Neway air suspension systems are widely used in heavy-duty trucks, trailers, and buses for their durability and ride quality. Understanding the individual parts of a Neway suspension can help fleet managers, mechanics, and owner-operators troubleshoot issues, plan maintenance, and make informed replacement decisions. This article provides a detailed breakdown of the major Neway suspension components, their functions, common failure points, and practical care tips.
Overview of Neway Suspension Systems
Neway (now part of Hendrickson) manufactures air-ride suspension systems for commercial vehicles. These systems use air springs instead of traditional steel leaf springs, allowing for adjustable ride height, improved load leveling, and reduced vibration. A typical Neway suspension consists of several key assemblies: the air spring system, the shock absorbers, the height control valves, the trailing arms or beams, and the axle attachment hardware. Each component plays a critical role in vehicle handling and load support.
Air Springs
Air springs, also referred to as air bags or air bellows, are the heart of the suspension. They are rubber-reinforced bladders that hold compressed air to support the vehicle's weight and absorb road impacts.
Construction and Types
Neway uses two main types of air springs: convoluted and sleeve. Convoluted air springs have a rolling lobe design that allows for a compact package and good durability. Sleeve air springs are simpler but less common on newer systems. Both types are made from multiple layers of rubber and fabric, with steel bead rings at the top and bottom for mounting.
Common Failure Modes
- Cracking or dry rot from age and ozone exposure.
- Punctures from road debris or improper installation.
- Leaks at the bead ring or air line connections.
- Sagging due to internal delamination.
Maintenance Tips
- Inspect air springs visually every month for cracks, bulges, or abrasions.
- Check air pressure regularly; low pressure can cause bottoming out and damage other components.
- Replace air springs in pairs on the same axle to ensure balanced ride.
- Use only genuine Neway or equivalent high-quality replacements to avoid fitment issues.
Shock Absorbers
Shock absorbers dampen oscillations of the air springs and control chassis motion. Neway suspensions typically use hydraulic shocks tuned for the system's spring rate.
Function and Wear Indicators
A failing shock may leak oil, have a weak damping effect, or make clunking noises. Worn shocks reduce ride comfort and can lead to accelerated tire wear and poor handling.
Replacement Guidance
- Replace shocks if they show signs of leakage or excessive bounce.
- Always replace in pairs (both sides of an axle).
- Use shocks that match the original equipment specifications (OEM shock part numbers are usually stamped on the body).
Height Control Valves (Leveling Valves)
Height control valves (HCVs) regulate the air pressure in the air springs to maintain a consistent ride height regardless of load. They are mechanical or pneumatic valves linked to the chassis and axle. As the load changes, the valve opens or closes to add or release air.
How They Work
A typical Neway HCV has a linkage that connects to the suspension. When the vehicle is loaded, the chassis lowers relative to the axle, the linkage moves the valve spool, and air enters the springs to raise the vehicle back to the set height. When unloaded, air is exhausted.
Troubleshooting
- Vehicle leans to one side: defective valve on the low side.
- Slow or no height adjustment: linkage binding, stuck spool, or air line blockage.
- Air leaking from exhaust port: internal seal failure.
Maintenance
- Lubricate the linkage pivots annually.
- Check rod adjustment after any suspension work.
- Replace faulty valves promptly to avoid uneven loading and tire wear.
Trailing Arms and Beams
Neway suspensions use trailing arms or beams to connect the axle to the chassis and control wheel alignment. They are typically constructed from forged steel or cast iron and feature bushings at both ends.
Types
- Parallel trailing arms: two arms per axle, parallel to the chassis. Common on drive axles.
- Single trailing arm (beam): a one-piece design that combines both sides. Often used on trailer axles.
Bushing Wear
Bushings are the most common wear item. Worn bushings cause loose steering, wheel hop, and uneven tire wear. Replacement intervals depend on usage but typically every 200,000-300,000 miles.
Inspection
- Check for cracks or bends in the arm.
- Test bushing play by prying on the wheel with the vehicle lifted.
- Replace if excessive movement or metal-to-metal contact is present.
Axle Attachments and Fasteners
The axle is attached to the suspension via U-bolts, torque rods, and brackets. These components must be properly torqued to maintain alignment and prevent axle walk.
U-Bolts
- Used to clamp the axle to the suspension.
- Must be torqued to manufacturer specs (typically 250-400 lb-ft, but check the manual).
- Retorque after initial run-in (500-1000 miles).
Torque Rods (Track Rods)
- Prevent fore-aft movement of the axle.
- Have bushings that wear over time.
- Inspect for loose or broken bushings; replace in pairs.
Air Lines and Fittings
The air system includes nylon or rubber hoses and brass or stainless steel fittings. Miniature leaks can cause air loss and compressor cycling.
Common Leak Points
- Push-to-connect fittings: O-ring failure or improper insertion.
- Hose cuts from rubbing against chassis components.
- Loose connections at air springs or valves.
Repair
- Use a soapy water spray to detect leaks.
- Replace damaged hoses with DOT-approved air brake line (rated for 200 psi).
- Use thread sealant on tapered fittings, not PTFE tape.
Electronic Height Control (Optional)
Some modern Neway systems use electronic height sensors and solenoid valves instead of mechanical leveling valves. These offer more precise ride height control and can be integrated with vehicle ECUs.
Differences from Mechanical
- Height sensors produce a voltage signal.
- Solenoids control air flow.
- Requires diagnostic tools for calibration.
Reliability
- Sensors can fail due to corrosion or wiring issues.
- Solenoids may stick or fail electrically.
- Generally reliable if kept clean and dry.
Practical Maintenance Schedule
To maximize Neway suspension life, follow this schedule:
Monthly:
- Inspect air springs for cracks or damage.
- Check ride height and adjust if necessary.
- Listen for air leaks (hissing).
Quarterly:
- Lubricate height control valve linkage.
- Check shock absorber for leaks.
- Inspect bushing condition.
Annually:
- Replace air filter on air suspension system (if present).
- Tighten all suspension bolts to spec.
- Flush moisture from air tanks.
Final Recommendation
Understanding how each Neway suspension part works and what to look for during inspections is essential for preventing costly downtime. For replacement parts, always choose OEM or certified aftermarket components that match the original specifications. Pay extra attention to air springs and height control valves, as they are the most failure-prone items. If you are not experienced with air suspension repairs, consult a professional technician—especially for torquing procedures and ride height calibration. Regular maintenance will keep your Neway suspension performing smoothly for hundreds of thousands of miles.