When lift trucks were introduced nearly 100 years ago, they were simple pieces of motorized equipment designed to move pallet loads from point A to point B. Today, sophisticated lift trucks are available in a combination of designs, weight capacities and lifting heights. The vehicles also come with a variety of enhanced safety features and ergonomic designs for operator comfort.
Perhaps the only universal features of today’s diverse selection of lift trucks are the forks used to lift loads and the tires used to move them.
This article looks at the basic design and application of several types of lift trucks used in manufacturing, warehousing and distribution:
Counterbalanced lift trucks
• Electric trucks
• Internal combustion (IC) trucks
Narrow-aisle lift trucks
• Reach trucks
• Turret trucks
Low lift pallet trucks (or pallet jacks)
• Non-powered pallet trucks
• Electric-powered pallet trucks
The most common type of lift truck, also known as a forklift, is the counterbalanced, sit-down truck. A weight located in the rear of one of these trucks counterbalances the weight of the load, ensuring the truck doesn’t tip forward.
A typical counterbalanced lift truck has:
• a capacity of 4,000 to 6,500 pounds;
• a lifting height of about 16 feet (with 189 inches being the most poplar);
• and comes outfitted with lights, backup alarms and other safety features.
Counterbalanced trucks are powered either by internal combustion (IC) engines or electric motors. The split is about 40% IC and 60% electric, according to Jeff Rufener, president of the Industrial Truck Association (ITA) and vice president of marketing for Mitsubishi Caterpillar Forklift America.
Electric counterbalanced lift trucks
Electric trucks, which make up about 60% of the market, get their power from large, heavy lead-acid batteries, which provide much of the counterweight.
The ITA classifies electric counterbalanced trucks as Class 1 lift trucks. Class 1 also includes stand-up counterbalanced trucks and other electric trucks built for general use.
While the initial investment in an electric truck is more than IC trucks, electric trucks are less expensive to operate, due to lower fuel and maintenance costs.
Most of the electric rider trucks shipped in North America are moving material inside the four walls. “Electric trucks have historically been limited to indoor applications that are clean,” explains David McNeill, manager of product strategy for electric riders at NACCO Materials Handling Group. “However, with the launch of several new Class 1 products, it is becoming increasingly possible to use electric rider products in some outdoor applications.”
Compared to IC trucks, electric trucks are the preferable indoor choice because they are quiet, produce no emissions and can usually run a full eight-hour shift on one battery charge. Removing, recharging and reloading batteries—which typically weigh around 3,000 pounds—can be cumbersome and time consuming and usually requires a dedicated space for battery handling. Newer fast charging technologies, however, are changing that paradigm.
One new charging technology is called opportunity charging. “This basically means that rather than waiting until the end of the shift to recharge the battery, it happens throughout the day,” explains Niels Ostergaard, CSSR training manager for Toyota Material Handling U.S.A. “When the truck is parked for a break, the operator takes the opportunity to plug it in at charging stations located throughout the facility.”
Fast-charging is another enhanced charging technology. According to Ostergaard, advances in battery technology and charging systems make it possible to cut charging time by as much as 50%.
Internal combustion counterbalanced lift trucks
IC engine trucks run on a variety of fuels, including gasoline, diesel, liquid propane gas (LPG) and compressed natural gas (CNG). The larger lift trucks, which are used outdoors, are typically gasoline- or diesel-powered and have pneumatic tires that make them suitable for rough terrain and steep inclines as opposed to cushion tires, which are made of solid rubber and are best for indoor applications on smooth surfaces.
LPG is the most common fuel for indoor trucks. With more than 600,000 propane-fueled lift trucks in operation today in warehouses and DCs, these units offer a number of benefits. For example, propane-fueled lift trucks maintain consistent, 100% power throughout operation and have faster ground speeds than other power sources. They can also run 24 hours a day, with longer run times between refueling than lift trucks fueled by other power sources, according to Brian Feehan, vice president of Propane Education & Research Council (PERC).
Propane cylinders require little space and can be kept in a storage area inside or outside of a facility. And while it takes little time to switch out a propane cylinder, it does require operator training and knowledge of safety standards like the Occupational Health and Safety Administration (OSHA) Standard 1910.178.1, says Feehan.
