EHR in a tractor – what it is, how it works, and whether it’s worth installing on older machines?

Table of contents:

1. EHR in a tractor – what it is and what it’s used for
2. How does the EHR system work? Components and control
3. Main advantages of electro-hydraulic hitch control
4. How to build a DIY EHR system? Installation and modifications

EHR in a tractor – what it is and what it’s used for

Many farmers switching to newer equipment ask themselves: “what is EHR in a tractor?” The abbreviation EHR comes from the German term *Elektronische Hubwerksregelung*, which means Electronic Hydraulic Hitch Control.

Put simply, EHR in a tractor replaces the manual manipulation of the hydraulic valve with electronic control. Instead of wrestling with a lever, the operator uses a convenient panel with knobs and buttons. The onboard computer processes these signals and controls the solenoid valves, which precisely set the position of the lift arms.

The operation of EHR is based on three main modes:

• Position control: maintaining a constant height of the implement above the ground (e.g., a fertilizer spreader).
• Draft control: maintaining a constant working resistance (essential when ploughing variable soils).
• Mixed control: a combination of both.

How does the EHR system work? Components and control

This system is far more advanced than standard hydraulics. To understand how EHR works, we need to look at its key components:

• Control panel: located in the cab, it allows you to set the working depth, drop speed, or maximum lift height.
• Controller (ECU): the “brain” of the system that processes data.
• Draft sensors: usually strain-gauge pins on the lower lift arms that measure the load from the implement.
• Position sensor: monitors the current height of the lift arms.
• Solenoid valves: they execute the controller’s commands, directing oil to the cylinders.

Thanks to this design, the system reacts to changing soil conditions within fractions of a second, automatically raising or lowering the plough to maintain the set engine load and ploughing depth.

Main advantages of electro-hydraulic hitch control

A tractor equipped with EHR offers not only convenience but also several other benefits:

• Transport damping: the EHR system automatically reduces vibrations from heavy implements suspended on the hitch during road travel. This protects the hydraulics and hitch components.
• Work precision: the ability to set the working depth with millimetre accuracy.
• Fender-mounted controls: exterior buttons make attaching implements easier – a standard feature in EHR systems.
• Quick lift: a single-button fast lift function for headland turns.

How to build a DIY EHR system? Installation and modifications

For owners of older machines (e.g., Ursus C-360, Zetor or older MTZ models), the topic of how to build an EHR system is very appealing. Factory systems are expensive, so farmers often look for alternatives.

Does a cheap EHR kit make sense?

Online, you can find products described as cheap EHR kits. However, caution is advised – these are often simple setups based on an electric actuator and relays, which have nothing to do with true draft or position control. They work, but compared to factory systems they are extremely basic.

For a DIY EHR kit to work properly, it should include a high-quality electrically controlled valve block with solenoids and a controller that, with sufficient knowledge of electronics and programming, can be built on microcontroller platforms such as Arduino. An essential component of such a system is also a lift-arm position sensor, for example a rotary potentiometer.

EHR for a tractor – what to keep in mind when building it yourself?

When choosing to build an EHR system yourself, safety and smooth operation must be top priorities. The system must include an emergency shut-off that allows instant disconnection of the pump or valves. Smooth operation is equally important – instead of simple on/off control, which causes jerky movements, proportional PWM control of the solenoid valves is necessary. When installing external controls on the fenders, ensure they are waterproof and protected against accidental activation during driving.

Once you understand the benefits of electro-hydraulic hitch control, making a decision when buying a new machine or upgrading an older one becomes easier, as this system has a real impact on work efficiency and operator comfort. Although building a budget DIY kit is possible, matching factory systems in terms of safety and precision requires advanced technical knowledge.