Forklift Charging Pump 15583-80221 — Transmission Oil Supply Pump for Heli Powershift Transmissions

The 15583-80221 is a gear-type charging pump (also called a supply pump or charge pump) for Heli forklift powershift transmissions. This pump is driven directly from the torque converter impeller hub or from a dedicated PTO on the transmission input shaft, and its sole function is to supply pressurized ATF at 8-12 bar to the transmission control valve body — it does NOT provide the main hydraulic system pressure (that is the function of the separate hydraulic gear pump). The charging pump is a positive-displacement external gear pump with a flow rate of 15-25 L/min at 2,000 RPM engine speed, sized to maintain adequate control pressure to the clutch packs even at idle when engine RPM drops to 700-800 — if the pump flow rate drops below 10 L/min at idle, the clutch pack pressure will fall below the minimum engagement threshold of 6 bar, causing the transmission to slip out of gear. The pump housing is cast aluminum with a hardened steel gear set running in needle bearings — the bearing clearances are critical because any wear that increases the gear-to-housing tip clearance beyond 0.12mm will cause internal leakage that reduces pump output by 10-15%.

A failing charging pump is often misdiagnosed as a worn clutch pack because the symptoms are similar — both cause transmission slipping. The definitive diagnostic test is to connect a pressure gauge to the transmission control pressure test port and observe the pressure at hot idle in gear: a healthy pump should maintain 7-9 bar; a pump with worn gears or excessive internal clearance will drop to 4-5 bar at hot idle, at which point the clutch pack cannot maintain full engagement. If pressure is normal at 1,500 RPM but drops at idle, the pump is the cause, not the clutch pack. When replacing the pump, the suction strainer in the transmission oil pan MUST be replaced simultaneously — a clogged suction strainer is the most common cause of charging pump failure, as it starves the pump of oil and causes the gears to run dry, scoring the gear teeth and housing bore within seconds. Common failure symptoms: transmission slipping out of gear when the engine returns to idle after acceleration (pump cannot maintain pressure at low RPM), all clutch packs engaging slowly (2-3 second delay from lever movement to transmission engagement) regardless of which direction is selected (low pump output affecting all circuits), and a high-pitched whine from the transmission that increases in pitch with engine RPM (worn pump gears).

This charging pump fits Heli forklifts using the 15583-80201/15583-80221 series transmission. Verify the pump mounting bolt pattern and the drive gear configuration before ordering. For related transmission components, visit our Forklift Hydraulic Transmission section.

Technical Specifications

• Part Number: 15583-80221
• Pump Type: External Gear Positive-Displacement
• Flow Rate: 15-25 L/min at 2,000 RPM
• Operating Pressure: 8-12 bar (Control Circuit)
• Min Idle Pressure: 7-9 bar (Hot, In Gear)
• Application: Heli Powershift Transmissions

Compatible Forklift Models

Each pump is flow-tested and pressure-calibrated, packed in protective packaging, and ships within 1-2 business days. 12-month warranty. Browse our Forklift Hydraulic Transmission catalog.