A hydraulic failure usually ends the same way: you are holding a pump or a motor, you know a part has to be ordered, and all you have is a few strings of letters and digits on the housing, none of which looks like a catalogue number.
In our experience this is the single most common reason an order takes days longer than it should. Not stock shortage, but the inability to identify the unit. Below we explain how to read a hydraulic nameplate step by step and which details actually matter when ordering.
Where to find the nameplate
The nameplate is usually a metal label or riveted plate on the housing. On working machines it is rarely in an obvious spot. Check, in order:
- the flat area of the housing opposite the shaft,
- the side of the casing between the suction and pressure ports,
- the mounting flange and the area around it,
- the rear cover, a common location on variable displacement pumps,
- anywhere hidden under dirt and oil, which is where most nameplates actually are.
Before concluding there is no nameplate, wipe the likely areas with a degreaser. In practice the plate is usually there, just buried under grease.
Some manufacturers also cast or engrave markings directly into the housing. Those numbers become valuable when the label is gone.
What the fields on the nameplate mean
- Manufacturer name or logo: Bosch Rexroth, Sauer Danfoss, Linde, Kawasaki, Parker, Casappa, Poclain, Liebherr, Nachi, KYB.
- Type code, labelled Typ, Type, Typenbezeichnung or Model. The longest string on the plate, describing the unit's design.
- Material or part number, labelled Material-Nr, MNR, Ident-Nr or Part No. This is the commercial number used for ordering.
- Serial number, labelled S/N, SN or Serien-Nr. It identifies one individual unit, not the model.
- Production date, often shown as FD or just the year.
- Operating data: displacement in cm³/rev, maximum pressure in bar, sometimes rated speed.
- Direction of rotation, marked R or L, sometimes as an arrow on the housing.
The key rule: ordering requires the type code or the material number. A serial number alone is usually not enough.
Part number, serial number and machine number are three different things
The type code describes the design: size, control type, direction of rotation, shaft and port configuration. Two units sharing a type code are interchangeable.
The material number is the commercial number assigned to one specific configuration. At Bosch Rexroth it normally starts with the letter R followed by digits. If you can see it, quote it, because it is unambiguous.
The serial number refers to one unit off the production line. The manufacturer can trace a specification from it, a distributor generally cannot.
The machine number belongs to the excavator, loader or tractor, not to the pump. It helps as supporting information, but a single machine model often carried different pumps across production years, so it is not sufficient on its own.
Codes used by the most common manufacturers
You do not need the full syntax. You need to recognise the manufacturer and locate the size within the code. In most systems the number in the code is the displacement in cm³ per revolution, which immediately narrows the search.
The sections below cover the general rules. If you are looking for one specific designation, the full list of series is in Hydraulic pump and motor series. Manufacturer designations.
Bosch Rexroth
Open circuit piston pumps are marked A10VSO, closed circuit ones A4VG, with A11VO and A2FO also common. Motors include A6VM and A2FM. Gear pumps belong to the AZPF and AZPN families.
A typical type code reads A10VSO45DFR1/31R-PPA12N00. The number after the series, here 45, is displacement in cm³/rev. The R or L before the dash gives the direction of rotation. A segment such as DFR1 describes the control, and 31 identifies the design series, which matters for repair kits because parts are not always interchangeable between series.
On a Rexroth plate also look for the MNR field. That material number is the most reliable ordering reference.
Sauer Danfoss
Series 90 dominates in travel drives and series 51 among motors. A code such as 90R075 reads simply: series 90, pump version, 75 cm³/rev. Likewise 51V060 and 51D080 are motors of 60 and 80 cm³/rev displacement.
Linde Hydraulics
Variable pumps belong to the HPR family, motors to HMV and HMF. The number, as in HPR105 or HMV105, is the unit size in cm³/rev. A suffix such as 02 or 02R indicates the design version and direction of rotation.
Kawasaki
Excavator pumps are mainly K3V and K5V series. Codes such as K3V63DT, K3V112DT, K3V180DT or K5V140 carry the displacement directly. These pumps are usually tandem units with two sections, which matters when ordering because the sections may differ in equipment.
Parker and Casappa
Parker piston pumps belong to the PV family, where the number indicates size, for example PV092. Bent axis motors are the F11 and F12 series. Gear pumps fall under PGP.
Casappa mainly produces gear pumps in the PLP20 and PLP30 ranges. The code starts with the range, and the remainder defines displacement and port configuration.
