Turn the vehicle duty into a wheel requirement
An integrated servo wheel cannot be selected from payload alone. The vehicle must generate enough tractive force to roll, climb, accelerate and overcome defined external resistance while staying within traction, thermal, braking and structural limits. Speed must be checked at the wheel, and the continuous duty must be separated from short-duration demand.
Use the servo and motion family to locate reviewed product records, the mobile handling robot solution to place the wheel inside the control architecture, and the industries hub to identify application conditions that may change the duty. Those pages are starting points; the final vehicle requirement remains subject to engineering review.
The official Kinco iWMC10411 specification sheet is the manufacturer source for one model record used below. The ISO 3691-4:2023 overview identifies the safety standard scope for driverless industrial trucks and their systems. A product sheet and a standard overview support different decisions; neither replaces the vehicle risk assessment or validation plan.
Collect inputs before applying formulas
Create a vehicle worksheet with one owner and one unit system. Record worst credible operating states as well as the nominal route. A maximum loaded climb, repeated shuttle cycle and emergency stop may each control a different part of the selection.
| Input group | Required evidence | Why it matters |
|---|---|---|
| Vehicle and load | Gross vehicle mass, payload range, load position, wheel loads | Sets force demand, traction and structural loading |
| Route | Floor material, joints, debris, ramps, transitions, curve radius | Changes rolling resistance, grade demand and wheel contact |
| Motion | Target speed, acceleration, deceleration, reversals, positioning need | Sets wheel speed, transient torque and control response |
| Architecture | Driven-wheel count, steering arrangement, wheel radius, gear path | Allocates tractive force and converts force to torque |
| Duty and environment | Cycle timeline, dwell, repeats, ambient temperature, enclosure | Determines continuous and thermal demand |
| Braking and safety | Stop categories, holding need, loss-of-power behavior, detection zones | Defines brake, control and validation boundaries |
Do not insert a generic rolling-resistance coefficient, efficiency or safety factor just to complete the sheet. Obtain values from tire and floor evidence, measured vehicle tests, the selected module documentation, or the responsible engineer. State every assumption and keep the sensitivity visible.
Calculate force, wheel torque and wheel speed
Build the force model as named contributions:
F_total = F_rolling + F_grade + F_acceleration + F_other
F_rolling represents tire, bearing and floor resistance. F_grade represents the component of weight along the ramp. F_acceleration represents the force required by the chosen motion profile. F_other captures reviewed loads such as a process force or cable drag. Keep direction and sign conventions explicit so downhill regeneration is not hidden inside an absolute value.
Allocate tractive force to the driven wheels according to the actual architecture. For an initial equal-share check:
T_wheel = F_total × wheel radius ÷ driven-wheel count
That expression is not the final motor selection. It must be adjusted through the documented mechanical path and checked against load distribution, traction, steering geometry and losses. Unequal wheel loads, caster behavior, floor transitions or control allocation can make equal sharing unrealistic.
Convert vehicle speed to wheel rotational speed from the rolling radius:
wheel rpm = vehicle speed ÷ (2 × π × wheel radius) × 60
Use the effective rolling radius justified for the tire and load, not only a nominal diameter. Then compare required torque and speed as an operating curve rather than as two unrelated maxima. The wheel must produce the required torque at the required speed for the required time.
Separate continuous demand from peak demand
Rated torque is the reference for sustained operation under the manufacturer’s stated conditions. Peak torque is a short-duration capability governed by the drive, motor, supply, thermal state and permitted overload profile. It should not be used as the continuous value for a long ramp or repeated acceleration.
Turn the route into a timeline: accelerate, travel, curve, climb, decelerate, hold, dwell and repeat. Associate force, speed and duration with each segment. Review the repeated cycle and the worst single event. A wheel that passes one acceleration may still overheat when that event repeats without enough cooling time.
Check the DC supply at the same time. Confirm operating voltage range, expected voltage under load, current capability, cable drop, protection, energy returned during deceleration and the response when the battery approaches its limits. Torque availability and braking behavior cannot be separated from the maintained power system.
