Floor Transport vs. Rack Putaway: Pallet AMR, Autonomous Pallet Trucks, and Reach Trucks Compared

Pallet handling is not a single task. It has two distinct phases: horizontal transport (ground-to-ground pallet movement) and storage interaction (putting pallets into or taking them out of racks).

Many selection failures happen because buyers try to do both phases with one device. In reality, the two phases demand completely different capabilities:

Horizontal transport: Needs payload capacity, runtime, navigation, and aisle passability — no lifting height required.

Storage interaction: Needs lift height, rack depth, precision alignment, and load stability — horizontal transport is secondary.

Once you separate these phases, the selection logic becomes clear: do you need a device that only does horizontal transport? One that can do storage interaction? Or two specialized devices?

Ground-to-Ground Pallet Movement

Pure horizontal transport AMRs — typically called pallet transport AMRs or autonomous pallet trucks — only do ground-to-ground pallet movement.

Typical scenarios:

• Receiving area to staging area
• Staging to production line entrance
• End of line to shipping staging
• Cross-warehouse pallet transfer

Equipment characteristics:

• No need to lift to rack height — only enough height to clear the pallet from the floor.
• Payload capacity is the core parameter.
• Aisle width depends on load width + safety clearance.
• Runtime and charging strategy determine continuous operation capability.

Advantages: Simple structure, lower cost than high-lift equipment, low maintenance, small aisle width requirement. Limitations: Cannot do rack putaway — ground transport only.

Low-Lift Pallet Trucks and Pallet Handling Architectures

Low-lift pallet trucks sit between pure ground transport and high-level rack putaway.

Low-lift capability:

• Lift height just enough to clear the pallet off the floor — not for rack putaway.
• Can be manually guided, semi-autonomous, or fully autonomous.

Difference from pure AMR chassis:

• Low-lift pallet trucks have forks — they insert into pallet fork pockets.
• Pure AMR chassis (top-carry) does not insert into pallets — it lifts the entire pallet or uses a top module.

Selection by pallet presentation:

Rack Putaway and Retrieval

Rack putaway requires lifting pallets to rack height. The equipment choice depends on how high your racks are.

Equipment options:

Key judgment: A standard lift-top AMR that lifts a carrier off the ground is not the same as a purpose-built low-lift or stacking vehicle with a fork, mast, and rack insertion capability. If your application requires placing pallets into racks, confirm the equipment has the required fork, mast, reach, and rack-level insertion capability — do not assume a top-carry lift module can perform rack putaway. Confirm the maximum lift height and rack interface with the supplier and compare against your actual rack height.

Aisle Geometry and Approach Direction

Rack aisle geometry determines which equipment can be used.

Aisle width:

• Wide aisle: Any equipment works.
• Narrow aisle: Needs reach truck or narrow-aisle AMR.
• Very narrow aisle: Needs VNA (very narrow aisle) truck or ASRS.

The specific width thresholds depend on the equipment model, load dimensions, and approach angle — do not rely on generic numbers. Ask the supplier for the required aisle width for your specific load and equipment configuration.

Approach direction:

• Front approach: Forklift/AMR enters from the rack face — aisle width = equipment width + load width + clearance.
• Side approach: Side pickup — aisle can be narrower but equipment is more complex.
• 90° turn: Rotate 90° in a narrow aisle — needs rotation space or omnidirectional drive.

Measure all rack aisles’ actual width (not nominal), confirm approach direction and turning space.

Pallet Detection, Fork Entry, and Load Center Checks

Rack putaway precision requirements are far higher than ground transport.

Pallet detection:

• Forks need to precisely enter pallet fork pockets — position deviation causes forks to hit the pallet instead of entering.
• Pallet condition — damaged pallets, deformed fork pockets, non-standard pallet sizes all cause pickup failure.
• Pallet position — pallets not placed correctly (offset, rotated) require the AMR to adjust.

Fork entry:

• Fork height must match pocket height — uneven floors cause height deviation.
• Fork spacing must match pocket spacing — different pallets have different pocket spacing.
• Entry depth — forks must fully insert to safely lift.

Load center check:

• Pallet load CG position — eccentric loads affect lift stability.
• Load center distance — affects lift capacity (farther load center = lower effective lift force).

Separated Task Architecture: Transport Robot + Storage Equipment

The optimal solution is often to separate tasks: AMR for horizontal transport, another device for rack putaway.

Separated architecture:

• AMR transports pallets from receiving to a transfer position at the rack aisle entrance.
• Autonomous reach truck picks up the pallet from the transfer position and puts it away.
• Each device does what it does best — no single device doing both transport and high-lift putaway.

Advantages:

• AMR does not need high-lift capability — lower cost.
• Forklift does not need long-distance transport — focused on putaway.
• Each equipment runs in its strongest scenario — higher efficiency.

Transfer point design:

• Transfer position needs precise positioning — where the AMR places the pallet must be findable by the forklift.
• Buffering at the transfer point — if the forklift is not ready, the AMR needs to wait or stage.
• Transfer height — after the AMR lowers the pallet, the height must allow forklift fork entry.

Decision Tree by Pickup Height and Storage Height

Pallet Workflow Decision Tree

Storage Operation Decision Inputs

1. Separate horizontal transport and storage interaction — different phases need different equipment capabilities.
2. A standard lift-top AMR is not a rack putaway device — confirm the equipment has the required fork, mast, reach, and rack-level insertion capability for rack putaway.
3. Pallet condition affects pickup success rate — damaged, deformed, or non-standard pallets are common failure causes.
4. Separated task architecture is often optimal — AMR transport + forklift putaway, each specialized.
5. Transfer position design is the key to separated architecture — where the AMR places pallets must be findable and fork-accessible.
6. Aisle width determines equipment choice — ask the supplier for required aisle width for your specific load and equipment configuration.