Kales Dump Trailer (Tipper Trailer) User Manual: A Complete Guide from Hydraulic System to Safe Unloading

1. Dump Trailer Types: Rear Dump vs. Side Dump

In bulk cargo transportation, dump trailers (also known as tipper trailers) are primarily categorized by their unloading direction:

1.1 Rear Dump Trailer

• Unloading Direction: Body tilts backward, discharging material from the rear
• Ideal For: Mines, gravel yards, construction sites, and open areas
• Advantages: Simple structure, high lifting force, excellent stability, low maintenance cost
• Kales Application: Widely used in heavy-duty transport, equipped with a high-strength telescopic cylinder and lifting balance frame for smooth operation

1.2 Side Dump Trailer

• Unloading Direction: Body tilts to the left or right side
• Ideal For: Narrow roads, railway corridors, trench backfilling, and single-side discharge scenarios
• Advantages: Flexible unloading, no need to turn around, high operational efficiency
• Kales Application: Features a multi-cylinder synchronized lifting system (typically 2–4 cylinders). Precision hydraulic control ensures smooth, twist-free tilting—ideal for extra-wide or extra-long bodies

✅ Whether rear dump or side dump, all Kales dump trailers use the same high-reliability hydraulic lifting system, ensuring component compatibility, easy maintenance, and adaptability to diverse global operating conditions.

2. Hydraulic System Structure of Kales Dump Trailers

Kales dump trailers utilize a mature hydrostatic hydraulic system, known for high pressure, fast response, and precise control. The system consists of five core components:

2.1 Power Unit: PTO-Driven Hydraulic Pump

The hydraulic pump converts mechanical energy from the tractor’s engine into hydraulic energy. Kales standardizes a high-reliability external gear pump with:

• Rated working pressure: ~2.0 MPa
• Max speed: ≤2,500 RPM
• Driven directly by the tractor’s Power Take-Off (PTO) via the gearbox for efficient power transmission

2.2 Control Unit: Pneumatic-Hydraulic Integrated Valve Block

Kales employs a pneumatic-to-hydraulic control logic for simplicity and responsiveness:

• 3-Position, 6-Way Manual Pneumatic Control Valve: Operator selects “Lift / Neutral / Lower”
• 3-Position, 3-Way Lifting Control Valve: Receives air signals to switch oil flow direction
• Mechanical Limit Valve: Automatically restricts lift height to prevent over-extension
• Solenoid-Controlled PTO Valve: Ensures safe PTO engagement/disengagement

✅ All control components feature industrial-grade sealing, suitable for dusty, humid, or sub-zero environments.

2.3 Actuator: Telescopic Hydraulic Cylinders

Kales offers tailored cylinder configurations:

• Rear Dump Models: Single high-strength multi-stage cylinder, center-mounted with a balance frame for rigidity
• Side Dump Models: Multi-cylinder synchronized system (2–4 cylinders) with hydraulic balancing circuits to ensure uniform motion and prevent body twist or rollover
• All cylinders use a single-port design: High-pressure oil enters during lift; gravity returns oil during lowering—energy efficient
• Cylinder rods are hardened and chrome-plated for corrosion and wear resistance

2.4 Auxiliary Components

Includes high/low-pressure hydraulic hoses, pneumatic lines, ball valves, large-capacity oil tank, high-efficiency filters, and anti-loosening fittings—ensuring long-term leak-free operation.

2.5 Working Fluid

Use L-HM anti-wear hydraulic oil. Select the correct grade based on ambient temperature for optimal performance and system protection.

3. Kales Dump Trailer Operating Guide

Kales dump trailers operate via a “pneumatic command + hydraulic execution” logic. Follow this standardized procedure and safety protocol for safe, efficient unloading.

3.1 Pre-Operation Preparation

1. Parking Requirements:
   • Park on solid, level ground with a slope ≤3°.
   • ❌ Never lift on slopes, soft soil, or uneven surfaces—risk of rollover is extremely high.
2. Braking & Parking:
   • Engage the parking brake and ensure the vehicle is fully stationary.
3. Side Dump Specific Preparations (Side Dump Models Only):
   • Before lifting, operate the side door lock control valve to unlock the side gate.
   • If the body has manual lock hooks, release them manually before tilting.
   • ⚠️ Warning: When opening side gates, stand outside the gate area to avoid injury from falling cargo.
   • For left-side unloading (factory default is right-side):
     • Remove the locking pin from the right-side tilt support,
     • Insert it into the left-side support,
     • Secure with a cotter pin,
     • Open all left-side panels.

