Choosing the Right Indoor Electric Lift Solutions to Maximize Productivity
By Greg Mason, General Manager – Products & Training, Jungheinrich Lift Truck Corp.
When it comes to selecting the right electric lift trucks for your indoor fleet, you have many choices. Ultimately those choices will either positively or negatively impact your productivity and profitability, so it is critical to understand the technology options and how they will work in your operation.
First consider your facility and the materials you move. Begin your research by answering these basic questions.
- How will the product be prepared for handling (long rolls, on a pallet, in cases, etc.)?
- How is the product received (tractor trailer, via conveyor, from another lift truck, etc.)?
- How much is received or shipped? Go beyond average shipping volumes or receiving volumes to also consider peak volumes. This does not mean you have to buy trucks for peak volumes, but that you would consider alternate resources such as rentals for those peak periods.
- What are the load dimensions - how wide and long are the pallets? The typical North American pallet is 40 inches wide, 48 inches long and has a load center of 24 inches. If your loads are longer, your truck may not be able to lift its full load capacity because that load center is extended out.
- How many cycles will the truck be expected to handle on a shift and what will the weight of the load be? Higher levels of voltage provide higher levels of performance for both number of cycles and load weight. Typical voltage for lift trucks is 24, 36, 48, 72 or 80.
- Will the operator be on and off the truck often? This is important in choosing between a stand-up or sit-down model.
- How will the product be stored? Floor stacks? If the product will be stored in a racking system, how will the lift truck integrate with that racking system?
- How will the product be shipped? How will product leave your production area or racks, and be delivered for output from the facility?
- What is the travel distance? This is a big factor to determine whether to use a pedestrian-style truck or rider-style truck. Rider trucks can carry more pallets and can carry those pallets faster than pedestrian trucks.
- What are the route requirements? Are there bottle-necks through doorways that might limit the size or number of trucks able to move through?
- What is the size and layout of the facility? What about the condition – confined spaces, wet or slippery floors, etc.? How wide are your aisles? A narrow aisle is less than 10 ft and a very narrow aisle is categorized as less than 7 ft. Greater than 10 ft, is considered a counterbalance aisle.
- What are the racking heights involved? When you get to very high levels, you want to start looking at specialized trucks, and using those specialized trucks for the specialty applications – that’s going to give you the highest levels of performance, and functionality and productivity.
- What technologies can you use to improve productivity? Scanner, RFID and voice picking technologies are intended to speed up the picking process, and get more product through the warehouse faster. Lift trucks are a factor in that, but they are part of the system.
Once you have a clear understanding of the challenges or limitations facing you, it is time to move on to choosing the right trucks for your application. To help with your selection, this article covers those trucks predominantly used in indoor applications, ITA (Industrial Truck Association) for North America Classes I through III. They are discussed in increasing logistical complexity (ie the most simple trucks are discussed first, culminating in the most complex logistical arrangements).
Class III Trucks
The Electric Walkie
The most basic and least expensive Class III truck available is the electric walkie pallet truck. It typically features a single, electric motor that performs all the manual work normally required from the operator of a hand pallet truck. A mechanical or electric brake holds the truck in position until travel is requested.
Trucks feature short head lengths which allow for maximum maneuverability in restrictive spaces such as smaller warehouses or inside tractor trailers. Electric walkies commonly utilize a 24-volt system powered by a battery pack with on-board charger. Capacities range from 3,000 to 6,000 lbs and average travel speeds of approximately 3.5 miles/hr (based upon operator walking speeds). Applications with longer travel distances, heavier loads and / or ramp travel can benefit from a more appropriate solution than a hand pallet truck. However, if an operator’s roundtrip is 100 ft or more and/or you would like to stack pallets to increase your productivity, a rider-style truck would be a better choice.
End Rider Pallet Truck
The second most popular Class III product sold in North America is the end-rider pallet truck.
The bulk of the trucks on the market are 24 volt, with capacity ranges of 4,000 to 8,000 lbs. The primary advantage of the end-rider design is its ability to carry up to several pallets at once (based on fork length) over short or long distances and a relatively low acquisition cost. In addition, the operator rides on a platform attached to the end of the truck, allowing for faster travel speeds (6 to 9 mph) and greater productivity when loading trailers, shuttling loads or low level order picking.
