The Ultimate Kales Semi-Trailer Maintenance Manual & Service Guide

⚠️ Important Safety Note: While this guide covers mechanical systems for Kales trailers, for ABS (Anti-lock Braking System) diagnostics, please refer strictly to the specialized ABS manufacturer’s manual.

🆕 CRITICAL: New Kales Trailer Break-In Protocol (First 5,000 km)

During the first month of operation, metal components will “settle” and stretch. According to Kales Vehicle engineering standards, it is mandatory to perform the following checks after the initial loaded run-in period of approximately 5,000 km or one month:

• 🔹 Axle Alignment: Re-measure and correct alignment as suspension settling can alter the wheelbase, affecting tire life.
• 🟥 Suspension U-Bolts: Retorque to 600–650 N·m. Loose U-bolts are the #1 cause of leaf spring breakage in commercial trailers.
• 🟥 Wheel Nuts: Retorque to 450–500 N·m to prevent wheel loss.

💡 Inspection Legend:

• Daily: Driver pre-trip check (Walk-around inspection).
• 1 / 3 / 12 Month: Professional maintenance required by certified mechanics.
• Condition: Most checks should be performed in the Towing State (connected to tractor) or Unloaded where specified.

🔩 Kales Vehicle Official Torque Specifications Cheat Sheet

Use these Kales factory-recommended torque values to prevent mechanical failure. Save this section for quick access by your maintenance team.

Note: These specifications are proprietary to Kales Vehicle Co., Ltd. and ensure the optimal performance of Kales-manufactured trailers.

Proper air brake maintenance is critical for heavy-duty trailer safety. Follow these Kales Vehicle diagnostic steps:

• ✅ Connect the trailer’s air brake system to the tractor’s system.
• ✅ Check all hoses and connectors for cracks, abrasions, or leaks. Replace immediately if damaged.
• 📅 Maintenance Schedule: Replace all rubber air hoses every 2 years as per Kales safety recommendations.
• ✅ Pressurize to operating level and verify pressure via tractor gauge or emergency system gauge (Normal: 0.7~0.8 MPa).
• ✅ With engine idling, fully depress the brake pedal and hold. Pressure drop must not exceed 30 kPa per min.
• 🧼 Leak Detection: If leakage is suspected, apply soapy water to fittings—bubbles >25 mm in 3 seconds indicate a leak. Tighten or replace as needed.
• ⚙️ Check the emergency relay valve:
  a) Close the semi-trailer air supply line shut-off valve on the tractor, then disconnect the air coupling and check whether the brakes automatically apply. If they do not apply automatically, the emergency relay valve is faulty.
  b) Reconnect the air coupling between the tractor and the semi-trailer’s air supply line, then open the shut-off valve and check whether the brakes automatically release.
  c) Check all parts of the emergency relay valve for air leaks. If soap bubbles formed at any connection do not exceed 7 mm in diameter within 3 seconds, the valve is considered leak-free and functioning normally.
  d) When the brakes are released, verify that exhaust air is discharged from the exhaust port. If so, this indicates normal operation.e) If the valve operates sluggishly or fails to function properly, replace the entire emergency relay valve.

⚠️ WARNING: Critical Safety Notices

Do Not Modify: Never modify the Kales brake air system, including adding water-spray brake cooling or tapping air from trailer tanks. This compromises braking performance and may cause catastrophic failure.

❄️ Winter Care: In cold weather, moisture in the brake system can freeze inside valves (relay/ABS), causing brake drag, delayed release, or total lock-up.

• Mandatory: Drain water from all semi-trailer air tanks DAILY.
• Check the Air Dryer desiccant cartridge efficiency and replace if saturated.
• Always drain air tanks after driving. If excessive air loss affects brake function, re-pressurize.

🔧 Brake Chamber Checks:a) While operating the brakes, check whether the pushrod of the brake chamber moves freely and whether its stroke is within the specified range (standard working stroke: 30–35 mm). If the stroke exceeds 50 mm, an adjustment is required. *Note: For Long Stroke (LS) chambers, the limit may be higher (~64mm). Verify the chamber type tag before adjusting.

b) With the brakes applied, check the brake chamber for air leaks:

• Apply soapy water to the clamp area and inspect for leaks. If leakage is detected, tighten the clamp retaining nut to a torque of 30 N·m.
• Check the front vent hole for air leakage. If leaking, replace the rubber diaphragm.
• Inspect the exterior of the brake chamber for cracks or damage. If any are found, replace the entire brake chamber as necessary using Kales genuine parts.

