Dean 0. J. Ferguson


Every student now enrolled in the College of Engineering looks forward to a successful career—to a life of expanding experiences, of growing interests, of increasing values. He expects gradually to become a more important man to his organization, and to his community. He presumes that his worth will be recognized by his fellows, and that he will be invited to occupy higher places and to do greater deeds. He sees the time when his efforts will be required for the rendering of the great services which an advancing civilization expects of the engineer. In short, he expects to have continual advancement in the field of responsibilities.

Upon what is he basing his expectations? Are they more than rosy hopes? What will cause him to advance?

In the study of electric railways, a common problem is that of selecting the proper motors for a given car.

The elements of the solution involve a study of the car weights, the load to be transported, the gear ratio used, the profile of the road, the speeds to be attained and the characteristic curves of the motors available.

When the calculation is begun, we see that for a given permissible current in the motor, a certain torque will be developed, which produces a forward pull upon the car.

If this forward pull or tractive effort, as we call it, is sufficient, the car starts, even on an up-grade. The tractive effort will overcome all resistances to motion—rolling friction, atmospheric resistance, gear losses, grade lift, track curvature, friction of bearings and motor brushes, and it will accelerate the car.

How fast will the car run? How long will it continue to speed up?

That all depends upon how much tractive effort is left above the requirements for overcoming the train resistance losses.

The motor must produce an excess of torque for acceleration purposes.

What is true of the motor car is true of the human machine. The friction of the daily grinds must be met and overcome. The variations in the hills to climb must be recognized and their demands supplied. The losses from indirection of effort must not take all of the energy. There must be developed an excess of tractive effort available for the acceleration of the human train.

Some day not far in the future, when you are nursing a discontented, grumpy feeling that the world is losing something of inestimable value in "keeping you down," spend a few moments in deep, honest thought trying to answer the questions, "Have I any acceleration torque? How much more have I really been doing than I have been paid for in my weekly envelope?"