Cascade 633874 - Ring - Back UP
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A back-up ring fitted behind an O-ring to stop the seal extruding into the clearance gap under pressure. Used throughout Cascade attachment cylinders and valve blocks.
Key details
- Prevents O-ring extrusion at higher working pressures
- Fitted on the low-pressure side of the O-ring — orientation matters
- Always replaced together with the O-ring it supports
- Material and cross-section are matched to the groove and the seal it backs
Specifications
| Part number | 633874 |
| Component type | Back-up ring |
| Part type | OEM-grade aftermarket |
| Fits brand | Cascade |
| Category | Forklift Attachments |
Where it is used
Components of this type are used across Cascade attachment lines including Carton Clamps, Bale Clamps, Fork Positioners, Rotators, Push/Pull attachments, Drum Clamps and Hydraulic ReachForks. This is category-level context, not a fitment list — confirm the part number against your own attachment before ordering.
Service notes
Note the original orientation before removal. A back-up ring installed on the wrong side of the O-ring offers no extrusion protection and the seal will fail early.
Fitment & availability
This is an OEM-grade aftermarket replacement manufactured to OE specification. It is cross-referenced to Cascade part number 633874 for identification and is not supplied by the original equipment manufacturer.
Check the part number against your model and serial number before ordering. If this item is not showing as available, use Check Availability and our team will confirm lead time and fitment.