5T 6M Forklift Load Capacity & High-Lift Safety Technical Specification

Document No.: KSF-LIFT-SAF-2025  

Revision: 1.0  

Applicable Models: Kaystar LandTiger and Pioneer Series 5T 4WD Forklifts (High-Lift Configuration-6M)  

Compliance Standards: ANSI/ITSDF B56.1-2023, EN 1726-1:2021  

1. Scope and Purpose

This technical specification defines the safe load capacity limits, operational requirements, and inspection protocols for Kaystar forklifts during high-lift operations (≤4500 mm and ≤6000 mm). It is intended for operators, maintenance personnel, and safety managers to ensure compliance with North American and European industrial safety standards, mitigate risks of equipment failure, tip-over, or personnel injury.

2. Load Capacity Fundamentals

2.1 Key Definitions

• Load Center (LC, mm): Horizontal distance from the vertical face of the fork carriage to the load’s center of gravity (CoG), measured per ANSI/ITSDF B56.1 Section 4.3.
• Rated Lift Height (LH, mm): Maximum vertical elevation of the fork carriage’s top surface, excluding fork extensions (per EN 1726-1 Clause 5.2).
• Safe Working Load (SWL, kg): Maximum allowable load under specified LC and LH conditions, derated for stability per ISO 22915-4:2020.
• Load Moment (Nm): Product of SWL and LC, representing the overturning force resisted by the forklift’s counterweight and stability triangle.

2.2 Core Stability Principle

The forklift’s safe load capacity is inversely proportional to both lift height and load center distance:  

• Increased lift height raises the combined CoG of the forklift and load, reducing lateral and longitudinal stability.  
• Extended load center shifts the CoG outward, increasing overturning momentum (per EN 1726-1 Annex D).  

3. Load Capacity Quick Reference Table

(LC, mm)	LH ≤3000 mm	LH ≤4500 mm	LH ≤6000 mm
500mm	5000kg	3500kg	2000kg
700mm	3200kg	2300kg	1400kg
900mm	1800kg	1300kg	900kg

Note: All values are derated by 10% from maximum design capacity to account for dynamic operational factors (e.g., minor ground irregularities, load oscillation) as required by ANSI/ITSDF B56.1 Section 5.7.

4. Pre-Operation Inspection Protocol (High-Lift Specific)

4.1 Load Verification

• Calculate actual load center (LC) using load dimensions and CoG data; cross-reference with Table 3 to confirm SWL compliance.  
• Verify load weight via certified scales; ensure no exceedance of SWL (including packaging and securing materials).  
• Inspect load integrity: no loose components, uneven distribution, or protrusions that could alter CoG during lift.  

4.2 Equipment Inspection

• Lift System: Check hydraulic cylinders, hoses, and fittings for leaks; inspect chains for tension, wear (≤3% elongation per EN ISO 606), and corrosion.  
• Forks: Verify straightness, no cracks (magnetic particle inspection recommended annually), and fork tip alignment (≤3 mm deviation).  
• Stability Components: Inspect counterweight fasteners, tire pressure (±5% of manufacturer’s specification), and tread depth (≥4 mm for pneumatic tires).  
• Safety Devices: Test lift limit switch, overload warning system, and tilt angle sensor (functional per ANSI/ITSDF B56.1 Section 7.9).  
• Operational Environment: Confirm ground bearing capacity (≥120 kPa for 6m lifts), no slopes (≤3° for high-lift operations), and clear overhead obstacles.  

5. High-Lift Operational Procedures

5.1 Lift Sequence

1. Position forks under load with equal spacing, ensuring load is centered and fork tips extend ≥2/3 of load length.  
2. Lift load 100-200 mm above ground; pause to verify load stability and forklift balance.  
3. Elevate load at a constant rate (≤0.5 m/s) to the target height; avoid rapid acceleration/deceleration.  
4. At maximum lift height (4.5m/6m), engage parking brake and disable travel function (if equipped) before adjusting load position.  

5.2 Prohibited Actions

• No personnel on forks, load, or mast during high-lift operations (per EN 1726-1 Clause 8.3).  
• No lateral movement (travel) with lift height >3000 mm; lower forks to 300-500 mm above ground before traversing.  
• No load stacking or adjustment at full lift height without secondary stabilization (e.g., load braces).  
• No operation in wind speeds exceeding 12 m/s (Beaufort Scale 6) for lifts ≥4.5m (per ISO 22915-1:2019).  

5.3 Emergency Response

• In case of load shift/instability: Cease all operations, slowly lower load to 100-200 mm above ground, and reposition load or reduce SWL.  
• For hydraulic system failure: Activate emergency lowering valve (per manufacturer’s manual) and evacuate the area until the load is safely grounded.  
• For tip-over risk: Operators must remain in the cab, grip the steering wheel, and lean away from the direction of tilt (ANSI/ITSDF B56.1 Safety Alert No. 4).  

6. Post-Operation Requirements

• Lower forks to full retracted position (≤100 mm above ground) and engage parking brake.  
• Turn off ignition, disconnect power, and secure forklift with wheel chocks in outdoor or sloped areas.  
• Document operational data: load weight, lift height, and any anomalies (e.g., hydraulic leaks, instability) in the equipment log.  
• Perform daily maintenance check: Clean fork surfaces, inspect chain lubrication, and verify safety device functionality.  

7. Compliance and Liability

• This specification must be followed in conjunction with the forklift’s Operation and Maintenance Manual (OMM).  
• Non-compliance with load limits, inspection protocols, or operational procedures may void equipment warranties and expose users to regulatory penalties (OSHA 29 CFR 1910.178, EU Machinery Directive 2006/42/EC).  
• Operators must complete certified high-lift forklift training (per ANSI/ITSDF B56.1 Section 9.2) before operating at heights ≥4.5m.