12 Difference Between Hydraulic Motors And Hydraulic Pumps

calendarJul 13, 2022 · 6 min read  ·
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What Is Hydraulic Motor?

Hydraulic motors are rotary actuators that convert hydraulic or fluid energy into mechanical power. Hydraulic motors provide the force and supply the motion to move an external load. There are two common types of hydraulic motors:

  • Vane and gear motors
  • Piston and plunger motors

In addition, several other varieties exist that are less commonly used, including gerotor or gerolor (orbital or roller star) motors.

Hydraulic motors can either be fixed or variable-displacement and operate either bi-directionally or uni-directionally. Fixed-displacement motors drive a load at a constant speed while a constant input flow is provided.

Variable-displacement motors can offer varying flow rates by changing the displacement. Fixed-displacement motors provide constant torque; variable displacement designs provide variable torque and speed.

What You Need To Know About Hydraulic Motor

  • Hydraulic motor is a conversion device that converts the pressure energy of the liquid into mechanical energy and outputs torque and speed.
  • Hydraulic motor is connected with the load, such as gears, pulleys, sprockets etc whereas its main shaft will bear a higher radial load.
  • Hydraulic motor has the small suction and oil discharge port size.
  • The working speed of the hydraulic motor is relatively low.
  • The volumetric efficiency of hydraulic motors is lower than that of hydraulic pumps.
  • The internal leakage of hydraulic motor is larger than that of the hydraulic pump. This is due to the fact that the leakage direction is the same as that of motion.
  • The vane of the hydraulic motor is installed radially.
  • A hydraulic pump has a vacuum in its low pressure chamber, to ensure that it is able to be more efficient at oil absorption.
  • Hydraulic motors typically need negative and positive rotation which then causes the motor’s internal structure to be symmetrical.
  • Hydraulic motors should have large start-up torque to overcome static friction during start-up and sufficient start-up torque when the minimum fluctuation occurs.
  • Hydraulic motors are designed for construction work and mechanical supplements to provide convenient working experience.
  • There are two types of hydraulic motors; they are vane and gear motors; and piston and plunger motors.

    • What Is Hydraulic Pumps?

    A hydraulic pump is a mechanical source of power that converts mechanical power into hydraulic energy. It generates flow with enough power to overcome pressure induced by the load at the pump outlet.

    When a hydraulic pump operates, its mechanical action creates a vacuum at the pump inlet which allows atmospheric pressure to force liquid from the reservoir into the inlet line to the pump. Also, its mechanical action delivers the liquid to the pump outlet and forces it into the hydraulic system.  

    There are three types of hydraulic pumps:

    • Rotary vane pump
    • Screw pumps
    • Piston pumps.

    What You Need To Know About Hydraulic Pumps

  • The hydraulic pump is a conversion device that converts the mechanical energy of an electric motor into hydraulic energy. It outputs a flow rate and pressure.
  • Hydraulic pump is connected with the prime mover and the pump shaft has no additional radial load.
  • Hydraulic pump has a large oil suction port and a small oil discharge port.
  • The working speed of the hydraulic pump is relatively high.
  • The volumetric efficiency of hydraulic pump is relatively high when compared to hydraulic motors.
  • The internal leakage of hydraulic pump is smaller than that of the hydraulic motor.
  • The vane of the hydraulic pump must be installed diagonally.
  • Hydraulic pumps do not require a vacuum in its lower chamber.
  • Hydraulic pumps usually rotate in a single direction, which negates the need for positive and negative rotation.
  • Hydraulic motors have small start-up torque.
  • Hydraulic pumps are typically used for hydraulic drive systems.
  • There are three types of hydraulic pumps; they are Rotary vane pump, screw pumps and piston pumps.

    • Also Read: Difference Between Servo Motor And Stepper Motor

    Difference Between Hydraulic Motors And Hydraulic Pumps In Tabular Form

    BASIS OF COMPARISONHYDRAULIC MOTORSHYDRAULIC PUMP
    DescriptionHydraulic motor is a conversion device that converts the pressure energy of the liquid into mechanical energy and outputs torque and speed.  The hydraulic pump is a conversion device that converts the mechanical energy of an electric motor into hydraulic energy.
    ConnectionHydraulic motor is connected with the load, such as gears, pulleys, sprockets etc whereas its main shaft will bear a higher radial load.  Hydraulic pump is connected with the prime mover and the pump shaft has no additional radial load.  
    Oil SuctionHydraulic motor has the small suction and oil discharge port size.  Hydraulic pump has a large oil suction port and a small oil discharge port.  
    Working SpeedThe working speed of the hydraulic motor is relatively low.  The working speed of the hydraulic pump is relatively high.  
    Volumetric EfficiencyThe volumetric efficiency of hydraulic motors is lower than that of hydraulic pumps.  The volumetric efficiency of hydraulic pump is relatively high when compared to hydraulic motors.  
    Internal LeakageThe internal leakage of hydraulic motor is larger than that of the hydraulic pump. This is due to the fact that the leakage direction is the same as that of motion.  The internal leakage of hydraulic pump is smaller than that of the hydraulic motor.  
    VaneThe vane of the hydraulic motor is installed radially.  The vane of the hydraulic pump must be installed diagonally.  
    VacuumA hydraulic pump has a vacuum in its low pressure chamber, to ensure that it is able to be more efficient at oil absorption.  Hydraulic pumps do not require a vacuum in its lower chamber.  
    Positive &Positive RotationHydraulic motors typically need negative and positive rotation which then causes the motor’s internal structure to be symmetrical.  Hydraulic pumps usually rotate in a single direction, which negates the need for positive and negative rotation.  
    Start-up TorqueHydraulic motors should have large start-up torque to overcome static friction during start-up and sufficient start-up torque when the minimum fluctuation occurs.  Hydraulic motors have small start-up torque.  
    ApplicationHydraulic motors are designed for construction work and mechanical supplements to provide convenient working experience.  Hydraulic pumps are typically used for hydraulic drive systems.  
    Types  There are two types of hydraulic motors; they are vane and gear motors; and piston and plunger motors.  There are three types of hydraulic pumps; they are Rotary vane pump, screw pumps and piston pumps.  

    Also Read: Difference Between 2 Pole Motor And 4 Pole Motor

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