Pilot stage rebuild
Torque motor pilot stages, nozzle flapper, and pilot trim cleaned and aligned against documented procedures on Moog 72 / 73 series valves.
HPM Servo Valve Repair
Independent third-party component-level repair of servo and proportional valves on HPM injection molding machines: Freedom, Hemipac, Toggle Press (TP), and Direct Clamp. Bosch Rexroth 4WRPEH / 4WRZ proportional valves and Moog Series 72 / 73 servo valves come through the bench.
Where These Valves Sit
Four HPM machine contexts
HPM machines were built for heavy-duty molding work. Below are the four common platforms seen at the bench.
01
Freedom series
200 to 4,000+ US tons. Later-generation hydraulic line. Rexroth 4WRPEH / 4WRZ proportional valves and Moog servo valves come off these for rebuild.
02
Hemipac series
Toggle-clamp machines. Rexroth proportional directional valves and Moog Series 72 / 73 servo valves come through routinely.
03
Toggle Press (TP) models
400-TP, 600-TP, and other tonnages. Rexroth proportional valves come off these for rebuild.
04
Direct Clamp models
500 to 4,000+ US tons. Moog servo valves and Rexroth proportional valves come off these for rebuild.
What NC Servo Does
Component-level repair on HPM 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 heavy-duty HPM valve bodies.
Coil & feedback work
Burned coil rebuild, feedback wire repair, and LVDT verification on closed-loop 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 HPM valves, including discontinued Moog 72 series bodies.
Repair scope
Bench-level component work on the valve hardware. PLC programming, machine parameter setup, and integration stay with the customer.
Brands
HPM servo valve brands
Top brands seen on HPM hydraulics. Click through for the dedicated brand page.
Common Faults
What usually shows up on HPM valves
Common failure modes seen on HPM valves at the bench.
| Spool & body | Spool wear, contamination scoring, and lap-surface degradation on heavy-duty HPM valve bodies. |
|---|---|
| Pilot stage | Pilot null shift, nozzle plugging, and torque motor wear on Moog 72 / 73 series and D661 servo bodies. |
| Internal leakage | Worn seals and lap surfaces drive internal cross-port leakage on aged Rexroth and Moog bodies. |
| Coil & feedback drift | Burned coils after surge events, feedback wire wear, and LVDT signal drift on closed-loop bodies. |
Workflow
From part number to ship-back
Same four-step path through the shop whether the unit came off a Freedom or a Direct Clamp.
- 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 HPM valve repair
Application-specific questions. For brand-specific FAQs, see the dedicated brand page above.
What servo valve brands come off HPM machines?
HPM Freedom, Hemipac, TP, and Direct Clamp machines typically run Bosch Rexroth 4WRPEH and 4WRZ proportional valves alongside Moog Series 72 / 73 servo valves. All come off the bench for rebuild.
Can you repair valves from HPM Direct Clamp models?
Yes. Direct Clamp machines (500 to 4,000+ tons) run Moog servo valves and Rexroth proportional valves. Both come through the bench routinely.
What about Moog Series 72/73 servo valves on Hemipac?
Yes. Moog Series 72 and 73 servo valves on Hemipac and other later HPM platforms come through the bench. Spool, sleeve, pilot, and coil work all standard scope.
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 HPM machine programming or software configuration?
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 HPM hydraulics.
IMM hub
All injection molding builders we cover, plus shared hydraulics context.
Cincinnati Milacron
Other heavy-duty North American IMM coverage.
Van Dorn / Demag
Other US-built IMM coverage with similar hardware.
Bosch Rexroth
Rexroth 4WRPEH, 4WRZ, and proportional valve coverage.
Moog brand page
Moog 72 / 73 series, D661, and broader Moog servo valve hardware.
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.
HPM 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.