Center-Controlled Ride-on Truck
Like the end-rider, the center-controlled electric pallet truck is primarily used in low-level order picking and product shuttling applications. Operation and features are similar between both styles. However, unlike the end-rider pallet truck which features an open operating platform attached to the end of the truck, the operator of a center-controlled truck is better protected within a centralized compartment positioned between the drive unit and forks of the truck.
In general, the center-controlled design is not as popular as the end-rider due to its longer wheel-base and shorter ground clearance which often prevents the truck from being used to load and unload trailers – a major disadvantage in high volume distribution applications.
The Tow Tractor
The 24-volt tow tractor is often built upon the same chassis as a center-rider, minus the forks. A tow hitch is mounted in place of fork tines, allowing the truck to be used as a tow vehicle. Dependent upon design, operators typically either stand up or sit within the operating compartment. Trucks are typically used to pull trailers or carts, and the total number of carts is limited by the weight of the combined loads. Tow capacities generally range from 10 to 15,000 pounds.
Tow tractors are primarily found in ’milk run’ applications. A common “milk run” has a truck delivering product or materials to multiple assembly or pick locations in bins, picking up empty bins for refill at a centralized location.
The Walkie Reach
and Straddle Stacker Trucks
The walkie reach truck is designed for stacking pallets in smaller operations with limited racking space, narrow aisles and short transport distances. A reach mechanism allows the truck’s fork carriage to extend out past the base legs to pick up a pallet. The fork carriage and pallet can then be retracted over or between the base legs of the truck, effectively decreasing its turning radius during travel. Trucks are usually 24 volts and feature capacities of 3,000 lbs.
The straddle stacker is the more popular of the stacker designs due to its lower cost and higher reliability. However, it does not have a reach mechanism, so the base legs have to straddle the pallet before the forks can enter the pallet, making it wider and limiting its use in some applications. As a pedestrian truck, it uses the less than 100 ft round trip rule of thumb. Straddle stackers have capacities of up to 4,000 lbs - best suited for smaller applications.
Also realize there isn’t a fork tilt function, so it is ill-suited for higher racking applications.
Counterbalance Stacker
The counterbalanced stacker is a pedestrian operated counterbalance truck with capacities up to 4,000 lbs. Since it is a counterbalanced truck, it does not need support or straddle legs – a real advantage in applications which require pallet loads to be lifted directly alongside machines or where load clearance is critical.
However, due to its design, counterbalanced stackers are longer and heavier than their reach and straddle stacker cousins, prohibiting their use in narrow aisles or on weak floors.
Class I Trucks
Stand-up End Control Counterbalanced and Sit-down Counterbalanced Trucks
The stand-up end control, counterbalanced rider is a bridge product between the typical counterbalanced world and the narrow aisle world. Available primarily in a 36 volt power unit and with 3,000-6,000 lbs capacity, the operator stands in the compartment and can quickly and easily get on and off.
Wheel sit-down counterbalanced trucks are suited for short shuttle applications such as those found on a dock. They are easily maneuvered even at higher speeds and can stack product in racking. There are a variety of sit-down counterbalanced trucks available with 24 volt, 36 volt or 48 capacity. Cushion tires are typically used in warehouse applications with sealed, hard, flat leveled floors, whereas pneumatic or pneumatic-shaped tires are for mixed operations (in and out of the warehouse, rougher floors, etc.).
They are the smallest, most maneuverable of the sit-down counterbalanced style trucks, and can operate in aisles as small as 10 ft. Capacities typically range from 2,500- 4,000 lbs.
The 36, 48 and 80 volt 4-wheel riders with cushion tires are the most common type of electric counterbalanced truck sold in the market place. This is a general purpose forklift truck commonly used for dock work and in manufacturing facilities. They have a wide capacity range of 3,000 to 12,000 lbs and they operate best in aisles 12 ft wide or greater.
Some manufacturers offer 4 wheel 80 volt trucks, which give greater performance. With pneumatic tires, these trucks can also be used outdoors.
Class II Trucks
Low Lift Pallet Rider
The low-lift pallet rider is a rider-style truck with an operator compartment. It has hydraulic or electric steering for superior maneuverability and it’s designed for use in narrow aisles. Expect 24 volts and 8,000 lbs capacity with multiple pallet transport capabilities. The pallet rider also allows the operator to either sit or stand. The downside is the electric steering and the operator’s compartment make it a more costly product than a typical end-rider.
