Key Technical Specifications
- Product Model: ROSS 400C79
- Manufacturer: ROSS Controls
- Product Type: Dual Solenoid Pneumatic Valve
- Operating Pressure: 2-10 Bar (29-145 PSI)
- Coil Voltage: 24VDC
- Response Time: 0.05s Excitation Time
- Operating Frequency: 4 Cycles/Second
- Operating Temperature: -5°C to 60°C (23°F to 140°F)
- Media: Compressed Air (Filtered to 5 Microns)
- Connection Type: Bolted Flange
- Function: Directional Control / Fast Exhaust
Product Introduction
ROSS 400C79 is a dual solenoid pneumatic valve designed for fast actuation in heavy industrial machinery. It serves as a pilot valve to control larger air cylinders in stamping presses, forging equipment, and steel mills.This valve delivers a 0.05-second excitation time, enabling rapid mechanical braking when needed. The 400C79 operates reliably between 2 and 10 Bar, making it suitable for high-cycle automated systems. (We’ve seen these fail prematurely when installed without proper air filtration.)
Installation & Configuration Guide
Preparation (10 min)
Lock out and tag out all pneumatic and electrical power. Verify zero energy state. Gather a 5-micron filter, compatible lubricant, and a calibrated torque wrench. Inspect the air supply line for moisture or debris.Removal (5-10 min)
Disconnect the 24VDC electrical connectors. Unbolt the valve from the manifold or actuator flange. Cap all open ports immediately to prevent contamination. (Always photograph the wiring and plumbing before disconnecting anything.)Installation (10 min)
Verify the flow direction arrow on the ROSS 400C79 body matches your system. Install new gaskets or O-rings. Torque the mounting bolts to the manufacturer’s specification in a cross-pattern. Reconnect electrical wiring, ensuring polarity is correct for the 24VDC coil.Power-On & Test (10 min)
Restore air pressure gradually while monitoring for leaks. Apply 24VDC to each coil individually and verify the valve shifts fully. Cycle the valve 10 times at operating pressure to confirm consistent response. Listen for unusual hissing that indicates internal seal leakage.
Troubleshooting Quick Reference
| Symptom | Probable Cause | Probability | Quick Check | Action |
|---|---|---|---|---|
| Valve fails to shift | No coil voltage | 80% | Measure 24VDC at coil terminals | Repair wiring or replace power supply |
| Slow shifting | Contaminated air supply | 70% | Check filter/drain for water or oil | Replace 5-micron filter element |
| Air leaks from exhaust | Worn internal seals | 60% | Listen for continuous hissing at exhaust | Rebuild kit or replace valve |
| Coil burns out | Overvoltage or stuck plunger | 50% | Measure actual coil voltage | Verify 24VDC ±10%; check for mechanical binding |
| Intermittent operation | Loose electrical connection | 40% | Wiggle connectors while energized | Reseat or replace connector |
Dimensions, Mounting & Wiring Notes
- Mounting: Bolted flange connection to manifold or actuator
- Electrical: DIN connector or flying leads (verify specific sub-model)
- Air Ports: Verify port size matches your manifold (typically 1/2″ or 3/4″ NPT/BSP)
- Filtration: Mandatory 5-micron filter upstream. Unfiltered air is the #1 killer of these valves.
- Lubrication: Use only ROSS-compatible lubricant. Incompatible grease swells seals within weeks.
- Exhaust: Install anti-clog silencers rated for the valve’s exhaust flow. Restricted exhaust causes sluggish operation.
FAQ
Can I use the ROSS 400C79 with unfiltered shop air?
No. ROSS specifies a 5-micron filter for this valve. Unfiltered air introduces particulates that score the spool bore, causing internal leaks and eventual failure. I’ve replaced dozens of these valves that were destroyed by dirty air. The 50 filter saves the 1,500 valve.Is the ROSS 400C79 still being manufactured?
ROSS Controls has discontinued this specific model. We carry New Original (New Surplus) stock, but quantities are finite. If you need a long-term solution, contact us to discuss the current replacement model. We can verify cross-compatibility before you commit.What voltage does this valve require?
The standard 400C79 uses a 24VDC coil. However, ROSS produced variants with 110VAC and 220VAC coils. Check the coil label or the original equipment wiring diagram before ordering. Applying the wrong voltage will destroy the coil instantly.How do I know if my valve needs rebuilding or replacing?
If the valve shifts but leaks air continuously from the exhaust port, the internal seals are worn. A rebuild kit may restore function, but at 0.05s response times, even minor seal wear degrades braking performance. For safety-critical press applications, we recommend full replacement over rebuilding.Why is your price lower than the OEM list price?
We source New Surplus inventory directly from factory overstock and cancelled project allocations. These are genuine ROSS products, never used or refurbished. The discount reflects excess inventory clearance, not compromised quality. Every unit receives full functional testing before shipment.I installed a new 400C79 and it won’t shift. What did I do wrong?
First, verify 24VDC is actually reaching the coil (don’t trust indicator lights alone). Second, confirm the air supply is within the 2-10 Bar range. Third, check that the exhaust silencer isn’t clogged. I’ve seen brand-new valves shipped with protective caps still installed on the exhaust port. Remove all shipping protection before operation.
