Vehicle-building terms, and how they constrain each other

Four numbers decide most of what a player-built vehicle can do: its energy budget, its mass limit, its tonnage and its power score. Learning them separately is easy. The reason new players build something unusable is that all four move together.

Quick answer

The cabin sets the ceiling on everything else. It fixes a base mass limit, a top speed and an energy budget. Weapons and modules spend energy; parts of every kind spend mass; movement parts supply the tonnage that mass is spent against; and the total of all parts produces a power score that decides which opponents you meet. A build fails when it satisfies three of those constraints and quietly breaks the fourth.

The parts vocabulary

Games in this genre split a vehicle into part categories, and the categories are more consistent between titles than the item names are.

Cabin: The part everything is attached to. It carries the class identity — light, medium, heavy — and usually a perk that fires under some condition. Destroy the cabin and the vehicle is out of the match, whatever else survives.
Frames and structural parts: The skeleton. They contribute mass and absorb damage, and they are where mounting positions come from. Structural parts have no active function, which makes them the cheapest thing to lose.
Movement parts: Wheels, tracks, hovers, legs. They set speed, steering character and carrying capacity. They are usually the largest exposed surface, so their durability matters as much as their statistics.
Weapons: Mounted offensive parts, each with a fire pattern, a reload or heat cycle and an energy cost. Turreted weapons fire independently of vehicle facing; fixed weapons require the whole vehicle to aim.
Modules: Everything else that does something: generators, radiators, ammunition packs, boosters, repair kits. Modules compete with weapons for the same energy budget, which is the trade-off the whole system is built around.
Cosmetic parts: Paints, decals and decorative items that change appearance only. Worth confirming case by case, because some decorative items in some games also have a small structural value.

The four constraints, in the order they bind

1. Energy

Energy is a budget, printed on the cabin, spent by weapons and modules. A cabin offering ten energy might support two weapons at four each and one module at two, or three cheaper weapons and nothing else. Generators add energy at the cost of mass and a fragile part that frequently detonates when destroyed.

Energy is the cleanest constraint because it is discrete: a part either fits in the budget or it does not. It is also the constraint that produces the most genuine decisions, since almost every interesting module competes directly with a weapon.

2. Mass limit

The cabin's mass limit is a hard cap. Exceed it and the build cannot be deployed at all. Mass accumulates from every part, including the structural pieces that feel free because they do nothing.

3. Tonnage

Tonnage is what the movement parts can carry, and unlike the mass limit it degrades rather than blocks. A vehicle over its tonnage still deploys; it accelerates poorly, turns slowly, struggles on slopes and cannot recover from being pushed. This is the constraint that catches people, because nothing in the interface refuses the build.

Adding wheels raises tonnage, but wheels also add mass and power score, and unpowered support wheels raise capacity without adding drive. The circularity is deliberate: every fix costs something in another column.

4. Power score

Power score is a summary number derived from the parts fitted, and it decides which bracket the build is matched into. Because nearly every part raises it, a straightforward improvement — better armour, a second weapon, a heavier cabin — also promotes the build into tougher company. A build that wins consistently at one score and is helpless fifty points higher has usually gained capability more slowly than it gained score.

Worked example

Why a well-armoured build can perform worse than a bare one

Start with a medium cabin: a mass limit of 6,000 kg, an energy budget of 12, and four powered wheels carrying 5,000 kg of tonnage between them.

Two weapons at 5 energy each leave 2 energy, enough for one module. Fine so far.
Adding 1,200 kg of armour plating brings total mass to 5,400 kg — under the 6,000 kg cap, so the game deploys it without complaint.
But tonnage is 5,000 kg. The build is 400 kg over what the wheels carry well, so acceleration and steering degrade.
Two more wheels fix the tonnage, add their own mass, and push power score up by enough to change the matchmaking bracket.
The build now faces opponents it was not built for, while handling no better than the version before the armour went on.

The original problem was not the armour. It was that armour was added without checking the constraint that degrades silently.

A build order that avoids the common traps

Choose the cabin for its perk, not its statistics. Cabin perks are conditional, and a perk that never triggers in your play style is a wasted cabin regardless of the numbers.
Fit weapons next. They dominate the energy budget, so committing to them first tells you what is left for modules rather than the reverse.
Add movement parts and note the tonnage figure. Write it down. It becomes the budget for everything after this point.
Build the structure inward from the weapons. Protect the weapons and the cabin with expendable parts before adding armour anywhere else.
Check mass against tonnage, not against the mass limit. The cap is enforced; the tonnage is not, which is exactly why it is the one to watch.
Record the power score before and after any change. A change that adds score without adding effectiveness is a net loss.
Save the result as a blueprint. It costs nothing and makes the next revision a comparison rather than a memory.

Cabin classes compared

General characteristics of cabin classes across the titles covered in this reference. Individual games vary; the vendor's in-game figures are the authority for any specific cabin.
Class	Mass limit	Top speed	Typical energy	Suits
Light	Low	High	Low to moderate	Flanking and single-weapon builds that rely on not being hit
Medium	Moderate	Moderate	Moderate	Most first builds; tolerates mistakes in weight distribution
Heavy	High	Low	Moderate to high	Multi-weapon builds that expect to absorb fire rather than avoid it
Specialist	Varies	Varies	Often restricted	Builds designed around one perk, usually at a cost elsewhere

What to watch out for

Weight distribution is separate from total mass. A build comfortably under every limit will still tip on a slope if the mass sits high and to one side.
Exposed movement parts end matches. Losing two wheels usually removes a vehicle from the fight more reliably than losing a weapon.
Generators and ammunition packs detonate. Placing them at the centre of the build, surrounded by structure, is standard practice for a reason.
Copied blueprints hide their assumptions. A shared design built for a different cabin perk or a different bracket can behave nothing like it does in the screenshot.
Published part statistics rarely include reload or heat. Sustained output is the number that matters in a match.

Where this applies

These constraints describe the genre rather than any single product. Crossout, which supplies most of the construction examples used here, is built on player-assembled vehicles whose shape, armour, armament and support systems are all modifiable, alongside cosmetic accessories — so the same four-constraint problem appears there in its fullest form. Anything specific to that game's current parts, numbers or balance belongs to the vendor's own documentation rather than to a reference site.

The next step for most readers is progression and crafting, which covers where the parts in a build actually come from, and why the interesting ones are gated behind reputation rather than money.