DC Velocity - September 2016

54 DC VELOCITY SEPTEMBER 2016 www.dcvelocity.com
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This provides an eye-level view of the forks’ position and angle, allowing operators to adjust and guide them like a doctor conducting laparoscopic surgery. They’re especially useful when minimizing damage is a high priority, says Tim Forlow, senior product marketing manager at Crown Equipment Corp. He considers them essential for applications with double-deep racks. “Now you can see something you normally couldn’t see while down on the floor,” he says.

Camera systems are so beneficial, says Bruce Dickey, vice president–sales for Narrow Aisle Inc., that his company has made them a standard feature on its high-lift trucks.

Another visibility-enhancing option is a laser-line projector mounted on the fork carriage. “The laser line shoots right into where the fork goes into the pallet opening, so the operator can see that more easily,” A third option is a programmable shelf-height selector that automatically stops the forks at preselected heights instead of depending on the operator to visually assess when the forks have reached the right spot. Using all three of these tools together can significantly reduce the time required to pick or place loads.

Because a high-lift mast’s components can obscure the operator’s view of an elevated load, a mast design that tucks them out of the way is beneficial, notes Matt Barrow, product manager, warehouse solutions at Yale Materials Handling Corp. “Reducing wiring and electrical connections is not only good for reliability but also improves visibility, as does housing the cylinders and chains behind mast channels,” he says.

Yale and several other lift truck makers have gone out of their way to address that concern in their narrow-aisle models. One example is Crown’s MonoLift mast. The single-column design provides greater visibility than traditional two-column masts because operators don’t have to look in between columns, Forlow says. In addition, positioning the mast to the side rather than in the center of the truck allows the operator to look past the mast rather than through it, providing a clear view at all heights, he says.

SPEED

Operating cycle times (the total time it takes for the vehicle to travel to the correct spot and store or retrieve a load) for high-lift trucks are somewhat longer than those for conventional sit-down trucks. How big a difference is there? Dickey of Narrow Aisle points to this comparison of average cycle times for Class II narrow-aisle trucks with Class I electric rider trucks, calculated by the European Materials Handling Federation:

b Class I electric counterbalanced forklift truck (baseline)
b Flexi brand articulating very narrow aisle: 87 percent as
fast as a Class I forklift

b Turret truck: 71 percent as fast as a Class I forklift
b Reach truck: 55 percent as fast as a Class I forklift
Furthermore, because an on-the-ground operator’s sight
line is restricted and tall masts sway a little while in motion,
operators must wait for the mast to stop moving before
they can pull or put away a pallet, adding more time to the
cycle, says Perry Ardito, general manager for Jungheinrich’s
warehouse products group, North America.

Horizontal travel times are slower, too. A typical reach truck, for example, won’t travel as fast as a counterbalanced truck will because it’s specifically designed (right down to the tires) for moving up and down aisles, as opposed to long-distance transportation, says Tony Kordes, product manager for UniCarriers. “But what you lose in speed you make up in maneuverability in narrow aisles … [so] it may take less time to reposition a pallet,” he adds.

There are ways to compensate for slower operating speeds. For example, a man-up truck allows operators to pick both sides of an aisle, reducing total travel and raise/lower time, says Cesar Jimenez, director of product planning, technical services, and warranty at Toyota Material Handling U.S.A. (TMHU). Another possibility is to put order pickers on rails or guide wires, allowing operators to devote more attention to picking than they could if they also had to steer. In addition, says Scott Carlin, TMHU’s national product planning manager,

slotting fast movers down low and sequencing picks to minimize lifting and lowering can make a noticeable difference.

CAPACITY AND STABILITY

Man-up trucks like turret trucks are heavy-duty in design, but the allowable load weights at maximum height can be less than those for a reach truck, Ardito notes. “The difference really is that a man-up truck is lifting the entire operator compartment plus the load. With a reach truck, you’re lifting just the forks and the load.” Still, he continues, man-up trucks often can be more productive than reach trucks because they don’t have to make right-angle turns into racks; the forks themselves turn 180 degrees to pick either side of the aisle, he explains. (Articulating fork trucks also do that.)

Stability is another important factor in productivity, Ardito notes. “If there is any instability, it will affect the operator’s confidence, whether that person is in the air or on the floor … and if the operator lacks confidence in the truck, then it affects the operator’s productivity.” It’s not