"HammerheadFistpunch" (hammerheadfistpunch)
06/12/2018 at 13:38 • Filed to: None
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"HammerheadFistpunch" (hammerheadfistpunch)
06/12/2018 at 13:38 • Filed to: None | 7
| 11 |
So the hummer, for all its badass off road cred, didn’t actually come as standard (at least originally) with locking differentials. The military was concerned about the misuse of the locker and asked instead for a new type of limited slip call the torsen. Its a mechanical TORque SENsing type unit that doesn’t rely on a slipping wheel to bias torque. They specd a unit with a VERY high torque bias ratio of 4:1 and since the gears were reduced at the hub to the tune of 1.92 to one that mean that applying a small amount of brake torque to all wheels would bias a large amount of torque across the diff. Think of it like this, if you put 100 lbs of braking torque to all wheels the torsen would take that 100 and multiply it by 4 x 1.92 to get 768 lbs feet additional torque to the good wheel. So if you applied 200 lbs feet engine torque, the good wheel would get 33.3 x that for 6660, PLUS the 768 from the braked wheel, minus only 100 lbs-ft because the good wheel is also being braked. meaning a wheel in the air is getting 100 lbs-ft while the wheel on the ground is getting 7328 lbs feet. PLENTY to move it. Apply more brake, bias more torque to the tune of nearly 8 times the rate of the brake loss. Its a neat little trick that allows the HMMWV a lot of traction without having to do anything more complicated than ride the brakes a little. Stronger too. The clip above shows this in action, the red truck for sure is using it, The green truck too.
Its worth nothing as well that one of the trucks rear diff exploded early on the trail, the spider gears broke. It was equipped with the option e-locker and not the Torsen.
Duck Duck Grey Duck FTMFW!
> HammerheadFistpunch
06/12/2018 at 14:03 |
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Cool!
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HammerheadFistpunch
> HammerheadFistpunch
06/12/2018 at 14:04 |
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These clips also serve to illustrate how hilariously bad the H1 is at articulation.
winterlegacy, here 'till the end
> HammerheadFistpunch
06/12/2018 at 14:06 |
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I’m a sucker for Humvees and Hummers and general. I don’t understand it. I hate massive vehicles, but at the same time...
razorbeamteam
> HammerheadFistpunch
06/12/2018 at 14:14 |
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I was thinking the same thing, the springs are probably so stiff to accommodate the size of the vehicle plus all the equipment it was designed to carry. When they plop down on their airborne wheel the wheel hardly moves up into the fender.
Distraxi's idea of perfection is a Jagroen
> HammerheadFistpunch
06/12/2018 at 15:32 |
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New to Hummers, but not exactly new. The Torsen diff was patented in the 50s and has been in widespread use in road cars since the 80s. Particularly popular in powerful FWD cars pre e-diffs, as the nature of its operation means it doesn’t corrupt steering when traction is good.
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HammerheadFistpunch
> Distraxi's idea of perfection is a Jagroen
06/12/2018 at 15:46 |
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yup! I’ve still got an original sticker and brochure for mine.
Might be the only place a Vector and a hmmwv were featured in the same brochure
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Distraxi's idea of perfection is a Jagroen
> HammerheadFistpunch
06/12/2018 at 15:59 |
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Cool!
I remember driving a prototype Rover 220 Turbo with one. Ridiculously overpowered by FWD standards of the day, with 200 whole horsepower! Unlike the Maestro Turbos from a couple of years earlier with the same engine, it was actually driveable (even though it would still try to throw you into the next lane if you booted it in a low gear). Early versions didn’t play nice with ABS though, ABS being effectively a speed sensitive differential device. Obviously that issue got fixed, but I was out of the game by then so Idon’t know how.
TheRealBicycleBuck
> HammerheadFistpunch
06/12/2018 at 21:09 |
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HammerheadFistpunch
> TheRealBicycleBuck
06/12/2018 at 21:21 |
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Mostly right. The way it “locks” is a little oversimplified but that’s an easy to grasp general overview for a difficult to visualize concept.
dontknow265
> HammerheadFistpunch
06/13/2018 at 07:16 |
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All the HMMWVs and H1s have inboard brakes on the case of the differential so I think your math is slightly off as the portal hub gear ratio doesn’t come into play. Still certainly a cool concept.
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HammerheadFistpunch
> dontknow265
06/13/2018 at 11:46 |
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You are completely correct. I knew this, but wasn’t thinking.