Kalmar has rolled out a groundbreaking fully electric reach stacker tailored for intermodal rail yards and high-throughput port terminals, utilizing a tethered cable-reel system rather than a massive onboard battery pack. While battery-electric terminal tractors have gained popularity, scaling battery technology to a reach stacker capable of lifting 45-ton loaded containers presents a physics problem: the battery pack required for a full shift would weigh upwards of 15 tons, severely compromising the machine's static and dynamic stability margins. Kalmar's solution bypasses this bottleneck by drawing power directly from the yard's grid.
The reach stacker is equipped with a heavy-duty, automated cable reel mounted on the rear of the chassis. As the machine travels up and down the container yard, the reel deploys and retracts a specialized, high-tensile high-voltage cable connected to strategically placed power bollards. The core engineering challenge was managing the immense physical stress on the cable during tight maneuvers and preventing it from being crushed under the machine's massive tires. Kalmar developed an ultrasonic tension-monitoring system that keeps the cable under constant, optimal tension, automatically applying the machine's service brakes if the cable is pulled to its maximum safe distance.
Because the machine does not carry the dead weight of a massive battery, it retains its full 45-ton lifting capacity in the second and third rows of containers without requiring additional counterweights. The continuous high-voltage supply powers a 300 kW electric motor that drives the hydraulic pumps for the boom and spreader, delivering instantaneous hydraulic response without the lag or power droop associated with battery state-of-charge depletion.
For rail terminals operating 24/7, the operational advantages are staggering. There is no downtime for battery charging or swapping, and the electric drivetrain completely eliminates diesel particulate emissions and engine noise, significantly improving air quality and working conditions for yard operators. By proving that tethered electric operation is viable for ultra-heavy lifting, Kalmar is providing a pragmatic pathway for ports to achieve aggressive decarbonization targets without sacrificing container throughput.
