Servo Motor FAQ — Torque, Application Sizing, Pricing & Selection

XQ-POWER covers 2.5 g micro servos through 1000 kg·cm class industrial actuators. The range spans micro (2.5–20 g), slim and low-profile, coreless, brushed standard, brushless digital, and high-torque industrial models at 130, 180, 250, 390, 700 and 1000 kg·cm. Because one catalogue covers everything from a 7.7 g fixed-wing surface servo to a robot-joint actuator, selection starts with your load rather than with a product line.

At XQ-POWER this is a duty-cycle decision rather than a price decision. Brushed is the lowest-cost option for light duty and short run time. Coreless gives the fastest response and lowest rotor inertia, which is why it dominates UAV flight surfaces. Brushless holds high torque continuously with far better heat rejection and service life. As a rule of thumb: if your duty cycle sits above roughly 30% at high torque, brushless is the only sensible choice.

The XQ-POWER sizing method starts from the load: torque (N·m) = force (N) × arm length (m), then convert — 1 N·m is about 10.2 kg·cm. Add a 30–50% margin for acceleration, friction and shock, and evaluate the requirement at your real supply voltage rather than the headline figure. Oversizing wastes money and slows the loop; undersizing burns the motor. Read the full method in our servo sizing notes.

In most cases yes — XQ-POWER servos use the same case footprints, the same PWM convention, the same mounting pattern. What actually differs is case size, spline count and torque at your operating voltage. Send us the model you are replacing together with your load and supply voltage, and we will name the direct equivalent rather than the nearest-looking part.

Yes. XQ-POWER builds sealed IP67 and IP68 versions for lawn-mowing robots, subsea ROV thrusters and marine deck equipment. The rating only holds while the cable gland and output seal are intact, so we specify the sealing method against your application rather than quoting an IP number on its own. See sealed servo solutions.

XQ-POWER standard models take a conventional PWM signal with a 1520 µs centre. Smart serial-bus models add RS485, CAN Bus and Modbus, so you can daisy-chain nodes and read back position, current and temperature. The RS460 58 kg·cm 12 V is our reference serial-bus unit; browse the smart serial-bus range for the full set.

Yes — XQ-POWER servos use PWM as the standard interface, so compatibility is native. On Arduino the stock Servo library drives them over a signal wire plus power, with no driver board and only minor code changes. On PX4 and ArduPilot they work as ordinary servo-channel outputs for fixed-wing, multirotor and car or boat models, with travel, centre and direction calibrated in the ground station. One exception: narrow-band models such as the BLS8120H expect a 760 µs centre pulse, so check your controller can output that band before you specify one.

No. On an XQ-POWER servo the controller sets the target by changing the high-level duration of the PWM pulse, and the servo's internal circuit converts that duration into a target position; the feedback loop then reports where the output actually is. In effect the pulse says where to go and the loop confirms arrival. The maximum usable travel is whatever the datasheet allows for that model — never command past it.

On an XQ-POWER datasheet the voltages are performance test points, not a hard ceiling. Running a model above its published voltage is possible on some variants by factory configuration — the driver board and thermal design, not the number on the page, set the real limit. Example: the BLS8175D is published at 8.4 V and 75 kg·cm; a 12 V supply can be arranged through configuration, with torque still 75 kg·cm. Torque is not set by voltage alone; raising it requires a driver board change. Confirm the upper limit for your specific model with us before exceeding the published figure.

Yes — XQ-POWER digital servos accept user PID tuning, so proportional, integral and derivative terms can be matched to the inertia your mechanism actually presents [via the XQ-P8001 programmer]. A damping routine optimised for high-inertia loads suppresses angle overshoot and stops the unit hunting after it reaches setpoint, which shortens commissioning on robot-arm dynamics. Report the load and we will send starting values.

Neither by default — XQ-POWER makes stall behaviour configurable. The servo monitors current in real time, and once the stall threshold is reached it can be set either to hold position at full torque or to go slack and release the load. Protection trips before the winding is damaged, and normal operation resumes once the jam is cleared. That is precisely what collision protection on automated equipment needs.

