Investigation of braking system (efficiency) of converted Mercedes Benz buses (207)
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Date
2012-06-22
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Abstract
Road accidents as a major cause of misery, morbidity and mortality in Africa particularly in Ghana have been of considerable concern to the general public. More worrying is the accidents involving Benz 207 buses. This is attributed to the fact that the Mercedes Benz 207 bus is originally made as a van for conveying goods. When brought into the country it is converted to passengers’ bus by artisans in ‘fitting workshops’ in and around the country. This conversion increases the gross weight, affects the suspension and the stability of the vehicle. Also, a serious effect is that the performance of the braking system may be affected. This research highlights various modifications done to the Mercedes-Benz 207 van at the Suame magazine. The braking efficiency of the converted Mercedes Benz 207 bus as against that of the original and compared to the safest degree of efficiency required for these buses.
It was observed that the alteration of suspension (leaf spring) and chassis frame, brake adjustments, body and spraying works, construction of seats and fixing of glass were the major modifications that are done on the buses. Average ground height of the bus was increased and was found to be between 60.9 cm to 76.2 cm (2 to 2.5 feet) due to suspension alteration.
The gross weight of the original bus was increased by an average of 20% after conversion. The results show that 60% of the buses have no parking brakes and between 20% were having defective or no rear brakes. Also, 70% of the converted buses have their braking efficiencies decreased whilst 20% had increased braking efficiency with the rest remaining unaffected.
It was again observed that 60% of the original buses tested fell within the standard value required for the front imbalance and 50% of the converted buses exceeded the maximum value for the front imbalance.
It is recommended among others that the Driver, Vehicle and Licensing Authority (DVLA) should stop licensing the converted Mercedes Benz 207 buses or at best license those that are tested to have the required braking efficiency. Any future research should consider analyzing a bigger sample size for more information to be obtained on 207 buses regarding their braking system and failures.
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A Thesis submitted to the Department of Mechanical Engineering, Kwame Nkrumah University of Science and Technology in partial fulfillment of the requirements for the degree of Master of Science in Mechanical Engineering, May-2012