The performance of a truck can be evaluated in detail by examining its performance curves. Graph 4 shows the relation of vehicle speed at each gear of the transmission to engine speed, vehicle speed to tractive effort, and vehicle speed to running resistance.
As explained in previous chapters, the running performance of a vehicle is determined not solely by engine power, but also by the gear ratio of the transmission, rear axle ratio, G.V.W., and tire size. The formulae for vehicle speed, tractive effort, and running resistance, introduced in Chapter 4, are represented as the vehicle performance curves. If any of the set of factors involved Ñü transmission gear ratio, rear axle ratio, tire size Ñü are changed, the shape of the performance curves will necessarily change. Each set of these specifications has its unique performance curves. Since it may at first be difficult to understand the three curves in one graph, each will be explained separately. |
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Graph 4 VEHICLE PERFORMANCE CURVES
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