I don’t really know how a parking brake works. I have a passenger vehicle with a lever. If I depress a button on the lever, I can raise the lever and engage the brake. I assume when engaged, something is pressing against something else and friction somewhere causes the car to be harder to move. Note: When parked on an incline, my car doesn’t seem to move anyway, probably because of the parking pawl.
In the past, I have forgotten the brake was engaged and driven around normally. I eventually noticed and remedied the problem. But for all I know, I could drive around all day with the damn thing engaged. I have no idea if that causes permanent damage.
It seems to me that a better design would have the parking brake automatically disengage when the car is put into drive. Okay, suppose you needed to engage the brake while driving. I have never needed to, but let’s suppose. The driver could just yank up on the lever and it would engage even when driving. But it should not lock in place and should disengage when the driver lets go.
Even better, have a toggle option to automatically engage the parking brake whenever the car is put into park, to reduce stress on the drive components.
Okay, so what does this have to do with blow out preventers? According to 60 Minutes, a worker from the Deepwater Horizon rig said the BOP was accidentally left closed during a test where the pipe was moved up and down. This resulted in chunks of rubber and other material appearing in the drilling debris and the worker concluded there was permanent damage to the BOP.
But couldn’t they have designed the drill motors and the BOP to not both be engaged at the same time and thus prevented the spill in the Gulf?
Cars tend to have a little light to tell you the parking break is on. I guess they’re not idiot-proofing the system because they assume drivers are not idiots in general.
If you could drive off with the parking brake engaged, it was not adjusted properly. In most cars, the parking brake is controlled by a steel cable, which has a tendency to stretch. Adjustment is easy, but often forgotten about.
As for the BOP, yes, it would be almost silly easy to have logic in the control systems that enforce a mutual exclusion on having the BOP engaged vs drilling or moving the pipe. However, such an exclusion could easily prevent the BOP from being engaged when it was most needed if the drill pipe broke, or if a false signal fooled the system.
I don’t know much about BOPs, but if they’re emergency equipment, they may well be active 100% of the time, regardless of drilling or moving the drill pipe. Like your parking brake, it may have been out of adjustment and unable to withstand pipe movement.
THe typical configuration is for the parking brake lever to actuate the car’s rear driving brakes via a cable or linkage. These brakes press pads of friction material against a metal drum or rotor to inhibit wheel rotation.
The parking pawl on an auto-tranny car is enough to prevent movement when parked. However, on exceptionally steel hills, it can be difficult to get the transmission out of park if the pawl is heavily loaded, as when the parking brake has not been applied.
It can indeed cause permanent damage due to excessive heating of the rear brakes.
Rather than a complicated and expensive interlock with the gear selector, the traditional solution has been a red warning light on your instrument display to let you know that the parking brake is currently applied. When you first apply the parking brake, you should be able to see this light before you turn the ignition key off; that’s your opportunity to check and make sure the light itself isn’t burned out or malfunctioning. When you start the car, before driving away, that’s your chance to check the dashboard for any warnings that might indicate an unsafe condition or a need for maintenance - for example, the light warning you that your parking brake is still applied.
Seems like a very simple and inexpensive system to me. Just have the lock tied to park. When you move the transmission out of park, the lever is released and gravity pulls it down and disengages it.
As far as a warning light goes, that’s not a very good solution. I am not the first driver to forget to check. I am not the first driver to pull out of a parking space with the brake engaged. If you can honestly say that you and everyone you know have never made this simple mistake, then I stand corrected.
I am not an idiot and don’t need idiot-proofing. I don’t think the warning light system meshes well with a regular driver’s normal mental model of operating a vehicle.
And my proposed design would eliminate the need for having a warning light, thereby reducing the cost and complexity of a car by 1 system.
The emergency/parking brake lever or pedal pulls on wires which activate the rear brakes. It uses no brake fluid and is completely separate from the car’s normal braking system so that it will still function if your regular brakes fail.
My Cadillac does this.
The Cadillac is designed so that you can also use the brake as an emergency brake while the car is driving. Unlike most cars, the parking brake won’t “lock” into place while the car is moving so you’ve got more control over it in an emergency. It’s kinda like an extra brake pedal. When the car is stopped and in park, the brake functions like a normal parking brake. It locks into place and doesn’t unlock until you put the car into drive.
The parking brake doubles as an emergency brake, so the ability to engage it while driving is pretty critical. Having automated systems with the ability to disengage it adds another failure mode.
As for oil drilling rigs, I suspect they’re complicated beasts with any number of ways to catastrophically break them during normal operation. Automated interlocks to keep an operator from doing something stupid are hard to design once you move to things that are run by skilled operators making constant judgment calls. For all I know, moving a drill pipe up and down is done by a crane that may or may not be hooked up at any given time. To link that to the BOP would take some fancy sensors, lots of internal logic somewhere and add new and interesting ways for things to fail.
I’m sure you’re not. Then again, the guy who backs into your car in a parking lot probably isn’t exactly the first to make that mistake. Or the guy not signaling… or not stopping at a stop sign. There are drivers that know what they’re doing… and drivers that don’t.
As far as I know, nobody I know has done it… or at least hasn’t managed to actually move the car. Yearly compulsory checks tend to ensure breaks are pretty good here. Any driver even remotely familiar with the handling characteristics of his car ought to know something is up instantly.
Can we all agree that we are talking about a BRAKE system here, and not a BREAK system? A brake system is something (in this case) designed to inhibit or limit movement of a vehicle. A break system would be…well. hell, I don’t know, but it sure isn’t what we’re talking about.
