Introduction: Anti-rollover support legs widen a stacker's effective support base so a tall mast can lift loads with less risk of tipping during high lifting.
High lifting changes the physics of a stacker. When the forks rise, the load moves higher and the combined center of gravity shifts. A chassis that feels stable at 1.6 m can feel very different at 4.5 m. Support legs are not decoration; they are the part of the truck that answers that change. The explanation comes down to support area, center of gravity, mast behavior, and the limits of load capacity.
Stability is about the support area under the truck. A counterbalanced forklift uses rear counterweight to offset the load. A stand-on electric stacker with support legs uses a different geometry: the legs and wheels create a wide footprint, while the mast and load sit near the front. At low lift, the load's center of gravity is low, so tipping risk is modest. At high lift, the load's center of gravity is high. Even a small sideways force from a turn, a slightly uneven floor, or a sudden stop can push the combined center of gravity toward the edge of the support base. UK HSE guidance on lift trucks highlights load position, cornering speed, and overhead clearance for good reason: at 4.5 m, those factors have more leverage over the chassis. Mast deflection adds another layer. Steel masts are stiff, but they are not perfectly rigid. As sections extend, the mast can flex slightly under load. That movement shifts weight forward and can create a subtle pendulum effect. The operator may feel the truck rock or the mast sway. The higher the lift, the more noticeable the effect. This is why high-lift configurations need a support base that matches the mast's reach. The goal is to keep the combined center of gravity inside the support area during normal operating forces. In the CDD-20 2T stand-on electric stacker, the 4.5 m three-stage mast reaches 4,500 mm maximum lift and extends to 4,920 mm overall height. Those are tall numbers for a compact truck, and they explain why the support legs become part of the high-lift package.
Anti-rollover support legs extend outward from the chassis. They increase the distance between left and right contact points, and often between front and rear contact points. The result is a larger support polygon. A larger support polygon allows the same truck to tolerate more load shift before tipping. In the CDD-20 2T stand-on electric stacker, the 4.5 m three-stage mast configuration uses support legs with a 1,900 mm spread. The chassis is 990 mm wide in that configuration, and the machine weighs 920 kg. The legs are a deliberate part of the high-lift design.
FEM's industrial truck material frames stability around the truck's support area and load position, and that is exactly what these legs change. They do not change the load or the rack. They change how much room the truck has to stay balanced while the load is high.
Support legs improve stability, but the load chart still sets the safe working load. A 2-ton stacker does not automatically hold 2 tons at every lift height. The CDD-20 carries a 2,000 kg rated load at a 570 mm load center. That rating is tied to a specific configuration and load position. As lift height increases, the safe working load can be lower because the load has more leverage over the mast and chassis. The exact figure depends on the mast, load center, and truck configuration. Operators should follow the load chart supplied with the truck and local site rules for the exact machine. Support legs also do not fix bad floor conditions, off-center loads, or fast cornering. The EU Machinery Directive places lifting machinery in a safety framework, and HSE guidance tells operators to consider load position, speed, and overhead clearance. Those rules still apply. A wide support base gives the operator more margin, but it cannot replace training, inspection, and sensible speed. The legs are one part of a stability system that includes the mast, chassis, counterweight position, wheelbase, tires, and load handling practice. They are most valuable when the truck is used as intended: on a flat indoor floor, with the load centered, and at a speed that matches the aisle and the lift height.
High-lift electric stackers use anti-rollover support legs because a tall mast changes the stability question. The load rises, the center of gravity moves, and the support base needs to grow with it. The 4.5 m three-stage CDD-20 configuration shows the idea in numbers: 1,900 mm support leg spread, 990 mm chassis width, 920 kg machine weight, and a 2,000 kg rated load at 570 mm load center. Those numbers do not promise full capacity at full height. They show how the truck is built to keep the support area wide enough for high-lift work. For electric stacker manufacturers and warehouse handling equipment manufacturers, the support leg spread is a practical design answer to a physics problem. For operators, the lesson is simple: respect the load chart, keep the floor flat, and let the support base do its job.
A：A high lift raises the combined center of gravity of the truck and load, which reduces the margin before tipping. Support legs widen the effective support base, so the center of gravity must move farther before it crosses the tipping line. That extra margin helps during turns, mast sway, and minor floor changes. The legs improve stability, but they do not replace the load chart or safe operating rules.
A：A wider support leg spread creates a larger support polygon under the truck. On the CDD-20 4.5 m three-stage configuration, the legs spread to 1,900 mm while the chassis is 990 mm wide. That extra width gives the combined center of gravity more room to move before tipping. It helps most when the load is high, but the floor still needs to be flat and the load still needs to stay within the rated load center.
A：No. A 2,000 kg rating is tied to a specific load center and configuration. The CDD-20 is rated for 2,000 kg at a 570 mm load center, but safe working load can decrease as lift height increases. The load has more leverage over the mast and chassis at height. Always follow the load chart supplied with the truck and local site rules for the exact machine.
Directive - 2006/42 - EN - Machinery Directive - EUR-Lex