Straddle Trucks
The rider reach-style straddle truck, or narrow aisle straddle truck, will accommodate the smallest aisle because it has the shortest head length.
A 24 volt model is the perfect truck for an application in which you would do about 100 cycles a day. A 36 volt truck will withstand heavier use - about 120 cycles total per shift and handle more than just one shift.
This narrow aisle stacker design, whether it is be a straddle stacker or a reach truck, can take a heavier load to a higher height than a counterbalanced truck can. The load is actually partially carried within the truck wheelbase, unlike a counterbalanced truck, and as a result, can carry more weight.
It can also go to higher heights – extending up to 8 levels. Counterbalanced trucks are typically limited to 4 or 5 levels.
The reach style can be the fastest method for storage and retrieval, as the operator is not taking time to extend the pantograph out and back. With a straddle style, the operator also has to take care the load is aligned properly.
Reach Trucks
Reach trucks have a significantly higher height capacity than do straddle trucks and constitute the most popular Class II truck in the marketplace. Reach trucks are best suited for full pallet picking. You can choose either a single-reach or deep-reach version, as well as a stand-up or sit-down truck.
Models range from 24 volt to 48 volts, can lift loads up to 8 levels, and are available in two different designs - pantograph or moving mast -- with the load carried either in-between or over the top of the base legs (The pantograph truck also offers different baseleg openings to accommodate different size pallets.)
Reach trucks, and very narrow aisle trucks will allow you to put more racking into an existing footprint and operate in aisles 10 ft or less in width. Very narrow aisle trucks require either wire or rail guidance and are designed specifically for order picking and can work in aisles as small as 4.5 ft.
Order Pickers
If the facility is a narrow aisle application, and requires picking above the first level, order pickers will normally work with Reach trucks. They range in voltage from 24 to 48, with capacities of 2,000 and 3,000 lb. They are only for piece picking, not for lifting or moving full pallets.
Turret Trucks
Turret trucks are very narrow aisle (VNA) trucks designed for full pallet picking. The man-up design takes the operator up to the pick location; they can either pick the full pallet or piece pick. The man-down truck is made for full pallet picking. It is essentially a counterbalanced truck with a turret. Turret trucks are most productive when they stay in the aisle. For example, the truck picks up a pallet or places a pallet at a drop-off station which feeds another type of material handling equipment.
Voltages available are 48, 72 and 80. Capacities range from 2,000 lbs to 4,000 lbs. As a VNA, it will be wire guided or rail guided.
Turret trucks are a commitment to a systems style material handling philosophy and can be costly up front. But the significant advantages are high productivity levels and extremely high storage densities.
Side Loaders
A side loader is designed for maneuvering very long loads in and out of a warehouse in very narrow aisles. Capacities are typically up to13,000 lbs., but there are bigger trucks available, and some that can go outside. Side loaders are very popular in steel mills, lumber applications, as well as tube and pipe operations.
How Many Trucks?
Once you understand the capabilities of different style trucks, you will need to determine the right number of trucks for your fleet.
Consider the travel distance both unloaded and loaded. Look at acceleration time and distance – how long does it take to get up to speed, and how long does it take to decelerate?
For lift height you can look at averages or do a survey and make calculations based on actual working data. You would monitor how many times the operator will have to lift to full height, how many times lifting to lower levels. If you use any kind of slotting add in that action.
What auxiliary functions are necessary? Reaching out to get a product, sideshifting and tilting all take time. Even if it’s a few seconds, it adds up to over 60 cycles/hr.
How long does it take to pick-up or drop-off the load? How long does it take the operator to complete paperwork, or scan product?
What’s the operator efficiency? Here, the rule of thumb is 75% to 80%, but remember later in the shift efficiency goes down.
Assess traffic congestion. Too many trucks going to the same place will cause a problem.
So, armed with this information, you can apply the truck performance, and determine the number of trucks you need to move pallets or products.
Then, analyze total cost of ownership. This is not always the lowest purchase price truck. Look beyond purchase price to maintenance, productivity and energy or fuel consumption.
Tap your experts in-house, go to material handling dealers or consultants and seek their guidance and counsel. They will offer different strategies and solutions to accomplish what you need. At the end of the process, as you observe your productive operation the upfront work will have been well worth the time.
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