INDUSTRY COMPONENT

Filler Cap

A filler cap is a sealing component for hydraulic reservoirs that prevents contamination while allowing fluid addition and pressure equalization.

Component Specifications

Definition
A filler cap is a critical sealing device installed on hydraulic reservoirs to maintain system integrity by preventing ingress of contaminants (dust, moisture, particulates) while permitting controlled fluid replenishment and atmospheric pressure equalization through integrated breather mechanisms. It typically incorporates filtration elements and secure locking features.
Working Principle
The filler cap operates by creating a sealed interface between the reservoir and external environment using gaskets or O-rings. It allows air exchange through a breather filter to equalize pressure during hydraulic system operation while trapping contaminants. Some designs include pressure relief valves or desiccant elements for enhanced protection.
Materials
Typically manufactured from: Steel (SAE 1010/1018) with zinc plating, Aluminum (6061-T6) with anodizing, or Engineering plastics (PA66, POM) with UV stabilization. Seals: Nitrile rubber (NBR), Fluorocarbon (FKM), or Silicone.
Technical Parameters
ParameterTypical rangeNotes & selection driver
Seal TypeO-ring or flat gasket
Thread SizeM20x1.5 to M38x1.5
Filter Rating10 to 40 microns
Pressure Rating0.5 to 2 bar
Operating Temperature-40°C to +120°C

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards
ISO 6149, DIN 3852, SAE J514

Parent Products

This component is used in the following industrial products

Engineering Analysis

Risks & Mitigation
  • Contamination ingress leading to component wear
  • Pressure imbalance causing pump cavitation
  • Seal failure resulting in fluid leakage
  • Improper installation causing thread damage
FMEA Triads
Trigger: Clogged breather filter
Failure: Vacuum formation in reservoir
Mitigation: Regular inspection and replacement of filter elements
Trigger: Degraded sealing gasket
Failure: Contaminant ingress and fluid leakage
Mitigation: Scheduled seal replacement using compatible materials

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance
Thread tolerance: 6H/6g per ISO 965, Seal compression: 15-30%
Test Method
Pressure decay test per ISO 6149, Contamination ingress test per ISO 4406

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation
Request current drawings, revision history, and a signed specification sheet.
Manufacturing capability
Verify equipment lists, process limits, capacity, and representative production evidence.
Inspection readiness
Confirm test methods, calibrated equipment, sampling plans, and traceable reports.
Supplier transparency
Check the legal entity, factory address, ownership, certifications, and direct contacts.

CNFX does not score or rank suppliers. Buyers must verify all claims and documents with the legal manufacturer before ordering.

Manufacturers of Filler Cap

Manufacturer profiles associated with Filler Cap.

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Related Components

Upper Tool (Punch)
Upper Tool (Punch) is the active forming component in metal plate bending machines that applies precise downward force to create bends in sheet metal.
Main Frame
The main frame is the primary structural component of a hydraulic press, providing rigidity and stability to withstand high compressive forces during metal forming operations.
Shaft Bearing
Precision component supporting rotating shafts in vibration motors to reduce friction and maintain alignment.
Seal Groove
Precision-machined groove in aluminum bearing housings designed to accommodate sealing elements for fluid containment and contamination prevention.

Frequently Asked Questions

How often should hydraulic reservoir filler caps be replaced?

Typically every 1-2 years or 2000 operating hours, depending on environmental conditions and manufacturer recommendations. Inspect seals regularly for degradation.

Can filler caps affect hydraulic system performance?

Yes. Damaged or clogged caps can cause pressure imbalances, cavitation, fluid contamination, and reduced system efficiency.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records. See the editorial policy.

Preliminary Technical Classification
This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

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