Case

Case Highlights

A European intralogistics provider was upgrading its pallet-handling AGVs used in large distribution centers. Existing drive units showed gear wear and noise issues after long 24/7 operation, which affected uptime and operator comfort.

DD Gear engineered a small-module planetary + helical drive gearset for the wheel-hub and in-line AGV drives. The new design fits the existing mounting envelope while delivering higher torque density, lower backlash, and quieter running, all of which are key requirements for AGV gearboxes.

Customer Background & Project Scope

• Customer industry: European supplier of warehouse automation systems (AGVs and AMRs for pallet and totes handling).

• Application:

  • Drive wheels of pallet AGVs (up to 600–800 kg load per vehicle).

  • In-line gear reducers for towing and conveyor-type mobile robots.

• Operating profile:

  • 24/7 logistics environment, with frequent stop–start and direction reversals.

  • Tight energy budgets to maximize vehicle runtime per charge.

• Project goals:

  • Increase service life and reduce unplanned downtime of the drive unit.

  • Improve noise level around AGVs to keep warehouses comfortable (targeting mid-50 dB range near the drive).

  • Maintain existing mounting and wheel dimensions for a smooth platform upgrade.

Challenges

1. Gear & bearing wear in existing drives

   • The previous spur-gear solution, combined with undersized bearings, showed pitting and wear after extended full-load operation.

   • Growing backlash and micro-vibration led to harsher starts and occasional encoder-error trips.

2. Noise in mixed human-robot areas

   • Measured sound pressure around some AGVs approached high-50s to low-60s dB near drive wheels, noticeable in packing and picking zones.

   • Customers asked for a quieter solution, especially for night shifts.

3. Space & integration constraints

   • The OEM wanted a drop-in upgrade: same wheel diameter, shaft locations, and mounting, so that existing vehicles and fleets could be retrofitted during scheduled service with minimal redesign.

   • Control logic and speed profiles had to remain almost unchanged.

DD Gear Solution

1. Drive Concept & Gear Design

• Planetary primary stage

  • DD Gear replaced the legacy spur reduction with a small-module planetary stage integrated into the wheel-hub.

  • Planetary drives are widely used in AGV/AMR wheels thanks to their high torque density, compact structure, low backlash and high load capacity, ideal for tight spaces and heavy loads.

• Helical final stage

  • A short helical output stage interfaces the planetary carrier to the wheel or shaft, providing smoother torque transfer and helping to reduce audible gear noise, consistent with helical gear advantages in low-noise gearboxes.

  • Helix angle and face width were optimized to keep axial forces within the capability of the existing bearing arrangement.

• Backlash and stiffness tuning

  • Target backlash limited to a few arc-minutes at the planetary stage, in line with precision planetary reducers used in automation and robotics.

  • System torsional stiffness improved, reducing oscillation in the closed-loop servo control at low speeds.

2. Materials & Heat Treatment

• Gears

  • Sun, planet and ring gears manufactured from carburizing steels such as 20MnCr5 / 18CrNiMo7-6, which are widely applied in high-load planetary and automotive gearboxes due to their combination of high case hardness and tough core.

  • Case depth set to ~0.8–1.2 mm depending on module and tooth load.

• Heat treatment & finishing

  • Carburizing + quenching followed by precision grinding of gear teeth where required to achieve low surface roughness and accurate flank geometry, as recommended under ISO 1328 accuracy practices.

  • Target surface hardness HRC 58–62 for contact fatigue resistance.

3. Manufacturing & Quality Control

• Accuracy grade

  • Tooth profile and lead controlled to ISO 1328 Grade 5–6, suitable for high-precision, high-duty industrial drives.

• Assembly & validation

  • Each batch checked for backlash, runout, and tooth contact patterns.

  • Sample drive units tested on a dedicated AGV drive rig for:

    • Continuous cycling under rated load to simulate >10,000 h operation.

    • Sound pressure level at 1 m and temperature rise at steady state.

Results

After implementing the DD Gear planetary + helical solution, the customer reported:

• Noise & comfort

  • Average sound pressure near the drive wheel dropped into the mid-50 dB range, supporting more comfortable operation in open warehouses, consistent with modern low-noise AGV drive targets.

• Reliability & maintenance

  • Gear and bearing-related failures decreased markedly; maintenance intervals for drive units were extended in line with the customer’s 24/7 operation goals.

  • Low backlash and higher stiffness improved drive stability on ramps and during tight maneuvers.

• Integration

  • The new drive design reused existing housings and wheel dimensions, allowing both new AGVs and existing fleets to adopt the upgraded gearset without structural changes.

  • The platform is now used as a base design for several load classes of AGVs.

Typical Technical Specifications

Case Summary

By combining planetary torque density, helical low-noise meshing, and ISO-controlled accuracy, DD Gear helped this intralogistics provider:

• Increase drive reliability in 24/7 warehouse operation.

• Lower noise levels in areas where people and robots share space.

• Upgrade an existing AGV platform without changing the frame or wheel layout.

This solution is suitable for AGVs, AMRs, warehouse shuttles and other mobile robots that need compact, quiet, and durable drive gearboxes.

Planning the next generation of warehouse AGVs or AMRs?

Contact DD Gear’s engineers to develop a custom small-module planetary drive for your mobile robots.