Advance lever
The advance lever is part of the external gate control of a steam locomotive, the most famous of which is the Heusinger control .
Application and purpose
The advance lever transmits the movement of the cross head to the control rod via the handlebar . This transmission is directly influenced by the position of the slide pushrod. You can see in the photo the double-sided forked design and the triple bearing, whereby the fork on the push rod is larger than on the handlebar. It can also be seen that the advance lever is not forked in the area of the crosshead guide. This causes the offset between the piston rod and slide rod guide. The advance lever is one of the areas of control with greater movement and must therefore be intensively lubricated.
On the sketch you can clearly see the tripartite division of the advance lever. When the control is set to 0 , i.e. the slide pushrod is horizontal, no oscillating movements are transmitted to the advance lever. Since only the movement of the cross head is transmitted to the slide pushrod via the pivot point at the advance lever. The lever ratio is such that the crosshead movement is always greater than the slide movement. In addition, the crosshead and slide run in opposite directions on this sketch. In the newer steam locomotives, the pivot point is in the slide rod outside the bearing for the slide rod, as can be seen in the photo, so that both slide rods are aligned. If the control is now designed for filling, i.e. in the position as shown in the sketch, the movement of the rocker is also transferred to the advance lever. Since the counter crank transmits the movement to the rocker by 90 ° in advance, it is achieved that the control rod remains in the end positions, and thus when the cylinder is filled with steam, and is only withdrawn from the end position after the cross head has moved backwards.
literature
- Edmund Heusinger von Waldegg: Special Railway Technology, Third Volume, Der Lokomotivbau , Leipzig 1882
