What is an HST Plus transmission?

An HST Plus transmission is a sophisticated system developed by Kubota that significantly enhances the control, power, and efficiency of tractors. The term “HST” stands for Hydrostatic Transmission, a type of transmission found in certain types of heavy machinery and vehicles, especially tractors. Hydrostatic transmissions offer the ability to adjust speed while maintaining a constant rate of power. Kubota’s “HST PLUS” system takes this concept a step further, combining traditional HST with modern electronic controls and advanced features for a highly customizable, responsive, and efficient transmission system.

Electronic Control Unit

The foundation of the HST Plus system is a variable displacement oil pump and a two stage motor, governed by an Electronic Control Unit (ECU). The oil pump supplies oil to the motor, which then generates torque to drive the wheels.  The ECU controls this flow based on the engine’s RPMs and the load on the tractor, optimizing power and fuel efficiency.

Stall Guard

One notable feature of the HST Plus system is the “Stall Guard”. This advanced function detects when the engine RPMs are dropping dangerously low, which usually precedes a stall, and it automatically reduces the flow of oil to the motor. This reduces the load on the engine and prevents stalling, ensuring uninterrupted operation even under heavy loads or tough conditions.

Hydro Dual-Speed

Another innovative feature of the HST Plus system is the “Hydro Dual Speed (H-DS). AS the mane implies, this function offers two speed ranges, which can be manually controlled by the operator. However, in automatic mode, the ECU takes over, shifting the speed ranges based on engine RPMS and load. This automated shifting optimizes engine performance and helps maintain consistent speed and power.

HST Response Control

In addition to these, the HST Plus system also includes the “HST Response Control”. This feature allows the operator to adjust the responsiveness of the transmission to the HST pedal. Depending on the setting , the tractor can respond more rapidly or more gradually to the pedal input. This enables precise control of the tractor’s movement, which is particularly useful in tasks that require finesse, like landscaping or maneuvering around obstacles.

Auto Throttle Advance

Another noteworthy feature of HST Plus is the “Auto Throttle Advance” This functionality synchronizes the engine throttle with the HST pedal. This means that the pedal not only controls the transmission, but also adjusts the engine’s RPMs. This harmonized control provides a smooth and efficient operating experience.

HST Plus Advantages

The HST Plus transmission’s advantages are manifold. For instance, the Stall Guard feature provides the operator with peace of mind, knowing that the tractor won’t stall mid-operation. The Hydro Dual-Speed feature provides versatility in various terrains and work scenarios, enabling optimal power and speed. The HST Response Control and Auto Throttle Advance improve overall control, leading to better precision and a more comfortable operating experience.


The HST Plus transmission is available on a number of Kubota tractors, catering to a broad spectrum of needs, from homeowners and agricultural producers to professional landscapers and ground maintenance specialists.


The HST Plus transmission system exemplifies the blending of traditional mechanical systems with modern electronic controls, offering an unprecedented degree of control and efficiency. Whether for agriculture, landscaping, or any task requiring a heavy-duty vehicle, the HST Plus transmission stands out as a versatile, powerful, and user-friendly solution.  With its suite of intelligent features and optimization, it sets a new standard in the tractor industry for ease of operation and efficiency.

Where to Go for More Information

If you’d like to learn more about Kubota products or the HST Plus transmission in particular, speak to one of the experts here at Mission Valley Kubota. We are authorized distributors for Kubota, Land Pride, Gearmore, Towmaster Trailers, Paladin, and Echo Outdoor Power Equipment, making us one of the area’s best resources for rugged farming and construction equipment. We’re committed to putting our customers first, which allows us to provide our clients with tough and durable equipment for a variety of uses. In addition to offering new and used equipment, we have a staff of highly trained and experienced technicians that can complete any repairs or preventive maintenance you may need.

We’re conveniently located in San Jose on Brokaw Road, making us easily accessible from both Interstate 880 and Highway 101. If you would like more information about the products and services we offer, give us a call at 888-284-7471, or stop by and see us.

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