Anyways.
Individual use of the parking brake system in an automatic transmission car is spotty at best. My wife drives an automatic, and always applies her parking brake BEFORE putting the car in Park and removing her foot from the brake pedal. IMHO, the only way to do it. As someone said earlier, this takes the weight of the vehicle (if on an incline) off of the parking pawl, which is a relatively small piece of metal in the transmission. My Mom has never used a parking brake in her life, wouldn’t know what one is if you asked her. Me, I drive a stick, so kinda different, but I always use the parking brake.
And, yes, if your parking brake is adjusted correctly, you wouldn’t be ABLE to drive away with it engaged. In other words, you should need no warning system, a properly adjusted p-brake is it’s own warning system.
Definitly not a true statement. I’ve worked for two of the major suppliers of braking systems and you would be laughed out of a meeting for even suggesting that the parking brake be used in an emergency situtation. Hell, you could even be fired for sending out emails that referred to the parking brake as an emergency brake. Definitly not designed to stop the car in an emergency situation even though in may in fact be able to do so. Braking systems are one of the most highly tested and regulated systems on the car; your life depends upon them working consitantly and reliably everytime. A manufacturer would get thier ass sued pretty quickly for advertising them as emergency brakes and then have one fail when an idiot tried to use them as such.
Automotive engineers fuss over costs down to the penny. If a system costs $1 more per vehicle, and they make 75,000 vehicles per year, that’s enough money to pay someone’s salary (including benefits such as health insurance).
You’re suggesting a mechanical interlink between the gear selector and the parking brake. Knowing the forces involved in operating a handbrake, the link would have to be robustly designed and include friction-reducing bearings along with perhaps some kinematic mods to the gear selector; I can guarantee that this solution would be far more costly than an electrical switch and an indicator bulb.
And yet idiot-proofing is exactly what you are recommending. You want a solution that absolves the driver of any need to examine the instrument panel for relevant information regarding vehicle status. Even if you take away the parking brake indicator, there are still lots of reasons to check the warning light cluster:
I’ll confess I’ve forgotten to release the parking brake before, but it was immediately obvious - because my parking brake works well. If you don’t notice, then the parking brake on your car is maladjusted and incapable of providing the needed brake effort. This suggests that you not only neglect the information in front of you, but the general mechanical upkeep of your vehicle as well.
You may be right; this speaks to the inadequate level of attentiveness of a “regular” driver in this country. As described above, there are many warning lights that provide important information to the driver, and eliminating one of them won’t obviate the need to check the dashboard on a regular basis.
You would replace the simple warning light circuit with a mechanical gear selector interlink; cost and complexity would go up, not down.
While I can’t fault your wife’s method, I have to admit that I rarely use my parking brake. I live on an almost flat street, I park at work on flat spot.
Now if I go somewhere where and I park on an incline I will apply the brake AND crank the wheels to the curb (comes from growing up on a steep hill.)
Should I use the PB all the time? Probably but I have saved enough time to type this post.
Actually on some cars you can drive the car with the PB engaged.
[funny story] I was teaching in Vancouver BC. Technician came to class and told me this story. the day before they had gotten an S40 Volvo towed in with 2 complaints.
Car was way down on power, would barely move.
Car had 2 flat rear tires.
It seems the customer (of the clueless variety) left the parking brake on and drove away. The Volvo being front wheel drive proceeded to drag the rear wheels and wear the tires out.
I didn’t believe him at first, so I went out and got into my school S40 put of the brake and tried. Sure enough you can drag the rear tires with the brake on.[/FS]
This also point out the problem with trying to make something idiot proof, they get inventing better idiots.
the parking brake was in decades past referred to as the emergency brake in the USA.
if you engage it without its locking mechanism (operating its release while applying) the parking brake has and will operate as a brake in an emergency.
One of my favorite Mitch Hedberg quotes: “A lot of times, I’ll drive for like 10 miles with the emergency brake. That doesn’t say a lot for me, but it really doesn’t say a lot for the emergency brake.”
For the record, my state refers to parking brakes as required equipment. They also describe how to use the parking brake in an emergency. Parking brakes are often referred to as emergency in common parlance. They really don’t function well in this auxiliary capacity compared to service brakes, the main vehicle brakes. It would be a simple process to increase the stopping efficiency of extra brakes. It might cost more money. Something along the line of the way trailer brakes lock up on large trucks would provide total braking. When the air in the system has a leak, the brakes operate on spring pressure and lock up. I’d like to see something because lots of folks with older vehicles never attend to brakes until a line rots out and the brakes fail. They should be able to pump up either the front or back, but in an emergency, people don’t always remember this technique or have time.
I do. Really, I have one from my first car (69 Camaro) at home; I’ll check on it tonight, but that may still be too recent because that was still after Ralph Nader came along and started calling the car companies out for saftey related design flaws. Just saying, when you are in the business you get pretty anal about terms like this. Personally, I still like going out on a snow covered parking lot and throwing the emergency brake on and doing soom donuts.
Simple for you to say, but the actuality of accomplishing what you suggest is perhaps not as simple or inexpensive as you imagine.
The automatic parking brake releases I’ve seen use engine vacuum to function. There is a vacuum switch connected to the shift linkage and a vacuum servo connected to the parking brake release lever. It’s a pretty good bet that this is the simplest and least expensive way to do it, and it adds the complexity of two significant parts (which can and do break or wear out) plus the vacuum piping to them.