Read published wheel data without turning it into payload data
The reviewed Kinco iWMC10411 record lists a 24–60 VDC integrated servo wheel with 40 N·m whole-machine rated torque, 99 N·m peak torque, 2.14 m/s rated linear speed and a 180 × 50 mm polyurethane tire. The reviewed iWMC10420 record lists the same voltage range and tire size, with 60 N·m rated torque, 150 N·m peak torque and 1.57 m/s rated linear speed.
| Published model record | Rated / peak torque | Rated linear speed | Tire |
|---|---|---|---|
| iWMC10411 | 40 / 99 N·m | 2.14 m/s | 180 × 50 mm |
| iWMC10420 | 60 / 150 N·m | 1.57 m/s | 180 × 50 mm |
These are manufacturer-published component fields, not a completed vehicle calculation. The “1 T” and “2 T” labels used in family positioning and site navigation are application groupings; they do not by themselves establish rated vehicle payload. Vehicle capacity remains dependent on wheel count, load distribution, grade, acceleration, braking, floor, duty, temperature, mounting and safety factors.
Do not mix module classes. Kinco iGMK lifting and rotary servo-reducer modules serve mechanism functions rather than the traction-wheel role described here. Their output-torque fields cannot be inserted into an iWMC drive-wheel calculation merely because both products are used on mobile robots.
Review traction, mechanics, braking and heat
Available motor torque does not guarantee usable tractive force. The wheel-to-floor contact must transmit the demand without unacceptable slip. Check normal force on each driven wheel throughout load placement, acceleration, braking and ramps. Review tire material, contamination, wear, floor transitions and steering state. A loss of contact or uneven loading can invalidate a torque calculation that looked sufficient on paper.
Verify radial and axial loads, mounting interface, fasteners, structure, bearing life and cable routing against the selected module documentation. Include shock and curb-like transitions only when they are part of the defined operating environment and supported by test evidence. Do not infer structural capacity from motor torque.
Braking has several meanings: controlled deceleration, regenerative energy handling, stopping after a fault, and holding on a grade or during power loss. Define each state and identify which electrical, mechanical and safety function owns it. A motor brake, if present in an exact order code, is not automatically the vehicle service brake or a complete safety function.
Thermal review must use the real cycle and environment. Consider repeated torque, low-speed operation, ambient temperature, enclosure, airflow, nearby heat sources and dwell. Record temperatures at representative locations during validation and compare them with the selected manufacturer limits and engineering acceptance criteria.
Validate the vehicle, not only the bench motor
Bench work should confirm communications, command scaling, direction, speed feedback, current and torque limits, brake control, fault reporting, power interruption and recovery. Vehicle tests then add real mass, load position, tires, floor, steering, battery behavior and route geometry.
Test normal and worst reviewed cases: empty and loaded travel, start on grade, repeated cycle, curve, floor transition, commanded stop, protective stop, communication loss, controller restart, low supply state and recovery. Measure the variables required by the acceptance plan rather than relying on operator impression. Keep results tied to vehicle configuration, software version, tire condition, load and test route.
Boundaries and limitations
This workflow organizes an initial wheel-sizing and validation process; it is not a vehicle rating, braking calculation, thermal model or safety validation. It intentionally provides no generic rolling-resistance, efficiency, service-factor, gradient or stopping-distance value.
- Published component torque and speed do not establish vehicle payload.
- Peak torque is not a continuous grade-climbing value.
- Traction, thermal behavior and load sharing require representative vehicle evidence.
- Certification or safety-function scope must be confirmed for the exact order code and complete system.
- Availability, documentation, price and lead time are confirmed at RFQ.
Next step: submit a reviewable vehicle duty
Send gross mass, load distribution, wheel layout, rolling radius, route grades, floor conditions, target motion profile, duty timeline, braking states, power-system data, environment and acceptance criteria through the application review form. The output should be a traceable shortlist and test plan, not a payload assumption.
Questions engineers ask
How do you calculate torque per driven wheel?
Add the reviewed rolling, grade, acceleration and other force contributions, multiply total tractive force by effective rolling radius, and allocate it across the driven wheels according to the actual architecture. Then account for the documented mechanical path, losses, load sharing and traction before comparing the result with product curves.
Can peak torque be used for continuous grade climbing?
No. Peak torque is a time-limited capability under stated drive and thermal conditions. A sustained climb must be checked against rated operation, vehicle speed, supply behavior, cooling, ambient temperature and the repeated route duty. Use the manufacturer limits for the exact order code.
Does a “1 T class” label equal rated vehicle payload?
No. It is an application grouping, not a stand-alone vehicle capacity. Payload depends on vehicle mass, wheel count, load distribution, floor, grade, acceleration, braking, duty, mounting, thermal limits, traction and the complete safety case.
Which inputs must be verified before RFQ?
Provide vehicle and payload mass, center and distribution of load, driven-wheel layout, rolling radius, route and floor, speed and acceleration profile, cycle timing, grade, braking states, battery and DC bus, temperature, communication, mounting, safety responsibilities and acceptance tests.