Hydraulic System Parts

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Hydraulic System Part Fitment and Compatibility

This is the plumbing and valve layer of the hydraulic system, the parts between the pump and the cylinder rather than the pump and cylinder themselves. They match by thread form, port size, and pressure rating, and since a fitting that threads in is not necessarily a fitting that is rated for the circuit, the OEM number is the only reliable match. Common replacements include the case drain kit replacing OEM 7246494, the piston assembly replacing OEM 6678933, the valve cartridge replacing OEM 7015575, the poppet replacing OEM 6675868, the bonnet replacing OEM 6803092, the back-up ring replacing OEM 947088, the tank sight gauge replacing OEM 7001421, and the control link replacing John Deere AT221783.

Case drain lines deserve their own note. High-flow attachments such as mulchers, cold planers, and grinders return motor leakage through a dedicated low-pressure line back to tank. Running one without that line leaves the motor's shaft seal as the only path for that pressure, and the seal is what fails.

Types of Replacement Hydraulic System Parts

Valve internals cover cartridges, poppets, bonnets, and springs. They are sold individually because a valve rebuild is usually one seat or one spool rather than a whole assembly, and swapping a cartridge is far cheaper than a valve body.

Sealing hardware covers back-up rings, which sit behind an O-ring and stop it extruding into the clearance gap under pressure. That is why the ring is listed as its own part and why leaving it out of a rebuild produces a joint that seals cold and weeps hot. Fittings and tube cover adapters, elbows, tees, and overflow pipes. Tank hardware covers sight gauges and fill components.

Whenever a hydraulic line comes apart, cap both ends. A system that was clean before the repair and contaminated after it is the most common self-inflicted hydraulic failure there is.

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Skid Steer Parts

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Hoses

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Valves

O-Rings

Seals

Hydraulic Filters