Hand brake is this type legal?

[ericmark]

It has been many years since I have worked as a mechanic and when I did there were three brakes.

Main
Secondary
Parking

Often the secondary and parking brakes were combined although with some wagons and automatic cars one could only apply the parking brake when stationary so in that case they were separate.

However there was always a secondary brake where should the main brake fail one had a lesser system still able to stop the vehicle.

However my father-in-law has a new car with an electric parking brake which by design can't be applied while the vehicle is in motion. I can see no secondary brake. In my day this would be against the law. Has the law changed?

 

[timtheenchanter]

what car is it? I've not driven loads, but the scenic, and Saab that I have you could apply the electric brake whislt moving (although you got lots of beeping and flashing lights whilst doing so)

the other question I did have, and had answered, is how do you release such a break in a breakdown situation (on the scenic the brake activates automatically when the engine is off), or if the mechanism fails?
The answer, in the case of the scenic is a lever somwhere under the back end that brakes the cable the activates the brake, releasing it, also then requiring expensive main dealer work to repair the damage.

 

[Mursal]

Back in the day you had a single line foot brake, now you have dual line brakes. So this redundancy increases reliability

You cannot safely apply the parking brake while on the move, or you will loose control of the vehicle. The wheels must always turn to keep control, this is why we have ABS (Anti Lock Braking Systems).

Dynamic safety systems now fitted as standard under the ESP (Electronic stability Programme) will brake, steer, accelerate, decelerate, one, two, three, or all four wheels before the driver realises they are loosing control.

 

[ericmark]

The car is a Toyota and although in the 1970s to 1990s we had some old cars on the road with single line brakes in the main all cars and wagons built from 1970's onwards had duel line brakes. So duel line braking was well in use when I worked on cars and wagons so is not a valid point in the removal of a secondary brake.

I will admit to if the air tanks ruptured applying the spring brake it was rather drastic, where a hardy splicer has failed and severed the air pipes causing the spring brake to auto apply it was hair raising to say the least. But it least one did stop even if not how one would like it.

Back in the 1990's we had instances where EMC problems caused the ABS to completely fail and this resulted in Vaxhall cars saying mobile phones should only be used with an external aerial. Yes and all people using the car are really going to switch off their phones.

The idea of having a non electronic brake so even if a 300W armature radio is being used in the car you have some brakes seemed a good idea and the old rules on three brakes seemed good.

I do not believe there is no electronic equipment which could possibly interfere with the brakes is being a little optimistic and in the real world we need a non electronic brake as a back-up.

 

[JohnD]

It has been many years since I have worked as a mechanic and when I did there were three brakes.
Main
Secondary
Parking

Are you talking about cars or some other vehicle?

Can you give me an idea of the time you were working, and give me some examples of the cars that had secondary brakes?

 

[ericmark]

1998 was last time as an auto electrician and I worked on wagons and cars although with wagons often they were all separate with cars often the secondary and parking brake was combined the only thing one worried about was the percentage braking effort which was around 75% for main, 25% secondary and 15% parking but they were still the three figures and although you could with an automatic car with the parking brake get great figures one was not allowed to use these for secondary brake as one could not engage when in motion.

So even with a parking brake which could lock the wheels if the secondary brake (hand brake) did not hit the 25% it was still a MOT failure.

Oddly the police did not seem to understand the difference between parking and secondary brakes one tried to do me for not applying the hand brake when I had left the vehicle in park. He did back down.

These electric brakes would not have complied in 1998 when I left the auto trade seems odd they do now.

 

[Avocet]

Electric parking brakes are perfectly legal and increasingly common. With most of them, if you want to stop the car in an emergency, using the parking brake, you just actuate the control but hold it there. It will bring the car to rest in as short a distance as possible. Loss of control is highly unlikely, but there are some failure modes where it might be possible. Let's face it, the loss of BOTH halves of a modern dual-circuit hydraulic system simultaneously would be an astonishingly rare event, but even if it WERE to happen, you'd still be able to stop on the electric parking brake. It's pretty stable too. I've tried doing "handbrake turns" with mine and the Electronic Stability Control system just won't let me. It just stops in a straight line.

I think part of the problem is that modern asbestos-free pads are just SO hard, you need enormous clamping forces to push them against the discs. In the type apporval test, you need to be able to stop the fully-loaded car from a set speed in a set distance WITHOUT applying more than 40kg force to the end of the handbrake lever. Increasingly, with the heavier cars like MPVs, this is getting difficult to manage, so the electric systems get round all that.

Personally, I don't like them, but that's because I keep my own cars a long time and do all my own work. It's just an additional level of complexity that I really don't want. Unfortunately, however, I think we'll be seeing more of them in the future!

 

[ericmark]

Thank you for that answer. If as you say the handbrake can be used in motion which my father-in-law said he could not do then it clearly conforms with even the older regulations.

