How to design the perfect trolley

Trolleys have been used for centuries to manually transport materials. The basic design of a trolley is simple, a set of wheels and a platform or basket-like structure to carry the items. Designing the perfect trolley is not that simple though, as anyone who has struggled with a supermarket shopping trolley will testify to.

The problem with trolleys

The problem with supermarket trolleys and other types with fixed or swivel castors is that they can be difficult to steer, often with inadequate handles

Trolleys may be fine on a smooth concrete floor, but become difficult to handle on carpets or rough terrain. Other trolleys may appear to work well, but can cause strain injuries.

Some people predict that robots will take over manual handling tasks in the future, but in the meantime, businesses need trolleys and other material handling equipment that is designed well and is built to last.

To design the perfect trolley, you need to start with some basic design principles.

Dimensions

If trolleys are used in more than one room, they obviously need to be narrow enough to fit through doors. They should not merely squeeze through as this will mean that the operator will need to take extra care every time they take the trolley through a door.

A trolley should not be too long either. It may seem a good idea to make a trolley very long to fit more items on it, but long trolleys are difficult to steer around corners.

The height of the trolley, plus the goods on it, should not obscure the operator’s view.

Weight

A trolley needs to be not too light and not too heavy. If the trolley is too thin, it will be light, but may not be strong enough to hold the castor head so that it can swing freely. If the trolley plus the load is too heavy, it will put a strain on the operator and manoeuvrability will be poor.

As a rough guide, the weight of the trolley should be 15% to 20% of the load carried.

Tubular steel is the best material to construct a trolley as it does not weigh too much and is strong.

Handle height

The optimal height for the average female is 910mm and for males is 990mm. This suggests that the best height for the trolley handle should be somewhere in between these heights, around 950mm.

If the trolley is pulled the handle needs to be far enough from the trolley body so that the operator’s feet do not hit the trolley.

Pushing the trolley

Health and safety recommendations say that the safe initial force to push a trolley should be between 17 to 21kg and sustained force for infrequent short distances should be between 6kg and 12kg. A spring scale is a simple way to measure the force needed to push or pull a trolley. Any forces outside of the recommended ranges could risk injury to the operator.

A trolley may be simple technology, but designing the perfect trolley is not easy.

Posted by Mark
11th June 2018
Manufacturing

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