VRT™ - Variable Ratio Transmission

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Zero-Max VRTs (Variable Ratio Transmissions) are a simple, efficient, and cost-effective way to ensure accurate and consistent application rates for agricultural seeding and fertilizing equipment.  Our Adjustable Speed Drives have been used successfully in agricultural applications ranging from Air Seeders to Plot Seeders for decades.  Now, the newly optimized design of the VRT takes this to the next level by providing uniform seed dispersal in a more compact solution for these applications that require lower input speed and higher torque capacity. 

The VRT can provide a critical link between the control system and the mechanical seed distribution mechanism. This seeding system, often ground-driven from the wheels of the implement, will maintain seed placement accuracy even when the ground speed of the equipment changes. The VRT is designed to meet the performance requirements for today’s agricultural equipment. The mechanical drive of the VRT is encased in a secure heavyduty housing to resist dirt and debris, is pre-lubricated, and can withstand the harshest environments and climates.  As a result, the VRT can be operated with minimal or no maintenance.

The VRT is available in different sizes, with the input and output shafts on the same side or opposite sides of the housing, with the output shaft rotation in the clockwise or counter-clockwise direction, and with a variety of control options.  Speed adjustments are easily and precisely made via the control shaft.

VRT Benefits

Zero-Max has more than 70 years of experience with Adjustable Speed Drives.  Their use in the field as Infinitely Variable Ratio Transmissions for the Agriculture Industry also dates back decades. The newly optimized Zero-Max VRT line of solutions can ensure optimum performance, efficiency, and economy.
  • Compact.  Simple to handle, install, and operate.
  • Rugged and sealed housing. Can be installed in any mounting orientation.
  • Input speeds up to 300 RPM.
  • Output Torque up to 300 in-lbs.
  • Output speed ratios ~ 0 to 0.25:1 of input speed standard, up to 1:1 in special designs.
  • Infinitely adjustable ratio can be adjusted when idel or when running.
  • Easily, quickly, and precisely make speed adjustments.
  • Variable Ratio or Constant Ratio operation.
  • Factory lubricated.  Minimal to no maintenance.
  • Delivers constant torque throughout the speed range.
  • Speed and torque capabilities can be expanded by use of chain and sprocket ratios at the VRT shafts.
  • Special Designs available.





Contact Us

If you have questions about our VRT Variable Ratio Transmissions, would like a quotation, or if you would like to discuss a special design to meet your specific application needs, contact us to speak with one of our representatives.