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Two questions about school buses

  1. Jul 26, 2010 #1
    Hello everyone... after recently taking quite a few trips by bus, I started thinking and came up with these two questions:

    1) Why is the back of the bus bumpier than any other part?

    and 2) Say you had two very large people that had to sit on the bus... Where would it be best for them to sit? In the middle next to each other? On either side, far from the middle?

    Thanks in advance.
     
  2. jcsd
  3. Jul 26, 2010 #2
    1) Is it? I've sat at the front of many a bus and thought it was very bumpy. Are we talking about a front or rear engine? Is the bus full of people or empty?

    2) What do you mean by "best" position to sit? Best for what?
     
  4. Jul 26, 2010 #3
    The first question is very tricky because it depends on many factors especially as i dont know the suspension of the those buses, the weight transfer and other things like Stonebridge sad before. For example some trucks with mechanical suspension the rear suspension is stiff to carry allot of weight so if you sit in the back of some empty truck its very bumpy ride.

    2) Best sitting position from the bus handling point of view is if the fat guys sit in the middle next to each other,because the moment of inertia will be lower that way.
     
  5. Jul 26, 2010 #4
    Thanks for responding you two, you answered my questions. I didn't realize the first question would include so many factors... It was a mini school bus with one teenager on every seat (So about half full).. I sat in the two last rows every time, and it was so bumpy that I would get air on occasion :)

    And about the second one, sorry for not clarifying.. Vlado answered it
     
  6. Jul 26, 2010 #5

    russ_watters

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    Staff: Mentor

    A typical bus is front-engine with the front wheels about 90% of the way forward and the rear wheels 75% of the way back and with twice as many rear wheels as front wheels - meaning they are designed to take twice as much of the weight. This makes the rear wheels carry most of the weight of the cargo and have a much larger variation in load between full and empty.

    Since the suspension must be designed for a fully-loaded bus, it must be pretty stiff, which also makes it too stiff for an empty bus - hence: bouncy.

    A design that would make the front-end bouncy (front or back wheels further back) would also make the bus tough to drive.
     
  7. Jul 27, 2010 #6
    The back of the bus also sticks out past the the wheels, which would exaggerate any up/ down motion.
     
  8. Jul 27, 2010 #7

    sophiecentaur

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    Gold Member

    I always reckon that the best place to sit would be about half way between front and back axles. If either the front axel or back axle hit a bump then your vertical movement will be half. (Yes, the state of the loading and the hardness of the suspension are also relevant but I can't do the sums easily or predict who will be getting on and off.) I think two small bumps will be less objectionable than one big bump.
    Sitting outside the wheelbase will magnify the vertical movement plus it means that your horizontal motion will be more as the bus takes sharp corners. On mountain roads it can be unnerving when the driver actually takes the front of the bus out over the edge on corners because he 'knows' where the wheels are and is keeping them well on the road.
    If you want a really exciting ride, get on the top deck of a double decker, at the very front, when the driver is in a hurry and the traffic is nose to tail! When you are a bit drunk it's almost an out of body experience.
     
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