Hydraulic Pump


Categories : Process Instrument Pumps


Checkball Pump Operation

Dynex High Pressure Pumps for Difficult Conditions

Individual piston check valves direct flow from the inlet side of the pump to the outlet port in these high pressure hydraulic pumps. The positive-seating checkball valves provide better wear and high volumetric efficiency, especially at high pressure. These checkball pumps operate at pressures to 20 000 psi (1380 bar).

During checkball pump operation, a fixed-angle wobble (cam) plate rotates with the drive shaft, causing the pistons to reciprocate. During its suction stroke, each piston is filled through its inlet check valve. During compression, the inlet check valve closes and pressure in the pumping chamber rises until it exceeds load pressure. The outlet checkball then lifts off its seat and fluid is pumped out of the chamber.

Checkball Pump Advantages

The checkball pump design is ideal for hydraulic systems with demanding conditions including:

  • pressure spikes
  • contamination
  • dirty environments
  • special fluids
  • extreme temperatures
  • long duty cycles

These high pressure pumps accommodate more force in a smaller package. At lower pressures, the pumps provide the life and performance margin essential in critical environments.


Pump Specifications

Fixed displacement pumps -
Flows from 0.22 to 60 U.S. gpm (0,83 to 227 L/min) at 1800 rpm, 
Pressures to 20 000 psi (1380 bar)
Variable delivery pumps -
Maximum flows from 12.7 to 60 U.S. gpm (48,1 to 227 L/min) at 1800 rpm, 
Pressures to 8500 psi (590 bar)

Special fluid applications include:

  • Wellhead Safety Control Systems
  • Blowout Preventer (BOP) Systems
  • Diesel Calibration Testing
  • Biodiesel Fuel Production
  • Hydrostatic Roll Balance Systems
  • Lubrication Systems
  • Hydraulic Test-Stands
  • Ground Support Equipment
  • Industrial Coolant Supply Systems
  • Hydroform Presses

Fluid Compatibility List

Various pump models are compatible with a variety of special fluids. Because many conditions affect successful operation, contact us for a review of your application using any of these special fluids.


This is a partial list which is updated regularly. Not all compatible fluids are shown here.


Water Glycol

  ACT FR WG 200-D
  Castrol Transaqua HT
  Citgo Glycol FR-40 XD
  Citgo Glycol FR-5046 HP
  Houghto-safe 419
  Houghto-safe 620
  Houghton Aqualink 300
  Houghton Aqualink HT-804
  Oceanic HW443
  Oceanic HW525
  Oceanic HW540
  Oceanic HW625
  Oceanic HW640
  Oceanic HW740
  Ucon Hydrolube HP-5046

 Other Water-Based Fluids

  95-5 Fluid

 Diesel Calibration Fluids


 Biodiesel Fuel Production

  Vegetable Oils

 Phosphate Ester

  Brake Fluids
  Skydrol Fluids

 Military Fluids

  MIL-C-7024C Type II (Stoddard solvent)

 Other Synthetic Fluids

  Isopar Solvents
  Quintolubric 822 (Polyol ester)

 Machining Coolant

  Milicron Cimtech 310
  Castrol Ilocut 334
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