Proper design keeps sound levels low despite increased glass surface. "With our new H Series, we moved noise sources away from the cab, such as the exhaust stack," says DesVeaux. "The result was improved cab pressurization, reduction of exhaust and engine noise to the cab and improved cab suppression to attenuate hydraulic noise. The results were a reduction of up to 4 dB, or 75 percent reduction in sound in the new H Series cab."
Slopes supply better views
Sloping rear hoods also serve to increase visibility. "With a longer rear hood, a higher angle is needed to retain acceptable rearward visibility," says Tullo. "Volvo designs its machines with safety in mind, and rearward visibility is no exception — shorter rear hoods, good departure angle from the cab seat and darkening the top of the rear hood for less glare and lower operator fatigue."
Glare can be a problem. "Some manufacturers maintain bright colors on the rear hood that can cause eye strain and glare. Some even promote chrome exhaust stacks, perhaps creating an unsafe situation if the operator should become blinded from sun reflection," says Tullo.
Removing obstructions is a major focus of many new designs. "Komatsu has worked to move the muffler underneath the hood and keep a small exhaust stack," says Gidaspow. "This greatly helps to improve the rear visibility. We have also sloped and narrowed the engine hood and made flat windows standard equipment."
But Tier III standards limit how much you can shrink the rear hood. "With the new Tier III emission requirement, the cooling package changed slightly in our new H Series machine," says DesVeaux. "To maintain rear visibility, we took advantage of strategic locations to increase width only where necessary and still maintain good line of sight."
Dash designs reduce clutter
"Many manufacturers tend to keep instrument panels low and centered to balance between visibility and operator comfort," says Tullo. "Some are moving consoles aside or bundling the steering wheel and console together in a narrow tower."
The results are mixed. "Although that may seem to increase forward visibility, it's placement and configuration that truly determine the effectiveness of that design," says Tullo. "By moving the console aside, is there higher visibility where it's needed, or does the movement just allow the operator to see the rear of the tower and the front frame? Moving the console aside may lessen visibility to the ground and/or tires. Also, since the console is no longer centered, the operator is constantly moving his neck and head to see the gauges, adding to fatigue over the entire work day." Poor placement could also restrict operator movement in the cab.
"We put the operating information in front and the service information on the side," says Gidaspow. "This keeps the dash small and allows the operator to concentrate on the job and not worry about the machine. Komatsu has also lowered the belt line of the machine in the front and sides to improve visibility."
Caterpillar has carefully arranged its instrument gauges to take advantage of natural obstructions. "On the H Series, we have two areas where we have clustered instrument gauges and operator controls," says DesVeaux. "The instrument gauges are located on the front dash by the steering wheel for ease of visuals to the operator. The operator controls are integrated into a control panel located on the front of the right-hand ROPS post. We took advantage of the ROPS post visibility limitations and maximized component placement in this area to prevent additional obstructions."
Hyundai has centralized all gauges into a cluster. "The Hyundai cluster has integrated manual gauges and digital readout," says Pooley. "The operator has many options to set the display the way he wants to see it as he is working. Backlight has always been a complaint of the operators, as the sunlight drowns out the digital display. Hyundai has a new backlight system that allows the operator to see clearly in any lighting condition."