Compared to electric trucks, IC trucks are quicker and easier to refuel, but they can be noisy and produce air-polluting emissions. The federal Environmental Protection Agency (EPA) and the California Air Resources Board have set standards that limit emissions. The Industrial Truck Standards Development Foundation (ITSDF) also offers a number of lift truck standards on their Web site free of charge.
The ITA classifies internal combustion counterbalanced lift trucks with cushion tires as Class 4 trucks and those with pneumatic tires as Class 5.
NARROW-AISLE LIFT TRUCKS
The ITA’s Class 2 includes a variety of electric lift trucks built for use in narrow aisles.
At 12 feet wide, standard storage aisles allow a counterbalanced lift truck to turn in the aisle and put away a load. Narrow aisles are typically only 8 feet wide—and very narrow aisles are only 5.5 to 6 feet wide—requiring specialized lift trucks that can put away loads without turning or that are small enough to make tight turns.
Three of the most common narrow-aisle trucks are reach trucks, turret trucks and orderpickers.
Narrow-aisle reach trucks
Reach trucks are considered the original narrow-aisle lift truck. These trucks are small enough to turn in narrow aisles because they don’t need a large counterweight. Instead, outrigger arms extend in front of the trucks to provide stability. The outrigger arms, however, can prevent the trucks, depending on storage configuration, from getting close enough to the storage rack to deposit and retrieve loads. To overcome this, a reach truck is designed with a telescoping mechanism—called a pantograph—that allows the forks to reach into storage locations.
The best environment for a narrow-aisle lift truck is one that is clean, has good lighting, an ample turning aisle, good traffic flow and well-maintained floors.
The lift truck often chosen for work in very narrow aisles is the turret truck. These trucks have pivoting forks that turn 90 degrees on either side and traverse from side to side.
To put away a load, an operator drives down the aisle with the load facing forward and then stops at the designated storage location. The forks pivot to the appropriate side and lift the load to the desired height. Then the forks traverse to their full extension, depositing the load. The forks return to their original position before forward travel resumes.
Turret trucks can be completely operator guided or can run on a wire guidance system—an attractive option in very narrow aisles. In man-up trucks, the operator compartment rises with the load. In man-down trucks, operators remain at floor level.
A good rule of thumb when choosing a turret truck is to measure speeds at different elevations and compare mast sway.
While reach trucks and turret trucks are used for storing and retrieving pallet loads, orderpickers are used for handling individual items or cases. An orderpicker, also known as a stockpicker or order selector, lifts the operator on a platform along with the forks. The operator picks items from bulk storage locations and places them directly onto a pallet on the forks of the truck.
Orderpickers can safely move forward while in an elevated position. They can be completely operator-guided or can run on wire guidance systems.
LOW LIFT PALLET TRUCKS
The simplest and least expensive lift trucks are non-powered pallet trucks, also known as hand pallet trucks or hand pallet jacks. Powered and non-powered pallet trucks are included in ITA’s Class 3.
Non-powered pallet trucks
Non-powered pallet trucks use a lifting device—usually hydraulic—to raise pallets just a few inches off the floor. Operators then grab the truck’s handle and pull the load behind them.
Electric-powered pallet trucks
Electric-powered pallet trucks are also available. These trucks are easy to maneuver, relatively inexpensive, and available with forks long enough to accommodate two or three pallet loads.
Powered pallet trucks come in two versions, known as “walkies” and “riders.” The walkie is designed for the operator to walk along with the truck, while the rider has a platform on which the operator can stand. These trucks are often used in warehouses for order picking, with operators stacking cartons on pallets as they work their way down the picking aisles.
The right fit
One of the most important factors associated with any lift truck is using the right sized unit for the right application. The application should always drive the product selection, says NACCO’s McNeill.
As the economy has become more complex and competitive, customers are looking for efficiencies to lower operating costs while increasing productivity. Lift trucks can play a role in accomplishing those goals, says Ostergaard. “In today’s market, it’s critical to ensure that you’re using the proper sized lift for the application. The wrong sized lift truck can have a dramatic negative effect on productivity, profitability and the bottom line. It’s like buying a new pair of shoes. They may be beautiful and priced right, but if the size is wrong, you won’t be able to walk.”