IN 1970, Skylab planners decided to provide the astronauts with extendible booms to convey film cassettes weighing 125 earth pounds between the Airlock Module and the Apollo Telescope Mount. This paper describes the boom and its dispensing mechanism, and discusses problems encountered with the mechanism during the test programme. These problems were mainly associated with operation in cold temperature, lubrication, and the motor/ gearhead assembly. Another set of problems which arose during crew training in the MSFC water tank is also discussed.

Experience from this programme leads to the conclusion that attention to detail is the cardinal rule for mechanisms designers. Such things as the correct choice of lubricant, the build-up of tolerances, and the effect of differential contraction of metals can make or break a design.

Two Film Transfer Booms were used during six separate EVAs over the almost nine-month Skylab mission. At these times, film for five solar physics experiments was replenished and retrieved from two work stations on the Apollo Telescope Mount (ATM), and the touch of a button sent extendible stainless steel booms carrying bulky cassettes at six inches a second across thirty feet of space.