Vertical lift module extractor vertical travel is typically adjustable up to 2.0 m/s (6.6 ft/s), and the horizontal feed that delivers the tray to the access opening runs at roughly 0.7 m/s, the figure published for the Kardex Remstar Shuttle XP [S4]. A separate VLM spec sheet quotes a maximum vertical lift speed of 2.3 ft/s (0.7 m/s) with horizontal feed up to 0.83 ft/s (0.25 m/s) [S9], so the realistic operating envelope across vendors sits inside that envelope.
For a deeper look at how slotting affects that cycle, the VLM dynamic slotting for fast-moving SKUs piece on the height-sensor loop walks through the SKU-placement side of the same problem.
What "extractor speed" actually covers
Extractor motion is two-axis, not one: vertical travel on rails (cables, chains, or belt) and a short horizontal feed that pulls the chosen tray out of its column and presents it at the access opening. Vendor literature reports vertical travel adjustable up to 2.0 m/s (6.6 ft/s) and horizontal feed adjustable up to 0.7 m/s (2.3 ft/s) on the Shuttle XP class [S4]. A second published spec set quotes 100 to 200 ft/min (0.5 to 1.0 m/s) for the cable/chain lift mechanism, with per-tray payloads in the 500 to 1,500 lb band [S8]. The headline number on a brochure is therefore the vertical axis; the actual retrieval floor is the horizontal feed plus the extractor engage/disengage time, which is why a 2.0 m/s vertical lift does not translate to a 2.0 m/s retrieval cycle.
Why the horizontal feed is the bottleneck
The horizontal feed, the extractor reaching into the column, gripping the tray, and pulling it back to the operator window, is mechanically constrained by the tray width, the extractor carriage stroke, and the need to decelerate without spilling the load. Published horizontal feed sits at 0.7 m/s (2.3 ft/s) on the Shuttle XP spec [S4] and 0.25 m/s (0.83 ft/s) on the Vidir VLM [S9]. That axis dominates cycle time on short-retrieval cases (the top of the unit), where vertical travel is almost free and the floor is essentially the horizontal stroke at acceleration-limited speed. For a unit reaching 30 ft or more of effective height [S5], the vertical axis matters more, and the 2.0 m/s figure starts to count.
How vendor specs line up against each other
Comparing the publicly cited spec sets side by side: Kardex Remstar Shuttle XP class units publish 2.0 m/s vertical and 0.7 m/s horizontal [S4]; Vidir lists 0.7 m/s vertical and 0.25 m/s horizontal [S9]; and the generic 100 to 200 ft/min lift range (0.5 to 1.0 m/s) covers most mid-range units [S8]. The cross-vendor envelope is therefore roughly 0.5 to 2.0 m/s vertical and 0.25 to 0.7 m/s horizontal. The wide vertical spread reflects payload and chain/cable choice more than motor power, since the dominant mechanical cost is lifting the extractor plus the live tray load between every cycle.
What changes the real cycle, beyond the spec sheet
Three operational factors move a VLM's effective retrieval time more than the published peak speed. First, SKU slotting: putting high-frequency trays close to the access opening is repeatedly cited as a primary speed lever, and software-managed slotting is a standard feature on modern units [S2][S3]. Second, pick-to-light and laser-pointer guidance cut the operator-side dwell time inside the cycle, which matters because the tray is usually held at the window while the pick is made [S3]. Third, batching and the operator's pick pattern, not the extractor, typically set throughput for multi-line orders; the Kardex VLM order-fulfillment writeup covers the slotting half of that loop in detail. Safety hardware, including light curtains and variable-height sensors, is standard on current units [S9] and adds a small but fixed latency to every cycle.
Floor-space and throughput context
The vertical lift module encyclopedia entry is a useful cross-reference for tray geometry, column layout, and how the extractor fits between the two tray stacks. The headline value of the machine, in practice, is that it converts ceiling height into inventory positions while keeping the operator stationary, and the extractor speed envelope above sets the time cost of every retrieval.
Selection criteria and where spec numbers mislead
For a spec-first comparison, three numbers are worth tracking on any VLM datasheet: peak vertical travel in m/s (envelope 0.5 to 2.0 m/s), horizontal feed in m/s (envelope 0.25 to 0.7 m/s), and per-tray payload (500 to 1,500 lb typical) [S4][S8]. Beyond that, ask for the measured end-to-end retrieval time at the operating fill height, not the peak axis speed, since the horizontal feed and slotting distance dominate short cycles. Confirm the variable speed drive sizing on the lift motor, because the deceleration profile on the horizontal axis is what limits tray-handling speed without shifting light parts, and that loop is exactly the kind of detail a VLM integrator will quote only on request. Finally, a cable tray audit on the power and signal routing above the unit is worth doing before installation, because the lift motor and the access-opening controls both run back to the same cabinet.
Trackable signals to watch next
Two numbers are worth rechecking on the next vendor datasheet refresh: the horizontal feed in m/s, since that axis sets the floor of every cycle, and the published per-tray payload in lb, since heavier trays usually force a lower peak vertical speed. Any VLM datasheet that quotes only the vertical axis without an end-to-end retrieval time at a stated fill height should be treated as incomplete, and that gap is the most useful signal an integrator can close during a site survey. [S2]