AGV Drive Wheel Gearbox Backlash Requirements
Estimate gearbox backlash from loaded wheel diameter, vehicle stopping accuracy, and your budget share.
Set the wheel error budget
Enter project values. The sliders offer a quick way to explore nearby cases.
Enter 50–500 mm. Use the loaded rolling diameter if known.
Enter 0.1–10 mm. Use the project requirement at the vehicle, not a generic navigation-system claim.
Enter 0–100%. The default 30% is only a starting assumption, not a universal safety factor; reserve the rest for sensing, tire, structure, and control.
Reversal does not apply a hidden multiplier. It changes what you should ask the supplier to measure.
Screening result
A geometry-based upper limit for the gearbox share of your stated wheel-position budget.
Compare against a rated gearbox specification
Ask for the maximum output backlash or lost motion under a stated measurement torque and operating condition. A catalog class or no-load backlash figure alone does not confirm the wheel-level result.
Next engineering check
For reversing duty, compare measured lost motion across torque reversal at representative load. Include the wheel hub, coupling, tire, and mounting in the vehicle-level test.
Model boundaries
- Uses circular travel at the wheel tread: Δs = π × D × θ / 360°.
- Treats the entered accuracy as an available vehicle-level position budget, then assigns the selected share to gearbox backlash. It conservatively compares the full backlash travel span with that one-sided budget.
- Does not model tire compression, wheel slip, structural flex, control behavior, load-dependent torsional deflection, or dynamic impact.
Key decisions
Start with wheel-level error
Convert the gearbox output angle to travel at the loaded wheel radius, then reserve only the share of the vehicle stopping tolerance assigned to the reducer. A larger wheel produces more tread travel for the same angular backlash.
Specify the measurement condition
Backlash and lost motion are different output-angle measures. Compare supplier values only when output location, torque range, temperature, and acceptance method are stated.
What standards do and do not establish
ISO 3691-4:2023 covers safety requirements and verification for driverless industrial trucks and their systems. This calculator does not derive an allowable backlash value from the standard. Define stopping accuracy from the vehicle task and validate the complete drive, sensing, and docking system. ISO's listing shows a draft replacement in development, so check the current edition before relying on the standard. See the ISO standard scope and VDI 2510 AGVS listing.
Engineering model & evidence
The tool converts an output angle to circular travel at the wheel tread. With wheel diameter D in millimeters and output backlash B in arcminutes:
Example using the calculator defaults: a 200 mm wheel, a ±1.0 mm stopping target, and a 30% reducer share allocate 0.300 mm to backlash. The geometric ceiling is 10.31 arcmin after rounding down to 0.01 arcmin. This is a reproducible model example, not a vehicle test or a universal requirement.
How angle becomes tread travel
- 1 arcmin = 1/60th of a degree.
- At a 200 mm diameter, 1 arcmin corresponds to about 0.029 mm of circular travel at the tread.
- Boundary: This is the geometric contribution from reducer output backlash only. It does not predict total vehicle stopping error or load-dependent deflection.
Supplier terminology and test conditions vary. For one documented example, the Schaeffler TPI 280 precision gearbox guide specifies output backlash at 0 Nm and evaluates lost motion over ±3% of rated torque. This is one manufacturer's method; state the required metric and test condition in the RFQ.
Compare the effect and specify the test
The table below is calculated from the circular-travel equation. It shows why the same gearbox angle has a different wheel-level effect as diameter changes; it is not an application tolerance or gearbox-class recommendation.
| Wheel diameter | 1 arcmin | 3 arcmin | 5 arcmin |
|---|---|---|---|
| 100 mm | 0.0145 mm | 0.0436 mm | 0.0727 mm |
| 200 mm | 0.0291 mm | 0.0873 mm | 0.1454 mm |
| 300 mm | 0.0436 mm | 0.1309 mm | 0.2182 mm |
| 500 mm | 0.0727 mm | 0.2182 mm | 0.3636 mm |
Use these conditions in an RFQ
A single arcminute value is not comparable unless suppliers quote the same output point and measurement condition.
