02 March 2007
Gordon Leicester

Mobile elevating work platform isn't the snappiest name for a piece of work equipment, so it's not surprising that powered access machines are usually collectively abbreviated to MEWPs and better known individually by colloquial names such as cherry pickers, magic carpets and scissor lifts.

MEWPs have been around for three decades but they have recently come into their own as the following wind of the Work at Height Regulations made ladders the last choice for many tasks.

MEWPs have obvious advantages over traditional access methods such as ladders and scaffolding, including a more safe and secure environment to work in, reduced operator effort, and an increase in efficiency and security (where scaffolding might give thieves new means of access to a building).

Though there are as many as 90 different MEWPs, most of them fall into three broad categories set out below.

Vehicle-mounted platforms

Trailer-mounted and truck-mounted platforms, including cherry pickers, resemble a human arm with a cage for a hand. They lift the operator using a hydraulic pump from a power take-off attached to the main vehicle engine and provide access by moving the basket or cage up, down and across, allowing you to get to the exact place you want. The bending and stretching elements of the job are eliminated. Stopping and starting is minimised by their height and outreach (anything from two to 26m) and the average trailer-mounted machine takes approximately five minutes to set up. Cage capacity allows operators to carry extra tools.

Generally, trucks operate outdoors, trailers both inside and out, but there are many variations in each category depending on the job requirements.

Common uses of vehicle-mounted platforms include maintaining street furniture, tree surgery, work on the facades of buildings and window cleaning.

Scissor lifts

Scissor lifts are "lift tables" that allow equipment and materials to be moved vertically, while using minimum floor space. This, once again, eliminates the bending, stretching, stopping and starting elements of a job. Scissor lifts can be driven from controls in the cage, so may be moved along the length of a job while extended.

They are popular in construction because of their capacity for carrying bulky materials and heavy loads and come diesel powered for exterior use and battery operated for indoors. Extension decks mean they can provide a stable platform up to 2.7m long up to 30m off the ground. Some of the newer machines have on-board generators that supply power to the platform for tools, eliminating trailing cables. Another advantage of scissor lifts is that when retracted, they are a fraction of the extended height. Common uses include bricklaying and glazing.

Self-propelled booms

Self-propelled boom lifts are good for hard-to-reach jobs which call for a combination of height and outreach. Capable of carrying up to two people and with a reach of up to 46m, there are many boom variants, from four-wheel drive for uneven ground to narrow aisle - particularly useful for access to factory and warehouse roofs without disturbing racking or production lines. Like scissor lifts, they can be driven along the ground by the person in the cage. Common uses include steel erection in construction.

There are six factors you need to consider when choosing a MEWP for a task.

• Height: the height quoted on machines is a measurement from ground level to the maximum platform height, plus the reach of the average person.
• Outreach: the outreach of a machine is measured from the centre of the turret to the fingertips of the average male on a fully extended boom. Remember to include the vehicle width.
• Weight: outreach is dependent on weight in the MEWP's cage. The less weight, the greater the outreach. Always calculate the total weight that the machine will have to carry, including any tools, and compare this to the machine's safe working load.
• Site conditions: special machines are needed for work on gradients, wet or rough ground. For work inside, electrically powered machines are preferable.
• Operator skills: apart from HGVs and a few specialised types, MEWPs can be self-operated.

Gordon Leicester is managing director of Facelift, providers of access equipment and training, www.facelift.co.uk

Categories:
Construction, Work at height, Article, Manufacturing / engineering, Work equipment