Stacker crane telescopic fork extension stroke spans 600 mm to 2200 mm across the current OEM specification window, with single-deep pallet units rated to 1500 kg and double-deep units derated to roughly 1250 kg, as published in MIAS PAL 23 and compact ASRS load-handler datasheets [S2][S4].
Stroke is the linear travel the telescoping fork section adds beyond the mast face, and it sets how many pallet positions the crane can service from one aisle. For projects sized on a stacker crane aisle, stroke is the variable that decides double-deep versus single-deep storage density.
Telescopic Fork Stroke Range and Load Capacity by Configuration
ASRS telescopic fork OEMs publish a stroke window of 600 mm to 2200 mm for the compact load-handler class, covering single-deep, double-deep, and shuttle-interface geometries; the same stroke envelope pairs with 100 kg light-duty carton attachments used in miniload cranes [S2][S4]. At the heavy end, single-deep pallet stacker cranes carry 1000 kg on the forks at a 3600 mm wheelbase, with 5120 mm lift height from the bottom rail head, and 1.5 t single-deep / 1.25 t double-deep ratings apply to the MIAS PAL 23 platform [S2][S6]. For general warehouse spec work the pallet stacker class stacks 1000–1500 kg per position, and stroke above roughly 1000 mm is the threshold where double-deep storage becomes mechanically viable.
Stroke and load interact: doubling stroke roughly doubles the moment arm on the telescopic section, which is why double-deep ratings sit 15–20% below single-deep on the same chassis. A practical 1.0–1.3 m load depth and ≤1300 mm load width window is standard for heavy-load ASRS stackers, with 14,500 kg net crane weight typical at the top of the class [S10].
Operating Envelope: Speed, Height, and Temperature
Horizontal travel, vertical lift, and fork extension can run simultaneously on ASRS stackers, which is what compresses single-cycle time below what a sequential motion budget would predict [S8][S9]. Operating temperature spans –25°C to +70°C for compact telescopic fork units rated for cold-chain and high-ambient ASRS aisles [S4].
High-bay stacker cranes run along a fixed aisle track, with the mast extending vertically and the telescopic fork reaching forward into the rack; compared with a general mobile crane or a runway-mounted gantry crane, the stacker crane trades free-floor mobility for sub-second positioning repeatability inside a narrow aisle [S3][S9].
Selection Criteria: Stroke, Depth, and Rack Geometry
Four criteria decide telescopic fork spec for a new build. First, required storage depth: single-deep needs ~600–800 mm stroke, double-deep ~1200–1600 mm, and shuttle-interface geometries run to 2200 mm [S4]. Second, pallet envelope: ≤1300 mm load width and 1000–1300 mm load depth define the heavy-load spec band, with crane net weight around 14,500 kg in that class [S10]. Third, throughput: ≥240 m/min travel and ≥120 m/min lift on the PAL 23 platform target SGL (single-aisle) throughput above 100 cycles/hr when paired with a WMS-driven stacker crane controller [S2][S9]. Fourth, environment: –25°C to +70°C ambient with sealed drives for cold storage, and IP-rated mast sections for dusty or washdown aisles [S4].
For general comparison, the three telescopic fork geometries line up as: (1) single-deep pallet fork, 600–800 mm stroke, 1500 kg load, 1-cycle pallet face; (2) double-deep pallet fork, 1200–1600 mm stroke, 1250 kg load, 2-cycle pallet face at the cost of 15–20% capacity derating; (3) compact ASRS / miniload fork, up to 2200 mm stroke, 100 kg carton load, 5-deep storage with lateral belt conveyor [S2][S4]. A crawler crane or rough-terrain carrier is the wrong reference class for this comparison; the right comparison is aisle-rail ASRS equipment, where stroke and mast height are the binding constraints.
Automation, Controls, and Energy Recovery
ASRS stacker cranes integrate with WMS and WCS layers through PLC-based controllers, and modern OEM platforms run horizontal travel, vertical lifting, and fork extension concurrently to keep cycle time under the sequential-motion budget [S3][S8]. Extraction options include telescopic forks, pallet shuttles, or on-board conveyors; selection is set by storage density and throughput, not by aisle width, since the crane rides a fixed track either way [S3]. Energy-recovery stacks on the lift axis are now a default option on the PAL 23 generation and similar OEM platforms, regenerating into the DC bus on each descent [S2][S3].
For comparison with the broader handling family, a crane scale is the WMS-side weight verification accessory that pairs with a telescopic fork stacker, validating load mass before the mast commits to lift on a 1500 kg-rated chassis. Sourcing teams pairing duty-drawback filings with re-exported ASRS spares should review the 2026 customs rules in Duty Drawback for Re-Exported Industrial Equipment: 2026 Rules and Filing Traps before shipping telescopic fork assemblies out of the EU or US.
Limitations and Failure Modes
Double-deep storage cuts aisle count roughly in half but costs 15–20% of single-deep payload on the same crane, because stroke and moment arm grow together [S2]. Telescopic mechanism wear is the dominant field-failure mode: rope-driven telescopic sections on current OEM platforms use a large-diameter deflection pulley specifically to extend service life, and the bolted guide rail is specced for field replacement without mast removal [S2]. Operating above +70°C or below –25°C violates the published compact-fork envelope and risks drive-trip on the lift inverter; cold-chain builds need sealed grease and heated encoder housings, which most OEMs list as options outside the base model [S4].
Stacker cranes are not the right tool for very low-density, very long-load storage: flow-rack and long-goods applications sometimes route through a gantry crane instead, because the stacker crane's narrow-aisleless geometry penalises loads above the standard 1000–1300 mm depth band [S3][S10].
Applicable Standards and Sourcing Signals
Stacker crane design is not pinned to a single ISO or EN standard the way pressure equipment is; instead it sits under machinery safety (EN ISO 13849-1 for control-system safety functions, EN 60204-1 for electrical equipment of machines) and the FEM 9.341 / 9.511 calculation rules for lifting appliances, which is what most OEM datasheets reference for the S/W/F duty classification [S2][S3]. Material handling buyers should ask the OEM for the FEM group, the duty cycle rating, and the seismic / wind classification if the aisle is outdoors or in a seismic zone.
Trackable signals for the next sourcing window: (1) more OEM datasheets publishing telescopic stroke as a 600/1000/1600/2200 mm discrete-option matrix rather than a continuous range, which simplifies WCS configuration; (2) deeper energy-recovery data on the lift axis, with regen percentages published per cycle; (3) extended-temperature variants below –25°C for pharmaceutical cold storage.