Pilot stage rebuild
Torque motor pilot stages, nozzle flapper, and pilot trim cleaned and aligned against documented procedures on Moog D660 / D661 / D662 valves.
Van Dorn Demag Servo Valve Repair
Independent third-party component-level repair of servo and proportional valves on Van Dorn HT and Demag Ergotech, El-Exis SP, and Systec injection molding machines. Moog D660 / D661 / D662 servo valves and Bosch Rexroth 4WRPEH / 4WRSE / 4WRZ bodies come through the bench.
Where These Valves Sit
Four Van Dorn / Demag machine contexts
Below are the four common platforms seen at the bench across Van Dorn HT and Demag's Ergotech, El-Exis SP, and Systec lines.
01
Van Dorn HT series
28HT through 700HT (28-700 US tons). Moog D661 / D662 servo valves and Rexroth 4WRPEH / 4WRZ proportional valves come off these for rebuild.
02
Demag Ergotech series
25 to 1,000 metric tons. Ergotech, Compact, and Extra. Rexroth 4WRPEH / 4WRSE / DBEM proportional and Moog D633 / D634 servo valves come through routinely.
03
Demag El-Exis SP
150 to 750 metric tons. Moog D660 / D661 / D662 servo valves come off these high-speed packaging machines for rebuild.
04
Demag Systec series
35 to 1,000+ metric tons. Successor to Ergotech. Rexroth 4WRPEH, 4WRSE, 4WRZ proportional valves come through routinely.
What NC Servo Does
Component-level repair on Van Dorn / Demag valves
Each unit is opened, inspected, and rebuilt at the component level. Failed parts come from inventory or off donor units. Bench verification before ship.
Spool & sleeve service
Spool wear, contamination scoring, and lap restoration on the servo and proportional valve bodies that come off Van Dorn / Demag machines.
Coil & feedback work
Burned coil rebuild, feedback wire repair, and LVDT verification on closed-loop servo valve bodies.
Bench testing
Hagen-Busch and older-style hydraulic stands. Hysteresis, null shift, and step response data on request.
Donor parts service
Aftermarket and donor parts for legacy Van Dorn HT and Demag Ergotech bodies.
Repair scope
Bench-level component work on the valve hardware. PLC programming, machine parameter setup, and integration stay with the customer.
Brands
Van Dorn / Demag servo valve brands
Top brands seen on Van Dorn HT and Demag hydraulics. Click through for the dedicated brand page.
Common Faults
What usually shows up on Van Dorn / Demag valves
Common failure modes seen on Van Dorn / Demag valves at the bench.
| Spool wear | Worn spool edges and contamination scoring on Moog D660 / D661 / D662 and Rexroth 4WRPEH bodies. |
|---|---|
| Internal leakage | Worn lap surfaces and degraded seals drive cross-port leakage past the spool. |
| Pilot & coil | Pilot null shift on Moog servo bodies, plus burned proportional coils on Rexroth valves. |
| Slow valve response | Sluggish valve dynamics from contamination and aged spool surfaces. |
Workflow
From part number to ship-back
Same four-step path through the shop whether the unit came off a Van Dorn HT toggle or a Demag El-Exis SP high-speed press.
- 01
Get in touch
Call or email with the part number, machine model, and a photo of the nameplate if it helps.
- 02
Bench review
Tech opens the unit, inspects pilot and spool, and runs it on the hydraulic stand to confirm what failed.
- 03
Cost & approval
We call back with the cost and a rough turnaround. Nothing is started without your sign-off.
- 04
Repair, test, ship
Failed components replaced from inventory or off donors, the valve verified under pressure, and shipped back.
FAQ
Common questions about Van Dorn / Demag valve repair
Application-specific questions. For brand-specific FAQs, see the dedicated brand page above.
What servo valve brands come off Van Dorn and Demag machines?
Van Dorn HT and Demag Ergotech, El-Exis SP, and Systec machines typically run Moog D660 / D661 / D662 servo valves and Bosch Rexroth 4WRPEH / 4WRSE / 4WRZ proportional valves. All come off the bench for rebuild.
Can you repair valves on El-Exis SP high-speed machines?
Yes. El-Exis SP machines (150-750 metric tons) run Moog D660 / D661 / D662 servo valves. The valves come through the bench for full rebuild.
What's the difference between Ergotech, Systec, and El-Exis on the bench?
Ergotech and the successor Systec line run Rexroth 4WRPEH / 4WRSE / 4WRZ proportional valves; high-performance configurations use Moog D633 / D634 servo. El-Exis SP focuses on Moog accumulator-injection servo bodies. Repair scope is similar across all three.
How long does a repair usually take?
Lead time varies job to job, partly because parts are often pulled from donor boards. Give us a call with the part number and the situation.
Do you provide Van Dorn or Demag machine programming?
No. NC Servo handles bench-level component repair on the valve hardware only. PLC programming, machine parameter setup, and integration stay with the customer or OEM.
What if the valve is beyond economic repair?
If the valve is not fixable, we will let you know and help source a replacement.
What is the warranty?
One year on parts and workmanship for repairs and rebuilt units. Standard exclusions apply for contamination, improper installation, and out-of-spec operation.
More from NC Servo
Related repair coverage
Other injection-molding pages and the brand pages most-tied to Van Dorn / Demag hydraulics.
IMM hub
All injection molding builders we cover, plus shared hydraulics context.
Cincinnati Milacron
Other heavy-duty North American IMM coverage with similar Moog hardware.
Engel
Other European IMM coverage with Rexroth 4WRPEH bodies.
Moog brand page
Moog D660, D661, D662, G761, and broader Moog servo valve hardware.
Bosch Rexroth
Rexroth 4WRPEH, 4WRSE, 4WRZ proportional valve coverage.
Valve repair hub
Full directory of 20+ valve brands.
What is a servo valve?
Plain-English explainer on electrohydraulic servo valves and how they relate to proportional hardware.
What is a proportional valve?
How proportional and servoproportional valves differ from true servo valves, and what gets done at the bench.
Van Dorn or Demag valve down? Send a part number
Give us a call or send a part number with the machine model and the symptom. We'll check the donor pool, suggest a rebuilt match if we have one, and walk through repair or cross-brand options if we don't.