Kobelco SK120 SK120-3 midikaivuri YY30V00001F1 virranjakaja

SK120 SK120‑3 Control Valve Assy for Kobelco Excavator spare parts YY30V00001F1 KMX13YBB33001‑00 Distributor OEM

Product Overview

The SK120 and SK120‑3 fill the 12‑ton slot in Kobelco's range — machines used for trenching, roadwork, drainage and small‑site excavation, where the operator is judged on how clean the finished edge looks. Their distributor carries two identifications: the Kobelco parts number YY30V00001F1 and the valve maker's own code KMX13YBB33001‑00. Either reference can be used to confirm fit, which matters when the machine's original plate has weathered away.

On a machine of this age, block wear rarely announces itself. It presents as work getting slower: the boom sinks while a loaded bucket is held over a trench, the arm takes up slack before each stroke, swing placement lands short and hunts back. Travelling with a loaded bucket feels heavier than it should. The common cause is internal leakage — spools and bores worn enough to let oil pass between circuits. This OEM‑grade assembly replaces the whole block with fresh internals trimmed to Kobelco values, so the old unit comes off and the replacement goes into the stock hose positions with no plumbing changes.

Core Advantages

1. Two numbering systems resolved to one correct block
Parts catalogues and valve makers list this assembly differently. We check both against your tag and serial, so the order is right even where the original plate is unreadable.

2. Trench edges come out clean first pass
Utility work is finished work. Restored metering means the bucket stops where the lever stops, so walls do not need a trim pass.

3. Loaded travel feels normal again
Cross‑circuit leakage bleeds pressure into the wrong function, making loaded tracking sluggish. Renewed isolation keeps travel steady under bucket load.

4. Boom holds position while the operator checks grade
A drifting boom forces continuous lever pressure. Fresh spool clearances keep the load where it was set, freeing the operator to inspect the work.

5. OEM clearances at a practical price
Original dealer assemblies on a machine this age are hard to justify. Equivalent build quality and tested settings at a fraction, with tiered pricing for workshops.

Manufacturing & Quality Control

Spool and bore pairs are machined to print, matched by size, and hand‑run‑in until full‑stroke movement is free of stick‑slip. Each assembled block is flow‑tested circuit by circuit with relief values recorded against SK120‑3 figures; units outside window are stripped and corrected before packing. Blocks ship internally oil‑fogged, ports capped, and crated on foam.

Frequently Asked Questions

Q1: My plate only shows the KMX number — is that enough?
A: Yes. Send a photo of that plate with the machine serial number and we cross it to the Kobelco reference before dispatch.

Q2: What symptoms indicate the block rather than the pump?
A: Drift on held loads, slack at stroke start, inconsistent swing placement and load‑dependent tracking point to the valve. Uniform slowness with rising oil temperature points to the pump. A leak test confirms.

Q3: Is a rebuild kit a sensible alternative?
A: If the casting is sound and never rebuilt, a kit can restore it. Where several circuits leak, a complete assembly is usually cheaper over the following years. Photos help us judge.

Q4: How long should the machine be out of service?
A: Most of a working day for removal and refit with the cover open, plus bleeding and pressure verification. Plan it as a scheduled stop rather than between jobs.

Q5: What hydraulic work accompanies the swap?
A: Drain and flush, renew the return filter, clean the suction strainer, refill with specified oil. Reusing contaminated oil undoes new clearances within weeks.

Q6: What is excluded from cover?
A: Material and assembly faults are covered. Failures from dirty oil, water entry, a spool forced against a bind, or reliefs set outside specification are not. Photograph the crate before opening if damage is visible.