Part

Arm shell

You might say: ribbed arm, bellows sleeve, robot jacket, cosmetic skin, outer sleeve, gooseneck cover

A shell is the arm's outer cover: a ribbed sleeve or bellows can protect and style a mechanism while the internal structure carries the load. A passive poseable gooseneck holds a manually set pose through friction or locks; an actively driven arm changes pose through actuators.

What it does

It protects or hides the mechanism, makes a snake-like silhouette readable and clears joint travel without becoming an unplanned structural member.

Ask

Is this cover carrying load or only covering it, and does it clear the full bend and cable path?

Typical

Straight link: sleeve. Moving joint: accordion bellows. Whole body: jacket. Passive display/tool holder: poseable gooseneck. Actuated body: keep the load path explicit instead of relying on the cover.

Trouble

A shell that wrinkles, binds, snags a tendon, transfers torque into a joint, or is mistaken for the load-bearing backbone is the wrong shell even if it looks convincing.

Catalogue: Outer treatment

• Cosmetic / protective ribbed bellows: A folded cover follows a bending joint while a sleeve covers a straighter link; keep collars and clearances separate from the actuator and structural backbone.
• Exposed segmented mechanism: Leave links, tendons and guide tubes visible so a newcomer can inspect the actual load path instead of mistaking spacers for joints.
• Passive poseable gooseneck: A ball-and-socket or segmented hose arm is positioned by hand and held by joint resistance or a lock; it is not an actively driven robot arm merely because it looks articulated.

Connections

• See also: Links and joints
• See also: Tendon drive
• See also: Safety

Sources

1. RCC, Robot Sleeves, Bellows and Jackets: The Complete Guide to Robot Protection Components, Robot Sleeves, Bellows and Jackets: outer protectionSleeves, bellows and jackets protect the outer surface of the arm.
2. RCC, Robot Sleeves, Bellows and Jackets: The Complete Guide to Robot Protection Components, Robot Sleeves, Bellows and Jackets: sleeve vs bellowA sleeve covers a straight, largely static section of the arm, while a bellow is accordion-folded to move with a rotating or bending joint without restricting its travel.
3. Alex Rich, Locking ball and socket gooseneck system, Project logs: Loc-Line comparisonNo spring back - unlike the metal coil goosenecks, the ball and socket joints have no spring back.

Unverified: No opened maker or lab source in this pass establishes a universal home-built sleeve material, thickness or load rating. Treat a cosmetic shell as non-load-bearing until the specific build proves its clearance, wear and load path.

Use it on your project

teardown-apply: hold "Arm shell" (arm-shell) from the teardown at https://teardownatlas.com/robotics/ against my project

Paste it into a coding agent that has the teardown skills.

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