Single Acting Piston Seals

Single Acting Piston Seals

Piston Seals or Piston Rings are used in hydraulic cylinders for fluid sealing and are designed to ensure that pressurised fluid does not leak across the cylinder head as the system pressure pushes the piston down the cylinder bore.

The choice of piston seal is decided by the way in which the cylinder operates. For a cylinder which is exclusively single-acting, capable of sealing dynamic pressure from one side (unidirectional), it is always best to choose the type of seal designed to provide optimum sealing qualities for single-acting functions.

The best sealing capacity of a double-acting cylinder, capable of sealing dynamic pressure from both sides (bidirectional), is achieved by choosing a double-acting seal.

A piston design where two single-acting seals on the piston for a double-acting cylinder are used can easily give rise to a breakdown. The reason is that a very high pressure can be trapped between the seals.

Piston seals, both single and double-acting, can be designed for and used with integrated or separate back-up rings and guide rings.

Hallite offers a wide range of piston seals that provide the ultimate in leakage control. Piston seals are usually manufactured in our high performance polyurethane Hythane® 181, Hallprene® rubber/fabric composite or polyester elastomer.

Single Acting Piston Seals

  • 15 15 Max pressure 300 Bar
    Temp range -30°C to 100°C
    Max speed 0.5m/sec
    15
    15 Max pressure 300 Bar Temp range -30°C 100°C Max speed 0.5m/sec

    The Hallite 15 rod seal has been well proven in many applications requiring a compact, low friction seal to work efficiently both at low and high pressures.

    The seal comprises a rubberised fabric U ring to give strength and durability, to which is moulded a rubber header. It is designed to have a controlled pre-load across the angled rubber lips which are accurately trimmed, to ensure a good seal at low pressure.

    The seal becomes more effective as the pressure increases and the rubberised fabric deforms to the housing increasing the seal contact area. The surface of the fabric has pockets which retain lubrication to reduce friction and wear.

    The proportions of the range have been determined to give a satisfactory performance when used with the recommended operating conditions. Many other sizes are available outside this range.

    The range should be fitted to split housings as shown, but sizes marked* can be fitted to a grooved gland housing, if assembled with care.

    NB: Size lists give "on line" tolerances for rod applications.

  • 18 18 Max pressure 500 Bar
    Temp range -30°C to 100°C
    Max speed 0.5m/sec
    18
    18 Max pressure 500 Bar Temp range -30°C 100°C Max speed 0.5m/sec

    A medium to heavy duty single acting seal, the Hallite 18 has shown itself over the years to be an effective and robust seal in a wide variety of applications.

    The seal comprises a rubberised fabric U form base to which is bonded a rubber energiser.

    The seal section is pre-loaded by the housing when installed to ensure effective sealing at low pressure. When the pressure increases the rubber energises the U form to increase the sealing area and hence the efficiency of the seal. The strength and durability of the rubberised fabric combines with its ability to retain lubricant keeping friction and wear to a minimum.

    In a piston application the Hallite 18 should not be used back to back to make a double acting assembly.

    NB:  Size lists give "on line" tolerances for rod applications.

  • 71 71 Max pressure 700 Bar
    Temp range -30°C to 100°C
    Max speed 0.5m/sec
    71
    71 Max pressure 700 Bar Temp range -30°C 100°C Max speed 0.5m/sec

    Design
    The Hallite 71 single acting fluid seal assembly consists of the standard Hallite 18 single acting fluid seal and the Hallite 62 L shaped bearing ring (wear ring). Manufactured in very hard wearing polyacetal resin, the bearing ring was originally designed to replace conventional bronze or cast iron piston bearings, reducing the problem of cylinder bore scoring to a minimum and allowing the designer to use compact, strong, cost effective steel pistons. The inherent nature of the material enables it to settle to the bore size once it has been pressurized, therefore providing an excellent anti-extrusion member and also increasing seal life.

    Due to its flexibility it should not be used primarily as a bearing where severe knuckling or excessive side loading may occur. Under these conditions we suggest the use of conventional bronze or cast iron bearings or the additional use of the Hallite 506 bearings. The proportions of the range have been determined to give a satisfactory performance when used with the recommended operating conditions.

    Other sizes are available outside this range.

  • 601 601 Max pressure 400 Bar
    Temp range -45°C to 110°C
    Max speed 1m/sec
    601
    601 Max pressure 400 Bar Temp range -45°C 110°C Max speed 1m/sec

    The Hallite 601 is a high performance general purpose seal suitable for rod and piston use.

    Manufactured in Hythane® 181 - Hallite's 601 is engineered to effect a good seal in most industrial cylinder applications.

    The sealing lips are accurately machined trimmed to ensure good low pressure sealing while the material resists extrusion at high pressures.

    NB:  Hallite 606 is a preferred option for back to back piston applications.

    Part numbers commencing 46 . . . . . are designed to suit popular Asian housings.

  • 606 606 Max pressure 400 Bar
    Temp range -45°C to 110°C
    Max speed 1m/sec
    606
    606 Max pressure 400 Bar Temp range -45°C 110°C Max speed 1m/sec

    The Hallite 606 is an asymmetric piston seal designed to offer effective bore sealing in a wide variety of applications.

    The outer dynamic lip is shorter and more robust to provide improved sealing and compression set characteristics over conventional U rings.

    The seal can be used by itself as a single acting seal or fitted back to back in seperate grooves for double acting applications.

  • 659 659 Max pressure 400 Bar
    Temp range -45°C to 110°C
    Max speed 1m/sec
    659
    659 Max pressure 400 Bar Temp range -45°C 110°C Max speed 1m/sec

    The Hallite 659 is an asymmetric piston seal designed to offer effective bore sealing in a wide variety of applications.

    The outer dynamic lip is shorter and more robust to provide improved sealing and compression set characteristics over conventional U rings. The seal also features a secondary lip that provides a pocket for lubrication as well as the benefits listed below.

    For use in single acting applications only, the seal is manufactured in Hallite's high performance polyurethane Hythane® 181.

    Note:  Variations of this seal are available in other sizes, please contact your local Hallite sales office for additional information and technical details.