When a maintenance crew has to lower someone into a sewer, a tank, or a manhole, they set up an aluminum confined space tripod over the opening. It is one of the most critical pieces of rescue and fall protection equipment on a job site, yet it is also the most neglected. Because tripods spend 360 days a year folded up in the back of a utility van, safety managers rarely give them the mechanical attention they desperately need. Treating a tripod like a static piece of scaffolding is a massive mistake; it is a highly tuned piece of load-bearing machinery.
The most overlooked part of the tripod is the winch mechanism. Many modern tripods use a bi-directional winch with a built-in retrieval mechanism. This means if a worker falls into the hole, the mechanism locks, and the top man can crank a handle to pull them out. The internal mechanics of these winches rely on a ratchet and pawl system, along with a centrifugal brake. If the tripod has been sitting in a van through a humid summer or a freezing winter, the thick, heavy grease inside the gear housing can congeal or dry out.
If you set up the tripod, hook a worker to it, and never test the retrieval function before they go in the hole, you are gambling with their life. When the gear oil gets thick from the cold, the centrifugal brake can become sluggish. Instead of engaging instantly during a fall, it might slip for a foot or two before catching, causing a severe shock load to the worker's spine. During your monthly inspection, the tripod must be fully extended, the winch must be operated empty, and the retrieval brake must be physically tested under load. If the crank handle feels gritty, stiff, or makes grinding noises, the gear housing needs to be opened and re-lubricated with the specific lightweight gear oil recommended by the manufacturer.
You also have to inspect the cast aluminum head where the legs pivot. Aluminum does not bend; it fatigues and cracks. If a tripod leg was ever dropped hard on concrete, or if the tripod was set up unevenly with too much side-load on the winch line, micro-cracks can form in the aluminum casting. These cracks are usually hidden under a layer of dirt and paint. Running your fingernail along the edges of the cast joints and the leg locking pins is the only way to find them before the head literally snaps in half while a 250-pound man is dangling 20 feet below the surface.