3.2 Lift Preparation

1. Press the clutch pedal to disconnect drivetrain power.
2. Engage the PTO switch (lever or button):
   • ✅ Correct: With clutch depressed, engage PTO so gears mesh smoothly.
   • ❌ Never engage PTO without pressing the clutch—this will damage transmission and PTO gears.
3. Slowly release the clutch. Engine power now drives the hydraulic pump, generating high-pressure oil.
   • At this stage, the directional control valve is in neutral (return-to-tank) position—no lifting occurs.

🔒 Note: Some models feature safety interlocks on PTO/lift switches. Press the safety button before turning the switch.

3.3 Lifting Procedure

1. Initiate Lift:
   • With the pump running steadily, move the pneumatic control valve to “Lift”.
   • High-pressure oil flows through the directional valve into the cylinder, raising the body.
2. Control Lifting Speed:
   • Gently press the accelerator pedal to adjust engine RPM and pump output for smooth, controlled lift.
   • ❌ Avoid sudden throttle input to prevent shock loading.
3. Mid-Stroke Hold (Stop at Any Height):
   • To pause at a specific angle (e.g., for cleaning sticky material):
     • First, disengage the PTO (stop oil supply),
     • Then return the control valve to neutral.
   • The hydraulic circuit locks automatically—body remains stable at any position.
4. Automatic Height Limit Protection:
   • When the body reaches its designed maximum angle (typically ~20 cm between rear gate and ground), the built-in relief/flow-diverting valve in the cylinder opens automatically.
   • High-pressure oil returns to the tank via the directional valve—lifting stops.
   • ⚠️ Critical: If the limit valve pull-cord breaks, immediately stop lifting and repair. Failure to do so may cause “cylinder pull-out,” rendering the cylinder unable to lower and potentially causing permanent damage.

🔧 Safety Protocol for Limit Valve Adjustment:
Always use approved safety props and support bars to mechanically secure the body before any adjustment. Never rely solely on the hydraulic system for support.

3.4 Lowering Procedure

1. Prepare for Lowering:
   • After unloading, disengage the PTO switch to stop the pump.
   • Move the control valve to the “Lower” position—this opens the return oil path.
2. Control Descent Speed:
   • The body lowers under gravity, with oil returning to the tank through the directional valve.
   • By fine-adjusting the lever position, you can control descent speed or pause at any height.
3. Side Dump Reset:
   • Once the body is fully lowered, close the side gate and re-engage both pneumatic and manual locks.

⚠️ Absolute Prohibitions:

• ❌ Never lower under heavy load at high speed
• ❌ Never drive with the body raised
• ❌ Never operate the PTO while driving (will destroy the hydraulic pump)

3.5 Post-Operation Safety Check

• Verify no air leaks in pneumatic lines
• Confirm no hydraulic fluid leaks
• Ensure PTO engages/disengages smoothly with no abnormal noise
• Confirm body is fully seated and all locks (pneumatic + mechanical) are secured

3.6 Critical Safety Prohibitions (MUST FOLLOW)

3.7 Routine Maintenance Reminder

• Lubrication: Grease all modified-component lubrication points (e.g., balance frame pins, lift brackets) with #2 lithium-based grease, 1–2 times per month.
• System Readiness: If the solenoid valve loses power or air pressure is insufficient, the cylinder will not respond. Always verify pneumatic and electrical systems before operation.

✅ Summary: Standardized operation = Safety + Efficiency + Long Equipment Life. Every lift is a test of professionalism.

4. Common Fault Diagnosis & Quick Troubleshooting

Kales dump trailers may experience hydraulic issues during long-term use. Below is a detailed, step-by-step guide for rapid diagnosis and repair.

4.1 Body Won’t Lift

This is the most frequent issue. Diagnose in this order: Electrical → Pneumatic → Hydraulic

4.1.1 Electrical Check

• The PTO is pneumatically controlled via a solenoid valve.
• With engine off, press the PTO switch:
  • ✅ Normal: You hear a “click” (solenoid actuation) + “puff” (air exhaust)
  • ❌ Fault: No sound → likely electrical issue (blown fuse, open/shorted solenoid coil, stuck solenoid)
  • → Inspect wiring and replace faulty components.

4.1.2 Pneumatic Check

• System relies on compressed air. In normal operation, moving the lever produces a “puff” at exhaust ports.
• No sound?
  • Disconnect inlet air line at pneumatic valve—check for system air pressure.
  • ❌ No/low pressure → inspect air circuit (kinked line, frozen moisture in winter, or pinched hose).
• Air pressure OK?
  • Disconnect “Lift” air line from pneumatic valve, move lever to “Lift”—check for airflow.
  • ❌ No air → pneumatic valve failure (usually non-repairable; replace unit).

