Guided by a conductor, gravity cars carried up to 30 passengers from East Peak to Mill Valley. Cars were powered by gravity, no engine, and pulled back up the mountain by a locomotive.

One story about the Double Bow Knot was that when Cliff Graves was Conductor on the run from East Peak to Muir Woods, he was required to throw a switch to send the train down to Muir Woods.  He would ride the last car down and get off, unobserved, just above the Double Bow Knot, cut down through the brush a short distance, throw the switch and be waiting for the train when it appeared around the corner.  It always amazed the passengers.

Another story was about Volley Thoney, who was a long time employee of the Railroad.  He claims to have come down the Mountain on a single Gravity Car from the top to downtown Mill Valley in 21 minutes.  That is a distance of 8.2 miles and was done late at night when no other cars were on the road.

Construction of the fantastically accurate Gravity Car replica is a story in itself.  Jerry Coe of Berkeley, California built the replica and was supported by California State Parks. Urging and incentive was provided by Park Ranger Randy Hogue, now deceased. Consultation and advice was received from many sources, not the least of which was the fertile mind and memory of 90 year old Bill Provines, former gravity car man on the railroad during its heyday.

Historical research for construction was long and extensive since neither plans nor original parts could be located.  Research involved investigating many sources of railroad memorabilia at museums throughout the States of California and Nevada, including the San Francisco Cable Car Museum.  All the metal parts were cast, forged or milled largely by the methods in use at the turn of the century.  The wood used was also carefully selected and sawn to conform to processes in use at that time.  The nearly completed Gravity Car was transported to San Francisco where it was painstakingly painted during the week before the 18 August 1996 Centennial Celebration.  It was taken to the top of Mt. Tam for the day on the 18th for the celebration and will be placed there permanently in the near future.