Two different things, and two different uses. Using a parking brake during an emergency is like dragging your foot … 
If you keep going like this I will be forced to demonstrate……
At low speed, David - at low speed…
Frank
xj6 85 Sov Europe (UK/NZ)
Sorry, David, but “emergency brake” is just the very misleading English term - no idea who created it, but the emergency brake on a car is nothing like the emergency brake on a train.
That being said, our regulations mirror the emergency aspect in the requirement that the function needs to be independent of the operating brakes. Other than that the emergency brake in German is correctly termed " Feststellbremse" (translating into something like"locking brake") and indicating that the emergency brake, different from the operating brakes, is fixable in order to lock the brakes while the car is stationary and no one is there to push the pedal or pull the lever.
As for sheer braking power: our regulations require that the operation brake is capable to reduce speed at 5 m/s² on average; the emergency brake only needs to be capable to hold the car stationary on the steepest incline the car is capable to do + be cabable to brake the car at 1.5 m/s² on average.
And, as a data point: my recent test yielded 268/273 daN on the rear axle for the operation brake and 135/126 daN for the hand brake.
And - to find back to the OP’s question: with the brightness of the SII warning light cluster a handbrake operation like the one described for the XJS seems prohibitive for our cars - I’d never ever remember the hand brake is pulled if the lever is retracted …
Enjoy the Easter holidays!
Jochen
75 XJ6L 4.2 auto (UK spec)
Your main rear brakes tested much stronger and the handbrake much weaker than mine. The values from those brake dynos are not really comparable.
When I drove with the handbrake applied it felt really sluggish and I hadn’t pulled it very strongly. I doubt it’s stronger than the engine though.
It’s definitely not.
Same with my 2006 Range Rover…
My 1990 Mercedes though won’t bulge, but that’s Deutsche Technik!
Jochen - your point about the emergency brake being separate from the operational brake must be old rules as I doubt it is the case any longer. With my 2007 Range Rover Sport when you apply the emergency brake it activates the disk brakes on all four wheels (the same brakes when you apply the foot pedal) to bring the vehicle to a stop.
When stopped, if you apply the handbrake (the same lever as the emergency brake) it only activates the rear handbrake drums built as part of the rear disks - so the handbrake only has to be able to hold the car.
How do I do quotes on this forum?
Garry
Garry,
sorry, but the regulations are current. It was - and is - correct to use the same braking surface - either drum or disc, but they need to be independent. On electric brakes this is achieved by an electric motor that moves the rear (or all) brake cylinders via a twin worm gear. Due to the high gearing of the worm gear it is basically impossible to turn the e-mot backwards and hence the electric brake remains locked even without current on the motor.
The crucial information is that the electric brake does not use the same hydraulic system to move the brake calipers as the operation brake.
At least, that is what I’ve been told;-)
Best wishes and happy Easter
Jochen
75 XJ6L 4.2 auto (UK spec)
P.S.: You can quote by either marking statements and copying them into your post or by using the quotation mark icon in the header of the posting frame.
7 clicks hold it. 12 to be safe, during the picture. Steepest hill I could find for now. In neutral.
You can hear me pull the handle and it’s an even road (closed course naturally), in D/top. I think that is pretty good enough if the mains fail.
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Ok - if that is the case how are new LandRovers and other makes allowed to be sold in your country and I guess the EU. As I indicated when the emergency brake is activated in my RRS all the hydraulic brakes (the same as used in normal braking) are applied - the force being dictated by the speed of the car. This is done via the computers that control the ABS, Hill Decent, Stability Control and Traction Control systems - so is not independent. There is not direct electrical connection to the individual brakes. The parking brake just applies the drum brake built into the rear disk brakes.
Thanks for the tip on quotes.
Garry
Indeed, David - the handbrake should really be pulled reasonably hard on when parking. Giving adequate ‘warning’ that it is ‘on’ by car being more than just ‘sluggish’ - I have fallen into the same trap more than I like…
Frank
xj6 85 Sov Europe (UK/NZ) `
"The text you shared appears to be in German. Here’s the English translation:
- Motor vehicles must have two independent braking systems or a braking system with two independent operating devices, each of which can function even if the other fails. The independent operating devices must act on separate braking surfaces through separate transmission means, which may, however, be located in or on the same brake drum.
- If more than two wheels can be braked, common braking surfaces and (wholly or partly) common mechanical transmission devices may be used; however, these must be constructed in such a way that in the event of a part failure, at least two wheels that are not on the same side can still be braked. All braking surfaces must act on parts that are necessarily connected to the wheels and cannot be disengaged. A portion of the braking surfaces must act directly on the wheels or on components that are connected to the wheels without the interposition of chains or transmission parts. “This does not apply if the transmission parts (not chains) are designed in such a way that their failure is not to be expected and there is a separate braking surface for each relevant wheel. The brakes must be easily adjustable or have an automatic adjustment device.”
I hope that helps! Let me know if you have any other questions."
Beautiful, David - thanks!
Malapropos; in my younger days, waaay back in time, I was present at a testing station where a heavy truck was tested. It had a propeller shaft parking brake, with a warning label clearly shown on the dash; ‘do not apply while the vehicle is in motion’.
The inspector, knowing better, did just that - and the very efficient parking brake tore the shaft from the diff. The truck driver was not best pleased - but I learned a lot of new words of insult…
So some procedural nous never comes amiss regardless of regulations…
Frank
xj6 85 Sov Europe (UK/NZ)
I also tried that and the engine has no trouble overcoming the handbrake, does not reach stall speed as it begins to move. I thought it might be weaker.