Question - whats the "pssst" sound made by buses?

[Waffenss]

just curious..whats the "pssst" sound that buses make when they are moving or stopping? been taking buses so long still dunnoe

[Subzro]

Pneumatics? If I'm not wrong, the doors, brakes are air-operated. But I'm not sure of the sound generated while on the move.

 

EDIT: I think the sound while moving is the bypass valve opening due to sufficient air being compressed into the tanks to supply air into the necessary components. The parking brake will emit the sound when engaged too.

Edited July 28, 2010 by Subzro

[Cotrox]

BOV!

[Prodrive7354]

I think is the air operated brake system. Letting go the excess pressure.

[Ysc3]

yup. its the brake system. same as those big lorries/trucks and also containers trailers also.

[Yuan]

Read that air brakes are pretty efficient for buses and heavy vehicles.

[Best_ctzn]

just curious..whats the "pssst" sound that buses make when they are moving or stopping? been taking buses so long still dunnoe

Is it heard on those newer buses? Those buses are designed with adjustable suspension. When on the move, the bus is raised higher. When stop, it will lower itself for passenger to alight, so called stepless. Very hi-tech.

 

[SimonTan]

Turbo diesel...of course has the piss sound lah.

Bus are powerful engine leh.

 

[Mike1234]

There are quite many old buses around...

 

But newer buses like the scanias, Mercs, etc....

 

Generally are much quieter .....

 

[laugh]

[Virus]

Should be the brake sound. If driver press/depress the brake during stopping, some gas will be release from brake cylinder. When during move off, it will pump air into brake cylinder which has a high pitch sound too. When air-cylinder full , the excess air will be release again and the pump will stop.

[Saycheese78]

Confirm brake sound. same sound on Fiat 3 tonner.

[Robo]

they are the airbrakes

 

[Evo07]

its the release of high pressure air from the compressor tank used for pnematic doors and their brakes. saf 3 & 5 tonner also same.

[Yagami85]

last time when i was a kid, my mother will tell me that wan is bus fang pi... so must fasted siam

[Mockngbrd]

Turbo la... ppssst ppssst....

i think got boost meter also

[Hiphiphoray]

Its the air-operated braking system.

 

Should be the same like those SAF 3-tonnes i've driven before in NS.

 

Have to warm-up and let the air charge up first. Orelse if just start engine and go, you wont have any brake.

 

The system needs to charge up continueously, everytime it chargers to a certain level, you will hear a pss sound.

 

Hence u will hear the pan pui sound quite frequently.

[Keira]

Air brake sound. The air release sound will came off after the driver release the brake pedal or pull up the handbrake.

[Bankai87]

Its the air-operated braking system.

 

Should be the same like those SAF 3-tonnes i've driven before in NS.

 

Have to warm-up and let the air charge up first. Orelse if just start engine and go, you wont have any brake.

 

The system needs to charge up continueously, everytime it chargers to a certain level, you will hear a pss sound.

 

Hence u will hear the pan pui sound quite frequently.

 

not true. the air pressure is generatated to release the brake,

i think some air brakes work like this

 

no air, brakes is ON. u need the air pressure to release the brakes

 

hence if somebody cut the air hose, the brakes will be permanently ON, and not like in the movies cut the air hose equal no braking

 

is a safety feature. so if u just start e engine and try to move off u cant.... cuz air no air pressure to release the brake, u will be stuck

Edited July 29, 2010 by Bankai87