Sun Fire 6800 Unload
In November of 2008, I was tasked with the retrieval and storage of two Sun Fire 6800 computers. These are large, very powerful multiprocessor UNIX systems. Each system has 24 64-bit, 1.2GHz UltraSPARC-III+ processors, with fully redundant I/O, power supplies, and cooling subsystems. Each system is contained within a six-foot rack that weighs about 1200lbs.
I had limited time and resources with which to unload these systems, so I ended up doing it alone. This was not easy. The physical difficulty of moving such heavy equipment without the aid of a forklift was made more stressful by the fact that these machines cost a small fortune, and they belong to my employer. If one of them were to have hit the ground, Bad Things would happen.
The first thing I did was remove several components from the systems. Aside from obvious removable things like the decorative doors and plastic covers, each machine contains six processor/memory modules, six power supply modules, and two fan trays, all of which are hot-swappable and as such are easily removed. This adds up to quite a bit of weight, so removing them made things a bit easier. The processor/memory modules alone easily weigh 35lbs each. Removing them also minimized the chance of damaging any of the modules. I estimate that the rack weighed about 1000lbs after their removal. I placed them aside, out of harm's way.
The first system to be unloaded had been placed on its back directly on the floor of the truck. There was significant friction between the back of the rack and the wooden floor of the truck. This, combined with the fact that the truck was sitting on a slight incline in the wrong direction, made it very difficult to push the rack toward the rear of the truck. I was able to do it, though, an inch at a time. As more of the rack hung off the back of the truck, the pushing became easier, due to the decreasing contact area between the back of the rack and the floor of the truck.
Long before there was any risk of tipping, I took a 2" ratchet strap, looped it through two openings in the bottom of the rack, and hooked it directly above the rack to the horizontal structural member of the truck's box. I performed a quick mental calculation of the required length of the resulting "U" shape, configured the ratchet strap to that length, and then pushed the rack a bit further out toward its tipping point. These ratchet straps are very strong, but I didn't want to take the chance of it snapping, and I was also concerned about tearing the top structural member of the truck apart, so I kept the rack on the safe side of the tipping point and performed some load tests. I pulled the base of the rack down a bit to put some weight on the strap.
Satisfied that the assemblage would hold, I climbed back onto the truck and pushed the rack past its tipping point. The strap held nicely, carrying nearly all of the weight (over half a ton) of the computer suspended above the cement. I placed some folded packing pads underneath the lowest point of the rack to cushion its eventual landing. Of course I would try to minimize any impact, but with this much weight and lacking proper lifting equipment, some light jarring is unavoidable.
At this point, I decided that I had taken all the precautions that I could take, I really didn't have any other options, so I proceeded to lower the rack using the strap's ratchet mechanism. This proved somewhat difficult due to the pulling of the strap through the holes in the rack. Very slowly, over perhaps half an hour, I got the rearmost corner of the rack down to the ground. This involved constant running from side to side, inspecting the situation from all angles to make sure nothing bad was happening. I then carefully added some slack to the strap and pushed the rack to the upright position, and removed the strap.
The last step was to get the machine into the storage area and reinstall its processor/memory modules, power supplies, fan modules, and doors.
The second system to come off the truck was actually the first one loaded when I picked up the equipment. We thought it might be a good idea to place the first system across two pallets, to make it easier to move it around in the truck with the forklift. This proved to be such a pain that we didn't do it for the other system. It also proved to be a big pain on the unloading end, due to the wood-on-wood friction being far worse than the metal-on-wood friction in the system described above.
Being completely unable to slide the system across the floor of the truck due to this friction, I ended up doing something a bit drastic. My house has three garage doors, with cinder block support columns between them. I took a 2" ratchet strap, tied one end around one of those support colums, and the other end to the rearmost point of the rack. I then got into the cab and drove the truck forward, very slowly, half an inch or so at a time, resulting in the rack being pulled out of the back of the truck. The rearmost pallet came along with the rack until most of that pallet was hanging off the back of the truck. I then moved the ratchet strap into a "U" around the bottom of the rack, attached it to the upper support member of the truck, hoisted the rack up a little bit, and removed the pallet.
After that, the unloading was accomplished in the same way as the first system described above.