Common EOH Models for Application

Welcome to our article about EOH systems in machines! EOH stands for “electro-hydraulic,” which means using electricity and oil to make machines work. We use these systems in big machines like dump trucks and small ones like lift gates.

In this guide, we’ll talk about different kinds of EOH systems – some are simple and do just one thing, and others can do more. We’ll look at special models made by a company called Monarch and see how they are used in different machines.

So, let’s start exploring these amazing EOH systems and learn how they help machines do their jobs!

January 9, 2024
eoh models and applications guide


When working with dump trucks and trailers, it’s important to know about the different types of hydraulic systems they use. These systems help lift and lower heavy loads, which is a big part of what makes dump trucks and trailers useful.

The first thing to figure out is whether you have a “single-acting” or “double-acting” hydraulic system in your dump truck or trailer.

Single-Acting Systems

These are simpler systems. They use pressure to lift things up and then rely on gravity to bring them back down. If your hydraulic power unit has just one place to connect a hose (a pressure port), it’s a single-acting system. Some special types might have an extra port to send the fluid back to the tank. In Monarch single-acting systems, the motor works only when lifting things up.

Common single-acting units include:

Double-Acting Systems

These systems are a bit more complex. They can push to lift things up and also pull to bring them down. This means they need two places to connect hoses (two pressure ports). Monarch’s double-acting units make the motor work for both lifting and lowering.

Common double-acting units include:

Knowing whether your dump truck or trailer has a single-acting or double-acting system is really helpful for understanding how it works and for fixing any problems that might come up.


Lift gates on trucks and trailers are really important for loading and unloading heavy stuff easily. They use special systems called hydraulic systems to move up and down. Let’s find out what type of hydraulic system your lift gate has and how it works.

The next step is identifying if you have a single or double-acting configuration.

Single-Acting Lift Gates

These are the simpler kind. Imagine your lift gate going up like a balloon filling with air. Single-acting systems do just that – they push the lift gate up. Then, they rely on gravity, like a balloon deflating, to bring the gate back down. If your lift gate’s power unit has just one place to attach a hose, then it’s using a single-acting system. Some special kinds might have an extra spot to let the fluid flow back to the tank. Monarch’s single-acting units power the gate only when it’s going up.

Common single-acting units for lift gates include:

Double-Acting Lift Gates

These are a bit more advanced. They can make the lift gate go up and down using power, kind of like a robot arm. This is great for when you need more control, especially if you’re lowering something gently. These systems need two hose connection spots because they work in both directions. Monarch’s double-acting units use the motor to move the gate up and down.

Common double-acting units for lift gates include:


Bale spikes are handy tools used in agriculture to handle hay bales. They need a strong and controlled movement, and that’s where double-acting hydraulic systems come in.

Why Double-Acting Systems Are Essential for Bale Spikes

  • Double-Acting Systems in Action: Imagine needing to pick up a heavy hay bale and then carefully placing it down. Bale spikes do this with the help of double-acting hydraulic systems. These systems are strong because they apply pressure in two ways: they push out (extend) and pull back (retract). This dual action is perfect for the precise movements needed in farming tasks.
  • Two Pressure Ports for More Power: These systems have two places to connect hoses (called pressure ports) to do their job. This allows the bale spike to move in both directions with plenty of power. When the motor of a Monarch double-acting unit is on, it can move the bale spike up and down, giving you total control.

Common Double-Acting Units for Bale Spikes

For bale spikes, using the right hydraulic system is key. Monarch offers a few models that are well-suited for this job:

  • With a manual handle: M-310. This is great for when you want hands-on control.
  • With solenoid controls: M-3551, M-3554, and M-642. These models are fantastic for more automated control, where the press of a button does the work.

Knowing about these systems helps in choosing the right equipment for your farming needs, ensuring you get the job done efficiently and safely.


Bale beds are really important in farming for moving large items like hay bales. They use special systems called hydraulic circuits to work. These circuits can be set up in different ways, depending on what the farmer needs.

