Roll cages: the number that matters is not the load rating

The first question asked about a roll cage is almost always how much it carries. It's the easiest one to answer, and less useful than it sounds.

Where the time goes in replenishment

The handling chain from the back of the lorry to the shelf edge has only a few steps, and nearly all the time collects at the steps where stock gets touched twice.

If goods come in on a pallet, someone lifts them off it, puts them on a trolley or carries them, then lifts them onto the shelf. Three handles. If goods come in a cage already sorted by store zone, the cage rolls straight to the end of the aisle and stock goes from cage to shelf. One handle.

The part people forget is the return leg. Empty cages have to get back to the depot or onto the next outbound vehicle, and cages that nest or fold take up noticeably less space doing it. That's a real cost in both the trailer and the stockroom.

Starting force is the actual constraint

The manual handling guidance in general use gives these figures for pushing:

All of them assume good conditions underfoot. Slopes, poor flooring and long distances reduce every one.

What matters here is that starting force doesn't come from weight alone. It comes from wheel diameter, bearing type, tread material and floor condition. Two cages carrying exactly the same load can need twice the starting force as each other if the castors differ.

The part that gets discussed too little: visibility

Standard cages stand roughly 1,550 to 1,830 mm tall. Most people working with them can't see over anything above about 1,400 mm.

Which means a cage loaded to full height is several hundred kilos being pushed with no view of what's in front of it. On a sales floor with customers on it, working rules handle that risk better than equipment does: a maximum load height, a rule to push rather than pull, and defined routes during trading hours.

On the equipment side, what helps is mesh you can see through, and matching cage height to the job instead of running one height across the whole operation.

What EN 12674 actually tests

The European standard for roll containers runs to four parts: Part 1 terminology, Part 2 design and safety principles, Part 3 test methods, Part 4 performance requirements.

Part 4 is the one procurement can cite, because it sets out what a container has to pass.

• Stability — minimum inclination angles without tipping, loaded and unloaded.
• Frame strength — diagonal resistance, side frame strength and stiffness, with limits on deflection and permanent deformation.
• Castors — resistance to lateral loads, which is the force generated every time a cage turns in a tight space.
• Base — distributed floor loading, edge impact, localised edge and end loading, and a free-fall drop test.
• Movement — starting and rolling resistance, matching the section above exactly.
• Handling — mechanical lifting by forklift, and stacking for storage.

The Wanzl products ACE SITHA supplies are built to this family of standards. Ask any supplier for paperwork naming which part applies to which model.

Ramps and tail-lifts

A ramp changes the problem entirely. Moving a cage up one takes far more force than on the flat, and more dangerously, so does stopping one coming down.

Any site with ramps or tail-lift vehicles needs brakes specified at order, since they can't be added afterwards. It also needs a rule that cages above a given load take two people.

What to put in the specification

Those two lines depend on each other. Raise the load rating and leave the castor specification alone, and you end up with a cage that carries the weight while nobody can get it rolling. That breaks differently from a cage that breaks, and it happens more often.