We all know that the wheels on the bus go round and round, round and round.
But, what about the axles?
What are the front & rear axles on a school bus so close together, compared to a city bus?
What is the advantage?
The weight of the engine has to be carried by the rear wheels on a city bus because the engine is often in the back. Many school buses have the engine in the front.
I’m not sure the wheels are closer together, but the rear wheels are usually closer to the *back *of a city bus.
Note, I didn’t see your examples of a “school” and/or “city” bus. I google-imaged the examples used to formulate my reply.
Generally a shorter wheelbase results in smaller turning radius, but worse high-speed stability and comfort. School bus routes often take them into residential roads where turning radius is important.
Also, most US school buses seem to be front-engine, while city buses are rear-engine. Which I think is one reason why the rear axle on a city bus is much further back. Though I don’t know which is the cause and which is the effect.
School busses up here are seen both ways, front engine (long nose) and rear engine (pusher). The long nose are built on medium truck chassis, Sterling and Navistar being common. The bus builder then puts a body on the chassis. Pushers are built by the bus builder all the way through, the only major components from outside being the engine and driveline. City busses (and highway and tourist or sightseer busses) are all rear engine.
As to the axle placement, pushers have axles set to the rear partly because the heavy bits are there, and partly to utilize floor space a bit better. School busses tend to be modular. School board wants a 56 seat bus, so the builder plops down a nose and a tail and fills in the space with modules of about 6 feet until they get the right number of seats. With a pusher this is easy. Long nose busses with real high capacity 72 seats or more, will usually have a nose and a rear axle spacing set by the chassis builder, which the body people just add in modules both fore and aft to get lots of seats. Some of them can have 30 seat behind the rear axle, and in tight corners the rear end swings out a bunch.
However, for a given capacity, pushers tend to cost rather more then longnose. And since the tail end is pretty much standard across the line, longer busses have longer wheelbases. If you want large capacity with tight turn radius, longnose works. If you want smooth ride and low noise (which most riders of school busses don’t much care about) you go with pusher. There are other, rather minor issues involved. You want front axle weight kept low so you can use single wheels (and at one time you also saved the cost of power steering), and you can use duallys for the rear, and the rear axle position partly determines front axle load. Front engine obviously puts more weight up there, so the axle is set way forward. With most pushers you have the front axle behind the driver (and the front door).
Help any? Any engineering decision like this is a bundle of compromises. We have good, fast and cheap. Pick any two.
GREAT!
Thanks, to one & all. 