Even in modern, congested City streets, most drivers know the hazard of tangling with cable cars and give them a wide berth and grudging respect. The procedure by which a cable makes turns was conceived in the early years of cable expansion throughout the City.
This was the standard until , when a new and often-expensive innovation made turns possible along a route. Of course this was only practical where two streets descended as the cable car approached an intersection. This type of curve could be installed at any intersection, regardless of street physiognomy. The pull curve involved a series of many small pulleys holding the cable in place as it makes the turn.
When the car approaches, the grip is pushed away from the pulleys and guided by a chafing bar set above and outside the pulleys, negotiates the turn. After the turn is completed, the cable returns to its usual position on the pulleys. This type of curve is recognizable by the series of access plates abutting one another around a turn.
All of these turns have given rise to the colorful shout of the conductor: "Look out for the curve", often parodied by writers as a brassy Brooklyn dialect, although it is more likely to have been a Mission district accent at the time, similar in tone, yet distinct and almost extinct in modern San Francisco. Finally, the cable car system employs two types of terminal arrangements for sending cars back up their route.
The California line uses a double-ended "California Car" with identical machinery on either end, except for the grip, which fastens to the opposite lever by a connecting rod.
This allows the car to proceed back on its route from either terminal without turning the car physically around. Instead the car uses a system of switchbacks and crossovers on the tracks to set up the cars for a return trip. This arrangement was used on early cable car lines, like the Clay Street Hill Railway, to facilitate changing direction.
The California Street Cable Railroad used this on the California street line and continues to do so to this day. Major cable innovations occurred in the s with such inventions as the steel cable and the detachable grip. During this time period, cable was largely used for industrial purposes. Cable was first adapted for human transit in the form of cable cars, with cities such as San Francisco and Chicago pioneering this mode.
As transit technology shifted to electric power, these systems became largely obsolete. At this point, around the s and 40s, cable, for the movement of people, shifted to the recreational market, where it continued to grow and innovate until the last few decades.
Thus, two parallel cable strands run through it in each direction, allowing extremely high wind stability. Under aerial cableways, a distinction is also drawn between single-cable and multiple-cable systems. Because of the lower tension in the winding cable, single-cable systems have greatersag,whichiswhytheyrequire more supports and tend more to follow the course of the terrain.
As the name indicates, they have only one cable, which holds and moves the gondola. With multiple-cable systems, the gondola rolls over a supporting cable that is fixed into place, and it is moved by a circulating traction cable. Two, three and four-cable systems therefore have a more tightly tensioned supporting cable, which allows greater span lengths and thus a smaller number of supports.
Taxonomie der Seilbahnbauweise Grafik: Kremer. Thomas Surrer. Modesof operation. Eine besondere Form der Umlaufseilbahn stellt das Funitel-System dar.
Foto: Doppelmayr. Cable system. Each cable has its own set of winding wheels. The rearmost winding wheel in each set is adjustable. When a cable is new, this rearmost wheel is close to the other winding wheels. As the cable naturally stretches out with use, the wheel is gradually moved back by shop workers to keep constant tension on the cable. The cables are over an inch in diameter, with six steel strands of 19 wires each wrapped around a core of sisal rope.
Each cable car has a mechanical grip two on the double-end California cars which latches onto the cable, much like a huge pair of pliers. The cables move at a constant 9. At some terminals, you will notice the conductor pulling on a lever in the street.
This lifts the cable upward so the grip can grasp it. At other terminals and at other locations on the system , you will see a noticeable dip in the tracks. This lowers the car, and its grip, to the level of the cable underneath, allowing the grip to grasp the cable. Among other locations, this happens in both directions where the Powell and California cable lines cross.
Adhering to the original cable tradition, the California line, which was built first in is entitled to the upper cable.
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