Hydraulic Oil Filter Elements — Quick Reference (English)

Items: 3870-01-071-C· HP311-12(mounted on GE equipment) · GE

1) 3870-01-071-C— Return-Line Filter Element

This is a disposable pleated filter element installed inside a pipe-mounted return-line canister on the hydraulic power unit. The last letter C indicates the seal material is NBR nitrile rubber — the O-ring will be black or dark grey in colour, suitable for standard mineral hydraulic oil.

What to check before fitting

• Go to the filter head and read the metal nameplate near the pipe ports — it should show a model beginning with 3870…, plus the pressure rating and a flow arrow. The element must be installed so oil follows that arrow.

  
  

• Compare the new element against the old one: check that the overall height, outer diameter, and centre-hole diameter match. A ruler is all you need — if the dimensions are wrong, the element will not seal properly even if it "looks close."

  
  

• Confirm the O-ring is black/grey (NBR). If the old one was brown/red (Viton), stop and get the correct seal variant — mixing compounds causes leaks or hardening.

  
  

Replacement steps

1. Stop the pump. Open the vent/bleed screw on the filter head until pressure drops to zero.

   
   

2. Support the bowl so it does not hang by the piping. Release the clamp band or retainer.

   
   

3. Lift the element straight out — do not twist or pry against the bowl wall.

   
   

4. Look at the bottom of the bowl for bright metal shavings — this tells you if a pump or cylinder is wearing.

   
   

5. Wipe the sealing surfaces clean. Put a thin film of clean hydraulic oil on the O-ring — no grease, no sealant.

   
   

6. Drop the new element squarely onto the centre support tube until it seats.

   
   

7. Close the vent, bring pressure back slowly, and check that the differential pressure indicator is green with no seepage.

   
   

Procurement wording

3870-01-071-C — Element for 3870-family housing shown on the head nameplate. Require supplier to confirm OD / height / centre bore / seal groove match before delivery. No "looks the same" substitutes.

2) HP311-12— High-Pressure Guard Element

This is a pressure-side filter element — it sits in a heavy cast-steel head between the pump and the valves, so the oil passing through it is still under high pressure. The code points to a specific element size and seal combination for the HP311 housing family.

Why this one needs more care

• Because it lives on the pressure leg, trapped pressure is dangerous — always close upstream isolation if fitted, and crack the bleed slowly until the gauge reads zero before touching anything.

  
  

• This position protects expensive components downstream; if the element is wrong or installed off-square, it can deform under pressure and bypass unfiltered oil.

  
  

Replacement steps

1. Isolate upstream → bleed slowly until pressure = 0 and you hear no more hissing.

   
   

2. Support the bowl — pressure hardware is heavy and can damage piping if it drops.

   
   

3. Open the retainer → lift the element straight up/out (depending on whether your HP head opens from the top or bottom — follow the arrow on the head).

   
   

4. Check for bright metal particles in the bowl — pressure-side debris is a direct pump/valve wear signal.

   
   

5. Clean seal lands → thin oil on O-ring → seat square → torque evenly → close vent.

   
   

6. Bring pressure up slowly and watch closely for leaks before walking away.

   
   

Procurement wording

HP311-12 — Element for HP311-series pressure housing — supply exact match confirmed against the head nameplate model. State OD / length / seal material when ordering.

3) GE— Equipment Tag Reference

GEhere is not a filter part number — it is shorthand for the equipment owner/maker (the unit supplied by / labelled for GE). In your BOM it simply tells the storeroom which machine this filter position belongs to, so nobody accidentally swaps parts between unrelated systems.

The practical instruction is: whatever element goes into that GE machine's filter head must still be verified by the housing nameplate and the old element dimensions — the letters "GE" alone are not enough to pick a spare.

4) One-Line BOM (copy-paste)

• 3870-01-071-C— Return-line element, NBR seal (C), fits 3870-family housing per head nameplate

  
  

• HP311-12— Pressure-side element, fits HP311 housing per head nameplate (high-pressure — full depressurize first)

  
  

• GE— Equipment reference only (General Electric-labelled hydraulic unit) — all elements mounted on it must still be verified by the filter head nameplate

  
  

One rule that covers all three

The metal nameplate on the filter head is always the boss, not the sticker on the box. If the nameplate is painted over, use a ruler on the old element (height / OD / centre hole) + O-ring colour as your fallback — and write those numbers on the BOM line so Stores can never guess again.