July 24 2006 04:19 PM

For years, the workhorse for industrial and commercial material handling of heavy loads has been the forklift with an internal combustion (IC) power plant. Accepted as a necessary evil are the noise, emissions and performance limitations of conventional forklifts. However, one of the most significant trends in the industry is the increased use of electric-powered forklifts. And now that an 80-volt, 5,000- to 6,000-pound capacity truck is available, the applications arena for electric forklifts is limitless.


Twenty years ago, the ratio of forklift sales in the US was 55% IC engine powered and 45% electric powered, and the electric vehicles were typically used for lighter duty applications. Today, electric forklift sales approach 60% of the overall market. The recent growth can be attributed to several factors including performance and operational improvements, extended range of vehicle capacities, environmental and OSHA concerns and operating cost benefits.


Performance Enhancements

The general need of all material-handling equipment is the ability to move an item from point A to point B, and the advantage held by IC-powered forklifts is power the ability to move heavy loads quickly and efficiently over any terrain. More specifically, they can climb ramps and grades, they can accelerate faster, they reach higher top-end speeds, and they can lift loads faster. Overall, they are regarded as true workhorses of the industry.


Recent advancements in electric forklifts with 48-volt and now 80-volt AC motors have generated a lot of interest in the forklift market. AC motors offer several advantages: high performance, reduced maintenance and improved energy consumption. However, the load capacity limits for electric trucks have been a drawback. Operators want the freedom (flexibility) to convey all loads with a single truck.


In addition to advances in performance, operators are getting more comfortable with electric forklifts, realizing they are cleaner and significantly more quiet. Also, there is less vibration transferred from the engine through the seat, floorboard or steering wheel. Tests have shown reduced vibration keeps operators alert and less fatigued, especially in operations that require extended periods of forklift use.


Advancements in Detail

Several improvements and enhancements have increased the popularity of electric forklifts. The switch to AC drive technology versus DC has provided several operational benefits as well as environmental advantages. Also, ergonomic controls and digital displays provide a more user-friendly vehicle.


An AC-powered pallet truck still uses a DC battery. However, an inverter in the trucks controller converts the DC current to three-phase AC current. AC power is then delivered to the trucks motor, controlling the speed and acceleration of the vehicle. The end-user realizes the following benefits:


Higher performance AC motors allow for quicker speeds (up to 12.5 mph), better acceleration and gradeability and lift speeds up to 108 fpm. Operators notice a faster and smoother response when changing from forward to reverse and vice versa. This improvement in directional changes increases productivity output.

Reduced maintenance Unlike DC motors, AC motors do not have brushes, controller contactors needed for switching the direction of the motor rotation or motor commutators. Fewer moving parts translates into reduced maintenance costs. In addition, the elimination of brushes allows AC motors to be much smaller than comparable DC motors.

Improved energy consumption One of the weak points of electric, DC-powered trucks has been the decrease in performance as the battery loses its charge. An AC power system offers the control needed to maintain power, even as battery charge runs low, which translates to up to 30% less energy consumption when compared to conventional trucks.


Typical AC systems recover battery energy using three forms of regenerative braking: when the accelerator lever is released (coasting), when the brake is applied and when the directional lever is operated (switch back or plugging). Essentially, the inertia energy that is created by these actions is converted to electrical energy and returned to the battery, extending overall operating times and operating cycles.


Industrial truck manufacturers are constantly searching for ways to meet the pending EPA clean-air regulations. Using California as a model, where the California Air Resources Board (CARB) has set standards for emission limits, new trucks take a new approach to emissions. Technical advancements for IC engine trucks, such as three-way catalytic converters, have been designed to meet the standards. However, electric trucks with their zero-emission capabilities provide the buyer with the ultimate solution to environmental concerns.


Apart from emissions, the elimination of fuel costs can add to acceptance of electric trucks. For example, an electric forklift may use $4 in electricity, whereas an IC forklift may need $10 in fuel to accomplish the same amount of work. The initial costs of an electric truck with battery and charger may be higher, but the overall true operating costs over time will provide significant savings.


Electric vehicles have digital displays, providing operators with instant information regarding the status of their vehicles condition. Speedometer readings, battery discharge gauges, warning messages and multiple-hour meter readings are common on most trucks. Using built-in analyzers and self-diagnostic capabilities, electrical forklifts with digital displays often take less time to troubleshoot.


Dirk von Holt is president of Jungheinrich Lift Truck Corp. in Richmond, Virginia. For more information on AC Travel Drive Trucks, contact Multiton MIC Corporation by phone at 804-737-7400 or visit www.multiton.com.