They are different performance points in the XQ-POWER 8-series, not a base model and an uprated one. The 8140H is rated at 40 kg·cm and moves 60° in 0.07 s; the 8120H is rated at 20 kg·cm and moves 60° in 0.03 s. Twice the torque, about 2.33× the transit time — slower by design. Different motor windings, internal ratios and gear stages produce that split even when the housing, gear material and output shaft look identical. Choose the 8140H where output force matters and a slower response is acceptable; choose the 8120H for fast, lightly loaded axes such as helicopter tail-rotor control.

XQ-POWER brushless models typically move 60° in 0.07–0.12 s; high-speed variants reach 0.03–0.05 s per 60°. Unloaded, the tuned PID loop and magnetic feedback hold position with no visible jitter. Within rated torque there is a small transient at impact that the loop suppresses quickly, rather than a sustained oscillation. High-torque models get additional drive filtering against gear backlash, and every unit is checked for positioning stability before it ships.

On every XQ-POWER datasheet, rated torque is the continuous figure — the load the servo can hold long term with temperature rise and current inside safe limits and no damage to gears or driver board. That is the number to design to. Stall torque is the peak delivered the instant the shaft is locked; it is short-duration only, and a sustained stall overheats the unit and wears the gears. Every figure is measured at the voltage printed beside it — commonly 6.0 V or 7.4 V for RC servos, 8.4 V, 12 V or 16.8 V for HV brushless, higher for industrial models — at standard room temperature. See maximum torque in detail.

The XQ-POWER servo uses fast position sampling and a short closed-loop path, so short-cycle back-and-forth motion is handled well. End-to-end response is not the servo alone, though: load inertia, drive-train stiffness, the host's command period and the acceleration profile all set the ceiling. In continuous cycling, accumulated dynamic change in the mechanism can shift response over time — run a long-duration test on the complete assembly to confirm no lag develops.

To stop an XQ-POWER servo resonating, identify the resonance band first with a frequency sweep on the actual mechanism, then attack it on three fronts: keep the operating band away from the resonance, retune the control loop (gain and filtering), and stiffen the mount. Supply stability matters too, because rail sag shifts loop behaviour. Because the fix depends on model, load and controller, verify it on your real duty cycle rather than a bench run.

It can. On an XQ-POWER servo a strong RF field couples into the control line, the power leads or the internal circuit and may produce brief jitter, position offset or control faults. Actual risk depends on the model's EMC performance, transmitter power, frequency, distance and wiring. Mitigate by moving the antenna away from the servo, shortening the control run, shielding the signal line and keeping the supply clean. Where the RF environment is aggressive, confirm with an EMC test on the real installation.

On an XQ-POWER servo it depends on wiring, signal integrity and EMI rather than on length alone. With a long run, make sure the controller and the servo share a solid ground, and route the PWM line away from high-current power cables and strong noise sources. Where the run is very long or the electrical environment is noisy, confirm the waveform and the servo's behaviour by test instead of assuming. Powering multiple servos has its own rules — see our note on multi-servo power and real response speed.

Most XQ-POWER models use a full aluminium case; some use high-strength engineering plastic. High-torque brushless models ship with a CNC one-piece aluminium housing as standard. Aluminium conducts heat far better than plastic, pulling heat out of the motor and driver board under continuous load — which lowers internal temperature rise and directly reduces torque fade and component ageing. The same housing adds structural rigidity against shock and deformation, which is what RC monster trucks, helicopter linkages and robot arms actually need. The engineering detail is in our heat dissipation note.

On an XQ-POWER servo, temperature rise depends on load, supply voltage, motion frequency, ambient temperature and how the unit is mounted. Four things address it: an over-temperature protection routine in the servo firmware, an aluminium case for heat rejection, metal gears that carry the load, and brushless motors that generate less wear heat. For continuous-load applications we verify your actual duty cycle first and recommend from that, not from the peak torque figure alone.

XQ-POWER built a metal horn for the 8-series because plastic horns deform elastically, wear at the spline and the linkage hole, and lose repeatability under long cyclic load — which surfaces as inconsistent centring, a parameter customers test closely. Metal horns are stiffer, deflect less at the same load and hold the linkage geometry. The 8-series is used heavily on helicopter and UAV control surfaces where load varies continuously, so a horn that survives the cycle count and returns to centre is part of the performance rather than an accessory. Metal horns are supplied with the 8-series.

