Fundamentals of Variable Displacement Pump Controls

Variable displacement pump controls play an integral role in hydraulic systems. Usually, they use different mechanisms to control fluid flow in many hydraulics components.

Depending on the design and function, you can choose pressure compensated, load sense, proportional throttle or torque limited options.

Fixed Displacement Pumps compare to Variable Displacement Pumps

Variables to Compare Fixed Displacement Pumps Variable Displacement Pumps
Displacement Capability ·       Depends on hydraulic energy

·       Exhibits a definite liquid flow hence the fluid rate is predictable

·       Uses hydraulic energy

·       No fixed fluid flow

·       Flow rate depends on the purpose and nature of application

Types of Variable Displacement Pump Control

Variable displacement pumps come in different types. These varieties have been developed to meet different tastes, purposes, and needs of different users.  Here are some common options:

Pressure Compensated Control

A pressure-compensated control system is a special type of variable displacement pump that controls flow rates in fluids.  Furthermore, it differs from other types of variable displacement pumps in terms of their working principles.

For instance, its working principle closely resembles that of a fixed displacement pump since they both have a fixed rate of flow of fluids during their operation. In this case, they consist of valves that are controlled by constant adjustment of pressure in the valve chamber.


This type of control system has a variety of benefits to the user. These include;

  • Reliability: They are a reliable type of variable displacement pump control since they can effectively perform under adverse pressure and temperatures.
  • Efficiency: They are termed efficient to use since they require minimal maintenance as opposed to other types of variable displacement pumps.
  • High performance: They have high-performance rates since they are designed with an internal mechanism of regulating adverse pressure to optimal effective performance.

Pressure Compensated Control

Types of Pressure Compensated Control Systems

There are different types of pressure-compensated control systems. They include but not limited to;

  • Proportional control systems: They are known for their ability to effectively control pressure to optimum levels thus increasing performance.
  • Load-sensing control systems: As opposed to proportional control systems, load-sensing systems are designed with sensors that aid in regulating pressure.
  • Pre-compensated control systems: They consist of a specially adapted orifice that significantly helps in regulating pressure.


  • May have reduced performance when extremely overloaded.
  • In-build limitations such as internal stops thus inhibiting maximum displacement.

Recommended Applications

Agriculture: These types of variable displacement pumps are commonly applied in agriculture. As such, most agricultural machines e.g. planters, and harvesters are designed to control hydraulic pressure.

Construction: Pressure-compensated controls are also applied in the field of construction in various ways. For instance, a variety of machines used in the field of construction such as mixers, heavy lorries, and excavators are fitted with these systems.

Manufacturing industry: Large machines used for manufacturing are designed with compensators to regulate their pressure.

Pressure Compensated Control Systems

Load Sense Compensators

This type of compensator is specially designed to meet applications that require low pressure and flow rates of fluid.


  • Less energy is required in their operation as compared to other types of sensors.
  • Are highly durable and hence require little maintenance.
  • Are highly reliable and efficient.


  • Can be in-economical to use especially when the choice for the component was poorly made.
  • Are sometimes slow since they depend on the engagement of the actuators.


  • Agriculture: They are commonly used in agricultural machines such as tractors and planters.
  • Construction machines.

Adjusting Load Sense using Proportional Throttle

Adjusting load sense using proportional throttle can be a complicated and demanding activity. This can be achieved by use of either a throttle or electronic flow control system.

As such, the electrical signal in this case is significantly used in differentiating the various hydraulic signals in the load sense. Additionally, this helps in the determination of the flow rate in a given type of pump.

In the same way, the electronic signal is also used to monitor and regulate the pressure in control systems remotely. In this instance, it allows remote monitoring of two distinct systems at the same time.

Horsepower/Torque Limiting Control

Torque limit control systems are vital systems used in variable displacement pumps. They help in regulating unexpected mechanical failures of these systems which might result in damage to significant components.

They are designed with features that enable them to automatically disconnect whenever the limit is exceeded. Due to this reason, they are commonly applied in various industrial applications such as textile, woodworking as well as robotics.

Open-loop, Variable-Displacement Piston Pumps

These types of piston pumps have a wide range of applications. For instance, they can be applied in construction, cleaning, and various agricultural applications. They provide various functions to the user such as load-sensing, pressure control, and electronic sensing.

Get in Touch With Us Now
Upload File
AddressDinghai Road 66#, Zhenhai, Ningbo, Zhejiang, China
Update cookies preferences
Scroll to Top