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Tough Jobs Case Study: Grain Hopper

Hopper Motor Gets Cranking

Dirt, particulates, mud, grain, heat, cold, water and vibration. Can it get any uglier? These are just a few of the critical application considerations faced by this OEM. Their new product design for an automated hopper motor assembly retrofits commercial duty grain trailers and wagons, replacing the mechanical hand crank system. With this tough environmental challenge, they came to Groschopp for OEM gearmotor design expertise in executing their product concept.

The Challenge

This OEM, a premier supplier to the agricultural equipment industry, had a new product design for an automated grain hopper motor assembly to retrofit  trailers and wagons. The gearmotor specs included:

  • Ingress protection (IP) against dust and particulates (meet or exceed IP66 ratings)
  • High vibration, harsh environment package
  • High torque output for intermittent loads
  • 12 VDC, 100A power supply limitation

The Solution

  • Permanent magnet DC motor operating at 12 volts, 100 Amp current limit
  • High efficiency planetary speed reducer with strengthened output gears
  • Special corrosion protection features and rugged duty package enhancements

“During the initial stages of this project [Jared and I] kept going back to our experience with assemblies for trucks and buses” commented Commercial Product Manager, Loren Kamstra. “Designing for commercial agricultural equipment is not unlike extremely demanding automotive specifi cations— which allowed us to deliver a higher value solution.”

“We started by performing a complete MOTORTEC™ analysis to determine the exact speed/torque parameters,” added Matt Decker, Groschopp Mechanical Engineer. The OEM’s engineering team knows agricultural environment well, and required a rugged duty gearmotor for the extremes. “The overall physical design was equally critical to success as the performance,” Decker continued.

Tight space requirements and cost objectives led the team to a Right Angle (RA) DC gearmotor, which fit the application’s 12 VDC power supply, but exceeded the 100A available current – another tough design constraint. High starting torque and the DC power source made the PMDC a good motor choice, but the RA gearbox needed more power to provide the needed torque output. “Power loss relates to torque loss,” said Decker. “There wasn’t enough power available to compensate for the gearbox efficiency loss.”



“The final design gave them everything they wanted, plus a lot more,” said Decker. “Instead of the initial Right Angle gearbox design, for the final product we used a higher effienciency Planetary Speed Reducer with special material enhancements for the overall strength of the output gears.” Separate testing of the motor and speed reducer is a technique used by Groschopp to ‘push’ the limits of the components and prove out high torque performance.

Once the gearmotor performance ‘fit’ was determined, the harsh environmental specifications were tackled. “We drew from our experience with heavy automotive motor assemblies to quickly apply environmental protection techniques,” said Kamstra. “The gearmotors are built to IP66 standards, and withstand submersion testing at 1 meter—not a test requirement, but we felt important given this harsh agricultural environment.”


Grain Hopper: Groschopp Case Study