Harmonic Drive CSF and CSG Housed Gear Units Review: Specs, Price and Applications
Updated: 4 days ago
Harmonic Drive CSF-2UH and CSG-2UH combine cup-type strain-wave gearing, a housed mechanical assembly and a cross-roller output bearing with flange. CSF is the standard-torque choice and CSG the higher-torque choice; LW versions reduce unit mass in selected configurations. These are externally driven gear units, with a supplied output support arrangement that distinguishes them from bare 2A component sets.
Quick Verdict
Consider the 2UH families when an OEM wants zero-backlash reduction and an integrated output-bearing structure without designing a complete component-set housing. Choose CSF or CSG by matched torque-duty data, then compare standard and LW bearing stiffness as well as weight. The motor, drive, holding strategy and machine safety remain separate parts of the finished axis.
Harmonic Drive CSF and CSG Housed Gear Units at a Glance
Specification | Details |
Scope | Housed strain-wave gear unit, cross-roller output bearing and flange |
CSF-20-100-2UH | 40 Nm rated L10; 82 Nm repeated peak; 147 Nm momentary peak |
CSG-20-100-2UH | 52 Nm rated L10; 107 Nm repeated peak; 191 Nm momentary peak |
Size 20 standard mass | 0.98 kg for the above CSF and CSG units |
Size 20 LW mass | 0.64 kg for the corresponding CSF and CSG LW units |
Size 20 standard accuracy | 1 arcmin for the above ratio-100 entries |
Size 20 output moment stiffness | 12.8 × 10^4 Nm/rad standard; 10.5 × 10^4 Nm/rad LW |
Size 14 CSF accuracy example | CSF-14-50-2UH lists 1.5 arcmin, rather than a universal sub-one-arcminute value |
Electronics | Motor, feedback and servo drive selected separately |
Price | Request a quote for exact torque class, frame, ratio and lightweight option |
Design and Engineering Assessment
The size-20 ratio-100 pair demonstrates why the CSF and CSG labels matter. CSF lists 40 Nm rated L10, 82 Nm repeated peak and 147 Nm momentary peak; CSG lists 52, 107 and 191 Nm respectively. Both standard units list 0.98 kg. That gives a concrete 30% increase in rated torque for this matched example, without implying every machine can carry 30% more payload.
The lightweight comparison has another important boundary. At this same size and ratio, both torque classes retain their listed torque limits while mass changes from 0.98 kg to 0.64 kg. However, output moment stiffness changes from 12.8 to 10.5 × 10^4 Nm/rad. A claim of unchanged torque performance therefore should not be expanded into a claim that every mechanical characteristic is identical.
An output cross-roller bearing can carry combined loads, but the axial, radial and overturning limits remain distinct from transmitted torque. Calculate tooling loads at the actual distance from the output support. A long gripper or off-center fixture may impose a bearing moment that becomes the governing constraint before the gearing torque limit is reached.
Zero backlash describes the reduction mechanism, while transmission accuracy, repeatability and torsional deflection describe different aspects of motion. The size-20 ratio-100 examples list 1 arcmin standard accuracy, and the size-14 ratio-50 CSF lists 1.5 arcmin. Avoid turning a family headline into a guaranteed sub-one-arcminute accuracy for every model.
Choosing CSF or Higher-Torque CSG
Use a complete motion profile to compare torque demand with rated and peak limits. Include acceleration, deceleration, gravity, process forces and controlled stops. The CSG torque increase is useful only if motor output, thermal duty, gearing life and load-support requirements are also satisfied.
The source announcement describes relative service-life improvements, but that does not establish a fixed lifetime for any installed machine. Load spectrum, speed, lubrication, assembly and environment influence life. Compare both families under the same calculation assumptions rather than presenting a family percentage as guaranteed maintenance-free service.
Standard Housing Versus Lightweight LW
A lower reducer mass can help a moving wrist or upstream axis, but the relevant budget includes the motor, mounting hardware, brake, cables and tooling. Record the actual mass and center of gravity of the whole assembly. The verified size-20 mass reduction is about 35%; the old 20–30% or 30% family descriptions are not a universal value for all configurations.
Where a long cantilever makes output tilt important, compare output moment stiffness alongside torque stiffness. The size-20 standard/LW difference is a reason to calculate load-point deflection explicitly. Saving mass is beneficial only if the assembled axis still meets its stiffness, vibration and settling requirements.
How the Unit Differs From a Component Set
A CSF-2A or CSG-2A set gives the OEM the gearing elements to integrate into its own housing and support structure. A 2UH unit supplies a housed arrangement with a defined output-bearing and flange architecture. The products share a reduction principle but have different design responsibilities and purchased scope.
The GH servo-mount families add another interface approach with a motor-specific Quick Connect arrangement and different output options. Do not substitute a GH drawing or mass for a 2UH unit simply because the torque class and frame number match. Select the mechanical architecture before finalizing the motor mount.
