Now, those 25 underground sheaves will be rebuilt from the ground up as part of an already-planned replacement of the motorized gearboxes that rotate those pulleys.
The San Francisco County Transportation Authority board, comprised of the Board of Supervisors, approved on Tuesday $280,999 to repair the sheaves. The large wheels were last rebuilt between 1982 and 1984, according to the San Francisco Municipal Transportation Agency. [...]
The cable cars' first power sources were steam engines powered by "enormous amounts of coal each day," according to the Cable Car Museum website. San Francisco replaced that steam system with electric motors in the decade following the 1906 earthquake and fire, according to the museum, which is still used today.
If you have not visited the Cable Car Museum in person, you are missing out on something amazing.