Who actually builds the joints? The humanoid actuator supplier landscape

Ask who makes humanoid robots and you get famous names – Tesla, Figure, Unitree, Apptronik. Ask who makes their joints and the answer runs through Zhejiang machine shops, one Japanese gear maker whose brand became the generic word, a Swiss screw specialist, and a German bearing giant betting it can sell half the robot. This is the supplier map as of September 2026.

Sources: Schaeffler; Leaderdrive company disclosures via 404K Research; 36Kr, 2026; shipment data cited by humanoid.guide, Feb 2026.

One joint, five markets

A humanoid joint is not one product. It’s a stack of five: a frameless torque motor, a precision reducer or screw, an encoder or two, a torque or force sensor, and the bearings that hold it all together – each with its own market, its own margins and its own incumbents. Stack them up and the money is startling. Schaeffler puts actuators at about 50 percent of a typical humanoid’s bill of materials; Hyundai Mobis has said roughly 60 percent of material cost. Either way, the joint business is the robot business.

The per-robot arithmetic explains the gold rush. An Optimus-class machine carries 28 structural actuators. Chinese supply-chain reporting counts 14 to 16 planetary roller screws in the legs and arms, around 14 harmonic reducers in the rotary joints, and about 20 coreless motors in each dexterous hand – before you count the 40-plus servo motors that need rare-earth magnets. Multiply by Tesla’s stated ambition of a million robots a year and single component categories become billion-dollar markets on their own.

Figure 1 · Animated · One rotary humanoid joint, cut open – and who sells each slice

Illustration: humanoid.guide. Schematic only – proportions are not to scale, and supplier lists name representative vendors per component, not confirmed design wins. Rotor animation is CSS-only and respects reduced-motion settings.

The Tesla chain runs through Zhejiang

The most watched supplier relationship in robotics is Sanhua Intelligent Control, a thermal-management specialist from Zhejiang that Chinese reporting describes as the sole assembler of Optimus linear actuators. Sanhua has denied the biggest reported order figures – a rumoured contract worth more than 5 billion yuan – yet the physical commitments are real: a 3.8 billion yuan robotics R&D and production campus in Hangzhou, and capacity that supply-chain trackers put around 500,000 actuator sets a year. Its neighbour Tuopu Group, a Tesla chassis supplier since 2016, covers the rotary side – joint modules and dexterous-hand motors – and is spending 5 billion yuan on a dedicated robot electric-drive base. Xusheng, a third long-time Tesla supplier, machines the joint housings and structural parts.

The screws are the contested ground. Optimus’s planetary roller screws initially came from GSA, the Swiss owner of Rollvis, at a reported $1,350 to $2,700 apiece. A crowd of Chinese challengers wants that line item: Xinjian Transmission is investing 2.6 billion yuan toward a stated goal of one million roller screws a year, Beite Technology was bought outright by Yangjie Technology for 2.218 billion yuan in cash in September 2024, Wuzhou Xinchun sells reverse planetary roller screws at roughly half Rollvis’s price, and Zhenyu Technology is reported as a qualifying candidate for the linear actuator line. None of this is officially confirmed by Tesla, which says little about its robot supply chain – the picture is assembled from investor disclosures, local-government filings and Chinese industry press.

Why it matters: analysts quoted by 36Kr argue that without Chinese suppliers an Optimus would cost $131,000 to build instead of $46,000 – and Tesla’s target is $20,000. Somewhere between 50 and 70 percent of humanoid manufacturing capability and core-component production sits in China today, which is why every Western robot program now has a sourcing strategy question attached to its engineering one.

Reducers: one incumbent, two challengers

For forty years the strain-wave gear market belonged to Harmonic Drive Systems of Japan – so completely that its trademark became the generic name for the component. Humanoids ended that comfort. Suzhou-based Leaderdrive, which J.P. Morgan credits with 30 to 40 percent of China’s harmonic reducer market, sold 425,158 reducers in 2025, up 72 percent on the year, on revenue of 570.7 million yuan; its customers include AgiBot and UBTech, and it is building toward an annualized capacity of 1.44 million units by the end of 2026. Green Harmonic, listed on Shanghai’s STAR Market, is the name most often tied to Optimus as a second reducer source alongside Harmonic Drive itself, at prices Chinese reporting puts at 40 to 60 percent of the Japanese equivalent.

A caution on the share numbers: they can’t all be true at once. Green Harmonic is variously credited with 25 percent and with over 60 percent of the Chinese market, Leaderdrive with 30 to 40 percent overall and with 80 to 90 percent of domestic humanoid programs specifically. The denominators differ – all reducers versus humanoid-only, units versus value – and several of the sources are investor notes with a position to talk. Treat every share figure in this market as directional. The volume and capacity numbers, which come from company disclosures, are the firmer ground, and they tell the story on their own.

