39Q8-42100 Fahrantrieb für Hyundai R300 Bagger

R300 Final Drive for Excavator spare parts 39Q8‑42100 Axial Piston Motor Aftermarket

Product Overview

The Hyundai R300 is the 30‑ton entry in the Robex range — a machine built for bulk earthmoving, quarry loading and large‑site excavation where a single lost hour of mobility costs real money. Under each track frame sits the axial piston motor and planetary reducer, reference 39Q8‑42100, that takes high‑pressure oil from the main pump and trades speed for the low‑speed torque dragging 30 tons across rutted, broken ground.

On a worked R300, drive wear is felt across the whole operation. One track lags on the climb out of the pit, the track shell runs noticeably hot after a shorter run than usual, and a deepening note comes through the floor plates under load. Continuing to work scores the piston group and reduction gears further, and worn metal then circulates through the travel circuit. This aftermarket unit reproduces the original motor‑and‑reducer pairing as one sealed, bench‑run assembly, so the worn drive lifts out whole and the replacement drops straight in.

Core Advantages

1. Torque to pull a loaded 30‑ton frame up ramps
Hardened gear stages multiply motor output down to sprocket speed, so the track digs in rather than spinning on muddy climbs. No laboured, whirring travel under a full bucket.

2. A lapped piston group that holds pressure
The cylinder block, piston shoes and valve plate are finished to close clearance, so oil pressure does not bleed internally. Both tracks pull in step — no wander on the haul road, no lazy side.

3. Sealed for quarry dust and standing water
Heavy Hyundai machines work through long shifts in quarry dust, mud and standing water. Fresh shaft and housing seals keep grit out of the lube — the line between a drive that lasts and one that fails early.

4. One complete, tested unit for a fast turnaround
Motor and reduction arrive pre‑assembled and bench‑checked, so the whole drive swaps in one operation. No sourcing separate parts, no mid‑job mismatches — critical when a stationary 30‑ton machine is losing money by the hour.

5. Aftermarket price for a high‑hour fleet
An original Hyundai final drive exchange carries a premium that is hard to justify on a worked R300. This unit restores full track mobility at a fraction of that cost, with sample and bulk supply available.

Manufacturing & Quality Control

Parts are machined to Hyundai print, heat‑treated at wear points, and assembled in a clean shop. Each finished drive runs on a hydraulic stand while torque, leakage and noise are logged; units outside spec are reworked before packing. The internals are fogged with preservation oil, ports are plugged, and the assembly ships on shock‑absorbing dunnage.

Frequently Asked Questions

Q1: Is 39Q8‑42100 the same as the R320 or R305 drive?
A: The platform is shared across the Robex 30‑ton range, but internal displacement can differ between models. Send the machine serial number and we confirm the correct variant before dispatch.

Q2: Is this the complete motor and reducer?
A: Yes — the listing covers the full axial piston motor and planetary reducer as one assembly, ready to bolt on. If you need only internal parts, ask and we will check availability.

Q3: What symptoms mean the drive is wearing out?
A: Uneven track speed, pulling to one side, a hot or noisy track motor, and tracks that slip rather than pull under load. Catch it before swarf spreads through the whole travel circuit.

Q4: Can I ship this by sea to African ports?
A: Yes — drives this size ship well by sea. Tell us the destination port and we will quote door‑to‑port or door‑to‑door, including any inland trucking needed.

Q5: What is the warranty position?
A: Materials and build defects are covered. Damage from dirty oil, debris in the motor, track obstruction, overload or incorrect fitting is excluded. Photograph any arrival damage before uncrating.