4.1.3 Hydraulic Check

• Limit Valve Test: With lever in “Lift”, disconnect both air lines from limit valve.
  • ✅ Air flows → valve OK
  • ❌ No air → valve stuck (common due to rust). Spray with penetrating oil—often resolves issue.
• Lift Valve Air Test: Disconnect “Lift” air line at lift valve.
  • ❌ No air → blockage in air line between pneumatic and lift valves.
• Hydraulic Pressure Test:
  • Connect pressure gauge to test port on lift valve. Engage PTO—system pressure should be ≥1.8 MPa.
  • ❌ Low pressure → check:
    • Hydraulic oil level
    • Ball valve open?
    • Low-pressure hose kinked?
    • Gear pump damaged?
  • ✅ Normal pressure but no lift → lift valve fault (stuck spool, low relief setting, air cylinder leakage). Disassemble and service.

4.2 Body Won’t Lower

Usually caused by pneumatic issues:

• Failed pneumatic valve
• Blocked or kinked air line
• Air leakage in lift valve’s pneumatic chamber
• Mechanical faults (e.g., bent cylinder, stuck spool) are extremely rare.

4.3 Slow Lifting

Common causes:

• Air leaks or kinked pneumatic lines
• Low gear pump output (worn pump)
• Air leakage in lift valve’s pneumatic actuator

4.4 Body Jitters During Lift

Most often due to low hydraulic oil level. Less commonly:

• Gear pump failure
• PTO malfunction (interrupted power transmission)

4.5 Slow Lowering

Primary cause:

• Air leaks or kinked pneumatic lines
• Adjustment: The lift valve has a hex-head lowering speed screw:
  • Turn inward → faster descent
  • Turn outward → slower descent

4.6 Body Drifts Down Automatically

⚠️ Critical Safety Hazard! Causes include:

• Internal leakage in lift valve
• Pneumatic chamber leakage in lift valve
• Faulty pneumatic control valve
• Severe cylinder seal failure

4.7 Oil Spray from Top of Hydraulic Tank

Caused by clogged return filter:

• High-pressure return oil ruptures filter housing
• Oil sprays inside tank top instead of returning to bottom
• → Replace entire return filter assembly and secure return line to tank bottom.

4.8 Leaks at Hydraulic Fittings

• All sealing washers are single-use. Always replace after disassembly.
• Ensure sealing surfaces are clean, flat, and free of debris or dents.
• Torque fittings to specification.

4.9 Oil Leaking from Pneumatic Valve

• Pneumatic valves should only carry air—oil indicates internal wear.
• Worn lift valve spool allows hydraulic oil to enter pneumatic chamber → oil exits via pneumatic valve.
• Key diagnostic clue: Oily residue on pneumatic valve = lift valve wear.

5. Kales Dump Trailer Operation & Maintenance Recommendations

5.1 Hydraulic System Maintenance

5.1.1 Hydraulic Oil Selection & Replacement

• Winter (low temps): Use ISO VG 32 L-HM anti-wear hydraulic oil (lower viscosity for cold starts)
• Summer (high temps): Use ISO VG 46 L-HM anti-wear hydraulic oil (higher viscosity for film strength)
• ❌ Never mix brands or grades

Replacement Intervals:

• Hydraulic oil: Every 6 months (every 3 months in harsh conditions)
• Always clean tank interior before refilling

5.1.2 Seal Inspection & Replacement

• Inspect all hydraulic seals before winter
• Replace if cracked, hardened, or leaking

5.1.3 Hydraulic Hose Inspection

• Check fittings for looseness or leaks
• Inspect rubber hoses for cracks, bulges, or abrasion—replace if damaged

5.1.4 Winter-Specific Care

• Clean tank surface and filler cap to prevent contamination
• Verify PTO gear engagement is smooth and noise-free
• Wipe cylinder rods; inspect for scratches or dents—replace if damaged

5.2 General Maintenance

5.2.1 Bolt Tightness

• Regularly inspect and torque all structural bolts

5.2.2 Brake System

• Check brake chambers for air leaks
• Inspect brake linings—replace if worn
• Ensure braking performance is reliable at all times

5.2.3 Lubrication Points

• Grease axle pins, kingpins, and all rotating joints regularly

5.2.4 Tailgate Locking Mechanism

• Ensure secure engagement—repair if loose or misaligned

5.2.5 Main Frame & Lift Frame

• Inspect for cracks or weld separation
• Repair immediately if damage is found

Conclusion: Professional Operation + Scientific Maintenance = Kales Efficiency

Whether rear dump or side dump, Kales dump trailers deliver safety, reliability, and efficiency through a robust hydraulic system. By following standardized procedures and proactive maintenance, you will:

• Reduce unplanned downtime
• Extend trailer service life
• Enhance operational safety
• Lower total cost of ownership

🔧 Need technical support? Contact our service team for expert assistance！