Description
The -5G generation is where Hitachi’s cooling package becomes a two-pump arrangement, and it is also where most mis-orders on this part happen. A buyer searching for a K7V63 fan pump may need the axial piston unit, or may need the gear unit that sits with it, and the two are not interchangeable. This page separates them, and puts the Kawasaki size data alongside so you can sanity-check what you are being quoted.
The two numbers, and which one you need
Hitachi’s parts data for the ZX870-5G and ZX670 cooling drive lists an axial piston pump under YA00011362 et 4712983, and a gear pump under 4700708. The photographs on this listing are of the axial piston unit: a dark grey cast body, splined input shaft, solenoid-operated control block, and a plate reading ORDE5K-31/40C03 with works number 2541, cast 2084 on the body.
Which one fails tells you what to buy. Loss of fan speed under load with normal pilot pressure points at the axial unit. Faults in the control and signal side of the circuit, or a machine that will not command the fan at all, point at the gear unit and its supply. Photograph the plate of the unit you removed and send it with the enquiry; that single image settles it faster than any parts list.
Kawasaki size data for the three families
Hitachi’s K3V, K5V and K7V designations refer to Kawasaki pump families. Published figures for the 63 size in each, which is what these fan drives use:
| Family and size | Cylindrée géométrique | Rated pressure | Pression de pointe | Maximum speed |
|---|---|---|---|---|
| K3V63 (single, S) | 63 cm3/rev, listed as 65 cm3 on current Kawasaki web data | , circuit de rotation | 39.2 MPa | 2,650 rpm self-priming, 3,250 rpm maximum |
| K5V80 (single, S) | 80 cm3/rev | , circuit de rotation | 39.2 MPa | 2,460 rpm self-priming, 3,000 rpm maximum |
| K7V63 (single, S) | 65 cm3/rev | 35 MPa | 40 MPa | 2,650 rpm self-priming |
The K7V is the newest of the three, and it is not just a re-marked K3V: the family runs from K7V63 at 65 cm3/rev up to K7V280 at 280 cm3/rev, at a higher rated pressure than the older ranges, and Kawasaki brought out a K7V320 at 322 cm3/rev with 37 MPa rated pressure in 2026. For a buyer this matters in one practical way: a pump ordered as a K7V63 replacement should be checked against the plate, because the regulator codes differ between generations even where the mounting faces do not.
What the machine expects from this pump
Hitachi’s own description of the cooling system on the ZX870-5G is that the radiator and oil cooler are arranged in parallel and that the system optimises the rotational speed of two cooling fans according to coolant and hydraulic oil temperature, giving cooling capacity and noise reduction. That is a demand-led system: the pump has to vary delivery in response to a signal, and the fan motor has to convert it into shaft speed.
Published data for the class, for reference when you are sizing the job:
- ZX870-5G: Isuzu BB-6WG1XQA-04 engine at 360 kW (483 hp), operating weight 80,800 to 84,200 kg, twin cooling fans.
- ZX870LC-6: Isuzu 6WG1-FT4 at 382 kW net, 85,600 kg, two cool-on-demand hydraulic fans, main pump delivery to 566 L/min.
- ZX670LC-5G: Isuzu BB-6WG1XQA-05 at 312 kW, approximately 66 tonnes.
- ZX690LCH-5A: Isuzu GH-6WG1XKSA-02 at 345 kW, 69,100 kg, main pumps 2 x 489 L/min with a 50 L/min pilot gear pump.
Diagnosis before purchase
On a machine with two fans, a heat complaint can be one fan rather than the drive itself, so check both. Then measure rather than infer: our guide de diagnostic des pompes de ventilateur hydrauliques covers flow and delivery pressure testing, and the regulator diagnosis and adjustment article covers the control signal that tells this pump to change displacement. Hitachi’s technical manual for the -6 series lists the same checks by name, including fan pump P-Q diagram, fan pump flow rate measurement, fan pump delivery pressure and fan motor drainage.
Two conditions destroy these pumps and get blamed on the replacement. A restricted case drain, which for this size band should stay within 0.1 MPa normally and 0.4 MPa at peak. And contaminated oil, where the working target is NAS 1638 class 9, that is ISO 4406 18/15, with a 10 micron return filter and an 80 to 150 mesh suction strainer. Change the element as part of the job. If the machine has already swallowed a pump, read the drive gear inspection guide before fitting.
Fitment list
ZX870LC-5B, ZX870-5G, ZX870H-5G, ZX870LC-5G, ZX870LCH-5G and ZX870LCR-5G, plus the ZX670 class where the parts book gives a K7V63S fan pump. Confirm against the machine serial, since Hitachi changed the cooling assembly between the -5B, -5G and -6 generations.
Conditions
Minimum order one piece, around 500 units a month available. New aftermarket units carry a three to six month warranty as stated on your proforma invoice. Each pump is bench tested, photographed after test against your order, and packed in a wooden case or to your specification. Delivery 5 to 8 working days from payment subject to stock, by sea, air, or DHL, FedEx, TNT and EMS. The fan motors for these machines are on our 4634947 replacement fan motor page, and the wider range sits under moteur hydraulique de ventilateur et Hitachi parts.
