Seals for Hydraulic & Construction Machinery

Seals & Polymer Components for Hydraulic & Construction Machinery

Application Overview

Construction and heavy-hydraulic equipment operates under extreme conditions: high cyclic pressure, strong mechanical vibration, temperature fluctuation and exposure to hydraulic oil, dust and debris. Seal failure such as torque relaxation, extrusion and leakage will cause downtime and costly maintenance. TOPSEALS supplies engineered sealing and polymer components for hydraulic manifolds, cylinders, valve blocks and connection ports.

Key Operating Challenges

• High working pressure up to 350 bar, frequent pressure cycling
• Continuous vibration and mechanical shock from excavator, loader operation
• Wide temperature range from -40℃ to 120℃
• Exposure to mineral hydraulic oil, contamination and dust particles

Recommended Sealing & Polymer Parts

• DIN7603 Bonded Washer (Dowty Washer) - anti-vibration port sealing for drain plugs and manifold connections
• Hydraulic & Pneumatic Seal Kits - cylinder rod and piston sealing repair sets
• TC Oil Seal - rotary shaft sealing for hydraulic motors
• Filled-PTFE Machined Parts - low-friction wear rings and backup rings
• CNC-PEEK Components - high-strength anti-extrusion backup rings and bushes
• Nylon Backup Rings & Washers - cost-effective extrusion resistance for low-to-medium pressure systems

What Products Are NOT Suitable For This Application

Some materials cannot withstand heavy-duty hydraulic vibration and high pressure. Avoid below items for main hydraulic circuit applications:

• Standard soft silicone seals: poor oil resistance, easy to swell under hydraulic fluid
• General-purpose pure PTFE without filler: low compressive strength, prone to cold-flow deformation under high pressure
• Low-grade rubber O-rings without anti-aging formulation: rapid degradation under cyclic pressure and vibration

Typical Installation Positions

• Hydraulic valve block port connections
• Cylinder head and rod end assemblies
• Hydraulic motor shaft output
• Drain plug and bolted flange joints
• Manifold pipe-to-block interfaces

Frequently Asked Questions

Q: Why do bonded washers leak after long-term vibration?

A: Vibration-induced torque relaxation is the main cause. DIN7603 bonded washers with optimized rubber-metal bonding are designed to resist this phenomenon. Improper tightening torque will also accelerate leakage.

Q: What material is best for high-pressure hydraulic backup rings?

A: For heavy-duty conditions, CNC-machined PEEK is preferred. For medium-pressure cost-sensitive projects, filled-PTFE or reinforced nylon are viable alternatives.