Beschrijving
The fan on a ZX470-3 does not turn because a belt tells it to. It turns because a small variable displacement pump, mounted in the gear train behind the main pumps, delivers metered oil to the fan motor. When that pump loses displacement, the fan stops reaching high speed, and the machine starts running hot under load while every other function still feels normal. That combination, heat plus normal digging power, is the signature of a fan pump problem.
What the unit carries
The pump in these photographs is a grey cast-iron axial piston unit with a splined drive shaft, a solenoid-operated control block and a nameplate reading K3V63 with a control code beginning ORDE5K-31/30C03 and works number 07105. The housing is cast 2084. That places it in Kawasaki’s K3V swash-plate family, single-pump configuration, which is the platform Hitachi used for fan drive on the 45 to 47 tonne -3 machines.
Where it fits
Supplied for Hitachi ZX450-3, ZX450-3F, ZX450LC-3-DH and ZX470H-3. The same 4633474 number appears in trade parts data against ZX470-3 machines, and 4633472 is quoted alongside it for the same application, which is typical of Hitachi numbering where a revision changes the suffix but not the installed dimensions. Confirm against your own plate. If your machine is a -5B, -5G or -6, the fan drive is a different assembly and this is not the part.
Reference data for the K3V63 platform
Kawasaki’s published catalogue for the K3V and K5V open-circuit range gives the following for the 63 size: geometric displacement 63 cm3/rev, rated pressure 34.3 MPa and peak pressure 39.2 MPa, with maximum self-priming speed 2,650 rpm and maximum speed 3,250 rpm. Two notes on those figures. First, rated pressure is the level at which the manufacturer’s guarantee of performance and service life applies; peak is the level at which the unit still functions but with reduced life, so a repeatedly spiking fan circuit is a life-shortening condition, not a normal one. Second, Kawasaki’s current web data lists the same model at 65 cm3/rev, a revision difference between catalogue editions that matters if you are comparing against a data sheet rather than a nameplate.
Reading a Kawasaki regulator code before you order
Two pumps with identical housings behave differently if the regulator is not the same. Kawasaki’s regulator coding for this family assigns a digit to each horsepower or pressure function and a letter to each flow function:
- 1 constant horsepower, 2 total horsepower, 4 pressure cut-off, 5 high-pressure cut-off, 9 variable horsepower.
- M manual flow control, P positive flow (pilot), N negative flow, C two-stage maximum flow, L load sensing, E electric flow control.
- Suffix letters on the order code identify combinations, because these machines commonly run a negative-flow function together with total horsepower and two-stage maximum flow.
Photograph the plate on your old pump and send it with the enquiry. Matching the plate takes one minute and prevents the most common return we get on fan pumps.
Fitting this pump so it lasts
Three rules decide the service life of any replacement fan pump. Keep the case drain below the manufacturer’s limit, which for this size band is 0.1 MPa normally and 0.4 MPa at peak, and route it to tank with no check valve and no tight bend. Hold the oil to NAS 1638 class 9, that is ISO 4406 18/15, changing the return filter element as part of the job, since a pump fitted to oil that has already carried wear metal from the failed unit will repeat the failure. And fill the casing with clean oil before the first crank, because dry starting an axial piston unit is a documented killer.
Then prove the circuit rather than assuming it. Run the tests in our hydraulic fan pump diagnosis guide, check the regulator signal with the regulator diagnosis and adjustment procedure, and inspect the drive gear that feeds the pump as covered in our drive gear inspection guide. If the transfer case behind the pumps has worn, a new pump inherits the same starvation, and the transfer case failure article explains what to look for.
Related parts on the same machine
The motor that this pump drives is listed under our YA00005829 KYB fan motor en 4634936 Parker fan motor pages, depending on which was fitted at the factory. Main pumps, control valves and the rest of the Hitachi range sit under hydraulische pomp graafmachine en de Hitachi parts section.
New aftermarket units carry a three to six month warranty as stated on your proforma invoice. Monthly output on this line is around 500 pieces, minimum order one piece, and we photograph the tested pump against your order before the wooden case closes.
