Design and Development of Front Air Suspension for Front Engine Bus with Floor at Entry Plus One Step 2012-01-1934

The automotive industry is heading towards introduction of newer and newer technology aimed at providing better comforts and value to the end user. The public/ private transport vehicles in urban/rural areas with FE has wide level of acceptance in South East Asian countries. The acceptance of FE buses is mainly because of the ram air cooling of the engine, lesser maintenance, higher fuel efficiency etc whereas rear engine buses with entry plus one step are deprived of these benefits. Hence, we have designed and developed a new Front Engine Semi -Low Floor bus having floor at E+1 step. The primary design challenge was to meet the uniform floor throughout the length of the vehicle.

This uniqueness will help in easy ingress and egress of the passengers which helps in reducing the turn around rime of the vehicle. Other challenges includes, meeting the customer requirements in terms of application, load and duty cycle for this new design. Commercial Vehicle industry in India finds reliability as one of the most interesting subjects to work on, as it has significant impact on warranty cost (for manufacturer) and on product uptime (for customers), both of which are definitely the key parameters that define the products success.

This paper explains the design and validation challenges faced during the development of front air suspension for front engine bus having floor at E+1. First half of the paper explains the design challenges and their solutions during the design and development of front air suspension for front engine bus having floor at E+1 and second half explains the validation challenge i.e. to optimize the validation method for this design. This has been done by closely co-relating the RLDA and the rig level testing of the front suspension of a typical front engine bus. The RLDA was captured at specified points and these points were derived based on the high stress areas in CAE analysis. The RLDA was then converted into block cycles and the rig level testing is carried out for the braking plus vertical load case. This co-relation activity helps in reducing the validation time.

The future scope of the study includes the extending same exercise for other load cases i.e. cornering plus vertical and vertical load case so that the complete testing time can be optimized.