COMPARISON OF METHODS OF SELECTING GEAR RATIOS OF AUTOMOBILE TRANSMISSION

Document Type : Original Article

Authors

1 Col. Dr., Lecturer s in the Department of Motor Vehicles, Militry Technic-al College, Cairo, Egypt.

2 Lt. Col. Dr., Lecturer s in the Department of Motor Vehicles, Militry Technic-al College, Cairo, Egypt.

Abstract

Inspite the fact that conventional gear boxes of automobiles have several -disadvantages, they can be made more efficient if the number of gear ratios and their selection are properly chosen. Inereasing the number of speeds improves the vehicle's dynamic performance which is expected to be optimal with steplesscontinuously variable speed drive. However, for a fixed number of speeds, selection of individual gear ratios plays an important role in improving the vehicle's dynamic performance. Selection can be done according to various mathematical progressions such as: arithmatic, harmonic, geometric with constant and increasing roots. The goal of this work is to compare these commonly used methods. Comparison is based on calculating the wasted energy represented by the difference between areas under the curves of discret and continuous power transmission. The wasted energy corresponding to each progression was calculated by a special computer Fortran program considering the technical data of a Jeep car as a real example.

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