Fuel injection and engine management now means that the vacuum assisted brakes may no longer get the lack of atmosphere required to give them the assistance required. However I suppose that was always the case! With throttle stuck wide open one had quite a problem bringing a vehicle to rest even with ignition cut as there was no vacuum.

So using electric for secondary brake does make sense. I know there was supposed to be a reservoir for the vacuum however other than annual MOT very few tested the one way valve operation. Unlike with wagons where it was done every service.

I do remember some automatic cars my old Morris Mariana for example if low gear was selected would not change down until save to do so as a result would use engine to stop as quick as it could. However the Mini would wreak the engine if second gear was selected (free wheel on first) so it required one to carefully read the owners manual.

This I see as a problem as rarely do we sit and read the manual other than to find how the radio works. So it is unlikely many read the Vauxhall manual where it warned against using any mobile phone without having an external aerial.

When using a company or hire car it is very rare to even have access to the manual even if you wanted to read it. I did find some things found in owners manual rather funny. In a Lada manual it warned not to tow start but to push start and instructed how to use tire as a buffer. I think both towing and pushing are dangerous and the idea of push start was from USA where automatic cars needed around 30 mph to start and would start sudden so very easy to ram the car towing one. However the Lada was manual!

Sometimes I do think we accept things with too little question. My father-in-law had an electric garage door installed inside the garage was the main consumer unit there was no side door and no way to open electric door manually. When I asked how to open if power failed he had no idea. I have can opener at the ready!

 

[Avocet]

No probs.

There's no reason that I can think of, why vacuum should be less on an injected petrol engine though. Obviously, diesels have separate vacuum pumps for their brake servos. There should be at least a couple of full brake applications worth of servo assistance in the servo itself - even if the engine vacuum is lost.

The mobile phone thing is interesting. These days, cars need to pass an "Electromagnetic Compatibility test as part of their type approval. It's exactly to look for that sort of thing. They get checked for the amount of interference they generate AND they get bombarded with various frequencies of interference to see if anything malfunctions. All electrical and electronic devices (not just cars) go through something similar nowadays.

 

[ericmark]

The mobile phone thing I first heard about while working in Suffolk around 1990 being a Radio ham able to use up to 400W without special licence I am very aware of what RF can do. That's why we have to sit an exam.

When I bought a Vauxhall Agila I was surprised to see the ban on using mobile telephones within the body of the car, only permitted with external aerial specially since it did not have ABS brakes. I will assume either it will effect engine management or more likely same was written in all Vaxhall car owners manuals to ensure they were covered for when ABS was fitted.

The EMC problem is as you say not limited to cars. I had an induction hob installed for my mother after carefully ensuring it met EEC EMC standards only to find her pace maker did not comply with EEC standards so it had to be removed and a halogen hob fitted instead. Better that than cut up my mum to fit a compliant pace maker.

All though the ages we have found problems with fail safe systems the Titanic was built by professionals as unsinkable. Moisture and other foreign bodies can make what would seem a fail safe system fail. I remember a wagon driver in the old days of air over hydraulic saying his brakes had failed and the police mechanic saying no way lucky the union insisted on brake fluid analysis and it was found some crystals had dissolved in the fluid which had caused the failure but gone unnoticed once dissolved. We should of course change the brake fluid but how many of us do?

The old Bedford TK and an independent cold brake but in practice I would not want to use the prop-shaft brake and I have seen the problems when a half shaft breaks.

Anyway thank you for putting my mind at rest.

 

[Avocet]

Blimey, 400W is a fair bit of power! In the early '90s, most the cars being built would have been type approved in the 1980s. The automotive EMC Directive hadn't even been written. They were still on some version of the old Radio Frequency Interference Directive, and then, only petrol engine vehicles had to comply! I can remember the furore when the EMC Directive (which was 95/54/EC at the time) was published, and people wandering round ashen-faced wondering how they could ever comply. Now it's just second nature! It's absolutely true, of course, that things can (and do!) fail, as you've said. However, the failures are getting less frequent. The problem is that the cars are now getting so complex that it's becoming almost impossible for the regulations to test for every possible failure mode. I expect that the next 10 years or so, will see a move away from the current "performance-based" regulations (where the regs say you have to not emit more than "x" at this frequency, "y" at that frequency (and so on), whilst not malfunctioning when bombarded with "z" at such-and-such a frequency" - and so on). Instead, they're likely to move towards a more "risk-based" approach, where the regulation is far more vague and talks about imposing a duty on the manufacturer to test for all foreseeable failure modes (and include "reasonably foreseeable" absuse too)! That makes the regulators' jobs much easier, of course, but dumps the responsibility back on the manufacturer. I can see the lawyers doing well out of that!