When an overhead tube is present, it is mounted on a track system, similar to an operating
room (OR) light, except that the amount of movement is much greater. The overhead
tube assembly will move in four horizontal directions. Detents (locking positions) and
stops on the tracks are required, to ensure safety and proper alignments. The security of
the detents and the stops must be verified on a regular basis. Keeping other devices from
infringing upon the area of movement of the overhead tube is difficult. Many devices have
been damaged by being hit during the movement of the tube. The end stops on the tracks
need to be inspected on a regular basis, to ensure that the tube assembly cannot fall off
the tracks. In many installations, a counter-balance system using cables and weights is
used to allow easy and smooth movement of the tube. These cables fray over years of use
and occasionally need to be replaced, especially with systems that brake or lock by
clamping on the cable. Frayed cables on the up-and-down movement of the tube over the
patient can be particularly dangerous.
With any locking system, locks will stick open, making it impossible to lock the tube
in position. Troubleshooting lock problems is a two-person function. While one person
observes the locks, often while standing on a ladder, the other energizes the lock from the
tube head handle. Broken wires in the locking system are common. A 10-foot length of
wire with alligator clips on each end can be used to locate a broken wire. One end is
clipped to the switch, and the other to the lock. If the lock energizes when the switch is
activated broken wire is indicated. Replacing lock wires is not easy, as it can be difficult
to route the wire properly. Temporary repairs to get through the case or, at worst case, the
day should not be considered permanent repairs. Rubber-jacketed wire should not be used
in any area where radiation exposure is expected. Radiation drives the rubber molecules
into the metal, creating high resistances over years of exposure. Use only plastic or
Teflon-insulated wires.