Legs and a humanoid torso.

: The inherent
: difference between vehicles and mechs (afaik) - mechs are intended to make
: use of the structural benefit of the humanoid build, only on a much
: larger, customizable scale.

Is 'benefit' really the right word to use for fragile meatsacks like us? = )
That said, a lot of the reasons I hear for why mechs are so good comes down to anthropocentric bunk. "Mechs are great because they're made in our image, and we are awesome."

What we are awesome at is navigating the living spaces that we have designed around our capabilities and limits. Someone four meters tall and 5,000 kg in mass will have a different experience.

: So comparisons only work where what's being
: compared demonstrates that fundamental difference between a 'mech' and a
: 'vehicle'.

Give me a test case.

: Can one with absolute certainty say that vehicles are better
: than mechs? Absolutely not.

Can anybody say what /advantages/ mechs have over vehicles? All I'm getting here is a bit of "they can climb over obstacles," which is an edge case considering how "All Terrain" conventional vehicles can be.

: Anything a vehicle with two legs can do that a vehicle with two wheels can't.

Which is?

: If that's a weakness, hopefully the builders would know this, and either
: alter its intended purpose or optimal strategy, or build it stronger to
: withstand the added risk of attack. It's not cut and dry.

Pardon me, but it sounds like you've got it backwards.
In your example, engineers design something and figure out what it's good for later. In the real world* designers are given specs to design to. And then come the compromises and the cost overruns.

*When the procurement system isn't screwing up and when a project doesn't become a 240 billion dollar sacred cow.

And yes, it's a weakness, and the question is "What are you trading off?" By basing your vehicle off a much more limited platform, what strengths are you gaining in turn?

: You're limiting what the builders can build. "Tank" is a vague
: term.

I assume that "Tank" means a vehicle that is heavily armored and intended to take a lot of punishment. Could be an actual tank, could be a troop carrier, could be an armored bulldozer.
So, you're incorporating legs into something that is heavily armored, and the advantage they provide is?

: Again, it depends on the strategy employed by the designers. If there is a
: weakness to its structure, then don't build it to make use of something
: hindered by that weakness.

Yes, but what are the strengths? What makes it worth incorporating those weaknesses in the first place?

: See first paragraph. You have the inherent difference between a 'mech' and a
: 'vehicle' (for the sake of this discussion).

Again, legs and a humanoid torso, the benefits of which have yet to be enumerated to my satisfaction.

: So, if you're building a
: mech, how can you take advantage of that difference to the purpose for
: which you're building the mech?

Um... *Pulls out notecard*
"Restrict operations to densely forested woodlands with a thick canopy that restricts air operations and artillery support. Trees must be spaced sufficiently close to obstruct the advancement of conventional vehicles, but leave adequate room for the mech to maneuver. Ideal targets are primitives without access to anti-armor weaponry.
Finally, internal and external factors must prevent our forces from simply napalming the area and hitting the beach."

: I'm not a mech builder.

I'm not a mechspert* either. I'm just an engineer and a hardware junkie who is somewhat frustrated by the prevalence of a sci-fi trope.

*God in Heaven, please forgive me for that. I saw the opportunity for a terrible, terrible pun, and the flesh was weak.

: I don't know. I
: just know that "vehicles are always better than mechs" is
: incredibly short-sighted and flawed.

Another benefit of vehicles: Their natural resting state is right side up, on the ground.
Natural resting state of mechs: Horizontal.

: You seem to focus on visible foot print being an inherent and unavoidable
: weakness of mechs which across the board makes them worse. Can't agree
: with that

There was a machine I saw once, made by... John Deere? Can't remember.
It was a walker. A logging machine with multiple legs and de-
Fine. I did a google search, and here it is:
http://www.theoldrobots.com/Walking-Robot2.html

Design intent: A logging machine that protects the environment. No, really. Y'see, tires and treads are excellent at distributing loads... but they tear up the ground when you turn in place. Also, they form wheel ruts that promote erosion and cause cancer in spotted owls.

It's an elaborate setup to do the same job that tires or treads can do, only slower and a little tidier.

So, can we add "crime scene investigation" and "Clearing minefields" to the list of jobs mechs might do?

(As an aside, do you think an operator of that tractor has ever reached the worksite and said "Yes, Lord Vader. I've reached the main power generators. The shield will be down in moments. You may start your landing.")

(As another aside, I just had the image of Greenpeace activists trying to stop it by hooking a rope to one of the legs and running around and around and around and around... until the operator clocks them with the harvester.)

: To each his own :)

I find it hard to sum up the disgust I feel when I look at that image. Probably just because I'm trapped in a festering pit of writer's block at the moment.

: Nope. In the context of Halo, I can't feasibly see the existence of a mech
: that's designed for a Spartan which adds nothing to the Spartan's Mjolnir
: capabilities.

: Discussions I've seen seem to be centered around how the Mantis and Cyclops
: fit in that context. Is the Mantis actually beneficial (feasible for a
: Spartan to actually use)?

Not the argument I'm interested.
Is the Mantis's role as an anti-aircraft vehicle enhanced in any way by the presence of legs?

: Does the Cyclops really have a believable place
: in the Halo fiction?

In my opinion? Yes.
Leaving out the fact that the Cyclops is very much a melee mech first, repair unit second, it's a "Forklift Mech". In most applications you'd use a forklift for, a mech would be impractical. Don't get me wrong, I've had to take pallets down from ten foot shelves, load gearboxes onto them, and then lift them back up, and I've wished that I had some sort of robotic arm to just plop the gearbox up there in the first place.

A forklift with a boom and mechanical hand would work better at my job than a Cyclops, because a forklift can roll across a concrete floor with a heavy load.
You can take a Cyclops, add counterweights for whatever load it might carry, adjust the gait so that the load doesn't get rocked, etc. But at that point, why bother?
And yes, forklifts handle pretty well off of asphalt and concrete. They just need bigger tires and a more robust (I.E: one that exists) suspension.

All that said, the Spirit of Fire is NOT my workplace (Alas). Cyclopses may be designed to repair vehicles in a mundane motor pool with a flat deck, but they might also have to repair the Spirit of Fire after a hard fight. Then, the ability to crawl through crumpled bulkheads would speak for itself.