Pallets for pallet trucks, forklifts and AGVs: forks and compatibility

In briefA standard pallet truck has 1,150 mm forks, 520-540 mm overall width and a lowered height of 85 mm, and its load rollers come down onto the floor. The pallet therefore needs a fork entry higher than 85 mm and an open bottom on the entry side. AGVs also need pallets that are identical and undamaged: before you buy, run a trial with the system supplier.

A pallet for a pallet truck, forklift or AGV can have the right size and load capacity and still not work: the forks will not go in, or the pallet truck's rollers cannot reach the floor. Before you look at load capacity and price, check which trucks will be picking it up.

The trucks compared

The figures come from the data sheets cited. Your truck may differ: take a tape measure to the forks and the pallet before you order.

Hand and electric pallet trucks

The pallet truck is the most demanding truck when it comes to the bottom of the pallet. The forks go in low, then the load rollers at the fork tips drop down and push against the floor to lift. If there is a board or a runner across the underside of the pallet, the roller lands on it.

Fork dimensions

A typical hand pallet truck data sheet gives ^[1]:

• forks 1,150 mm long (800 to 1,220 mm on request);
• width over forks 520 or 685 mm;
• single fork 156 mm wide;
• lowered height 85 mm, lift up to 200 mm;
• capacity 2,300 kg.

A trade technical guide gives the same standard length, 1,150 mm, and an overall width of 520-540 mm, which suits the euro pallet. For small pallets there are narrow versions at 380-450 mm; for wide pallets, or pallets taken from the long side, there are versions at 670-685 mm. According to the same source, a hand pallet truck raises its forks to 220 mm at most ^[2].

Fork entry height: the number to check

The opening must be higher than the 85 mm of the lowered forks, with some margin for uneven floors and for loaded pallets that deflect.

On an EPAL euro pallet the boards are 22 mm thick and the blocks 78 mm high ^[6], which leaves 100 mm from the floor between the bottom boards. Not every pallet is built like this. A US 32×40 inch plastic pallet lists 79 mm pockets on its data sheet ^[7], less than the 85 mm of a standard European pallet truck. Compare the two numbers before you order.

2-way or 4-way with a pallet truck

The entries that count are the ones where the forks cross nothing on the floor.

• Pallet on 9 feet: the pallet truck goes in from all four sides.
• Pallet with 3 runners: it goes in only from the two sides where the runners are parallel to the forks.
• Pallet with 5 runners or perimeter runners: often the pallet truck cannot go in from any side, and you need a forklift.

A pallet listed as "4-way" can therefore be 2-way for a pallet truck. The differences between feet and runners are covered in the guide to plastic pallet types.

Forklifts

A forklift lifts the pallet without bearing on the floor underneath it, so it accepts almost any bottom design. It only needs a fork entry higher than the fork thickness and pocket spacing that matches the fork spread.

ISO 2328 classes and fork sections

ISO 2328 defines how forks mount on the truck's fork carriage and groups them into classes by capacity ^[3]:

Sources: classes from the fork guide ^[3], average thicknesses from a fork catalogue ^[5].

The most common sections in catalogues are 100×40, 120×40 and 125×45 mm (width by thickness), with lengths from 800 to 2,400 mm ^[4]. On a class 2 warehouse forklift, 40 mm forks fit easily into a 100 mm opening. On heavy trucks with 50-65 mm forks the margin shrinks: check the opening with the pallet loaded and deflecting too.

Deflection on the forks

A plastic pallet deflects more than a wooden one under the same load. One maker of automated trucks reports that a deflection of about 6-10 mm (1/4-3/8 inch) is enough to cause problems with the forks, and that with loads over 2,500 lb (about 1,130 kg) the sagging deck can catch on the top of the forks ^[15]. Declared dynamic load capacity, and how ISO 8611 measures it, are explained in the guide to plastic pallet load capacity.

AGVs and AMRs: what they need from the pallet

A forklift driver sees a broken board and works around it; an AGV goes in anyway, stops or misses the pick. That is why automated trucks are stricter about pallets than any manual truck.

Types of AGV

Pallet-truck AGVs and fork AGVs. These are pallet trucks and forklifts with automatic guidance. Manufacturers' data sheets list euro pallets, pallets with bottom boards, roll containers and trolleys as accepted carriers, with capacities from 1,200 to 2,500 kg depending on the model ^[9]. One compact fork AGV accepts EUR 1 euro pallets, EUR 3 industrial pallets, EUR 6 half pallets and special carriers, with a capacity of 1,000 kg ^[10]. For pallet-truck AGVs one manufacturer sets a condition: the pallet must be open underneath, because the wheeled arms have to reach the floor; a closed-bottom pallet can only be picked up if it sits raised ^[8].

AMRs that lift the pallet. These are low robots that drive under a pallet resting on a station and lift it. One model for euro pallets handles 500-600 kg ^[11].

AGVs with a roller conveyor. They carry a roller or chain conveyor on top and transfer the pallet to and from fixed conveyors. Data sheets go up to 1,250 kg per pallet, on euro and industrial pallets ^[12]. Here you need continuous runners in the direction of the rollers; manufacturers' data sheets recommend runner pallets for conveyors and automated warehouses ^[20].

