New Forklift Transmission Parts Charge Pump A373663 for D20G 4TNE98 ENG

A373663 Transmission Charge Pump for D20G / 4TNE98 Forklift

The A373663 charge pump is a gear-type hydraulic pump mounted inside the transmission that supplies charge pressure to the hydraulic control circuit — the pressure that engages the forward and reverse clutch packs, lubricates the bearings and gears, and feeds the torque converter make-up circuit. On D20G forklifts powered by the Yanmar 4TNE98 diesel engine, a failed charge pump is the most common root cause of sudden complete loss of drive in all gears: worn gear teeth, scored housing bores, or a sheared pump drive tang produces zero charge pressure, and without charge pressure, no clutch pack can engage — the forklift sits motionless regardless of the direction lever position.

Built to the OEM A373663 specification for the D20G transmission, this charge pump features precision-machined cast iron housing plates and hardened steel gear sets with controlled gear-to-housing clearance. The housing end plates are ground flat and parallel to within microns — any plate warpage creates an internal leak path from the pressure side back to the suction side, reducing pump volumetric efficiency and lowering the available charge pressure. The pump drive tang is machined to match the D20G transmission pump drive slot, and the mounting flange bolt pattern matches the transmission case pump mounting pad.

Direct OEM replacement for D20G forklifts with Yanmar 4TNE98 diesel engine and A373663 transmission charge pump. Always replace the pump suction strainer when replacing the charge pump — debris from a failed pump contaminates the strainer and will starve the new pump of oil on startup. For complete transmission hydraulic components, browse our forklift hydraulic transmission parts.

Technical Specifications

• SKU / OEM PN: A373663
• Type: Gear-type transmission charge pump
• Engine Match: Yanmar 4TNE98 diesel
• Housing: Cast iron, precision-ground end plates
• Gears: Hardened steel, controlled clearance
• Function: Clutch pack apply pressure, lubrication, converter feed
• Failure Mode: Zero charge pressure → no engagement in any gear
• Fitment: D20G forklift with A373663 transmission specification

Compatible Forklift Brands

Each A373663 charge pump ships with ports capped and internal assembly lubricant. Prime the pump by filling the suction port with clean transmission oil before installation — a dry gear pump started against a dry suction line cavitates immediately and scores the housing bores within seconds. After installation, crank the engine with the stop lever pulled (no start) until charge pressure registers on the gauge, then start and recheck. For D20G transmission service specifications, consult Baldwin Filters. Kingstream stocks the A373663 for same-day dispatch — worldwide shipping with online tracking.