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Re: PE overhead contact system
Author: OldPoleBurner
Date: 04-10-2011 - 17:11
Wikipedia
catenary (plural catenaries)
1. (geometry) The curve described by a flexible chain or a rope if it is supported at
each end and is acted upon only by no other forces than a uniform gravitational
force due to its own weight.
2. (nautical) The curve of an anchor cable from the seabed to the vessel; it should
be horizontal at the anchor so as to bury the flukes.
3. A system of overhead power lines that provide trains, etc, with electricity,
having a straight conductor wire and a bowed suspension cable.
The original use of the word "catenary" in describing railroad overhead wiring, specifically referred to the geometric curve in definition #1; that the upper support wire tends to take due to the relatively uniform pull of gravity throughout its length. No such wires exist anywhere in this picture. So it ain't technically a catenary, though in common usage it is often called that.
In this case, it would be more correct to call it a "trolley wire". But even there, we might run amok; as the word "trolley" actually referred to the "trolley wheel" on the end of the "trolley pole" which maintained the actual contact with the wire. In turn, a cart with very small wheels was originally itself called a trolley. Thus the small, cart sized wheel, could be described as a trolley wheel.
Thereby the word trolley came to mean something very different than its original meaning. The same thing now happens to the word "catenary" --- Ain't English wonderful!
OPB
catenary (plural catenaries)
1. (geometry) The curve described by a flexible chain or a rope if it is supported at
each end and is acted upon only by no other forces than a uniform gravitational
force due to its own weight.
2. (nautical) The curve of an anchor cable from the seabed to the vessel; it should
be horizontal at the anchor so as to bury the flukes.
3. A system of overhead power lines that provide trains, etc, with electricity,
having a straight conductor wire and a bowed suspension cable.
The original use of the word "catenary" in describing railroad overhead wiring, specifically referred to the geometric curve in definition #1; that the upper support wire tends to take due to the relatively uniform pull of gravity throughout its length. No such wires exist anywhere in this picture. So it ain't technically a catenary, though in common usage it is often called that.
In this case, it would be more correct to call it a "trolley wire". But even there, we might run amok; as the word "trolley" actually referred to the "trolley wheel" on the end of the "trolley pole" which maintained the actual contact with the wire. In turn, a cart with very small wheels was originally itself called a trolley. Thus the small, cart sized wheel, could be described as a trolley wheel.
Thereby the word trolley came to mean something very different than its original meaning. The same thing now happens to the word "catenary" --- Ain't English wonderful!
OPB
