HPU-DA004 | RAM® Hydraulic Power Unit 4 Quart Double Acting 12V

• Dump Trailers & Trucks: Utility dump trailers, small-to-medium dump beds, and flatbed dump conversions (BTI, Big Tex, PJ Trailers, Load Trail, Midsota, etc.).

• Hydraulic Lifts & Hoists: Vehicle tailgates/liftgates, car haulers, hydraulic tilt trailers, and boat lifts.

• Snow & Ice Control Equipment: Snowplow angle/lift hydraulics and spreader systems (Boss, Western, Meyer, Fisher).

• Industrial & Agricultural Machinery: Scissor lifts, hydraulic presses, log splitters, farm implements, and hydraulic levelling jacks.

1. What is it?

Part is a self-contained 12V DC power pack that combines a high-torque electric motor, gear pump, dual-solenoid directional control valve, relief valves, and a 4-quart fluid reservoir. It supplies pressurized hydraulic fluid to extend AND retract a cylinder under power, rather than relying on gravity to lower the load.

2. Core Functions & Features

• Power Up / Power Down Operation: Uses a 2-button hand-held remote to power the hydraulic cylinder in both directions (extending and retracting), ensuring smooth and controlled movement regardless of load weight.

• Integrated Solenoid Valves: Dual 12V solenoids change fluid direction instantly based on operator input from the remote control.

• Internal Pressure Relief Valves: Built-in factory-set relief valves protect the hydraulic system and hoses from over-pressurization during heavy lift cycles.

• Compact Self-Contained Design: Mounts directly to trailers, equipment frames, or truck beds with simple battery cable connections and hydraulic hose hookups.

1. Motor Clicks But Won't Run (Low Voltage or Bad Solenoid)

• Symptom: Pressing the remote button produces a loud clicking sound from the starter relay/solenoid, but the electric motor fails to spin.

• Cause: Low battery voltage (<12V), loose or corroded battery cables, a bad start solenoid, or a seized motor armature.

2. Motor Runs, But Pump Fails to Lift the Load

• Symptom: The 12V motor whirs loudly when you press "Power Up," but the dump bed, lift, or trailer will not rise, or it stalls immediately under weight.

• Cause: Low hydraulic fluid level in the 4-quart reservoir, a stuck-open pressure relief valve, a worn gear pump, or internal hydraulic fluid bypass inside the cylinder.

3. Cylinder Refuses to Power Down (Retract)

• Symptom: The cylinder extends fine, but when you press "Power Down," nothing happens or it fails to retract under power.

• Cause: A faulty lower solenoid valve, burnt-out lowering coil, stuck directional spool, or a disconnected wiring connection in the remote switch.

4. Sluggish, Jerky, or Foamy Hydraulic Movement

• Symptom: The mechanism stutters, moves slowly, or the fluid in the clear reservoir looks milky, bubbly, or aerated.

• Cause: Air trapped in the hydraulic lines/pump (cavitation), contaminated or incorrect hydraulic oil (moisture/water mixing with oil), or a blocked suction filter screen.

5. Continuous Fluid Leaks Around the Unit

• Symptom: Pools of hydraulic oil forming under the power unit housing, cracked poly reservoir tank, or weeping fittings.

• Cause: Overtightened or loose SAE fittings, cracked reservoir body from impact or freezing, or worn shaft seals on the hydraulic pump face.