W4443T — Bertolini WM Series Triplex Piston Pump | 4400 PSI | 4.3 GPM | Tank Feed Variant

The W4443T — the tank feed variant — flagship base model of Bertolini’s WM Series — a professional-grade triplex piston pump engineered and manufactured by Idromeccanica Bertolini S.p.A. in Reggio Emilia, Italy. With over 100 years of pump manufacturing heritage dating back to 1918, Bertolini’s WM Series represents the company’s most advanced compact piston pump architecture. The W4443T delivers 4400 PSI at 4.3 GPM at 3450 RPM — the highest flow output in the WMG lineup — and ships exactly as it leaves the Bertolini assembly line. No shortcuts, no substitutions. This is the pump as shown in the Bertolini catalog.

What’s in the Box

• Tank Feed Inlet King Hose Barb — 1/2″ M NPT x 1-1/4″ Plated Steel Hose Barb — Factory-installed on the pump inlet port. Designed specifically for gravity feed and tank feed systems. Simply connect a 1-1/4″ non-collapsible inlet water hose directly to the barb — no adapter required. The barbed design prevents hose slippage and fluid leaks under suction load. The hex base allows standard wrenches for installation and is large enough to accommodate accessory ports. Compact tapered bore for smooth, unrestricted water delivery from tank to pump.
  • Connection: 1/2″ M NPT x 1-1/4″ plated steel hose barb
  • Hose size: 1-1/4″ non-collapsible inlet hose recommended
  • Application: Gravity feed and tank feed systems
  • No adapter needed — assembles directly to pump inlet
• SAE J609-1″ Flange with 4-Bolt and Lock Washer Kit — Everything needed for a seamless, rattle-free installation directly to your engine. Grade hardware included — nothing to source separately.
• Fully Assembled W4443T Pump — Ships exactly as it leaves the Bertolini assembly line. Bare pump configuration — no unloader or injector included. Ready to mount.
• Vented Dipstick — Must be manually installed prior to field testing. Do not run the pump without it installed. Critical for preventing crankcase vapor buildup and protecting the seals during operation.

WM Series vs 3PG Series — Understanding the Seal Difference

Buyers familiar with Bertolini’s 3PG Series will notice that the W4443T uses a different packing seal configuration. The 3PG Series uses Bertolini’s Super-U front seals — a double-U composite system designed for high-pressure longevity in standard cold-water duty. The WM Series, including the W4443T, uses a “V” front seal and “U” rear seal system. This is not a downgrade — it is a purpose-built difference in architecture.

The “V” seal in the WM Series is a fabric-reinforced nitrile buna construction engineered specifically for the larger plunger diameter and higher volumetric output of the WMG platform. The nitrile buna compound offers excellent resistance to chemical exposure, detergents, and a wide range of cleaning solutions — making the W4443T particularly well suited for applications involving frequent detergent use or chemical-heavy environments. The fabric reinforcement adds structural integrity under continuous-duty cycling, and the “V” geometry provides a self-energizing seal that tightens under pressure rather than collapsing. Both seal systems are self-lubricating and designed for long service intervals without routine replacement.

The Forged Brass Head — Built to a Higher Standard

The W4443T is built around a forged brass head of increased wall thickness — heavier than the 3PG Series head and engineered to withstand higher operating temperatures without deformation. Bertolini starts with a solid billet of high-grade brass subjected to a precision hot-forging process that aligns the grain structure of the metal, producing a head with higher tensile strength, better fatigue resistance, and zero porosity compared to cast alternatives. Once forged, the head is CNC-machined in Bertolini’s Reggio Emilia facility using fully automated, custom-engineered tooling with inspection and verification at every production stage.

The result is a head that seals perfectly under extreme cyclical pressure loads, operates reliably at elevated temperatures, and does not require Loctite on the valve caps — thanks to Bertolini’s LowStressthread™ recessed O-ring valve cap system that eliminates water pressure from the thread entirely.

