The PA Unitized Pistons are designed to handle a broad range of application parameters. The piston body is machined to exact dimensions and is constructed using four components: A high strength steel body, a non-metallic bearing, a rubber loading ring and a filled PTFE seal ring. The non-metallic bearing is molded to the piston using a special proprietary process.

These specifically sized seals are for certain OEM cylinders (primarily Heil & Timberjack). Their use is intended for existing housings where the old seals are dimensionally comparable to the table below. Please call your sales representative if you need additional assistance.

Nylon Step Cut
Some PS2000 piston seals utilize a round instead of a square energizer. Also, piston diameter "I" dimensions are given for pistons without wear rings. Many sizes shown are completely interchangeable with style PS914 piston seals.

Nylon Step Cut
NOTE: Piston diameter 'I' dimensions are given for pistons without wear rings.

Designed to fit on one or two piece pistons, this piston seal employs a nitrile seal for high sealability, nylon split back-ups for extrusion resistance, and two split bearing rings. No further support bearings required.

Compact and easy to install, the Style PSA-65 piston seal is a simple and economical design for pressures up to 3,000 PSI. The assembly consists of a nitrile rubber seal and two polyacetal bearings to support the piston. For 1-piece pistons.

The Style PSC is a double acting piston seal designed to replace o-rings, quad-rings, and T-seals with the same groove dimensions (O-ring dash number). Style 575 urethane back-up rings may be added to either or both sides of the 'PSC' to accommodate wider groove widths. The PSC is made of 95A Durometer polyurethane, giving it high extrusion and abrasion resistance. The crowned sealing surface produces a positive seal from vacuum to high pressure.

NOTE: Piston diameter 'I' dimensions are given for pistons without wear rings.

These Style PSC are molded from Fluorotrel which is a tough, wear-resistant material able to run at temperatures up to 275° F. Fluorotrel is also resistant to fluids that are incompatible with polyurethane such as water, glycol, water in oil, mineral oil and petroleum. Consult our Engineering Department for other fluids compatible with Fluorotrel
NOTE: Piston diameter "I" dimensions are given for pistons without wear rings.

These piston seals provide bi-directional, low friction sealing with increased stability and superior leakage control. The square cut energizer provides low pressure sealing and eliminates backside leakage. This seal also effectively seals between different fluids on each side of the piston seal, making gas/liquid sealing combinations possible. NOTE: Piston diameter 'I' dimensions are given for pistons without wear rings.

Our Style PSU piston seal, or uniring, is a laminated one piece double acting seal made of cast polyurethane. The tough outer layer is highly resistant to abrasion and is impregnated with molybdenum disulfide to reduce friction. The softer inner layer acts as a static seal and also energizes the OD to make full contact with the bore. This seal may be used to replace an existing Uniring or other seals of the same dimensions - O-rings, O-rings with back-ups, T-seals, U-seals, etc. NOTE: Piston diameter 'I' dimensions are given for pistons without wear rings.

SL=SLOTTED

• MATERIAL 95A URETHANE
• TEMPERATURE RANGE -40° to +225°
• PRESSURE RANGE 0 to 5,000 PSI
• SPEED 3 FT/SEC
• PART NUMBER (Prefix)(CS) - (ID) - (Height)

• MATERIAL 90A URETHANE
• TEMPERATURE RANGE -40° to +200° F
• PRESSURE RANGE 0 to 5,000 PSI
• SPEED 3 FT/SEC
• PART NUMBER (Prefix)(CS) - (ID) - (Height)

SG - 'Seal Guard' Metallic Rod
Each Seal Guard Wiper consists of two flexible bronze rings which are held in place by a nitrile cushion ring. The cushion ring absorbs side loads and energizes the wiper to maintain close contact with the rod. Particularly suited for hostile environments, seal guard wipers shave off sand, grift, slag, flux, paint, moisture, chips and slivers. Seal Guard Wipers are long-lasting, self-adjusting, and offer low friction. Seal Guard Wipers can be installed in standard Hercules® Sealing Products “ST” or “D” Style grooves by increasing the “F” gland dimension to the “F” Throat Diameter shown.

IRON PISTON RINGS
When using iron piston rings, it is crucial to use the correct groove design for proper performance of the cylinder. Please use the following guidelines when cutting an iron piston ring groove

GROOVE WIDTH:

To permit the ring to slide freely into the groove, the groove must be at least 0.001 in. wider than the maximum piston ring width with a tolerance of +0.003 in./-0.000 in.

GROOVE DEPTH:

Grooves must be at least 0.015 in. deeper than the maximum radial wall thickness of the piston ring with a tolerance of +0.003 in./-0.000 in. This is to avoid any possibility of the ring bottoming in the groove when the ring is compressed to its working diameter.

RADIAL CLEARANCE:

The radial clearance between the cylinder bore and piston should be less than 1/3 of the radial wall thickness of the piston ring to ensure sealing effectiveness.

END CLEARANCE
End clearance on piston rings depends on ring design, material and application. The following end clearances are provided as a standard for hydraulic cylinder applications.