The XQ-POWER design uses wide-temperature electronics, magnetic feedback and a low-backlash drive train, which keeps torque and positioning stable across a broad range. How much drift you actually see also depends on the temperature extremes, the rate of change, the load and the number of cycles. For extreme environments, validate the whole assembly under your real profile — room-temperature datasheet figures are not a substitute. See thermal drift under sustained high load.

It can. In an XQ-POWER servo, if moisture is already inside and the case drops below the dew point, condensate forms and raises the risk of leakage current, signal faults or a short. Actual protection depends on the model's sealing, the board's conformal coating and the environment. Avoid sharp temperature swings in high humidity; where condensation is suspected, power down, let the unit return to ambient and confirm it is dry before re-powering. For wide-temperature or high-humidity duty, run a humidity-cycle test on the real assembly.

XQ-POWER high-end models use a non-contact magnetic encoder, so there is no carbon track to wear and no intermittent contact point that can skip counts. Compared with a potentiometer, the position signal is far less prone to drift in continuous vibration and dust, and zero-point offset stays small after long reciprocating duty. Under high-g shock, whether a specific unit holds its absolute zero depends on that model's mechanical design and how it is mounted — for those applications we ask for a shock test on your fixture. The technology is covered in our magnetic encoder overview.

The XQ-POWER high-torque models use hardened steel gear sets with ground, surface-hardened tooth flanks, which resist the alternating loads vibration imposes. With correct sizing and an adequate torque margin, stripping is not expected in long service. It still happens when the margin is too thin, the linkage binds, or the servo drives into a mechanical stop — those turn vibration into impact. We run vibration and shock ageing before shipping; in service we recommend generous margin, mechanical end stops and periodic checks of mounting, backlash and bearings. Background on gear strength and design.

XQ-POWER holds CE, UKCA, FCC, RoHS, EN71, CPC and an ASTM test report — all downloadable as PDFs from our About page, and copies can be attached to a formal quotation. CE and UKCA cover the European and UK markets; EN71, CPC and the ASTM report cover toy and consumer-safety compliance for the RC side of the range. Tell us the market you are selling into and we will confirm which documents apply.

Every XQ-POWER actuator is powered continuously, cycled through temperature extremes, shaken on three axes and struck with controlled shock pulses before it is released for shipping. The 2,000-hour endurance report is published per model — the S9150D white paper is a free PDF on its product page. Read how the aging, vibration and shock programme is structured.

XQ-POWER qualifies every servo at four gates: incoming component inspection, full-load ageing, three-axis vibration plus shock, and a final torque, current and backlash check on the assembled unit. Units outside the inspection standard are scrapped rather than reworked into a lower grade. The inspection specification PDF publishes the acceptance values for each model, so you can audit against the same numbers we do.

Yes — XQ-POWER has delivered 1,000+ OEM/ODM programmes since 2010. That covers private label, mechanical modification, firmware behaviour and full custom development. We are the original manufacturer, so the tooling and the engineers are in-house rather than subcontracted, which is why a specification change can be quoted without a third party in the loop.

XQ-POWER can customise housing colour and marking, cable length and connector, output shaft and spline, gear ratio, case machining and mounting ears, firmware defaults (centre, travel, dead band, direction, PID), packaging and labelling. Anything touching the gear train or the magnetics needs a tooling review first, because it changes torque, backlash or thermal behaviour and has to be re-validated rather than simply re-drawn.

XQ-POWER needs five things to start: target torque and speed at your operating voltage, duty cycle and expected service life, envelope and mounting constraints, the interface you need (PWM, RS485 or CAN), and annual volume. With those we return a feasibility answer and a tooling quote. If your volume is still uncertain, say so — we would rather quote a range than have you commit to a number you cannot hold.

Yes — XQ-POWER signs an NDA before any drawing or specification changes hands. Send your template or ask for ours. We would rather start with the NDA than have you describe a mechanism you are not ready to disclose.

Send XQ-POWER the model, quantity and destination country through the inquiry form or WhatsApp. There is no online checkout on this site by design — industrial volumes are quoted, not listed, because price depends on quantity, configuration and shipping terms. Expect a reply within 24–48 hours; if your timing is tight, say so and it moves to the front of the queue.

