Just curious but passing orders this way seems lie a disaster in the making. Any stories of people losing fingers, hands or worse.
No.
However, there were some skills which made the process work better, when using the old tool -- the cane hoop. If the Operator, standing on the ground, would angle the pole of the hoop slightly toward the approaching train, and swing it as it was picked up, that would lower the speed of contact with the arm of the employee who received the hoop. Also, some ergonomic movement on the part of the employee aboard the train helped. Those cane hoops could sting and bruise sometimes, I was told by the old heads I worked with. Probably, somewhere, at some time, somebody broke a knuckle or a finger from contact with a cane hoop, but it would have been rare, and I cannot imagine an amputation resulting from picking up a hoop on the fly.
After around 1950, many railroads switched entirely, or sometimes mainly, to the "high speed order fork", for handing up orders. (And, just as information, that is the standard railroad term for the process. Orders were handed up, not hand passed.) Now, the high speed order fork only had a string and a set of orders or messages, and, if the fork was positioned in the proper direction, it did not sting when they were picked up on the fly. At locations where authorized track speed was substantial, railroads often installed a base that would accept a telescoping aluminum mast, which, in turn, would accept order forks (just the head of the fork, not the handle). That eliminated any danger to the Operator, as he or she did not have to stand next to the train to hand up orders. The Operator could attach the uppermost fork at his level, then raise the telescoping mast to accept the lower fork(s), then raise the mast to its locking position at engine window/caboose platform height. These were also often used at interlocking towers which issued train orders, so that the Operator could hang the orders, return to the tower, and take care of his other duties, such as lining trains through the limits of his interlocking plant.
Usually, it was not a great idea to pick up the orders at very high speed. At 55-60 MPH, the orders could be picked up with relative ease, but at 80 or 90 MPH, there was more likelihood that turbulence from the passing train would cause the Train Crew's copies to be released from the fork and go heaven knows where. This required stopping and backing up to retrieve the orders or messages. So, a prudent practice was to slow the train to 60 MPH or less for picking up orders. If they had to be picked up at a higher speed, I always used a flag stick instead of my arm.
On cab units such as EMD F7's, the normal practice was to open the side door of the cab, and lean down to snag the orders, especially if an employee was handing them up from ground level.
