|Open for Rigging|
Bill Greenwald gave me this ascender at the 2007 NSS Convention.
The Greenwald is 73 mm. tall, 69 mm. wide, 32 mm. thick, and weighs 335 g. It consists of a U-shaped shell made from 2.8 mm. steel, a cam cut from 12.5 mm. aluminum, a needle bearing for the cam, a cam pin and retaining clip, and a cam closer made out of a piece of stiff wire and a section of bicycle inner tube. The inner tube acted on a flat on the cam (below the pivot hole), acting to close the cam. The short cam face had four Z-shaped teeth.
Bill made a pair of these ascenders in 1969. He called it a "Hand Cam" because the device was held in the hand during climbing. Holding the ascender in his hand, he would thumb the cam to help open it while moving the ascender upward. He first tried these in a 20 m. (70 ft.) pit, and worried about the cams slipping. They held too well; he had to tap them with his rock hammer to get them to release.
He used this one as a foot ascender by rigging it with a carabiner and brake bar . He looped some webbing around the carabiner and connected the webbing to his foot.
I can only imagine what heavy cave mud would do to the needle