The five things an AGV needs

1. Consistent dimensions. According to one truck manufacturer, the biggest problem for robotic trucks is variability, and automated storage systems have strict pallet requirements, generally with a preference for non-wood pallets ^[16]. One automated warehouse integrator found that even pooled pallets were not consistent enough for its systems, and placed incoming pallets on slave pallets ^[15]. One pallet manufacturer quotes tolerances in the order of ±2-3 mm, to be confirmed with the integrator ^[17]: take the figure as an order of magnitude, not as a standard.
2. Compatible bottom. Open for pallet-truck AGVs ^[8], with continuous runners for conveyor AGVs.
3. Readable pockets. Many AGVs locate the pockets with 3D sensors. One system on the market, for example, recognises block pallets with pockets 0.24-0.44 m wide, in wood, plywood and plastic, at up to 2 m distance ^[13][14].
4. Undamaged pallets. One maker of automated trucks names broken boards on wooden pallets and deflection on plastic ones as the two main problems ^[15]. According to a sensor manufacturer, a faulty pallet can derail an AGV, jam a stacker crane or stop a conveyor ^[18].
5. Surface. Highly reflective loads are mentioned as a difficult case for detection ^[14]. The load must not slide when the AGV accelerates: some manufacturers offer anti-slip strips on the deck ^[20].

The load itself must be stable. One AGV maker for the paper industry points out that if the pallet leaves the line unwrapped, the load has to stand on its own ^[22].

Why plastic, and where it struggles

According to one industry operator, the use of plastic pallets is growing along with automation because they are durable and consistent in design ^[16]. Moulded and nail-free, a plastic pallet comes out of the press the same every time and does not lose boards along the way.

There are two limits. Deflection: a loaded plastic deck bends more than wood, and makers of automated trucks are asking plastic pallet manufacturers for more stiffness ^[15]. Slipping: a smooth deck is easy to wash, but without anti-slip the load can shift. For automation, look for pallets with anti-slip inserts and, for heavy loads, reinforced ones. Friction and anti-slip are explained in the guide to load securing.

ANSI MH1 and ISO 8611

ISO 8611 is the international test standard for flat pallets: it measures load capacities, but it does not tell you whether a pallet suits a given AGV. The US standard ANSI MH1 includes a section on performance for automated handling, including deck flatness and deflection measurement ^[19]. Neither replaces a trial on your own system.

Before you buy pallets for an AGV system

1. Ask the AGV manufacturer for its list of accepted carriers, with dimensions and tolerances. That is the document that counts, ahead of the pallet data sheet.
2. Run a trial with samples of the exact model, in the colour and material you will order, empty and fully loaded. A pallet pooling operator also recommends preliminary trials on automated systems ^[21].
3. Put the tolerances in the order: length, width, height, pocket opening, flatness. There is a template in the guide to specification and testing.
4. Check deflection at full load at the most critical point: forks, station, conveyor, pallet racking.
5. Ask for the anti-slip and colour the AGV manufacturer has already tested.
6. Decide who rejects damaged pallets before they enter the automated loop: a check at the loading dock costs less than a stopped system ^[18].

Common mistakes

• Buying "4-way" with the pallet truck in mind. On a runner pallet the pallet truck enters from two sides only, sometimes from none.
• Comparing the pallet size and forgetting the fork entry. 1200×800 tells you nothing about pocket height.
• Mixing pallets from different manufacturers in the same automated system. The same nominal size does not mean the same geometry.
• Using the static load capacity for a pallet that rides on AGV forks: the dynamic one is what counts.
• Leaving damaged pallets in circulation. A driver works around them; an AGV stops.
• Putting a reel on a flat pallet and sending it through the automated system. The load rolls and bears on a single line: you need reel pallets or roll chocks.

Which ROLL pallet for which truck

ROLL does not sell pallets for every system and does not make flat pallets. Of the ones it offers, two answer the questions on this page:

In pallet racking the pallet spans two beams, and the racking load applies, the lowest of the three ratings. On a solid shelf or on the floor it rests on a surface, and the static load (standing) and dynamic load (being moved) apply. For a 1200×800 runner pallet the usual position has the runners at 90° to the beams: the 800 side facing the aisle and the 1200 side running into the bay ^[25].

For AGVs, according to the PP08 data sheet, 4-way entry and closed, flat bearing surfaces are generally compatible, but the AGV configuration and the load class must be checked before the fleet goes into service ^[23]. Ask for a sample and have your system supplier test it.

The three flat pallets offered by ROLL

ROLL does not sell generic plastic pallets. Among flat pallets it offers only these three, each for a specific use.

For pallet racking ROLL PP69 1200×800 with 3 steel bars, 16 kg; 1,200 kg racking load according to the manufacturer’s datasheet. Designed for rack storage, with the pallet spanning two beams.

For hygienic environments ROLL PPH1 H1 type with closed runners, no steel bars, washable. Made from recycled material: not for direct food contact.

For floor handling ROLL PP08 Closed flat deck, 4-way entry, 9 feet: for moving pallets on the floor with a pallet truck. Not designed for racking.

Found a mistake or an outdated figure? Write to us at info@roll-packaging.com