Swing faults divide into four places: the swing motor, the swing reduction, the swing brake, and the hydraulic circuit that feeds them. Condemning the motor before a gauge has been on the machine is an expensive way to guess. This article sets out the numbers that belong to a Kobelco SK200-8, the checks that separate the four, and the photographs we need to quote — the same checklist the technical team at Guangzhou Shenyue Machinery Technology Co., Ltd. uses every week.
Which swing motor and reduction does a Kobelco SK200-8 use?
SK200-8 and SK210-8 class machines normally carry an axial-piston swing motor of the M5X130 class, quoted under Kobelco assembly numbers YN15V00077F1, YN15V00055F1 and YN15V00035F1.
The motor drives a two-stage planetary swing reduction, quoted under assembly numbers YN32W00025F1, YN32W00022F2 and YN32W00019F1. The reduction turns fast motor rotation into the slow, high-torque movement of the upper structure, and it is a separate assembly from the motor.
| Machine class | Swing motor | Swing reduction |
|---|---|---|
| SK200-8 / SK210-8 | M5X130 class — YN15V00077F1 / YN15V00055F1 / YN15V00035F1 | YN32W00025F1 / YN32W00022F2 / YN32W00019F1 |
| SK330-8 class and above | M5X180 class — LC15V00022F1 | Quoted against machine serial |
The bigger M5X180 is not a larger version of the same part you can fit instead: the class difference follows machine size. Generation is the other common source of a wrong swing order, which is why the nameplate on the motor — not the model name on the door — is the authority.
Six swing symptoms and what each one points at
- Slow swing in both directions. Low swing circuit pressure, or general internal leakage in the motor. Check pressure before parts.
- Slow swing in one direction only. Almost always the relief setting or a control valve spool on that side, not the motor.
- Swing drifts and will not hold on a slope. Swing brake wear, brake seal leakage, or internal leakage past the rotary group.
- Loud whine or knocking that rises with swing speed. Gear or bearing damage — suspect the reduction.
- Normal when cold, slow when hot. Internal leakage opening up as oil viscosity drops.
- Oil weeping at the swing motor shaft. Shaft seal; confirm there is no pressure build-up in the case drain line before resealing.
The four checks that settle it
- Swing circuit pressure at relief, both directions, at operating temperature.
- Swing brake test: release pressure, and whether the brake holds the upper structure on a slope with the lever in neutral.
- Case drain flow from the motor — excessive flow means internal leakage in the rotating group, the clearest single measurement of motor condition.
- Oil sample from the swing gearbox, checked for metal and water. If the reduction is the damaged part, no amount of motor work will fix the machine.
Repair, rebuild or replace
Rebuild the swing motor when the housing, shaft and splines are sound — new seals, pistons, valve plate and bearings restore swing performance for a fraction of the price of a complete assembly. Replace the assembly when the shaft or housing is damaged. For the reduction, replacement of the planetary assembly is normal once gear teeth or bearings are damaged, and the correct unit is confirmed against the machine serial number.
What we need to quote a swing motor or reduction
- A nameplate photograph of the swing motor — assembly number and maker, in focus.
- A nameplate photograph of the swing reduction, if that is the part in question.
- The machine serial number.
- The symptom, in your own words: slow, noisy, drifting, or leaking.
Guangzhou Shenyue Machinery Technology Co., Ltd. has specialised in Kobelco parts since 2007, with 4 warehouses over 1000 m² in Guangzhou and 30,000+ part numbers available to order. Consistency of number families is exactly why we ask for the nameplate: the same symptom on two machines built a year apart can need two different assemblies.
Related reading: our guide to ordering Kobelco parts by part number covers the whole ordering discipline, and the hydraulic components page groups the swing, travel and pump parts we supply. Machine-level pages: SK200 and SK210.
Shenyue is an independent supplier. We are not an authorized dealer or distributor of Kobelco Construction Machinery Co., Ltd.; genuine Kobelco parts are supplied through original supply channels, alongside quality replacement alternatives, with the condition of every item stated on the quotation. Bearing and seal data referenced above follows the published catalogues of SKF and NOK.
Frequently Asked Questions
What swing motor part numbers fit a Kobelco SK200-8?
SK200-8 and SK210-8 class machines normally carry an M5X130 class swing motor quoted under YN15V00077F1, YN15V00055F1 and YN15V00035F1, driving a swing reduction quoted under YN32W00025F1, YN32W00022F2 and YN32W00019F1. The motor nameplate is the authority for your machine.
Why is my Kobelco SK200-8 slow to swing in one direction only?
A single-direction swing fault usually points at the swing relief setting or a control valve spool on that side rather than the motor itself. Check swing circuit pressure in both directions before ordering parts.
Do you supply the swing reduction separately from the swing motor?
Yes. Guangzhou Shenyue Machinery Technology Co., Ltd. quotes the swing motor and the swing reduction as separate assemblies, which is why we ask for both nameplates. Metal in the gearbox oil or noise that rises with swing speed points at the reduction rather than the motor.
Can an M5X180 swing motor replace the M5X130 on an SK200-8?
No. M5X130 and M5X180 belong to different machine classes — SK200-8 and SK210-8 use the M5X130 class, while SK330-8 class machines and above use the M5X180. Fitment must be confirmed against the machine serial number and the motor nameplate.