Mechanism Trains

Mechanisms arranged in series or parallel combinations so that the driven member of one mechanism is the driver for another mechanism are called mechanism trains. With certain exceptions, to be explored, the analysis of such trains can proceed in serial fashion by using the methods developed in the previous chapters.

Parallel-Axis Gear Trains

Examples of Gear Trains

In speaking of gear trains it is often convenient to describe one having only one gear on each axis as a simple gear train. A compound gear train then is one that has two or more gears on one or more axes, like the train in Fig. 10.1.

Figure 10.2 shows an example of a compound gear train. It shows a transmission for a small- or medium-sized truck, which has four speeds forward and one in reverse. The gear train shown in Fig. 10.3 is composed of bevel, helical, and spur gears. The helical gears are crossed, and so their direction of rotation depends upon their hand. A reverted gear train, like the one shown in Fig. 10.4, is one in which the first and last gears have collinear axes of rotation. This arrangement produces compactness and is used in such applications as speed reducers, clocks (to connect the hour hand to the minute hand), and machine tools. As an exercise, it is suggested that you seek out a suitable set of