Servo & proportional valves
4WS servo valves and 4WE, 4WRA, 4WRAE, 4WRPH proportional directional valves. Spool work, nozzle-flapper rebuild, coil and pilot stage replacement on the bench.
NC Servo Technology - Westland, Michigan
734-326-6666
Independent Repair Shop. Not Bosch Rexroth.
Third-Party Repair of Rexroth Servo & Proportional Valves
Independent third-party repair of Rexroth hydraulic valves: 4WE proportional directional, 4WS servo, DBEM pressure, 4WRPH high-response, and 0811 series solenoid units. Backed by a 19,000+ unit in-house inventory we pull aftermarket and donor parts from. NC Servo is not affiliated with Bosch Rexroth or Mannesmann Rexroth. Working on this kind of hardware since 1975.
19,000+ unit pool
In-house inventory we pull aftermarket parts and donor units from.
Hydraulic test stands
Flow, pressure, null, and frequency-response checks before a Rexroth valve ships back.
One-year warranty
Standard on parts and workmanship for Rexroth repairs and rebuilt units.
Hydraulic Valve Repair
What NC Servo does with Rexroth valves
NC Servo repairs Rexroth hydraulic valves at the component level. The shop opens each unit, finds what failed, and rebuilds it with replacement seals, springs, spools, coils, and feedback components from the in-house inventory.
Pressure-control valves
DBEM, DBEE, and DBETBEX proportional pressure relief and reducing valves. Pilot-stage rebuild, calibration, and leak verification.
Discontinued and Mannesmann-era units
Older Rexroth and Mannesmann Rexroth valves the OEM no longer supports. Donor parts from inventory keep older lines in service.
Rexroth Series
Rexroth valve series on the bench
We are a small repair shop, not a Rexroth distributor. The series below are the ones that come through the door often enough to be familiar. If your valve is not listed, send the part number anyway.
4WE directional
4WE6, 4WE10, NG6 through NG32 proportional directional control valves with solenoid or proportional actuation.
4WS servo valves
Two-stage servo valves with nozzle-flapper pilot stages, used on injection molding and metal-forming machinery.
DBEM / DBEE pressure
Proportional pressure relief and reducing valves for closed-loop pressure control.
4WRPH high-response
High-response proportional directional valves for demanding industrial and mobile applications.
Common Faults
What usually shows up on a Rexroth valve
A description of how the valve was acting before it quit helps the diagnosis, but a part number is often enough. The categories below cover the kinds of trouble that show up on Rexroth hydraulic valves.
| Spool and internals | Spool wear, contamination scoring, internal leakage past the spool, sluggish step response, or sticking spool. |
|---|---|
| Pilot stage | Nozzle-flapper damage on 4WS servo valves, contamination plugging, pilot stage faults, or null shift. |
| Electrical and feedback | Burned coils, broken position-feedback links, control-electronics faults, or no actuation under command. |
| Physical condition | Heat damage, contamination evidence, corroded connectors, damaged solenoid housings, or prior repair attempts. |
Workflow
How a Rexroth repair runs
Most jobs run through the same four steps. Lead time varies because some Rexroth repairs need parts pulled off a donor unit, so we only commit to timing once the valve is in front of a tech.
Reach out
Call or email with whatever info you have on the Rexroth valve and the symptom. The shop picks up from there.
Bench evaluation
Once the unit arrives, a tech opens it, inspects internals, and runs it on a hydraulic test stand to confirm what failed.
Cost & approval
We call back with the cost and a rough turnaround. Nothing happens without your sign-off.
Repair, test, ship
Failed components are replaced from inventory or off donor units, the valve is verified on the bench, and it ships back.
Bench Verification
Hydraulic checks before a valve ships back
Repaired Rexroth valves get verified on the hydraulic test stands before they leave the shop. The Hagen-Busch stand handles current and CANbus-capable units; older stands cover legacy 4WE and 4WS valves the shop has kept around for decades.
- Flow characterization across the operating range for the model.
- Pressure gain and step-response measurement against documented procedures.
- Internal and external leakage checked after seal and spool work.