Chart 1 · Leaderdrive harmonic reducer output: sold units vs the capacity being built

Source: Leaderdrive disclosures compiled by 404K Research, 2026. The 2024 figure is implied from the stated 72.48% growth to 425,158 units in 2025; the 2026 bar is announced capacity, not sales.

The supplier map

One table, the whole landscape. “Reported” means investor disclosures and industry press rather than an OEM announcement – most robot makers keep supplier configurations private.

Table 1 · Humanoid joint and actuator suppliers, September 2026

Sources: company disclosures; 36Kr; Optimusk supply-chain tracker, Sep 2026; Yicai Global; J.P. Morgan via humanoid.guide; Schaeffler and Astute Group; Black Scarab supplier guide. Figures are supplier-reported and move quickly.

The Western counterweight

Schaeffler is running the most complete counter-strategy. It bought the linear-motion maker Ewellix in 2022, premiered an integrated rotary actuator – planetary gearbox, motor, encoder and controller in one 60 to 250 N·m module – and signed on as preferred actuator supplier to the London start-up Humanoid, whose HMND 01 robots Schaeffler’s own factories will also deploy: the company plans a hundred humanoid systems across its global production network by 2030. The pitch is blunt. Schaeffler says its portfolio covers roughly half of a humanoid’s total actuator content, from bearing to controller, and that no other single Tier-1 can say the same. Hyundai Mobis is making the parallel move from the automotive side, signed to supply Boston Dynamics’ Atlas actuators once the robot enters mass production.

Below the Tier-1 level, the Western bench is deep but fragmented: maxon’s motors are documented inside Reachy 2’s Orbita joints; Kollmorgen, TQ RoboDrive and Moog sell the torque-dense frameless motors; RLS encoders sit in PAL Robotics’ platforms, with Renishaw and HEIDENHAIN alongside; Bota Systems and ATI cover force-torque sensing; SKF, NSK, THK and Timken supply the bearings. What’s missing in public is confirmation – outside Schaeffler-Humanoid, maxon-Reachy and Mobis-Atlas, almost no humanoid design win is officially announced, and every serious map of this market says so.

In-house today, outsourced tomorrow?

The best-known humanoids mostly don’t buy finished joints at all. Unitree builds its own quasi-direct-drive rotary actuators. Apptronik’s Apollo runs on in-house linear actuators the company says have been through more than 13 generations. Tesla designs every actuator itself and contracts out the manufacturing. US builders such as Figure and 1X cite supply security and China exposure as a reason to keep integration vertical. The question for the suppliers above is when – whether – that changes. Three things to watch:

• Second sources. Procurement advice in 2026 is to qualify a second actuator source before scaling – single-supplier joints are the industry’s biggest concentration risk, and dual-sourcing deals like the reported Harmonic Drive/Green Harmonic split on Optimus are the template.
• The price gap. Chinese harmonic reducers at 40 to 60 percent of Japanese prices and roller screws at half of Rollvis’s – if quality holds at C3-grade tolerances, the cost curve of every robot follows it down.
• Capacity vs demand. Roughly 13,000 humanoids shipped in 2025. The capacity being built – 1.44 million reducers here, a million screws there, 500,000 actuator sets – assumes a market one hundred times larger.

FAQ

Sources

• Schaeffler – Humanoid robots (actuators ≈50% of BOM; product families; hundred humanoids in own plants by 2030)
• 36Kr – Who will build the joints for Tesla’s million robots? (Sanhua, Tuopu, Xusheng, Xinjian, Beite; 14–16 screws per Optimus; $46k vs $131k cost argument)
• 36Kr – How many motors, reducers and lead screws are made in China? (≈28 actuators; ≈20 coreless motors per hand; Green Harmonic and Wuzhou Xinchun price comparisons)
• Optimusk – Tesla Optimus supply chain: who makes the parts? (BOM shares; ≈14 harmonic reducers; dual-sourcing; capacity figures; updated Sep 2026)
• humanoid.guide – Leaderdrive harmonic reducers rise on humanoid demand (J.P. Morgan share estimate; 2025 financials; 13,318 shipments in 2025)
• 404K Research – Leader Harmonic deep dive (425,158 units sold 2025; 1.44M capacity target; AgiBot and UBTech)
• Yicai Global – Three core supply chains of humanoid robots (T-chain composition; Keli Sensing)
• Astute Group – Humanoid robots are creating a new demand curve for precision actuators (Schaeffler–Humanoid partnership; 60–250 N·m; second-source advice)
• Black Scarab – Humanoid robot components and suppliers (Western supplier bench: maxon, Kollmorgen, TQ RoboDrive, RLS, Renishaw, HEIDENHAIN, Bota, ATI, SKF, NSK, THK)
• RobotToday – Zhenyu as Optimus linear actuator supplier candidate
• humanoid.guide – Linear vs rotary actuators in humanoid joints (Hyundai Mobis–Atlas; GSA/Rollvis sourcing; the architecture behind this supplier split)