Choosing a swing device: swing motor plus FRG reduction gear
A swing device is a matched pair - the M5X swing motor and the FRG planetary reduction gear. Buying the two separately is where most wrong orders start, because the ratio and the mounting flange decide whether the assembly behaves like the original. This guide states what to match, in the order that matters.
The two swing motors we supply
| Property | M5X130CHB | M5X180CHB |
|---|---|---|
| Swing motor | M5X130CHB | M5X180CHB |
| Displacement | 121.6 / 129 / 129.2 cm³ (motor variants) | 148.5 / 169.4 / 180.1 cm³ (motor variants) |
| Rated pressure | 34.3 MPa | 34.3 MPa |
| Peak pressure | 41.2 MPa | 41.2 MPa |
| Max. speed | 1,850 min⁻¹ | 1,680 min⁻¹ |
| Max. brake torque | 874 N·m | 1,210 N·m |
| Machine class | 12–15 t hydraulic excavator | 20–25 t hydraulic excavator |
Match these four things, in this order
1. Ratio
The FRG range covers three ratios - 19.636, 20.04 and 25.2 - across the FRG11, FRG14 and FRG20 sizes. The ratio multiplied by motor displacement sets slewing speed and torque. Copy the ratio from the old unit plate; do not infer it from the machine model.
2. Motor displacement class
M5X130CHB is the smaller class, M5X180CHB the larger. The reduction gear flange and the motor mounting pattern must match the pair you are replacing.
3. Brake torque
The parking brake holds the upper structure on a slope. M5X130CHB is rated around 874 N·m and M5X180CHB around 1,210 N·m maximum. A weaker brake on a larger machine will not hold, whatever the motor displacement.
4. Shaft, flange and rotation
Two units can carry the same displacement and still differ in shaft spline and flange. Send the unit plate photo - we confirm all three in writing before dispatch.
What to send for a same-day confirmation
- A photo of the machine data plate
- A photo of the swing device plate (motor and reduction gear)
- The ratio stamped on the reduction gear housing, if visible
- Country and port of destination for the freight quote
With those four items we confirm the assembly, price and lead time the same day in most cases.
Where this usually goes wrong
The most common mistake is ordering a swing motor by machine tonnage alone. A 20 t machine may run either displacement class depending on the year and market, and the reduction gear ratio varies with the application (standard digging versus material handling). The second most common mistake is reusing a worn reduction gear with a new motor - debris from the worn gear damages the new motor within weeks. If the gear has metal in the oil, replace or rebuild the pair.