Overview – Engine Parts BACK-UP 242706 Series
If you run Hitachi hydraulic and cylinder as the backup ring, the Hitachi BACK-UP 242706 and its series variants give you flexible sourcing without compromising fit.
Parts Characteristics
A backup ring (back-up) that supports a soft seal against extrusion under pressure, sitting behind the O-ring so the elastomer cannot squeeze into the gap. It is the part that lets the seal survive high pressure, so a correct, gap-filling backup keeps the joint sealed where a ring alone would blow out.
Applicable Models & Applications
Fitted to Hitachi hydraulic positions specifying this back-up. Match the cross-section and bore against your old ring – backup rings differ in how they fill the extrusion gap.
Maintenance & Replacement
Replace the backup together with the seal it supports. A new seal onto a worn or missing backup still extrudes, and the extrusion is what cuts the seal on the first pressure cycle.
Match the backup to the gap it must fill. A backup too small leaves the gap open; one too large binds the joint and the seal cannot seat.
Keep the mating faces clean on fit – a backup assembled onto a dirty seat leaks and the circuit behind it loses pressure under load.
Keep the common backup rings for your hydraulic application on the bench. They cost almost nothing, they save the seal that costs far more, and they are exactly the part missing when a high-pressure joint needs sealing today.
Price Reference (USD)
As a reference, the BACK-UP 242706 is typically priced between USD 3 and USD 15 depending on configuration, lot size, and current exchange rates.
Value & Service
We supply brand-new backup rings with the cross-section confirmed against your Hitachi hydraulic application, so the seal stays supported under pressure.
The BACK-UP family includes 257007, 257527, 336407, 4027959, 4027963, 451036, 451037, 880605; we can cross-check which one matches your serial number.
Avoid counterfeit risk – Racer Machinery sources the Hitachi BACK-UP 242706 through verified channels and documents each shipment.
