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| Keepers rig Belle’s harness prior to lift-and-roll procedure using hoist and winch. |
When Belle, the elephant matriarch at the zoo in Portland, Ore., needed foot surgery, Allied Power Products in nearby Beaverton came up with a way to place the 6900-lb pachyderm on her side on a padded pneumatic mattress so veterinarians could perform a 2-hour operation.
Positioning the elephant posed a challenge to Allied Power Products, which specializes in custom-designed winches and hoists. Not only did she have to be lifted, she had to be rolled on her side and lowered — and then rolled back and lifted to her feet after surgery. As Allied President Bob Peterson said, “This wasn’t a hunk of steel or a load of concrete. You can lift 500-ton pier forms all day, but this was an irreplaceable, living creature. It was an absolute thrill to be part of such a special project, but our equipment had to work — period — or the surgery couldn’t have been done. There was no allowance for a miscue or redo. We couldn’t regroup and try again the next day.”
Further complicating the situation was a ceiling height that limited headroom to only 13 ft above the 8 ft tall elephant. Allied’s solution was a 2-winch system and a custom inverted trolley that ran inside the supporting I-beams at the ceiling, rather than below them, to provide maximum lifting clearance. An 8000-lb capacity hydraulic winch was used to drive the trolley back and forth. A 5000-lb capacity hydraulic hoist, rigged in a hammerhead with four parts of line through a special load block (shown at left), lifted the hefty animal. With this rig, the hook remains at the same height as the trolley moves. An existing hydraulic power unit — normally used to open and close the doors in the elephant house — supplied 1500- to 1800-psi pressurized fluid to the winches.
(Naturally inquisitive elephants often are unwittingly destructive, so protecting the equipment was another consideration. By mounting the winches between beams on a wall and keeping exposed components to a minimum, the possibility of the elephant damaging parts of the system was reduced.)
Bob Peterson manned two lever-actuated directional valves to operate the winches on surgery day. He lifted Belle about 8 in. off the floor, then moved her to the edge of the surgery mat. While keepers held her right-side feet stationary, he slowly moved the trolley farther to the right and simultaneously lowered the hook to roll her gently onto her side.