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Question for PSV drivers
Sider:
Believe me, there was no time for warnings. All of a sudden I heard this almighty bang, and all I could do was close my eyes and pray :D
More than a good driver, I'd say it was a good amount of sheer luck.
ian_s:
or the driver wasnt really driving. hence why the 'passenger' has scarperd
mmgemini:
--- Quote from: "BrumLee" ---
--- Quote from: "Sider" ---There is one but with your 1st theory. Air brakes are vacuum operated. If for any reason the tanks or lines blow up, the brakes go into emergency mode, slowly stopping the vehicle, and once stopped, applying the parking brakes. The air in the tanks does not apply the brakes, it keeps the brakes from working, until you force the air out with the brake pedal.
--- End quote ---
Not sure where you got your information about how air braking systems work :shock:
I could bore you with how air brake systems work, but roughly the handbrake works on a spring in the brake chamber. When the air is released from the chamber through a quick release valve the spring takes over and forces the brake on. If there was air failure then the spring brake would have come on automatically.
You can have a foot valve failure, but I've never know full loss of footbrake (although drivers tell you there was when they've hit something) Air brakes work on pressure (8 to 12 bar) and not a vacuum. Foot valves have dual circuit porting, so if one cicuit fails you still get brakes but increased pedal travel. If all else fails pull the handbrake lever on as this works the spring system.
Fat spring is park brake, next chamber is air chamber to force park spring for park brake off and final chamber is for foot brake application
This bus had just been mot'd so I suspect it was down to speed and driver panicing
--- End quote ---
The foot brake works in exactly the same way as the handbrake.
There is a [well was in my time] 3/4 AF bolt head theat up screwed in or out [again I can'rt remember] to release the brakes to allow the disabled vehicle to be towed.
How many ports are on the footbrake valve :roll:
BrumLee:
--- Quote from: "mmgemini" ---The foot brake works in exactly the same way as the handbrake.
There is a [well was in my time] 3/4 AF bolt head theat up screwed in or out [again I can'rt remember] to release the brakes to allow the disabled vehicle to be towed.
How many ports are on the footbrake valve :roll:
--- End quote ---
Handbrake and footbrake circuits work completely different :roll: Footbrake works on air pressure (8 to 12 bar max and 6 to 8 bar on trailers) and handbrake (park brake) works on spring pressure when the air is exhausted from the chamber. If the handbrake worked on air pressure and the pressure dropped the vehicle would roll away, very safe indeed :roll: :shock: Wouldn't want to drive any truck or bus that uses your braking system :shock:
As for ports on a foot valve, depends on the make of valve (i.e. Haldex, Wabco, etc..) What significance has ports on the footbrake valve got to do with the handbrake? :?
mmgemini:
--- Quote from: "BrumLee" ---
--- Quote from: "mmgemini" ---The foot brake works in exactly the same way as the handbrake.
There is a [well was in my time] 3/4 AF bolt head theat up screwed in or out [again I can'rt remember] to release the brakes to allow the disabled vehicle to be towed.
How many ports are on the footbrake valve :roll:
--- End quote ---
Handbrake and footbrake circuits work completely different :roll: Footbrake works on air pressure (8 to 12 bar max and 6 to 8 bar on trailers) and handbrake (park brake) works on spring pressure when the air is exhausted from the chamber. If the handbrake worked on air pressure and the pressure dropped the vehicle would roll away, very safe indeed :roll: :shock: Wouldn't want to drive any truck or bus that uses your braking system :shock:
As for ports on a foot valve, depends on the make of valve (i.e. Haldex, Wabco, etc..) What significance has ports on the footbrake valve got to do with the handbrake? :?
--- End quote ---
Sorry Lee you're reading me wrong or I'm not explaining correctly.
The way I understand it ALL air brake systems work the same.
The air pulls the spring off and no air stops the vehicle.
A much better system than any car or Land Rover
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