Questions about S'pore buses? Post them here! (Part V)
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Why was 1921L deregistered?
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Originally posted by TIB537B:
i believe the door system works in tandem and cannot open half the door. Only in cases where one of the door's hydraulic fails then the BC can actually open one door.
dont think bus doors will actually employ hydraulic systems to keep the doors in place during opening/closing.. unless there are obvious signs to show that the pivot has such systems... if hydraulics are really used, commuters would be 'crushed' if they happen to kena kiap by the doors. the most would be the basic mechanical system coupled with pneumatics [act as some form of seal effect]... from the sound of air hissing during the opening/closing of doors in some models. esp LO3X, VO3X, SMRT O405.
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Originally posted by collinnxk88:
dont think bus doors will actually employ hydraulic systems to keep the doors in place during opening/closing.. unless there are obvious signs to show that the pivot has such systems... if hydraulics are really used, commuters would be 'crushed' if they happen to kena kiap by the doors. the most would be the basic mechanical system coupled with pneumatics [act as some form of seal effect]... from the sound of air hissing during the opening/closing of doors in some models. esp LO3X, VO3X, SMRT O405.
paiseh....i don't really know what's it called but i know it's something with pipes and stuffs. lol
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Originally posted by ^tamago^:
no.
Back then yes, now no. -
Originally posted by ^tamago^:
Mealbreaks can occur at either T1 or T2 (non-looping) as long as there are places for BC's to eat. Preference is given to relief points with canteens inside the interchange as it is more likely not to have stipulated minimum mealbreak duration.
thanks
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Originally posted by TIB537B:
paiseh....i don't really know what's it called but i know it's something with pipes and stuffs. lol
pnuematics = use of pressurized air to affect mechanical motion.
compared to hydraulics, compressed air does not cause that much damage as compressed air absorbs shock better, whereas hydraulic fluid do not absorb the shock; instead it transmits mechanical power to the fluid and then turns back into mechanical power at the other end.
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Originally posted by collinnxk88:
pnuematics = use of pressurized air to affect mechanical motion.
compared to hydraulics, compressed air does not cause that much damage as compressed air absorbs shock better, whereas hydraulic fluid do not absorb the shock; instead it transmits mechanical power to the fluid and then turns back into mechanical power at the other end.
oh. so i got confused with those two terms. my bad
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Originally posted by SBS7382C:
Why was 1921L deregistered?
Burnt on 506.
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Originally posted by SBS7484S:
hi !
may i know what is the of ' suyou ' or smtg lyk dat ?
sounds like pump diesel? -
Originally posted by SBS7484S:
hi !
may i know what is the of ' suyou ' or smtg lyk dat ?
Preventive maintanence -
Originally posted by Oceane:
Back then yes, now no.
thanks for the info
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Originally posted by SBS7382C:
canteens are open for public 2 eat also rite? cos if not then tuas can close shop liao...
Got business, dont want earn?
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Originally posted by TIB537B:
i believe the door system works in tandem and cannot open half the door. Only in cases where one of the door's hydraulic fails then the BC can actually open one door.
Major models in the SMRT fleet can do so (built-in or not disabled). For Mercedes vehicles, there is a button on the dashboard beside the switch for 'hazard light on during door opening' function. Upon pressing this button, the valve system will only operate to open the left (forward) leaf of the door; the rearward leaf will remain closed.
Both of the leaves of the rear door share a single valve system, so the exit doors cannot open one-leaf only. However, some O405 or older door systems have problem closing together or in a synchronous manner, this would be due to either not enough compressed air or a fault within the valve.
The same could be done in the OC500LE. This half-door function is not only used for spoilt ez-link card readers; during rush hour at Little India (or some other festivities), this function is also used to prevent fare-evaders (althought they can board by the rear door(s)).
Doors are normally kept closed purely by the pressure in the valve/compressor. There are no additional door locking devices, neither mechanical or electrical.
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Originally posted by TIB1224Y:
Doors are normally kept closed purely by the pressure in the valve/compressor. There are no additional door locking devices, neither mechanical or electrical.
Then i read about the plug doors using the difference in air pressure to keep the door closed or something...? -
Originally posted by ^tamago^:
thanks for the info
From what i know 858 does jump bus, not sure about the intra-town services. -
Originally posted by TIB537B:
Then i read about the plug doors using the difference in air pressure to keep the door closed or something...?
yesplug doors close slower
i.e. lesser air pressure
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Originally posted by AEW5001:
yesplug doors close slower
i.e. lesser air pressure
I guess he questions whether the plug doors are held in close position by air pressure externally, and not that the doors operate using air pressure.
By right for a vehicle moving at less than 60 km/h, the air pressure holding against the door (air travelling across the door surface vs the air inside the cabin) will not be enough to hold the doors in i.e. prevent doors opening. Pressure in the valve system would suffice. Same goes to conventional leaf doors.
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Originally posted by TIB1224Y:
I guess he questions whether the plug doors are held in close position by air pressure externally, and not that the doors operate using air pressure.
By right for a vehicle moving at less than 60 km/h, the air pressure holding against the door (air travelling across the door surface vs the air inside the cabin) will not be enough to hold the doors in i.e. prevent doors opening. Pressure in the valve system would suffice. Same goes to conventional leaf doors.
unless there r hidden magnetic strips that hold e door together
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Originally posted by TIB1224Y:
Doors are normally kept closed purely by the pressure in the valve/compressor. There are no additional door locking devices, neither mechanical or electrical.
indeed. but for the older SBST models esp NAC/CAC ones, they purely rely on mechanical components? [perhaps besides having compressed air to help in the opening/closing motion only] alot of them the doors seem to vibrate alot when the bus is in fast motion.
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Erm juz asking if
Last Time TIBS (Now SMRT) , did they brought a demo bus that use hydrogen gas/liquid? to run?
If have, wad is the model? -
Originally posted by Bus&Soccer l0v3r (VO3x 1):
Erm juz asking if
Last Time TIBS (Now SMRT) , did they brought a demo bus that use hydrogen gas/liquid? to run?
If have, wad is the model?
nope...
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Originally posted by ^tamago^:
nope...
ok , so that was be a lie from my DM....
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Why the dennis tridents has door closing sign in chinese?
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Originally posted by fireice rox:
Why the dennis tridents has door closing sign in chinese?
Cos they were diverted orders from Hong Kong, and had Hong Kong specs.
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Originally posted by collinnxk88:
indeed. but for the older SBST models esp NAC/CAC ones, they purely rely on mechanical components? [perhaps besides having compressed air to help in the opening/closing motion only] alot of them the doors seem to vibrate alot when the bus is in fast motion.
For what I observed of the internal components moving indicated that the cylinders/valves operate the door, thereafter there are no more mechanisms involved. The cylinders have pressure inside (just like hydraulics) to keep the cylinder in closed position. Should there be any movement, that would likely be a leak in the cylinder or losing of pressure inside the valve system.
That also explains two things; when a test switch is pressed on the bus (seemingly only accessible when under inspection/repair), the compressed air in the system would all be let out (and yes, even a O405G Habit can kneel) and the doors will swing out, as the air inside is released and there is no more pressure to hold the cylinders in closed position. Solving this would require some revving of the engine and charging of the compressed air. Secondly would be that doors cannot operate when the compressed air inside the system is not sufficient/nil. The doors can open, but cannot close. Insufficient/nil compressed air also affect suspension systems, as the bus would likely tilt to one side, this applies on O405 and older systems particularly, as newer systems have better monitoring (but still can be override/fault developed).