# Variable displacement hydraulic pumps

• I
• wolfy3
In summary, designing the input pump's pistons to be larger, moving 3 times the volume of the motor's pistons would allow for a 1:3 ratio at maximum displacement and an increase in output speed, but the input speed must also be increased in order for this to occur.
wolfy3
In online examples of variable displacement systems with swash-plate pumps, the input pump & motor are usually of equal size. When the constant RPM input pump is at full tilt (max displacement) the fixed displacement motor is at the same RPM for a 1:1 ratio, and when the pump is at no tilt (no displacement) the motor doesn't turn at all, 1:0 ratio. So, the output can reach the same speed or lower.

If a design requirement was that ratio is 1:3 at maximum displacement, would designing the input pump's pistons to be larger, moving 3 times the volume of the motor's pistons do the trick? I'm trying to design a hydrostatic system for a vehicle, but haven't seen any examples of where the output is speed can be faster than the input. Thanks in advance.

Yes, designing the input pump's pistons to be larger, moving 3 times the volume of the motor's pistons would achieve your goal of a 1:3 ratio at maximum displacement. However, it is important to note that the output speed can only be increased if you also increase the input speed. This means that, for example, if you have an input pump with a constant RPM of 1000, the output motor will be able to reach a maximum of 3000 RPM if the piston size is 3 times larger.

## 1. What is a variable displacement hydraulic pump?

A variable displacement hydraulic pump is a type of pump that is used to convert mechanical energy into hydraulic energy. It is designed to regulate the flow of fluid in a hydraulic system by adjusting the displacement of the pump.

## 2. How does a variable displacement hydraulic pump work?

A variable displacement hydraulic pump works by using a rotating mechanism to draw in and pressurize fluid, which is then sent through an outlet to power various hydraulic systems. The displacement of the pump can be adjusted to control the flow of fluid, making it a versatile and efficient choice for many applications.

## 3. What are the advantages of using a variable displacement hydraulic pump?

One of the main advantages of using a variable displacement hydraulic pump is its ability to adjust the flow of fluid to match the specific needs of a hydraulic system. This can lead to increased efficiency, reduced energy consumption, and improved performance. Additionally, these pumps are often more compact and lightweight compared to fixed displacement pumps, making them easier to install and maintain.

## 4. What are the different types of variable displacement hydraulic pumps?

There are two main types of variable displacement hydraulic pumps: axial piston pumps and swash plate pumps. Axial piston pumps use a series of pistons to adjust the displacement, while swash plate pumps use a tilting plate to vary the displacement. Both types have their own advantages and are suitable for different applications.

## 5. What are some common applications of variable displacement hydraulic pumps?

Variable displacement hydraulic pumps are used in a wide range of industries and applications, including construction, agriculture, manufacturing, and transportation. They are commonly used in hydraulic systems for heavy machinery, such as excavators, cranes, and forklifts. They are also used in industrial equipment, such as presses and machine tools, and in many other hydraulic systems that require variable flow control.

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