- Null bias and frequency-response trim where the family calls for it.
Inventory & Parts Pool
A 19,000+ unit pool behind the bench
NC Servo's in-house inventory holds over 19,000 hydraulic valves and drives accumulated since 1975. That pool is where the shop pulls aftermarket parts, donor components for older Rexroth and Mannesmann Rexroth families, and rebuilt units when a swap saves time over a fresh repair.
- Aftermarket and donor parts pulled from inventory to keep older Rexroth families running.
- If we have a rebuilt match for your part number, trade in your old valve for a discount on the rebuilt.
- No match on the shelf? We can suggest a comparable Rexroth or cross-brand option, or repair yours.
- Rebuilt valves carry the same 1-year warranty as a fresh repair.
Repair Scope
Where the line is on a Rexroth repair
NC Servo works on the valve itself: spool, body, seals, springs, coils, pilot stage, and feedback hardware. Hydraulic system design, fluid choice, and getting it back on the machine stay with your team.
- Internal valve work: spool service, seal replacement, pilot-stage rebuild, coil and pilot stage work.
- System pressure setup and hydraulic schematic decisions remain on your side.
- Putting the valve back on the machine follows your normal startup process.
- Final machine validation and any tuning to the application are handled by your team.
More on Rexroth Repair
Related pages and brands
More reading on hydraulic valve repair, plus the related brand pages for Bosch-branded products and Bosch Rexroth's drive division.
Valve repair hub
The full range of servo and proportional valve repair NC Servo handles.
Bosch Rexroth combined systems
For combined Bosch Rexroth product pages covering both valves and drives.
Indramat servo drives
Bosch Rexroth's drive division. Drive needs that pair with Rexroth valves go here.
Repair vs replace
When component-level repair makes sense versus buying new or rebuilt.
Need a Rexroth valve looked at?
Give us a call with the part number, a photo of the nameplate, or a short description of the symptom. We will check the shelf, and if we have a rebuilt match you can swap your old one for a discount. If we do not, we can suggest a comparable valve or repair the one you have.
FAQ
Common questions about Rexroth repair
A few things customers ask before sending a unit in. Anything not covered, give us a call at 734-326-6666.
Is NC Servo affiliated with Bosch Rexroth?
No. NC Servo Technology is an independent, third-party repair facility and is not affiliated with, authorized by, or endorsed by Bosch Rexroth or Mannesmann Rexroth. All Rexroth trademarks are the property of their respective owners.
Which Rexroth valves do you cover?
Rexroth servo valves (4WS series), proportional directional valves (4WE6, 4WE10, NG6 through NG32, plus 4WRA, 4WRAE, and 4WRPH high-response), proportional pressure valves (DBEM, DBEE, DBETBEX), and 0811-series solenoid valves. Send a part number to confirm coverage on anything not listed.
What is the difference between Bosch, Rexroth, and Bosch Rexroth?
Rexroth was acquired by Bosch in 2001 and now operates as Bosch Rexroth. Older equipment carries the "Rexroth" or "Mannesmann Rexroth" label; current production is branded "Bosch Rexroth." We service all of these regardless of which generation the label says. For combined products, see the Bosch Rexroth or Bosch pages.
Do you service Indramat servo drives?
Indramat drives are not covered on this Rexroth valve page. Indramat was the drive division that became part of Bosch Rexroth, and we cover those drives on the Indramat brand page instead.
How long does a Rexroth valve repair take?
It varies. NC Servo is a small independent shop, and lead time depends on the valve, what is wrong with it, and whether parts have to come off a donor unit. Give us a call once the unit ships in, and we can give a current estimate after a tech has looked at it.
What happens if the valve is beyond economic repair?
If the valve is not fixable, we will let you know and help source a replacement: a rebuilt match if we have one on the shelf, or a comparable Rexroth or cross-brand alternative.
What is the warranty on a Rexroth repair?
One year on parts and workmanship for repairs and rebuilt units. Standard exclusions apply for contamination, improper installation, and out-of-spec operation. Flushing and filtering the hydraulic system before reinstalling a repaired valve is recommended.