Poclain
Radial piston motors carry the MS designation with a size number, such as MS05, MS11 or MS25. Versions with an integrated brake carry additional letters. With these motors the full code matters especially, because the number of build variants is very large.
Danfoss orbital motors
The simplest system in hydraulics. OMP, OMR, OMS, OMT and OMV identify the range, and the adjacent number is displacement in cm³/rev. An OMP 50 is a 50 cm³/rev orbital motor. Shaft and flange type still matter when ordering, so include a photo from the mounting side.
Drive axles, gearboxes and transmissions
The same rules apply outside hydraulics. Drive axles and gearboxes carry nameplates too, they are just in different places: on the axle housing, on the differential cover, or on the side of the gearbox casing. Numbers are also often stamped straight into the casting.
The manufacturers you will meet most often in construction and agricultural machinery are Carraro, Dana, ZF, Clark-Hurth and Kessler, plus Comer Industries and Bondioli in gear drives. The plate carries the model designation, the serial number and, on axles, very often the ratio.
On these units the ratio is critical information. The same axle type was produced in several ratio variants and internal parts are not interchangeable between them. The rules for writing down Carraro, Dana Spicer and ZF numbers are covered in detail in Drive axle and gearbox numbers. How to read the plate.
Check availability under Drive axles and Gearboxes and transmissions.
What to do when the nameplate is missing or unreadable
Entirely normal on units with fifteen years of service. It is solvable, it just needs more input. Collect whatever you can:
- numbers cast or stamped into the housing, including on the cover,
- photos from four sides, with the shaft and mounting flange in frame,
- the spline count and type, or a note that the shaft is keyed,
- port type and spacing, flanged or threaded,
- machine make, model, year and serial number,
- approximate overall dimensions and weight.
That is normally enough to narrow identification down to one family, with documentation settling the rest.
How to photograph a nameplate so it can actually be read
- Wipe the plate with degreaser, oil scatters light.
- Do not use direct flash. Stamped characters disappear in the reflection.
- Light the plate from the side, at an angle, so the characters cast shadows.
- Shoot perpendicular to the plate, not at an angle.
- Take one close-up of the plate and one photo of the whole unit.
- Send the original file, not a screenshot from a messenger. Compression destroys fine characters.
Common ordering mistakes
- Quoting the machine number instead of the pump number. The same machine model carried different units depending on the build year.
- Omitting the direction of rotation. Correct displacement with the wrong rotation will not work.
- Ignoring the design series. The same series in different versions has different internals and different repair kits.
- Confusing a pump with a motor. They look alike, the type code settles it.
- Ordering seals only when the wear is mechanical. If the unit ran loud or lost power once hot, internal components are usually worn too.
You have the number. What next
Once you know the type code or material number, sourcing the part is straightforward. Check availability in the relevant category:
- Hydraulic pumps
- Hydraulic motors
- Directional control valves
- Hydraulic valves
- Steering units and orbitrols
- Hydraulic cylinders
- Hydraulic accumulators
- Coils
- Drive axles
- Gearboxes and transmissions
- Hydraulic filters
- Machine parts
If the number could not be recovered, send us photos and machine details and we will identify the part from those. We do this daily, including for units not listed in the catalogue, since we source parts to order. Contact details and the enquiry form are on our Contact page.
With your enquiry include: a photo of the nameplate, a photo of the complete unit with the shaft visible, the machine make and model, and a short description of the symptoms. With that set we normally reply with price and lead time the same working day.
Frequently asked questions
Where is the nameplate on a hydraulic pump?
Most often on the flat part of the housing opposite the shaft, on the side between the ports, or on the rear cover. Wipe the housing first, the plate is usually hidden under oil residue.
Is the serial number enough to order parts?
Usually not. A serial number identifies one individual unit rather than its configuration. Ordering needs the type code or material number, or alternatively a full set of photos plus machine details.
How do I check the direction of rotation?
Usually from the R or L in the type code, sometimes from an arrow cast into the housing. If neither is present, rotation is determined from the drive side on the machine.
What does the number in the type code mean?
In most manufacturer systems it is the pump displacement or motor displacement in cm³ per revolution. It is the first detail that narrows down a search.
Will a replacement fit the same as an original?
Yes, provided the type code, design series, direction of rotation, shaft and port configuration all match. A mismatch in any of those means the part is not interchangeable, even at identical displacement.