Ratio, Motor and Feedback Integration
The gear unit has no native EtherCAT, CANopen or other control interface. Those features belong to the chosen motor and drive system. Verify motor shaft geometry, wave-generator connection, mounting alignment and allowable speed using the exact configuration and installation guidance.
A motor encoder observes motion on the input side of the reduction. It cannot directly measure every elastic movement between the reducer output and the tooling. If the application requires demanding load-side positioning, evaluate external measurement and the complete mechanical resonance behavior rather than adding encoder counts alone.
Commissioning and Mechanical Acceptance
Verify mounting-face condition, bolt retention and the load’s support geometry before tuning. Begin with restrained motion and check running current, temperature and unusual vibration. Then measure output positioning under representative loads in both directions, including thermal stabilization and settling.
Establish separate acceptance criteria for torque duty, output bearing behavior, accuracy and stopping. For gravity-loaded mechanisms, analyze holding and loss-of-power behavior with the selected brake and drive. A large gear ratio by itself is not a safety-rated brake or a guarantee against backdriving.
How the Three-Element Strain-Wave Mechanism Works
In the conventional fixed-circular-spline arrangement, an elliptical wave generator deforms the flexspline so that its teeth engage the circular spline across the ellipse. The tooth-count difference creates the reduction as the input rotates. This three-element principle underlies the CSF and CSG gearing discussed here; the housed 2UH unit adds the surrounding mechanical support and output-bearing architecture.
The general gearing portfolio also includes hollow-shaft and lightweight constructions with their own drawings and tables. Do not transfer a broad zero-backlash, accuracy or service-life headline to every family variant. Use the precise component-set, housed-unit or servo-mount code and its load, speed, bearing and accuracy data.
Applications and Selection
Precision robot, machine-tool and indexing mechanisms needing a configured gear unit with integrated output support.
For Harmonic Drive CSF and CSG Housed Gear Units, define the actual machine duty before selecting an ordering configuration. Include the required operating point, available installation space, environment and control interfaces. The specification table describes the product or family; the surrounding machine determines which of those features matters for the intended job.
Price and Value
Price: Request a quote for the exact configuration. Compare the product, compatible control equipment, required mechanical parts, cabling and commissioning as one installed system. A component price alone does not represent the cost of a working automation axis.
Evaluate an alternative against the same duty and acceptance criteria. Match the continuous operating requirement first, then compare transient capability, feedback, mechanical fit and support. This avoids choosing between superficially similar products whose ratings describe different operating conditions.
Pros and Cons
Advantages
Supplied cross-roller support and flange simplify the mechanical load path
Matched CSF and CSG tables provide a clear standard-versus-high-torque choice
LW options reduce moving mass without automatically reducing the listed gearing torque
Limitations
LW output moment stiffness can differ from the standard housing
Motor, drive, holding and safety functions remain external
Family accuracy and life headlines do not apply identically to every configuration
Who Should Consider Harmonic Drive CSF and CSG Housed Gear Units?
machine builders selecting a supported strain-wave reduction unit
Harmonic Drive CSF and CSG Housed Gear Units FAQ
What is included in a 2UH gear unit?
The family combines housed strain-wave gearing with a precision cross-roller output bearing and flange. The motor, drive and machine-specific accessories remain separate selections.
How do CSF and CSG differ?
CSF is the standard-torque family and CSG the higher-torque family. For size 20 at ratio 100, current rated L10 entries are 40 Nm for CSF and 52 Nm for CSG.
How much lighter is the LW size-20 example?
At ratio 100, current standard CSF and CSG units list 0.98 kg, while their LW counterparts list 0.64 kg. Compare other sizes separately and include the rest of the axis in the moving-mass budget.
Is LW stiffness identical to standard?
Not in every specification. The size-20 examples list output moment stiffness of 12.8 × 10^4 Nm/rad for standard and 10.5 × 10^4 Nm/rad for LW. Verify the complete selected model.
Does every unit have less than one arcminute accuracy?
No. The current CSF-14-50-2UH table lists 1.5 arcmin standard accuracy. Accuracy, backlash and repeatability should be read as separate configuration-specific specifications.
Can the bearing carry any load within the torque limit?
No. Radial force, axial force and overturning moment need separate evaluation, including their combined effect and the tooling’s distance from the bearing.
Does the gear unit include a control network?
No. Communication, feedback and safety functions belong to the selected motor-drive system. Mechanical gear reduction does not establish a particular fieldbus or safety rating.
What should be supplied for a quotation?
Provide the frame, ratio, CSF or CSG torque class, standard or LW construction, motor interface, duty cycle, bearing loads, environment and output-positioning requirements. Request current drawings and application confirmation.
Prices are indicative and may change. Confirm the final configuration, commercial terms and delivery schedule before ordering.
