LANXIN Industrial Machinery Spare Parts SY235 Rotary Motor Gearbox SY365 Rotary Assembly

Product Overview

On a Sany excavator the swing drive is the assembly an operator notices first when it starts to go, because the whole machine works around it. This rotary motor gearbox bolts into the slewing position and turns the upper structure through every digging cycle, working with the swing bearing and the control valve to keep the house rotating smoothly in both directions. It is supplied new rather than as a rebuilt exchange core, and it goes out as a single item, so one failed machine is reason enough to order. Few Sany excavator parts are bought under as much pressure — when swing stops, the machine stops. Ours ship from Guangzhou ready to fit.

Key Design Points

• Built for swing duty: the gear set and bearings are matched to the stop-start loading of turning a loaded house, which is a harsher job than steady rotation.
• New condition: units are supplied new, so internal clearances and seal seating are as built rather than reworked.
• Sealing where it counts: dust, water and fine metal in the oil are what end most swing drives early, so the hydraulic side and the gearbox side are kept apart by their own seals.
• Original mounting interface: the flange, bolt holes and output connection are made to sit in the machine's swing frame. Send the number off your old unit so the two can be checked side by side before packing.
• Straightforward replacement: the unit comes out and goes back as a whole, so the motor and gearbox stay together through the repair.

Specifications

Fitment Verification

1. Read the model and serial from the machine's data plate, and note anything that has been modified around the swing area.
2. Photograph the plate on the old swing unit, the hydraulic port positions and the mounting face before anything is unbolted.
3. Compare the mounting face, bolt hole pattern and output connection with the replacement — these are the details that decide whether the two excavator components line up on the machine.
4. If anything on the replacement looks different from your photographs, stop before fitting and call; pulling a swing unit twice is an expensive way to find out.

Failure Signs

• Weak swing under load: the house turns slowly or stalls when the machine is digging hard or working uphill — usually the complaint that starts an excavator spare parts order.
• Swing creep: the upper structure keeps drifting after the joystick is centred, or the house moves on its own when the machine is parked on a slope. The swing brake can cause the same symptom, so confirm which side is at fault.
• Grinding or whining: noise from the swing area that rises and falls with rotation speed instead of a steady hydraulic hum.
• Metal in the oil: fine particles on the return filter magnet, or oil that looks dark and smells burnt, point to internal wear.
• Weeping and heat: oil around the motor body or the gearbox joint, or a swing unit running noticeably hotter than the rest of the circuit after a shift.

Technical Support & Model Matching

Our technical team supports buyers before and after the order. Send us your OEM part number or machine and engine details and we will confirm the correct match for your repair, overhaul or replacement job. If you are unsure what has failed, share the symptoms and our specialists will help with troubleshooting and narrow down the right assembly. We also provide installation and commissioning guidance, and share product documentation on request. With coverage across Komatsu, Caterpillar, Cummins, Isuzu, Hitachi, Sany, Doosan and Kubota machinery, we can help consolidate your parts requirements into one order.

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