`The picture is of a fixed-head disk, very similar to a Borroughs unit I had the pleasure of disassembling (in 1975) after a catastrophic head crash (I got authorization from Gordon Bell himself to do it). It took me 3 days to whittle it down to nuts and bolts, and the platter weighed 18 pounds. The hub upon which the platter was mounted was phosphor bronze, and weighed an additional 17 pounds. So imagine the inertia of 35 pounds spinning at 3600 RPM. It had electric brakes, because if you just switched off the power, it would spin for a loooong time. There is an (apocryphal) story of movers just hitting the circuit breaker (not the off switch that engaged the brakes), and after waiting the requisite 5 minutes for spindown, loaded the drive into a truck. All the moves and hallways were right angles, of course. Since brakes had not been engaged, it was still spinning at 2000 RPM or so by the time it was loaded. When the truck turned a corner, the drive precessed right out through the side of the truck.’
There’s a slightly clearer picture of the giant hard drive of doom [as I have dubbed it :)] at Flickr.