# Connection catalog

> All registered connection kinds. Rules for how state propagates across edges.

- [`shaft-coupling`](/docs/connections/shaft-coupling) (mech) — Rigid 1:1 coupling between two rotational ports. Propagates ω unchanged; typically used to mount a gear on a shaft or to join two collinear shafts.
- [`gear-mesh`](/docs/connections/gear-mesh) (mech) — Couples two spur gears of the same module. The layout solver places the driven gear tangent to the anchor on the chosen side.
- [`belt`](/docs/connections/belt) (mech) — Flexible loop coupling two pulleys. Preserves direction (open belt) or flips it (crossed belt).
- [`rack-pinion`](/docs/connections/rack-pinion) (mech) — Couples a spur gear (pinion) to a rack. Converts rotational motion into linear translation along the rack local X axis.
- [`bevel-mesh`](/docs/connections/bevel-mesh) (mech) — Couples two bevel gears of the same module. Axes meet at pitchAngle_a + pitchAngle_b (typically 90° for mitre bevels).
- [`helical-mesh`](/docs/connections/helical-mesh) (mech) — Couples two helical gears of the same normal module on parallel axes. A mating pair must share the helix angle magnitude and have opposite hands.
- [`chain`](/docs/connections/chain) (mech) — Toothed loop coupling two sprockets of the same pitch. Non-slipping — driven sprocket ratios by tooth count (not diameter).
- [`worm-mesh`](/docs/connections/worm-mesh) (mech) — Couples a worm (driver) to a spur gear (the worm wheel). Yields very high reduction ratios; when `starts = 1` the pair is often self-locking.
- [`weld`](/docs/connections/weld) (static) — Rigid face-to-face junction between two structural parts. Prefer the assembly-solver hints (`face` + `align`): the driven part is placed flush against a named face of the anchor, gap 0 by default. Without hints it keeps the legacy world-axis `axis`/`side` placement.
- [`rest`](/docs/connections/rest) (static) — Gravity rest: the driven part sits on the top surface of the anchor. The layout solver aligns the driven bottom face with the anchor top face and centers it over the support.
- [`bolted`](/docs/connections/bolted) (static) — Fastened face-to-face junction: the driven part is placed flush against a named face of the anchor (like a weld), but the joint is bolted rather than welded — it feeds the fastener BOM. Zero gap by default.
- [`inset`](/docs/connections/inset) (static) — Interlocking junction: the driven part fits into the anchor. v1 places the driven flush against a named anchor face (`align: "center"` for a concentric let-in). Zero gap by default.