Descrição
When a DX380 or DX420 starts running hot at idle but pulls back to normal temperature once the engine is revved, the first component that is usually blamed is the radiator. More often the fan is simply not being driven hard enough. The K1057295 is the hydraulic motor that turns the cooling fan on these machines, and once its internal clearances open up it stops converting oil flow into shaft speed the way it should.
Where this motor sits in the cooling circuit
Doosan drove the fan hydraulically on the DX series rather than mechanically through a belt and viscous coupling. A dedicated fan pump in the hydraulic system delivers oil to a motor mounted behind the radiator, and control logic varies the airflow using engine coolant temperature and hydraulic oil temperature as inputs. Caterpillar describes the same arrangement on its own excavators as cooling the engine on demand, with a reverse function to clean the cores, and it is the reason a worn fan motor shows up as a temperature problem rather than a pressure problem.
The practical consequence for diagnosis: a machine with a tired fan motor still digs normally. Swing, travel and boom speed stay within spec because the fan circuit is not what powers them. The first symptom a plant manager notices is the coolant gauge drifting up during Idling on a hot day, or a fan that no longer kicks into high speed when the air conditioning and the hydraulic system are both loaded.
Fitment and cross-reference
Published data for the models this part is generally supplied to:
| Modelo | Published operating weight | Published rated engine power | Motor | Numbers listed in trade catalogues |
|---|---|---|---|---|
| DX380LC-3 | approx. 38.2 t | 213 kW (286 hp) at 1,800 rpm | Doosan DL08K | K1057295 |
| DX420LC-5 | 42.6 t (manufacturer figure) | 257 kW gross (345 hp), 252 kW net, at 1,800 rpm | Scania DC09, 12.7 litre | K1057295 |
| DX490LC-5 / DX500 | 49.5 t (DX490LC-5) | 380 hp gross (DX490LC-5) | Scania (confirm by machine) | K1057295, 400702-00084 |
| DX520 / DX520LC-9C | varies by market specification | confirm by machine | confirm by machine | K1057295, K1006254 |
| DX530LC-5 | 52.1 t (manufacturer figure) | 283 kW gross (380 hp) at 1,800 rpm | Scania DC13, 12.7 litre | 400702-00084 (see our DX490 / DX530 listing) |
The last row matters because buyers routinely search the DX380 part and end up needing the DX530 part, or the other way around. Weight and power figures above are taken from published Develon and equipment-data sources; where we could not verify a value we have written confirm by machine rather than guess at it.
What we actually send you
A new HTD-branded replacement manufactured in China. This is not a genuine Doosan or Develon part and we do not sell it as one. That distinction has commercial consequences you should plan for: new aftermarket units carry a three to six month warranty as stated on your proforma invoice, while genuine OEM parts and used cores are sold without warranty cover.
Every unit is inspected before packing and photographed so you can confirm the flange, the spline count and the port positions against the motor you removed. Monthly output for this line is around 300 pieces, so single-piece orders and container quantities come off the same production run.
Installation points that decide service life
Most replacement fan motors that fail early do not fail because of the motor. They fail because the oil that killed the original unit was never flushed out, or because the case drain line was routed with a restriction. Bosch Rexroth specifies a cleanliness level of at least 20/18/15 to ISO 4406 for its axial piston units in this class, and caps case drain pressure at 2 bar absolute. Both limits are worth respecting on a Doosan fan circuit.
The working sequence we send with each order: drain and catch the fan circuit oil, flush the lines and the core, confirm the fan pump is still delivering, fit the new motor with clean oil, keep the case drain running free to tank, then bleed the circuit with the fan held restrained and watch shaft rotation direction before the guard goes back on. Our guia de diagnóstico de motor de ventoinha hidráulica covers the tests to run before you authorise the part, and a lista de verificação de reconstrução do kit de vedantes explains where case drain leakage starts.
Related parts on the same machine
If the fan will not reverse, or the machine holds a high hydraulic oil temperature even with a new motor fitted, work outward from the fan circuit: diagnóstico da bomba do ventilador, coolant temperature sensor testing, e the check valve inspection that catches the cases where every wear part has been replaced and the oil still runs hot. Other Doosan wear parts we stock are listed under the seção de peças Doosan, e o completo hydraulic fan motor range covers CAT, Komatsu, Hitachi and Volvo equivalents.
Perguntas frequentes
Is K1057295 the same part as 300506-0007?
Not automatically. A large number of trade listings cross-reference the two, and 300506-0007 is also sold for the DX700. Treat the number cast on your own housing plus photographs of the flange and ports as the deciding evidence, and send both before payment.
Will it fit a DX520?
Many DX520 machines use this fan motor, while others, particularly later 9C-market builds, use a different housing. We confirm from your data plate and old-unit photos.
Can I buy one piece to test the market?
Yes. Minimum order is one piece and small consignments go by DHL, FedEx, TNT or EMS. Bulk orders ship by sea or air in wooden cases.
Why does my excavator still overheat after fitting a new fan motor?
Three usual causes: a collapsed or restricted case drain line, a fan pump that has lost displacement, or an external radiator core plugged with dust. Rule them out in that order before blaming the new part.
Do you send pictures before shipping?
Yes. We inspect the unit, photograph it against the order, and wait for your confirmation before packing.