Understanding Hydraulic Circuits in Bale Beds

  • Multiple Circuits for Versatility: Bale beds have more than one hydraulic circuit. This means they can do different things at the same time, like lifting and moving bales in various directions. It’s like having a multi-tool for farming!
  • Stand-Alone or Pumping Stations: Some bale beds are stand-alone systems, doing their job on their own. Others are set up as pumping stations. These are like powerhouses, supplying pressure to valves that control the movement of the bale bed. Depending on what the bale bed manufacturer decides, these systems can have different setups.

Common Units for Bale Beds

Choosing the right hydraulic unit for a bale bed is crucial. Here are some common units used:

  • Pumping station with remote reservoir: M-326. This setup is great when the reservoir, the hydraulic fluid tank, is placed away from the main unit.
  • Pumping station with reservoir: M-304, M-3504. These units have the reservoir attached to them, making it a compact solution.
  • With solenoid controls: M-3530, M-3515. These are controlled electronically, often with the push of a button, making it easier to operate.

Knowing about these different hydraulic systems helps farmers pick the right setup for their bale beds, ensuring efficient and smooth operation on the farm.


Pumping stations are a key part of many machines, especially when it comes to handling liquids like oil or water. They’re like the heart of a hydraulic system, pumping fluid to where it’s needed.

12VDC Pumping Stations: The Power Behind the Scene

  • Primary Pumps for Limited Use: 12VDC pumping stations are often used when you don’t always need to run the pump. They’re great for short tasks, providing enough power to do the job without wasting energy.
  • Backup for Emergencies: These pumping stations are also super helpful as backups. In emergency situations, like when the main system fails, they can jump in to keep things running smoothly.
  • With or Without a Reservoir: Some pumping stations have a built-in reservoir, like a storage tank for the hydraulic fluid. Others have a remote reservoir, which means the tank is separate from the pump. Both types have their own advantages depending on what you need.

Common Pumping Station Models

It’s important to choose the right model for your needs. Here are some common ones:

  • Pumping station with remote reservoir: M-326. This model is good when you want to keep the fluid tank separate from the pump, which can be useful in certain setups.
  • Pumping station with reservoir: M-304, M-3504. These are more compact because they have the reservoir attached right to them, making them easier to install and manage.

Understanding the different types of pumping stations and their features can help you make the best choice for your specific requirements, whether it’s for industrial use, farming, or any other application.


Snow plow units are essential for clearing snow efficiently and safely. They come in various designs, each with different features to suit specific snow-clearing needs.

Exploring Different Snow Plow Designs and Their Hydraulic Systems

  • Single-Acting Circuit for Plow Lift: The single-acting circuit is the most common setup in snow plow units. This design is used for lifting the plow. A cool feature of many of these units is the “float” option. This allows the plow blade to move up and down slightly, following the ground’s shape. It works by letting the hydraulic oil flow freely between the unit and the cylinder, adjusting as the plow moves over bumps and dips.
  • Double-Acting Blade Angle Circuit: Some snow plows have a more complex system called a double-acting blade angle circuit. This is part of the same system but gives you more control over the angle of the blade, which is super helpful for clearing snow more effectively in different conditions.
  • V-Plow Configurations: Monarch also provides power units for V-plow configurations, which are more specific to certain applications. These are often used in heavy-duty snow-clearing jobs and require specialized hydraulic setups.

Common Models of Hydraulic Units for Snow Plows

Choosing the right hydraulic unit is key to a snow plow’s performance:

  • Single circuit units (for plow lift):
  • Lift/Angle units (for both lifting and angling the blade):
    • With manual handle: M-500. This gives you direct control over both actions.
    • With solenoid controls: M-3583, M-3593, M-684, M-693. These models offer precision and ease of use for adjusting both lift and angle.

Understanding the different types of hydraulic systems in snow plow units helps in choosing the right equipment, ensuring efficient snow clearing during those cold winter months.

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