XQ-POWER ships samples by DHL, FedEx or UPS, typically 3–7 days door to door. Batch orders go by air or sea freight, consolidated from Shenzhen. In-stock standard samples dispatch within 48 hours of order confirmation. For custom products, the dispatch date is set when the order is confirmed, because build time depends on the change.

XQ-POWER exports worldwide. Quotations can be issued EXW, FOB or CIF — tell us which you need and we quote on that basis. Import duty and local clearance are the buyer's responsibility unless we agree DDP in writing. For regulated markets, tell us at quotation stage so the correct documents travel with the shipment.

Yes — at XQ-POWER the same engineers who design the actuator answer the questions, which is the whole point of buying from a manufacturer. We routinely review duty cycles, power distribution, inertia matching and protocol timing with customers before they commit to tooling. Support is in English and Chinese, and starting values for PID and travel are supplied with the drives.

Send XQ-POWER your load, geometry, voltage and duty cycle and we will return a shortlist with the reasoning — not just a part number. This is free, and it is the fastest way to avoid the two expensive mistakes: oversizing an axis and paying for torque you cannot use, or sizing on peak torque and discovering the thermal limit in month three.

A factory. Shenzhen XQ-Power Technology Co., Ltd., founded 2010, with our own plant in Longgang District, Shenzhen — 2.47 acres, 300+ employees and 800,000 units monthly capacity. Magnetic encoders, gear trains and brushless drives are built in-house. Company detail is on the About page.

XQ-POWER replies to an inquiry within 24–48 hours. Technical questions that need an engineer's input may take one exchange longer, and we will tell you when that is the case rather than sending a holding reply.

XQ-POWER publishes no single list price, because the range runs from a 2.5 g micro servo to a 1,000 kg·cm industrial actuator. Indicative FOB Shenzhen bands at 100–500 pieces: standard brushed and micro servos roughly USD 6–35; brushless HV models in the 20–60 kg·cm class USD 35–120; aluminium-case industrial actuators at 130–390 kg·cm USD 120–450; and the 700–1,000 kg·cm class USD 450–1,200. Add 10–25% for OEM changes. Every figure moves with quantity, configuration and Incoterm, so treat these as a budget band and ask for a quotation on the exact model.

One piece. XQ-POWER quotes single units for evaluation, and standard in-stock models dispatch within 48 hours of confirmation. An MOQ only appears when the order involves a change: a private-label run typically starts at 100–300 pieces depending on the marking method, and a mechanical or firmware change starts at 500, because tooling and re-validation have to be amortised. If your volume is still uncertain, say so at quotation stage — a staged first batch is usually cheaper than committing to a number you cannot hold.

Yes. XQ-POWER supplies paid samples for evaluation, and for a genuine programme the sample cost is normally credited against the first production order. Standard samples ship in 3–7 days by DHL, FedEx or UPS. For a sample that has to prove something specific — thermal behaviour, resonance, sealing — tell us the test you intend to run, because the right configuration for a long-duration duty cycle is not the one for a shock test.

Tooling for a housing or output-shaft change typically runs from a few hundred to a few thousand USD depending on whether it is a machining revision or a new mould; a firmware change usually carries no tooling charge. XQ-POWER quotes tooling separately from unit price so you can see exactly what you are paying for. Ownership normally stays with XQ-POWER as the manufacturing party — if your programme requires the tooling to be yours or transferable, raise it before the quotation, not after.

Standard in-stock samples dispatch within 48 hours of confirmation and arrive in 3–7 days by express. Standard batch orders typically run 1–3 weeks depending on quantity and stock position. A custom programme adds tooling and first-article approval, commonly 3–6 weeks before the first production batch, and the dispatch date is fixed when the order is confirmed because build time depends on the change. XQ-POWER quotes a date rather than an average, and tells you if the date moves.

T/T is standard: a deposit on order confirmation and the balance before shipment, with the split set by order value and whether it is a first order. PayPal is accepted for samples and small orders, and L/C is available for larger batch orders. XQ-POWER does not ship on open account for a first order, but terms can be reviewed once there is a payment history — ask rather than assume.

