Clay Street gripping system

The Clay Street Hill cable car on display at the Cable Car Museum in San Francisco features inventor Andrew Halladie's gripping system in which by turning the bottom wheel seen in this picture, a screw lowered the grip down into the cable slot, and then simultaneously turning the upper wheel grabbed the cable.

The system was difficult to use and often caused problems, such as bucking in the grip, and even the occasional cable car jumping off the line.