ABSTRACT
Link mechanisms are rarely used now for transmission of rotary motion, however in the past all steam engine locomotives were provided with a link mechanism to transfer torque from the driving wheel to other wheels. Figure 9.1 presents a ve-wheel arrangement of a propelling mechanism of a powerful locomotive. Here middle wheel 1 is driven by steam engine 2 by means of a crank mechanism that includes slider 3, guide 4, and connecting rod 5. From wheel 1 the rotational motion is transmitted to the other four wheels by means of a bar made (for technological reasons) of two pieces 6 and 7 connected by hinge 8. This mechanism has dead points both in the crank mechanism and in the wheels-and-bar mechanism. As far as the locomotives are considered, these negative features are inactive for two reasons:
• There are two such propelling mechanisms, one on each side of the locomotive, and they are phase-shifted, so that when one crank mechanism is in its dead point, the other one is about in the middle of the stroke. This enables the locomotive to start motion from any position of the mechanisms.
