Bonus post – John nerds out over cable cars

After all the hard work to walk over to the Cable Car Museum, I thought I’d better make the most of it. And that means I’d better make a post of it 🙂

The museum wasn’t all that big, but it was also the engine room of the whole cable car network.  The second you walk in you can hear the engines and see all the big wheels spinning, pulling the cables through the entire cable network. 

IMG_1878_Lively

 

It also had a number of old cable cars, signage, and equipment.

There are three main cable car lines – California, Powell/Hyde, and Powell/Mason but four cables (there’s  shared bit in the middle of the Powell lines, the used to be part of a different line, but that’s another story).  These lines are the three remaining, out of about 23 different lines running when the cable car system was at its peak.

The cables from all of those line converge here at the museum – coming in from all sides at all angles, requiring  huge pulleys (formally called ‘sheaves’) poised at different angles to line up all the cables ready to be whirled around the driving machinery and sent back out again.

Back in the good old days, the machines to run the cable network were all steam-powered, but these days they are run by electric engines, which has gotta make life much easier.  I thought it’d be noisier than it was but I guess it’s just an engine, a bunch of pulleys and a a few big-arse cables whirling around.

The cables themselves are only about 3cm across, made of steel strands, but with normal old rope at the core – to make sure it has some ‘give’ when the cable car grips on to it.  It runs at 9.5 miles per hour – so when your cable car is gripped on, no matter where you are, it’ll be the same speed.  Up hill, down hull, on the flat – it’s all the same.  Pretty different to all the buses, cars (and particularly people!), who generally go much slower uphill compared to down.  The cables don’t last all that long – somewhere between 70 and 250 days according to the museum.  Replacing them is a pretty huge maintenance effort, especially joining the cable to close the loop.   The ends get spliced together over a 90 foot distance of rope, to make sure the join is perfectly smooth and ‘invisible’, so it won’t get caught up or snagged on anything across the whole network.  The cable is coated in pine-tar to keep it moving, and to allow more slip when the cable gets gripped – kinda like a clutch to enable smoother starting and stopping.  Over the life of the cable it can stretch by about 100 feet.  So the engine room has 100 feet of free space, where another pulley exists just to keep the tension.  Over the life of the cable, this pulley is moved back slowly on a track 100ft long to take up the slack and maintain the correct tension on the cable the whole time.

For the gripman, it’s not  simple case of gripping the cable to go, and letting go of it to stop.  There’s the aforementioned slippage to ensure the take-off is smooth and doesn’t throw all the passengers off. And every intersection and corner may have to be dealt with in its own particular way.  It’s not real easy to get a big steel rope to take corners in such a way that a big grip can remained attached to it the whole way.  For some corners there’s a complicated set of pulleys to guide the rope around the corner, and other contraptions to make sure the pulleys get out of the way just in time for the grip to come through.  When we were walking around at night I noticed these corners were even noisier than the normal streets with the cable running underneath, due to all the extra equipment, pulleys etc.  Some of the other corners are known as ‘let go’ corners, where the gripman has to let go of the cable at just the right moment, then let the cable car drift around the corner just using its own momentum, then they have to pick up the cable again after turning the corner to continue the journey.   Not only that, when cables cross at intersections – there’s no two ways about it, one cable has to travel above the other one, that’s all there is to it.  So if your cable is the one running underneath, the gripman again has to let go of the cable, drift across the intersection, then pick up the cable again at the other end.  It must be a bit of a stressful job – mis-timing such a move would make for a very expensive mistake, bringing down two whole cable lines at once and who knows how long it’s take to get it all going again.  Don’t know if that’s ever happened – but since the cable network has been running for well over a hundred years, I’d say it inevitable.  When there were 23 lines, the newest one would have had the lowest cables – which meant picking up and dropping the cable a dozen times of more on every trip.

IMG_1881

Then there’s the braking – although holding on to the cable means you’ll travel downhill at just the same speed you go uphill, I guess 10 tons of Cable Car must create a lot of strain on the system so there are also brakes on the car that the gripman needs to operate.  The brakes are just made of pine, and brake the car by pressing down upon the tracks.  Apparently it’s not uncommon to smell burnt wood – not surprising I guess when two foot of pine is stopping 10+ tonnes of cable car.  The pine brake shoes need to be replaced every two to four days.  So it’s all  bit of a high-maintenance operation, it’s no wonder the city has wanted to shut it down completely at various points of its history, until its historical (and tourist-attracting) properties became too big to ignore.  There are also more conventional brakes on the wheels, plus an emergency brake – a great big wedge of metal that gets plunged directly into the cable slot to bring it to a (probably quite literally) grinding halt – it usually then has to be removed with gas welding equipment if it ever needs to be deployed.

IMG_1885

Whilst ‘gripman’ seems to be the official term, there have been two women who have done the job.  The first, Fanny Mae Brice, only started in 1998.  And as if the gripman didn’t have enough work to do already – when they get to the end of the line, they have to manually push the cable car on a big turntable, to point it to the right track for the return journey. 

But for us normal folks, all we see are cable cars, chock full of people hanging off them, going ding ding ding as it passes by … but there’s a lot more to the story. The whole thing is kinda impractical – but very beloved, and since tickets are at least double the equivalent bus or streetcar fare, it’s become quite a cash cow for the whole public transport system.  Public transport makes money, history is maintained, tourists have a blast … it’s  win-win-win situation.  And now, you know a bit more about it.

One thought on “Bonus post – John nerds out over cable cars

Comments are closed.