Seals

Hydraulic Seals for Pumps, Motors, Cylinders and Machinery

Hydraulic seals are critical components used to retain fluid, separate pressure zones and protect hydraulic assemblies against contamination. Even a small sealing failure can lead to oil loss, reduced efficiency, pressure instability and accelerated wear of expensive hydraulic components.

HPM Hydraulic supplies sealing products for construction machinery, industrial equipment and mobile hydraulic systems. The range includes oil seals, complete seal kits and O-rings for repair, overhaul and preventive maintenance.

Where Are Hydraulic Seals Used?

Sealing elements can be found throughout a hydraulic machine, including:

• hydraulic pumps,
• hydraulic motors,
• hydraulic cylinders,
• travel and swing drives,
• gearboxes,
• valve blocks,
• rotating shafts,
• hydraulic fittings and ports.

The correct sealing component depends on the application, pressure, temperature, shaft or bore dimensions, fluid type and movement of the sealed parts.

Oil Seals, Seal Kits and O-Rings – What Is the Difference?

Oil Seals

Oil seals are typically used around rotating shafts to retain lubricant and limit the entry of dirt, moisture and other contaminants.

Seal Kits

Seal kits contain a matched set of seals intended for the overhaul of a specific hydraulic component or machine assembly. They are particularly useful when several sealing elements should be replaced during one repair.

O-Rings

O-rings are circular elastomer seals used primarily in static or limited-movement joints. They are widely used in hydraulic ports, housings, valve blocks and component interfaces.

Choosing Seals by Application

Hydraulic seals should not be selected only by visual similarity. The same external size may be available in different materials or profiles designed for completely different operating conditions.

Depending on the application, verify:

• inside and outside diameter,
• seal width or cross-section,
• seal profile,
• material,
• working pressure,
• temperature range,
• hydraulic fluid compatibility,
• OEM or component reference.

Why Hydraulic Seals Fail

Seal failure is often a symptom of a wider problem rather than an isolated defect. Common causes include:

• contaminated hydraulic oil,
• incorrect installation,
• shaft or rod surface damage,
• excessive temperature,
• pressure spikes,
• incorrect seal material,
• misalignment,
• normal wear over operating time.

When a seal fails repeatedly, inspect the mechanical surfaces and operating conditions before installing another replacement.

Hydraulic Seal Identification

For machine-specific sealing parts, the OEM number and equipment model are usually the most reliable identification method. For standard seals, accurate dimensional measurement is essential.

When requesting assistance, provide the machine model, component reference, OEM number and photographs of the original seal or assembly whenever possible.

Sealing Components from HPM Hydraulic

HPM Hydraulic supplies seals and seal kits for hydraulic components and construction machinery, supporting repairs of pumps, motors, cylinders and related systems.

Correct sealing helps reduce oil loss, maintain hydraulic efficiency and protect components against premature damage.

Sealing Components for Hydraulic Repair

For complete component overhaul, browse our hydraulic seal kits. Seal replacement is often performed together with repairs using hydraulic pump spare parts or hydraulic motor spare parts.

FAQ – Hydraulic Seals

What seals are used in hydraulic systems?

Common types include O-rings, shaft seals, rod seals, piston seals, wipers, backup rings and component-specific seal kits.

How do I identify a hydraulic seal?

Use the OEM number or component reference where available. For standard seals, measure the relevant inside diameter, outside diameter and cross-section or width.

Can I reuse hydraulic seals during a repair?

In most overhaul applications, seals that have been removed, compressed or damaged should be replaced rather than reused.

Why does a new hydraulic seal leak?

Possible causes include incorrect size, damaged sealing surfaces, poor installation, excessive pressure, contamination or unsuitable material.