W4443T Performance

What’s Inside the W4443T

• Forged Brass Head — Increased Wall Thickness — Heavier construction engineered for higher operating temperatures and maximum rigidity under overpressure events.
• LowStressthread™ Valve Caps — Recessed O-ring design introduced by Bertolini in 2002. Thread never contacts pressurized water. No Loctite required. Torque reduced by 40%.
• AISI 316 Stainless Check Valves — Mirror-finish, rapid-action valves for corrosion resistance and maximum fluid dynamic efficiency.
• “V” Front Seal / “U” Rear Seal — Fabric-reinforced nitrile buna construction. Self-energizing under pressure. Excellent chemical and detergent resistance. Long service life under continuous-duty cycling.
• Tungsten Carbide-Coated Plunger Rods — Maximum wear resistance and volumetric efficiency across the pump’s service life.
• Bronze Connecting Rods (One-Piece) — Integral one-piece construction in a special bronze alloy. Superior anti-friction performance, lower operating temperatures, and extended service life vs aluminum rods.
• Oversized Premium Bearings — Extended service life even under heavy-duty and continuous-duty conditions including extreme working environments.
• Forged Steel Crankshaft — Extended Length — Increased shaft projection for solid pump-to-engine coupling in any version. Designed for maximum structural rigidity under load.
• Die-Cast Aluminum Crankcase — Anti-corrosion light alloy with an increased number of engineered cooling fins. Diamond-tool machined plunger guide surfaces for maximum smoothness and reduced seal wear.
• Ventilated Oil Dipstick — Performance-designed vented dipstick reduces the risk of crankcase leakage due to overpressure vapor buildup.

Lifetime Oil — The EASYlube™ System

Every W4443T ships from Bertolini pre-filled with SynPower Gear Oil 75W-90 — a specially formulated synthetic gear oil with an anti-wear additive package that bonds permanently to all lubricated surfaces. During the break-in period (50–100 operating hours), this oil suspends and removes residues formed inside the crankcase. After the break-in oil change to standard SAE 75W-90 transmission oil, the oil never needs to be changed again for the life of the pump. The LifeTimerod™ stainless steel martensitic plunger guide system — quenched, tempered, and mirror-polished — eliminates wear at the seal contact surface indefinitely, making this a genuine design feature rather than a marketing claim.

Specifications

Tank Feed and Gravity Feed Systems

The “T” suffix on the W4443T designates the Tank Feed configuration. Where standard pump installations draw water directly from a pressurized supply line, tank feed and gravity feed systems supply water from an elevated reservoir, IBC tote, buffer tank, or open container — relying on gravity head pressure or a low-pressure transfer pump rather than municipal supply pressure. This is common on trailer-mounted contractor rigs, skid systems with buffer tanks, agricultural washdown setups, and remote job sites where pressurized water supply is unavailable.

The Tank Feed Inlet King Hose Barb installed on this pump eliminates the adapter stack that would otherwise be required to connect a large-bore suction hose to the pump’s standard 1/2″ female thread inlet. The 1/2″ M NPT x 1-1/4″ plated steel hose barb accepts a 1-1/4″ non-collapsible suction hose directly — the barb profile locks the hose in place under suction without clamp slippage, and the hex base provides a wrench flat for a leak-free torqued connection. The result is a clean, low-restriction inlet path from tank to pump with no improvised fittings in the flow path.

Applications

• Professional pressure washing and contract surface cleaning
• Fleet and heavy equipment washing
• Chemical-intensive cleaning environments
• Self-service car wash bay systems
• Pre-painting and surface preparation
• Tank and vessel cleaning
• Industrial process and manufacturing washdown

7-Year Warranty

The W4443T is backed by Bertolini’s industry-leading 7-year warranty — a direct reflection of the confidence Idromeccanica Bertolini S.p.A. places in every pump that leaves its Reggio Emilia production line. With over 100 years of engineering history and millions of pumps operating globally across industrial, agricultural, and commercial applications, Bertolini’s commitment to quality is not a promise. It is a track record.