Truck Jumping
click for a close-up
My first truck was a 1950 Chevrolet pickup – probably around 1958. While it was not my first vehicle, it was most certainly among the most unique. It was yellow and heavily used and seriously rusted. The bed, including the side panels and tailgate, had been replaced, but the donor vehicle had been a red GMC pickup. If you saw mine coming toward you, you would say it was a yellow Chevrolet, but from the rear, it was red with a very large GMC embossed on the tailgate.
The other thing making it unique was that both red and yellow halves had rusted to the point where all the attachments from the body to the frame had rusted away, leaving the body to bounce around on country roads. Making a sharp left turn was particularly troublesome because the body would tilt to the right and jam the peddles in place. The only solution would be to switch off the engine and let it coast to a stop, then get out and go to the passenger side to push the body back up on the chassis. That was most troublesome in heavy traffic, which fortunately was not a problem in Three Rivers but extra care would be needed in Kalamazoo.
I have owned a half dozen or more trucks since then and my current one is a 2013 RAM, four-wheel drive. The table below describes some of the features of the 1950 Chevrolet/GMC, which I jumped out of many times as a teenager to the RAM, which I jumped out of once.[i]While it is not possible for a human to reach Terminal Velocity by jumping out of a truck in a Home Depot parking lot, I can attest to the fact that it feels “terminal” when you hit the pavement.
The table shows that while there is only a couple of inches difference in the bed heights of the two trucks, the top of the RAM toolbox is 9 inches higher than the Chev/GMC bed, making the impact velocity a bit higher.[ii]Ignoring wind resistance, it is independent of weight. The big difference is in the deceleration time – assumed to be half in the case of the asphalt parking lot, vs grass and sandy soil at Fishers Lake. That makes my 185 pounds feel like 1,212 pounds at the moment of impact.[iii]vs. 583 pounds, 65 years ago.
| Truck | Tire Size | Bed Height | Top Rail Height | Tool Box | Body Mass | Impact Velocity | Deceleration Time | G-Force |
|---|---|---|---|---|---|---|---|---|
| 1950 Chev/GMC | 15" | 30" | 51" | 0" | 155 lb | 11.275 mph | Grass 0.2sec | 2.76 / 583 lb |
| 2013 RAM 4X4 | 17" | 32" | 53" | 7" | 185 lb | 12.128 mph | Asphalt 0.1sec | 5.55 / 1212 lb |
15 |
All this adds up to my suggestion that one should not jump out of the back of his or her truck past the age of 75 or so, particularly not onto a Home Depot asphalt parking lot. In this example, the result of landing flat-footed and falling backward to land on one’s ass and both palms with arms fully extended is this , requiring one of these, followed a few years later, by this and two of these
By: Jim
Written: February 10, 2023
Published: February 11, 2023
Revised: February 12, 2023
Reader feedback always appreciated
footnotes
| ↑i | While it is not possible for a human to reach Terminal Velocity by jumping out of a truck in a Home Depot parking lot, I can attest to the fact that it feels “terminal” when you hit the pavement. |
|---|---|
| ↑ii | Ignoring wind resistance, it is independent of weight. |
| ↑iii | vs. 583 pounds, 65 years ago |
