In our 'user friendly' modern world, it's easy to forget that construction machinery hasn't always been a pleasure to operate. But you don't have to look too far in history to find construction equipment that you didn't so much operate as wrestle! Long, hard, cold levers with rudimentary hand grips had to be hauled using lots of upper body strength in order to manoeuvre in the required direction. To make matters worse, operators were often exposed to dusty, noisy and hot (or cold) conditions. Not only did this slow down the process, it exhausted even the strongest of operators, leading to health and safety issues and losses in productivity.
It is obviously true to say that the safety of modern construction machines has improved markedly - but equipment-related accidents have not been consigned to the past; a 1990s study of Swedish construction equipment operators (of all types and brands) found that over a third of accidents (36%) were caused by falls or missing a step on the machine - with being hit by falling/flying objects coming second. Avoiding accidents is still a major issue in 2004. It doesn't have to be accidents either, the same study found that among injuries that have built up over time, excessive physical effort caused two thirds of cases, with noise and vibration injuries making up a quarter. (With the neck and back being the most affected areas.)
Things are improving rapidly however, and a recent study of 338 operators found that, in terms of safety and comfort, machines under four years old were rated twice as good as those older than four years old, with 80% of excavator operators and 75% of wheel loader operators believing that the cabs in newer machines were either Good or Very Good in terms of comfort.
One reason for this rapid improvement has been the adoption of the concept of 'ergonomics' when designing new products. The name itself derives from the Greek ergon, meaning work and nomos, meaning law, but essentially it means fitting a tool or task to human requirements. Originally, ergonomics was about designing to achieve maximum efficiency and to avoid physical discomfort or pain in the working environment. Now it is far more subtle and even extends to the ideal weighting of joysticks and the tactility and sound of the switches. Because of this, ergonomics can be rather complex, incorporating such disciplines as anatomy, anthropometry, physiology, bio-mechanics and general psychology! The reason for this is that humans don't just use their muscles to operate machinery - they collect information from all the senses. To create a harmonious design that incorporates all these elements requires the services of an interdisciplinary team of experts.
Volvo CE, with among the youngest product ranges in the market, has for decades been a leader in developing machines that are not just effective in what they set out to do, but are also designed to be as comfortable and secure as possible. With a corporate philosophy of 'Quality, Safety and Environmental Care' it could hardly do anything else. "In terms of ergonomics," says Dr. Paul Piamonte, one of the experts at Volvo Technology, a Volvo Group consultancy, "this means enabling operators of varying heights and weights to reach the controls and to view the instruments and displays with equal ease, in order to perform the job quickly and easily." Volvo CE's ergonomists have been busy over the last couple of years, keeping up with the vastly increased product ranges at Volvo CE.
The emphasis on good ergonomic thinking has led to a degree of similarity among Volvo CE cabs, whereby the controls fall easily to hand in a recognizable manner; creating a sense of familiarity among operators moving from machine to machine. Within the cab there are dozens of design areas that must all work together, incorporating varying levels of equipment as well as possible new applications.
More electronics mean more switches, all which have to be accommodated in a logical way. Per Höglund, responsible for ergonomics and operator environment at Volvo CE Cabs, is keen to emphasize that design is not just about using high-tech software packages - but often largely based on getting close to the operator in the field. "Our engineers talk to the operators, observe the machines being used and actually use the machines themselves," he says. "We need a good understanding of the everyday life of the operator. What happens if you spill a coffee in the cab - we find out!"
A room with a view
As at least 90% of the task of operating machines is vision dependent, the view from the seat is crucial, as a good aspect of the direct working area reduces mistakes and the need for rework. The siting of the operator is also crucial, and in the case of articulated haulers the industry consensus now is to place the operator in a central position over the front axle - a position Volvo has advocated from the machine's earliest days. Volvo graders, however, have seen significant improvements since its 1928 model, which had neither cab nor heater - and the operator had to stand to see the moldboard. The moldboard had to be positioned by turning large wheels by hand - and the exhaust outlet was right by these wheels, which must have been deafening! Modern 2004 Volvo Motor Graders feature quiet cabs with noise levels of 75dB (A). The operator remains seated and lever efforts are low and within easy reach, as they are on an adjustable pedestal.
