|WikiProject Trains / Locomotives||(Rated Start-class, Mid-importance)|
The crosshead isn't an exclusively diesel thing. In fact, it's very old, and a part of steam engine technology for a long time. Most stationary steam engines and steam locomotives have them.
I'm going to be writing an update for this sometime soon, I think. --Morven 10:23, 1 Sep 2003 (UTC)
- Finally got around to that rewrite. I have removed some of the diesel engine info because I think it's not about crossheads but about big diesel engines. If you disagree, please feel free to re-add it. —Morven 12:29, 10 Feb 2004 (UTC)
Direction of force
I know of no case where the statement in the first paragraph of the Usage section "On smaller engines the connecting rod links the piston and the crank directly, but this transmits transverse forces to the piston, since the crankpin (and thus the direction the force is applied) moves from side to side with the rotary motion of the crank" is true. The smaller engines described have oscillating cylinders which adapt to the the variable direction of force. Very large oscillating cylinders were employed in the middle of the 19th century on ships, usually paddle steamers, in order to save space. Re. "Watt's famous linkage (i.e. parallel motion), it was not quite accurate in its movement as the piston rod end moved in a very shallow figure 8. At low speeds with very low steam pressure and hemp packing, this was no big issue, but already in Trevithick's engine of 1798 working a 40 psi pressure he fitted a crosshead and guides. One final point: it may be useful to modify the title of this article to make it clear that the crosshead and guide(s) are inter-dependent components of one unit.--John of Paris (talk) 09:34, 9 December 2007 (UTC)