Based on the requirement of the transports, buses can be classified as
4.Double Decker Buses and
There are two types of Frame concepts broadly used in the Bus manufacturing Industries.
1.Ladder Frame design and
2.Tubular Space frame design.
In the case of Ladder frame design the passenger cell super structure and the independent chassis are bolted together. The body and chassis which is ready for use are fully equipped.
In the case of Tubular space frame, the passenger cell and chassis together form an inseparable self supporting unit that has to be equipped with add-on parts.
Ladder Frame Design:
This particular design is widely used all over the world. In principle the Ladder Frame chassis is related to the commercial vehicle frame for trucks. It combines very stable side rails and cross rails to form a supporting sub frame. It has high degree of torsional stiffness can bear the entire vehicle weight. The Axles and drive units are integrated with this chassis which makes the rest of the body construction easier. In this type design the passenger cell need not have to be as sturdy as it otherwise would be as it is not fully self-supporting.
(LEGEND: A.Driver’s work place equipment , B.Ladder Frame side rail, C.Driven rear axle , D.Rear Engine)
Tubular Space Frame Design:
In this concept, the support points for axles and Engine and the passenger cell integrates in to a self supporting ribbed structure (integral design). This particular design is very complicated and very expensive to manufacture but having the advantage of high deformation stability with low weight-age. If any modifications or repairs to be carried out on the body or super structure the same can not be done easily. This would be a severe disadvantage.
However modern type of coaches and trailers are usually built on space frame structure so that the greater dimension passenger space or goods space can be achieved apart from greater safety and light weight construction.
Self supporting ladder frame chassis are among the most widespread bus chassis worldwide due to its light and flexible combination with superstructure of all types. Buses with ladder frames are easy to repair and there is flexibility in choosing or designing the body or super structure and because of that economical operation is possible even under rough operating conditions.