PMAX engine cooling blades — what they are and when to use them
PMAX stands for Pressure MAX. It is Multi-Wing's dedicated blade family for engine and radiator cooling — installations where the fan has to push air through a dense heat exchanger with meaningful pressure drop. Different design priorities from general HVAC, which is why a dedicated profile exists.
Why engine cooling needs a different blade
Radiator and charge-air cooler cores are dense. Pushing cooling air through them requires static pressure that a standard airfoil blade struggles to deliver without running at very high RPM.
Engine bays are also tight. The fan sits close to the radiator on one side and accessories on the other, limiting axial depth.
PMAX addresses both: 20% higher static pressure than standard airfoil profiles, at a shallower axial depth.
The PMAX range
Industrial Fan stocks the PMAX profile in four sizes, each suited to a different engine class:
- PMAX3 — 432-635mm diameter, up to 3,800 RPM. Compact engines (farm tractors, small backhoes, mid-size trucks).
- PMAX4 — 560-950mm diameter, up to 2,500 RPM. Mid-range engines (wheel loaders, medium excavators, larger trucks).
- PMAX5 — 760-1,195mm diameter. Large engines (medium gensets, mining haul trucks).
- PMAX6 — legacy first-generation PressureMAX blade (927-1,295mm). No longer manufactured by Multi-Wing; limited stock remaining in South Africa for legacy machines still in service.
- PMAX7, PMAX8, PMAX9 — larger high-pressure variants Multi-Wing makes for current engine-cooling specifications. Not held in SA stock; available on special order with a typical 4-5 week lead time (surcharge applies).
Tier 4 Final compliance
PMAX4 and higher are designed to meet Tier 4 Final and Stage V emissions standards for non-road diesel engines. The blade geometry is optimised for the airflow requirements of modern emissions-compliant cooling packages.
Material
All PMAX blades stocked in SA are PAG (glass-filled nylon) — the standard engine cooling material, rated −60°C to +120°C continuous.
Aluminium or alternative materials may be specified on special order from Multi-Wing for unusual high-temperature applications (typical 4–5 week lead time, surcharge applies).
Weight is low compared to steel equivalents, which reduces bearing wear on the cooling fan shaft and reduces starter load.
Specifying a PMAX replacement
To confirm the right PMAX for an existing installation, send us:
- Engine make and model (or the equipment — Cat D7, Scania R500, etc.)
- Fan diameter in mm
- Number of blades on the hub (PMAX3 has 3, 6, or 9; PMAX4 varies)
- Pitch angle if known (PMAX3 is fixed-pitch, moulded; PMAX4 supports 20-47.5° in 2.5° increments; PMAX5 is adjustable — specify desired angle)
- Rotation direction (R or L)
FAQs
Can I use a standard 4Z airfoil blade on an engine cooling fan?
Technically possible at the overlapping diameter range, but you lose static pressure performance. Modern radiators and charge-air coolers are dense enough that a standard airfoil blade struggles without running at high RPM, which in turn increases fan noise and motor load. PMAX is the right tool for this job.
What's the difference between PMAX4 and EMAX4?
Both are Multi-Wing blade profiles, but they target different duty: PMAX4 is optimised for high-pressure engine cooling; EMAX4 is optimised for efficiency in HVAC/R applications (condensers, chillers). Use PMAX for engine radiators, EMAX for refrigeration condensers.
Is PMAX available with adjustable pitch?
Yes. PMAX4 supports 20-47.5° pitch in 2.5° increments, letting you tune the airflow and power draw precisely to the engine cooling requirement. PMAX3 is fixed pitch (moulded). PMAX5 is adjustable.