An AGV steering axle is a holding-torque problem at near-zero speed, not a speed problem — size it on the scrub torque needed to turn a loaded wheel in place, then double it. XQ-POWER industrial models from 130 to 390 kg·cm at 12 V or 24 V cover most 300–1,500 kg platforms; step up to the 700 or 1,000 kg·cm class above that. Specify CAN Bus or RS485 rather than PWM when the steering node sits on a vehicle bus, and ask for absolute position feedback so the wheel angle is known at power-up without a homing move. See AGV steering solutions.

Those are two different problems. A robot arm joint wants backdrivability and a torque constant that lets you estimate contact force from motor current; XQ-POWER serial-bus models report current and temperature over RS485 or CAN, which is what makes that estimate possible without an added sensor. A humanoid actuator wants torque density in a flat envelope, so the low-profile and 130–250 kg·cm brushless frames are the usual starting point. In both cases the limiting factor is thermal rather than peak torque — specify the duty cycle before you specify the model.

XQ-POWER supplies sealed IP67 and IP68 versions for lawn-mowing robots specifically, because the failure mode is not rain falling on the case — it is the blade deck throwing water and grass up into the output seal. Size the drive on continuous cutting torque at your wheel diameter, add roughly 50% for wet grass, and specify the sealing method against the deck geometry rather than against an IP number on its own. Blade motor and drive wheels normally need different ratings; quote them as two specifications, not one.

Only if it is specified as one. A standard XQ-POWER servo is an enclosed actuator with an output spline, while AGV and AMR traction needs a wheel assembly rated on continuous wheel torque and radial load at the tyre. Ask for the AGV steering-wheel configuration and size on the loaded-wheel scrub torque plus the radial load from platform weight — radial load is the number most often missed in these specifications, and the one that decides bearing life. Custom output-shaft and housing geometry is quoted as an OEM programme.

A gimbal axis is judged on minimum resolvable motion and on how quietly the loop holds, not on torque — most gimbal axes are heavily over-torqued and under-damped. XQ-POWER coreless and slim frames suit this because rotor inertia is low, so the loop can be tuned fast without overshoot, and the magnetic encoder gives a clean position signal down to small angles. Specify payload inertia and required angular resolution rather than a torque figure; those two numbers decide the frame size.

Different product category, so compare carefully. Leadshine and Moons build servo drives and motors for general motion control — you buy a motor and a drive, then design the mechanics around them. XQ-POWER builds integrated actuators: motor, gear train, encoder, driver and case in one sealed unit with an output spline. If your machine already has a transmission, a drive-plus-motor brand is the better fit; if you would rather bolt on a sealed actuator and skip the gearbox design, that is what XQ-POWER is built for. Ask both for continuous torque at your duty cycle, not peak.

On specification the gap is narrowest on torque density and widest on documentation depth. maxon and Faulhaber publish full motor constants, thermal models and life curves you can design against; XQ-POWER publishes torque, speed, voltage and a 2,000-hour endurance report per model, which covers most integration work but not every corner case. On price and lead time the difference is large. If your application is safety-certified or medical, the documentation burden usually decides it; for industrial and robotics volume, XQ-POWER is the practical choice.

Comparable on the numbers a UAV integrator actually checks: transit speed, torque at 7.4 V or 8.4 V, centring repeatability and case rigidity. Where XQ-POWER differs is range breadth — one catalogue runs from a 2.5 g indoor servo to a 1,000 kg·cm industrial actuator, so a UAV programme and its ground-support equipment can come from one supplier. Where the established RC brands are stronger is distributor stock and local warranty in hobby channels. For a commercial UAV programme buying direct in volume, the trade is direct engineering access against shelf availability.

You lose margin, not features. An unbranded unit is usually built to a lower torque margin and a thinner gear section, so it still meets its headline number on a bench and fails earlier under shock, binding or a mechanical stop. What goes first is thermal headroom — the cheap unit reaches its limit sooner and fades torque — and then the gear train. XQ-POWER's position is that the endurance test is the specification: ask any supplier, cheap or not, for the 2,000-hour report on the exact model and read what the failure mode was. Background in our technical guide.