Chat & Social > The Bar - General Chat
Question for PSV drivers
Bob696:
Bus wasn't stolen I am afraid. Also there is no indication that the passenger jumped from the moving bus.
Aparently only the center 2 properties will have to be demolished now. Should be interesting as it will turn the 2 outer properties from end terraces into detached :P
Drift:
--- Quote from: "Sider" ---
--- Quote from: "Drift" ---Having been a bus driver for 18 years before moving to a nice cumffy office job in our area head office, I cant think of anything other than the complete failing of the air system (brakes) that would warrant me to jump from a bus at 20 MPH :?
The guy who jumped off must have been standing next to the driver when it happened, otherwise he wouldn't have made it off before the crash.
Which leads me to another question.
If as I mentioned the air system could have possibly gave up causing no brakes then the doors are air operated on 80% of buses and there would /should have been enough air in the system to keep these shut (emergency measure, to stop kiddies falling out if doors fail)
They would have had to force the doors open.
t doesn't take much, but at 20MPH heading to a house it would be difficult.
Leads me to believe the bus was stolen :wink: and they had the doors open and weren't used to the vehicle and straight forward crashed it.
Most likley wrong but a good theory :lol:
Ste
--- End quote ---
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 ---
Now there a point :wink:
Ive know on slightly older buses you can empty the air out of he system with as few as eight full brake depresions. (Its happened to me :shock: )
Only other two options are brake fade or just plain old bad driving, which looks the likely cause :?
Ste
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
Sider:
Ok, slight misconception on my behalf. I have to say that the way you explained it is much more understandable (and probably correct) than the way my fitter explained it to me.
However, when one of my air tanks blew out, my lorry came to a stop, with reasonable degree of control. It was a tad sudden, but I didn't leave any screech marks, although I was doing 56 mph at the time. Scary, since I was in lane 2 (3 if you count the slip road) of the M25, around junction 15
BrumLee:
The way it happened to you would be the case in most experiences, but the warning devices (either light, buzzer or gauge) would let you know there was loss of air. The compressor would try and maintain pressure, but if loss is greater than output the spring brakes would come on gradually. If you had applied the secondary or park brake the brakes would have locked on quicker, so you did the correct way of a controlled stop 8) :wink: (count that as a credit to a good driver).
Taking this into account its difficult to understand why a driver would jump from a cab fearing the vehicle was in danger of not stopping. The only reason it wouldn't stop is if there is a driver error, or worse, no driver :shock:
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version