🔧 Adjustment & Reservoir:Reservoir: Open drain valve daily to discharge condensate. Re-pressurize if emergency valve activates.

Manual Adjustment:

a) If stroke > 50mm, tighten worm shaft clockwise until seated.

b) Back off 90-180 degrees.

c) Depress pedal ~10 times to auto-adjust.

d) Road Test: Ensure vehicle does not pull to one side.

For detailed adjustment, refer to the axle manufacturer’s operating manual provided with your Kales trailer.

Ensuring your trailer axles are in top condition is key to longevity. Follow this hub bearing adjustment procedure carefully:

• Inspect axles and tires for bends, cracks, or damage. Use a jack with support blocks when lifting.

• Daily: Check wheel nut tightness. If loose, retorque to 450–500 N·m.

• 📉 Under-inflation: Causes shoulder wear, ply separation, blowouts, and higher fuel consumption.
• 📈 Over-inflation: Accelerates center tread wear and increases risk of impact damage.
• ✅ Maintenance: Maintain correct pressure (±20 kPa / ±3 psi) for all tires, including spares.
• 🔄 Rotation: Tire wear varies depending on load, road conditions, and braking behavior. To promote even tire wear, tires should be rotated regularly—every 5,000 kilometers—following the sequence shown in the Kales tire rotation diagram above.
• 🔧 Daily: The tightness of wheel nuts should be checked daily. If any looseness is found, the nuts must be retightened to a torque of 450–500 N·m.

A. Mechanical Suspension (Leaf Spring)

• Daily: Check springs for breaks. If one side is damaged, replace both sides to maintain balance.
• U-Bolts (Crucial):
  • Retorque to 600–650 N·m after heavy loads.
  • After replacing springs or every 5,000 km, inspect and retighten.
• Bushings: Check connecting rod bushings—replace if cracked or worn (Limit: 1mm).

B. Air Suspension

• General Care: Avoid long-term parking. Drive a few km periodically to cycle air springs.
• Cleaning: After muddy or asphalt roads, clean air springs and pistons. Replace if cracked, wrinkled, or abraded.
• Every 6 months:
  • Inspect air dryer/filter—replace if clogged.
  • Check air line seals and valve tightness.
  • Verify U-bolt and air spring mounting bolt torque.
  • Drain air tanks (increase to every 2 weeks in freezing weather).
  • Verify ride height (H-value): Must match factory specification to ensure proper coupling and stability.
• Every 3 months: Inspect shock absorbers for leaks or loose mounts.
• Monthly: Check main beam bushings—no play should exist when rocking the trailer.

The connection point between your tractor and Kales trailer requires diligent inspection:

• ✅ Daily: Inspect kingpin for cracks, wear, or scoring.
• 📏 Wear Limits: Replace if diameter < 48.0 mm (50#) or < 86.8 mm (90#).
• 📐 Check Verticality: Replace if kingpin is bent, deformed, or shows uneven “neck” wear.
• ✅ Clean and inspect fifth wheel plate—remove debris, check for warping.
• ✅ Check the bolts of supporting seat and connection plate to see if they become loose, and if the supporting seat is damaged.
• 🛢️ Lubrication: Lubricate kingpin and fifth wheel daily with high-quality grease (e.g., calcium-based ZG-4).

🔧 Adjustment Procedure:

1. Park on level ground, uncouple tractor, release brakes. Adjust landing gear so front/rear frame heights match (±2 mm).
2. Remove outer tires and dust caps. Drop plumb lines from hub centers to ground.
3. Adjust the middle axle first: Adjust the movable tie rod so that the perpendicularity of the middle axle centerline to the longitudinal center plane of the chassis in the horizontal direction is ≤6 mm—i.e., L₁ = L₂ (measured as the distance from the kingpin center to the center holes of the hub caps (axle end covers) on both sides of the middle axle). After adjustment, tighten the set screws on the rod ends.
4. Adjust the front axle: Adjust movable tie rod 1 to ensure the horizontal distance between the front and middle axles meets a tolerance of ≤5 mm—i.e., B₁ = B₂ (measured as the distance between the center holes of the hub caps (axle end covers) on both sides of the front and middle axles).
5. Adjust the rear axle: Adjust the movable tie rod to ensure the horizontal distance between the rear and middle axles meets a tolerance of ≤5 mm (measured as the distance between the center holes of the hub caps (axle end covers) on both sides of the middle and rear axles).
6. Tighten all bolts and nuts: Use box wrenches or socket wrenches to symmetrically tighten all fasteners to the specified torque values according to their specifications.