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W440 Cartridge

The W440 filter assembly can be manifold mounted to the hydraulic system. The size and material configuration are well-suited for today's demanding proportional and servo valve applications. Standard housing drain plug helps relieve system pressure during filter change-outs.


  • High Pressure Circuits
  • In-Plant Systems
  • Mobile Equipment


  • Rugged cast iron and steel construction for reliable performance
  • Highly configurable – this assembly and filter combination give you a lot of flexibility in a very high pressure working range
  • Featuring our high-performance DT filters with multiple efficiency options – allowing you to achieve the performance you need for most any application


  • Assembly has manifold mounting capability
  • Thermal lockout and surge control incorporated in many of the differential pressure indicators
  • High collapse filter available for use with non-bypass applications – collapse options range from 150 to 3,000 psi
  • Positive sealing poppet bypass for reliability and no leakage
  • Range of indicator options – visual pop-up, electrical/visual or all electronic models available
  • Compact design for use with servo or proportional valve
  • Two housing length options for design flexibility
  • Differential pressure indicator line works with an assortment of bypass valves
  • Viton® seals are used on high-performance DT filters
  • Working pressure to: 276 bar / 4000 psi
  • Rated static burst to: 690 bar / 10,000 psi
  • Fatigue pressure rating: 169 bar / 2450 psi
  • Flow range to: 76 lpm / 20 gpm
  • Porting size options: 
    • SAE-12 O-ring
    • Manifold mounting top-ported for subplate mounting
      • 17.5 mm / in. holes
      • 31.8 mm /1.25 centers
  • Standard bypass ratings of: 
    • 3.5 bar / 50 psi
    • No bypass

Available Media Types

  • Donaldson exclusive Synteq™ – synthetic fiber media for greater filtration efficiency and higher dust-holding capacity
  • Many different efficiency grades from which to choose
Viton® is registered trademark of E. I. DuPont de Nemours and Company.
The following are recommended practices for hydraulic filter servicing and handling. These steps are universal to many hydraulic systems. This servicing information is provided as a best practices guide. Donaldson recommends that you follow the filter service instructions supplied by your original equipment manufacturer. These recommended practices are not intended to replace or supersede the service instructions supplied by your equipment or vehicle manufacturer
  1. Check the filter service indicator
    Check to see that the OEM specified service interval has been reached or that the service indicator shows that the filter is due for servicing.

  2. Turn system off and release pressure
    Ensure that the hydraulic system is turned off.
    Check that there is no pressure present.

  3. Use oil drain port to better control oil removal from the housing 

  4. Unscrew the cartridge housing

  5. Remove the used filter and gasket, if applicable
    Properly dispose of the cartridge according to local regulations.

  6. Clean the head seal area and housing
    Clean out any sediment from the inside of the filter housing.

  7. Inspect the new filter cartridge for damage
    Check the new filter you will be installing for any shipping and handling damage. Do not install a damaged filter.

  8. Install and lubricate seals, gaskets and threads. 
    Lubricate the o-rings, gaskets, housing seals and threads with clean system oil.

  9. Install new cartridge into the housing

  10. Align threads. Spin filter until gasket contacts
    Fit the housing to the filter head as instructions on the housing.

  11. Install housing according to manufacturer instructions

  12. Bleed the hydraulic system and check for leaks

Donaldson Hydraulic Filtration Overview

Donaldson provides filters and contamination control products to protect hydraulic components -- in the factory and on heavy-duty equipment. This module provides an overview of hydraulic systems and the advantages of Donaldson hydraulic filters.

Donaldson Hydraulic Filter Servicing

Donaldson provides best practices and recommended steps for hydraulic filter servicing. By following these simple steps, discover how you can reduce maintenance costs and extend the life of your hydraulic system.