, but he lost enough speed to manage the VERY tight hairpin at the end of the wall?....

How did the brakes cook?... bad servicing by the owners.
Those brakes should have been replaced, but were not.
The van did 200,000 mile in three years on the same set of brakes....
We dont work for that firm any more.

It's all hypothetical anyway. The chances that you can stop the car by "fancy steering" are a lot better than the chance that you have a tea table bolted to your car you can use as flaps by pulling a rope.

There are many different possibilities of "all time" emergency systems which won't look stupid on your car. I well remember a TV show called "Zu lande, zu Wasser und in der Luft" (on land, on water and in the air) from the 80s. There were several different challenges the contestants have to come up with a solution. One was a "reverse race". The car must drive in reverse and the driver and steering wheel must be pointing the wrong way. In the later episodes almost all used a 2CV with a flipped over differential (4 speed reverse, 1 forward gear). Might be the reason why they stopped making the show since everybody copied what worked and in the end it was all the same.
One challenge was a steep ramp to a lake and a floating platform at the end. The challenge was a home-made vehicle pushed on the ramp. The vehicle speeds down and has to brake hard on the platform which then moves over the lake to a pole with a bell. The time is measured until someone rings the bell.
The problem is that the vehicle needs to be light enough or the platform will sink. But you need mass to make the platform move. Using a car was impossible since too large and/or too heavy. Then the platform could trip so you have to be accurate. At first most used bicycle or car brakes. Then someone made a vehicle where the rear axle pops out by pulling a lever. This had worked very well.

So you could make a car where "the wheels fall off" to emergency brake, maybe using explosive bolts or simply a hydraulic or pneumatic suspension. This would make a lot more sense than everything they had tried on the show.

Last Edit: Aug 12, 2015 20:06:39 GMT by c64