Problems

1 The stick diagram of a six-speed RWD MT is shown Figure 2.9b. The tire radius of

the vehicle is R (ft) and the final drive ratio i is 3.25. The numbers of teeth are labeled

in the drawing. Some gear ratios are given as: 1st gear (3.92), 2nd gear (2.76), 3rd

gear (1.91), 4th gear (1.41). The number of teeth of gears N; and N, are 19 and

23 respectively.

a) Determine the equivalent mass moment of inertia to be synchronized in a 1-2

upshift and a 5-4 downshift respectively, in terms of the mass moments of inertia

of the involved parts and the labels for the tooth numbers.

b) A 2-3 upshift is to be made at a vehicle speed of V (mph). Assuming the synchro-

nization time is At and the angular velocity change is uniform during synchro-

nization, determine the friction torque to be generated by the synchronizer

friction cones.

c) Determine the work done by the friction and the angle of rotation of gear N4c in

the process of synchronization for the shift in (b).

d) The synchronizers used in the transmission are the same and the angular velocity

change during synchronization is assumed to be uniform. If the magnitude of the

shift force in a 2-3 upshift, F23, is 10 N, determine the magnitude of the shift

force in a 1-2 upshift, F12. Both shifts are made at the same engine angular veloc-

ity, and within the same synchronization time At.