- State the maximum output backlash or lost-motion value, its measurement torque range, and whether it is a typical or guaranteed maximum.
- Identify reducer output shaft, wheel hub, or tread as the measurement point; include any coupler, hub, and bearing play in the vehicle-level acceptance target.
- Provide continuous and peak wheel torque, speed, duty cycle, reversal frequency, temperature, and the required service life so the unit is checked for the actual load.
- Agree on the test fixture, direction-reversal sequence, measurement resolution, and acceptance record before approving samples.
If you already have a supplier value, include its metric, output location, torque range, and test method for an engineering review.
Request an engineering review| Decision item | This page provides | Confirm before release |
|---|---|---|
| Wheel geometry | Travel from output angle and entered diameter | Loaded rolling diameter and mounted wheel test |
| Reducer backlash | A limit from the user-entered error-budget share | Model-specific maximum, metric, output point, and test torque |
| Vehicle positioning | No vehicle-level accuracy prediction | Repeatability under payload, floor, speed, and reversal conditions |
| Price, lead time, and service life | Not estimated from public data | Matched supplier quotes and rated duty/life evidence |
Use this backlash screen alongside the broader AGV/AMR drive gearbox sizing guide, the AGV/AMR platform integration overview, and the gearbox load and life validation workflow. For a separate thermal review, see the AGV gearbox thermal sourcing guide.
Check the complete position chain
The calculator covers reducer output backlash converted to tread travel. It does not combine sensor resolution, controller behavior, tire deformation, wheel slip, hub or coupling play, structural compliance, or floor variation. Validate stopping and repeatability on the assembled vehicle under representative load and direction changes.
FAQ
What stopping accuracy should I enter?
Use the project requirement at the vehicle or docking point, stated as a tolerance around the target. Do not infer it from a navigation method label; payload, floor, approach, sensing, and acceptance conditions all matter.
Is gearbox backlash the same as lost motion?
No. Backlash is commonly specified around zero torque; lost motion is an output angle evaluated over a specified torque range. Schaeffler TPI 280, for example, evaluates lost motion over ±3% of rated torque. Supplier methods can differ, so request the metric, output location, and test condition.
Why is the budget share a separate input?
The wheel’s complete position error also includes sensing, tires, coupling and hub, structure, control, and floor effects. There is no universal percentage for the gearbox, so the design team must allocate its own error budget and document the tradeoff.
Does frequent direction reversal change the formula?
The geometric conversion is unchanged. Reversal makes clearance and lost-motion test conditions more relevant, so validate the mounted wheel assembly under representative torque and repeated direction changes.
Can the drive compensate for backlash in software?
Compensation may help for a known, repeatable motion profile, but it does not remove mechanical clearance. Confirm the result with the actual output feedback, controller, loads, and reversal sequence.
Should I use nominal or loaded wheel diameter?
Use the effective rolling diameter under the relevant load when available. Tire compression and wear can change rolling circumference and odometry; this calculator does not model either effect.
Does this result select a gearbox type?
No. Check backlash or lost motion alongside ratio, continuous and peak torque, thermal duty, radial and axial loads, mounting, service life, and supplier test data. See the AGV/AMR drive gearbox sizing guide.
Sources & limitations
- ISO 3691-4:2023: official standard page describes safety requirements and verification for driverless industrial trucks and their systems. The calculator is not a compliance assessment.
- VDI 2510: VDI 2510 AGVS listing. Consult the applicable edition and full text for the project; no requirement from the standard is encoded here.
- Backlash terminology: Schaeffler TPI 280 specifies output backlash at 0 Nm and evaluates lost motion over ±3% rated torque. This is one manufacturer's method; always use the selected gearbox manufacturer's current datasheet and test conditions for procurement.
- Calculation and currency: Wheel-travel examples are derived from circular geometry and arcminute conversion; the budget share is a user-entered design assumption, not a standard or industry benchmark. Sources checked 7 October 2026.
Validate Your Design
The estimate is a screening limit. Share the vehicle error budget, loaded wheel diameter, torque and reversal duty, plus the supplier's backlash or lost-motion test conditions for an engineering review.