A double mast forklift, more commonly referred to as a duplex mast or two-stage mast, is a type of forklift mast that consists of two telescopic sections: an outer stationary section and an inner moving section. This design allows the forklift to lift loads to moderate heights while maintaining a compact collapsed height, making it a versatile choice for a wide range of warehousing and industrial applications.
What Is a Double Mast (Duplex Mast)?
The mast is the vertical assembly on a forklift that raises, lowers, and tilts the forks. A double mast features two nested channels:
Outer (Stationary) Section: Fixed to the forklift frame.
Inner (Moving) Section: Slides vertically within the outer section, powered by hydraulic cylinders and lift chains.
This two-stage design provides a balance between lift height and stability, offering greater lifting capability than a single-stage (simplex) mast while being more cost-effective and compact than a three-stage (triplex) mast.
Key Specifications
Double mast specifications vary by manufacturer and model, but typical ranges include:
Specification Typical Range
Lift Height 3,000 – 4,500 mm (10 – 15 ft)
Collapsed Height 2,000 – 2,500 mm (6.5 – 8 ft)
Free Lift 0 – 1,500 mm (0 – 5 ft)
Capacity 1.5 – 5.0 tonnes (3,300 – 11,000 lbs)
Tilt Range 6° forward / 12° backward (typical)
Free Lift refers to the height the forks can be raised before the inner mast section begins to extend. This is particularly important for container loading and low-clearance applications.
Double Mast vs. Other Mast Types
Mast Type Stages Lift Height Collapsed Height Best For
Simplex (Single) 1 2,000 – 3,000 mm Lowest Light-duty, low-height stacking
Duplex (Double) 2 3,000 – 4,500 mm Moderate Standard warehousing, container loading
Triplex (Triple) 3 4,500 – 7,500+ mm Tallest High-bay warehousing, tall racking
Quad (Four-Stage) 4 7,500+ mm Tallest Very high stacking, specialized applications
Applications
Double mast forklifts are suitable for a wide variety of material handling tasks:
Standard Warehousing: Lifting pallets to medium-height racking (up to 15 feet).
Container Loading and Unloading: The compact collapsed height allows operation inside shipping containers.
Manufacturing Facilities: Moving raw materials and finished goods between production areas.
Retail Distribution Centers: Efficient handling of palletized goods in medium-height storage.
Cold Storage: Moderate lift height with stable performance in low temperatures.
Advantages
Cost-Effective: Lower purchase price compared to triplex or quad masts.
Good Lift Height: Provides sufficient reach for most standard warehouse operations.
Compact Collapsed Height: Allows operation in areas with low overhead clearance.
Simpler Maintenance: Fewer moving parts than multi-stage masts.
Stable Load Handling: Shorter mast extension reduces sway compared to taller masts.
Limitations
Limited Maximum Lift Height: Not suitable for high-bay warehousing above 15 feet.
Reduced Residual Capacity: Lift capacity decreases as the mast extends; duplex masts generally maintain better residual capacity than triplex masts at moderate heights.
Popular Forklift Models with Double Mast
Many manufacturers offer double mast configurations across their forklift ranges:
Brand Model Examples Capacity Lift Height
Toyota 8FBE18T, 8FGCU25 1.8 – 2.5 t 3,000 – 4,500 mm
Hyster J2.0-3.5XN 2.0 – 3.5 t 3,000 – 4,500 mm
Clark C30 C, GEX 30 3.0 t 3,000 – 4,500 mm
Doosan B30X-7, D30S-7 3.0 t 3,000 – 4,500 mm
Heli CPCD30 3.0 t 3,000 – 4,500 mm
Buying Considerations
Determine Required Lift Height: Measure the maximum height you need to reach. If it exceeds 4,500 mm (15 ft), consider a triplex mast.
Check Overhead Clearance: Measure doorways, mezzanines, and overhead obstructions. A duplex mast's collapsed height must fit under all clearance points.
Evaluate Load Capacity: Ensure the forklift's rated capacity at the required lift height exceeds your heaviest load.
Consider Free Lift Requirements: For container loading or low-clearance areas, prioritize models with higher free lift.
Verify Attachments: If using side shifters, fork positioners, or clamps, confirm the mast can accommodate them without compromising capacity.
Inspect Used Units: Check mast channels for wear, listen for unusual noises during operation, and verify hydraulic cylinder condition.
Summary
A double mast (duplex) forklift features a two-stage telescopic mast providing lift heights of 3,000–4,500 mm (10–15 ft) while maintaining a compact collapsed height. It offers a cost-effective balance between lift capability and maneuverability, making it ideal for standard warehousing, container loading, and manufacturing applications. When selecting a double mast forklift, match the lift height to your racking requirements, verify overhead clearance, and ensure sufficient load capacity at full extension.