- Formerly Danzco -

StepLock Piston Seals

These seals are designed for 7,000 psi (480 bar) working pressure and pressure spikes to 20,000 psi (1380 bar). Our seals were developed for excavator attachment cylinders when no existing seal would meet our 1 year, 2,000 hour, minimum performance requirement. This patented ( US Patent 5,934,685) design has more than double the life compared to any other seal tested.

StepLock Piston Seal

Features

* Our piston ring is machined from moisture stabilized bearing grade Acetal.

* Steps of the piston ring are wider than the ring and fit tight in the groove, for excellent low pressure sealing.

* Expander and piston ring fill the groove volume by over 90% to eliminate explosive decompression of the expander ring when dropping from maximum pressure quickly.

Design & Patent Information

For design information click here.

For patent information click here.

To view the patent information in a print-friendly PDF click here.

Application Information

We recommend using carbon steel for the pistons such as C1040, C1045, 8620, 4140 and 4150. It is best to have a wear ring on each side of the piston seal with about .001” clearance per inch of bore diameter. A 4” bore cylinder should have .004” to .006” wear ring clearance, and a 5” bore should have .005” to .007” clearance. Using a step cut wear ring, or a lap cut wear ring, as the guide bearing will improve seal life when subjected to high pressure spikes. There should be about .002” per inch of bore size clearance at the land by the piston ring, which is about .050” wide. This reduces seal extrusion and doesn't damage the barrel. There can be more barrel clearance along the rest of the piston length.

Diagram of piston land

Piston Land Drawing
  • LC is land clearance
  • LW is land width
  • WRC is wear ring clearance
  • PC is piston clearance

Quick Ship Sizes

The quick ship sizes listed below are usually in stock, and can ship the same day if ordered before 2:00 pm Pacific time. The short lead time items are made to order and will take 1 to 2 weeks to manufacture.

Seal Part No. Bore Groove Width Groove Diameter
SL0000 3.525/3.528 .280/.282 2.967/2.969
SL0015 3.500/3.503 .280/.282 2.942/2.944
SL0017 4.00/4.003 .280/.282 3.442/3.444
SL0003 4.025/4.028 .280/.282 3.467/3.469
SL0053 4.525/4.528 .282/.284 3.874/3.876
SL0019 5.000/5.003 .280/.282 4.442/4.444
SL0009 5.025/5.028 .280/.282 4.467/4.469
SL0043 5.025/5.028 .376/.378 4.258/4.260
SL0065 5.500/5.503 .378/.379 4.726/4.728
SL0061 5.525/5.528 .378/.379 4.751/4.753
SL0021 6.000/6.003 .378/.379 5.228/5.226
SL0012 6.025/6.028 .378/.380 5.251/5.253
SL0083 7.000/7.003 .378/.380 6.226/6.228
SL0070 7.000/7.003 .629/.631 6.095/6.097
SL0086 7.025/7.028 .378/.380 6.251/6.253
SL0066 7.025/7.028 .629/.631 6.095/6.097
SL0076 8.000/8.003 .378/.380 7.226/7.228
SL0058 9.000/9.003 .378/.380 8.110/8.114

Short Lead Time Sizes

Seal Part No. Bore Groove Width Groove Diameter
SL0028 3.500-3.503 .579/.581 3.020-3.022
SL0031 3.525-3.528 .579-.581 3.045/3.047
SL0023 4.000-4.003 .579-.581 3.520-3.522
SL0026 4.025-4.028 .579-.581 3.545-3.547
SL0006 4.525-4.528 .280/.282 3.967/3.969
SL0033 8.040-8.043 .750-.752 7.312-7.314
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