Car-crushing mechanical claw

Date:3 May 2010 Tags:,

The top prizewinner of PM’s 2009 Backyard Geniuses, Christian Ristow, spent years dreaming of the perfect way to crush cars by hand. In 2007 Ristow, an artist and former animatronics designer for the movie industry, demonstrated his first working incarnation of the Hand of Man at a robotics festival in Amsterdam. Much of his time since then has been spent re-engineering and refining the design of the 8-m-long hydraulically actuated appendage, exhibiting more and more capable crushers at a series of public venues.

Ristow’s latest mechanical steel limb has 90-degree wrist rotation and improved mobility in the finger joints. It is powered by a 90-hp Perkins 1104C-44T four-cylinder diesel engine and is controlled through a glove worn by the operator. At demonstrations, that operator is usually a random member of the audience. “I’ve built other large-scale radio-control robots for shows over the years, but I always felt like I was the one having the most fun,” Ristow says. “This democratises the crushing power.”

In this video: Christian Ristow’s “The Hand of Man” at Maker Faire 2009. You’ll see that the forearm and hand are powered by an engine-driven hydraulic unit, such as those used in cranes or tractors. The entire machine is about 9 m long by 6 m wide and is able to move up and down by pivoting at the wrist. The arm can’t swing from left to right, but it will open and close all four fingers and the thumb

Man behind the machine
Name: Christian Ristow
Age: 39
Location: Taos, N.M.
The trouble with Muppets: Ristow once built puppets for Jim Henson’s Creature Shop, but was disappointed by the company’s “antimechanical bias.”

PM is looking for 2010’s Backyard Geniuses. Projects can be anything from a handcrafted treehouse to a robot assistant to an electric go-kart. Two rules apply: 1) You must have already built it; 2) Submissions must be in by 15 May 2010.

The best reader projects will be featured in a magazine story. Please send a description of your project with images (or links to images and video) to

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