Most off-road vehicles have crawl ratios—extra gearing to increase forward thrust—between 30 and about 100. But the Mercedes Unimog, with its “Super Crawler” gear, has an absurd crawl ratio over 3000. That means two things: unstoppable crawling power, and a hilariously low top speed.
Hop into a Mercedes Unimog, and the controls will probably scare the crap out of you. Just look at all of these levers, which YouTuber ExpedImports walks us through in his video of his 416:
The top lever is the transmission shifter, the bottom left activates four-wheel drive and lockers, the top left is the power takeoff lever, the center lever is for turning on and off the “crawler” gears, the top right activates the two crawler gears (the lower of the two being “Super Crawler,” or as they say in Germany “Superkriechgang” or “Schneckengang”), and the bottom right is the forward/reverse lever.
In first gear and in “super crawler” mode, the Unimog 406/416 is said to have a crawl ratio of over 4000, and a top speed of only about .08 kilometers per hour (or 300 feet per hour). By comparison, a three-toed sloth can walk three times as fast.
While I couldn’t confirm those Unimog 406/416 crawl ratio and top-speed figures with any official Mercedes documentation, I did find a brochure for the more modern Unimog U500. In it, I learned that the first gear ratio is 9.570:1, and that the gear can be used in “road gear” or “working gear” mode. In the latter mode, first gear is multiplied by a ratio of 5.757.
The “crawler” gear ratio—with the 5.575 “working gear” included—is 55.874, the rear axle ratio is 2.182, and the hub ratio (remember, this thing’s got portal axles), is 2.714.
So if you multiply that all out—first gear ratio (9.570) times crawler gear ratio (55.874—this includes the working gear) times axle ratio (2.182) and finally times hub ratio (2.714), you end up with a crawl ratio of almost 3,200.
This means the engine’s torque (700 lb-ft at 1,200 rpm) gets multiplied by that value, yielding a maximum of over 2 million lb-ft of grunt at the wheels. And if you want to see what that means, just watch this idling Unimog crawl up a stump effortlessly:
In that brochure, it says the U500 has an electronically limited top speed of 0.09 mph, or 475 feet per hour (or about 8ft per minute). And while that means it’s still much slower than a sloth, the Unimog might actually be better at climbing.