The new cabs on modern machines feature a large glass area, slimmer pillars and, if possible, no cross bar to reduce blind spots. To eliminate distortion, it is best to look through a window that is perpendicular to the viewing axis. However, more glass can mean more sun glare, more dust problems and susceptibility to damage from falling objects. Therefore cabs are offered with sun visors, rain shields and falling object and roll over protection systems.
Improving vision isn't just about glass area; it can also be bettered by reducing clutter in the cab, both in front of the operator and around the floor area. Modern cabs feature instrument binnacles with a simplified design that make them easy to read at a glance. On some models they can be sited to one side, thereby not obscuring the forward view. In Volvo's 'Care Cabs', fitted to its wheel loader range, the control panel is designed like a roof with a ridge where the driver can put his hand. This enables him to move along the ridge and to easily find the right switches, without looking. Cabs also feature storage areas and drink holders that further reduces clutter in the cab. A multi-filter air filtration unit, part of the ventilation system, keeps harmful dust particles at bay, as do cab pressurizers.
When operators can be sitting on them for up to 12 hours a day, 7 days a week, the importance of seats take on a much greater magnitude, as bad seating can lead to back, leg and shoulder injuries. Designing seats that can accommodate operators ranging in size from 1.9 m (6.3 ft) tall who weigh 106kg (234 lb) to those who are 1.5 m (5 ft) and weigh 38 kg (84lb) is not easy. But the leading equipment manufacturers have focused on good seat design, and developed strong undercarriages that are stable, have low vibration and low noise. In addition, on its loader range, Volvo CE also offers Comfort Drive Control (CDC), which features a collapsible and adjustable armrest that houses a small lever that the operator can move with his fingertips to steer the machine. This reduces the monotonous and strenuous turning of the steering wheel in repeated work cycles (e.g. high production truck loading); thus reducing the risk of hand, arm, shoulder or back injuries. The steering wheel remains operational at all times and the operator can switch from CDC to steering wheel when required. Elsewhere, where joysticks are fitted, these have been designed to nestle into the hand, and are made from an agreeably tactile material.
Shake, rattle and roll
Noise and vibration are two aspects of the same phenomenon, so when it comes to cab design, it makes sense to consider them together. Manufacturers are coming under intense pressure by legislators to reduce noise output, and employers too have a duty of care to minimize exposure to mechanical vibration. Anti-vibration components on construction equipment have to deal with a variety of operating conditions and shock inputs, from rough terrain to accidental impacts and unloading/loading heavy burdens. For example, Volvo CE's backhoe loader's cab is fitted with controlled-rebound mounts and overload washers, that help improve ride smoothness and lessen noise levels in the cab - significant factors in operator comfort.
Ingress and egress
Getting into and out of machines may seem child's play, but as noted earlier, wrong steps, slips and falls are a major cause of accidents. Where possible, modern machines should feature leaning ladders, straight entrance, wide door opening and anti-slip patterns and materials. The Volvo backhoe, for instance, features three entrance steps instead of the industry norm of only two. A small point perhaps, but such is the nature of ergonomic thinking - over time the small issues combine to create major benefits.
The ergonomic future
The need to develop safer, more comfortable and productive machines is becoming more intense by the day. Because of this, manufacturers are increasingly turning to virtual reality and 'human in the loop' technology to prototype new advances and see how they work in the field. As construction equipment operators' expectations from their in-cab working environment become more demanding, and legislation acts as a further spur, it is clear that equipment manufacturers will not be able to rest - comfortably and safely - upon their ergonomic laurels for long.