The MHM compact piston seal is a 5-component combination seal specifically designed for double-acting hydraulic cylinders . It consists of one NBR elastomer sealing ring, two polyester elastomer backup rings, and two POM guide rings . This integrated design provides both sealing and guiding functions in one compact assembly, with all components installed in a single groove to significantly save installation space .
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Product Overview
The MHM seal is a bidirectional piston seal designed for medium-duty hydraulic applications . The 5-component design features:
Elastomer (NBR) – The primary sealing element, providing effective sealing in both dynamic and static conditions
Backup Rings (Polyester Elastomer) – Prevent elastomer extrusion into the sealing gap on both sides
Guide Rings (POM) – Guide the piston within the cylinder bore and absorb radial forces
This compact design allows the seal and guide rings to share the same groove, resulting in a shorter piston length and reduced machining costs . MHM seals are suitable for installation in closed (integral) groove designs .
How It Works
The MHM seal operates through a combination of elastic sealing and pressure activation. The NBR elastomer provides initial sealing contact with the cylinder bore. As system pressure increases, the elastomer is activated and pushes outward against the cylinder wall. The backup rings on each side prevent the elastomer from extruding into the sealing gap under high pressure, while the guide rings provide smooth piston guidance and absorb radial loads .
The seal is designed to be insensitive to shock loads and pressure peaks, maintaining stable performance under demanding conditions .
Specifications and Parameters
| Parameter |
Detail |
| Product Name |
MHM Compact Piston Seal |
| Type |
5-Component Combination Seal |
| Structure |
1 Elastomer + 2 Backup Rings + 2 Guide Rings |
| Sealing Ring Material |
NBR (Nitrile Butadiene Rubber) |
| Backup Ring Material |
Polyester Elastomer |
| Guide Ring Material |
POM (Polyoxymethylene / Acetal) |
| Color |
NBR: Black / Backup Rings: Yellow / Guide Rings: Yellow |
| Working Pressure |
≤ 40 MPa / 400 Bar / 7,500 PSI |
| Temperature Range |
-35°C to +110°C |
| Working Speed |
≤ 0.5 m/s |
| Medium |
Mineral oil-based hydraulic oils |
| Application |
Piston seal for double-acting hydraulic cylinders |
Product Features
1. 5-Component Integrated Design
The MHM seal combines sealing ring, backup rings, and guide rings in one compact unit. All components share a single groove, saving installation space and allowing shorter piston length .
2. Bidirectional Sealing
The symmetrical design provides reliable sealing in both directions of piston movement, making it suitable for double-acting hydraulic cylinders .
3. Anti-Extrusion Protection
The backup rings (polyester elastomer) prevent the elastomer from extruding into the sealing gap under high pressure on both sides .
4. Smooth Piston Guidance
The guide rings (POM) provide excellent piston guidance and absorb radial forces, preventing metal-to-metal contact .
5. Insensitive to Shock Loads
Maintains stable performance under pressure peaks and shock loads, making it ideal for demanding construction equipment .
6. Suitable for Holding Cylinders
Provides good sealing effect even for holding cylinder applications .
7. Closed Groove Compatibility
Capable of installation in closed grooves, reducing machining costs .
8. Easy Installation
The split design of backup and guide rings allows for straightforward installation without special tools .
Need MHM compact piston seals for your hydraulic cylinder applications?
Contact SANPING SEAL today with your bore size and application requirements. Our team will provide a free quote and recommend the right seal within 24 hours.
