Features And Applications of 8 Types Forklifts
Forklift trucks are the main tools for material transportation, and there are many types of specifications. Each type of forklift truck has its own applicable environmental occasions, and wrong selection will cause inefficiency and accidents in storage operations.
This paper systematically introduces 8 types of forklifts, such as manual pallet truck, electric pallet truck, counterbalanced forklift and front extension forklift, which are commonly used nowadays, and analyzes the characteristics of each type and its applicable environmental situations as a result. At the same time, the testing and calculation methods of forklift capacity are also illustrated to obtain the quantity requirements of each type of forklift needed to maintain the normal work of the warehouse. There are many factors affecting the selection of forklifts, including flooring, frequency of access, etc., which are also discussed in the article.
With the development and progress of socialized production, the professional division of labor and machinery is also becoming more and more detailed, and the matching and articulation of various professional equipment makes the whole logistics system operate in an orderly manner and the efficiency is improved exponentially.
In the traditional storage system, because there is no more choice, all the transportation, stacking, loading and unloading may completely rely on a forklift to solve, performance in the warehouse, that is, showing the area, low space utilization, more people, scattered piles of goods, slow shipping, peak vehicle queues and other shortcomings. Nowadays, a whole set of inbound, shelving, picking, distribution to outbound process can be respectively by counterbalanced forklift, various indoor transport machinery or automated unmanned transport equipment and conveyor belt, automatic sorting equipment and many other kinds of professional equipment segmentation processing, various equipment and can be through the electronic form or wireless transmission to complete the instructions and interface. A bright, clean, fast and efficient, neat and orderly warehouse environment as the office can be achieved at any time.
Since the invention and use of pallets, forklift trucks (including indoor and outdoor forklifts) have been the main tools for material handling, and for a long period of time in the future, forklift trucks, with their continuous functional innovation and increasing automation, will continue to occupy a dominant position in the field of handling. In the following, we will discuss how to choose the appropriate forklift according to the environment and some influencing factors to be considered in the selection of forklift.
FIRST, LET’S LOOK AT THE CLASSIFICATION OF FORKLIFTS
According to the usage environment of forklifts, they can be usually divided into two categories: indoor and outdoor forklifts. Outdoor forklifts are usually large-tonnage diesel, gasoline or liquefied gas forklifts, such as container forklifts and cranes used in terminals or container transfer stations. Indoor forklifts are basically electric forklifts. Nowadays, the main forklift manufacturers in the world can provide hundreds of specifications, and we usually divide these different specifications into several series. Take the German Jungheinrich (JUNGHEINRICH), which is currently ranked in the top four in the world in terms of total sales volume and number one in terms of indoor equipment, as an example, its main products can be roughly divided into eight series.
* Hand Pallet Trucks
* Power Pallet Trucks
* Electric Pallet Stacker (Support Arm Stacker) can be divided into self-propelled, stand-and-drive and sit-and-drive types.
* Electric Counterbalance Truck
* Diesel/LPG Counterbalance Truck
* Forward Reach Forklift
* High Rack Stacker
* Order pickers
HOW TO CHOOSE?
Each of the above series has its most applicable occasion and environment, and there are overlapping parts in some functions, such as counterbalanced forklift, front reach forklift and high rack Stacker all can carry out access to the racking area, so what kind of benefits does choosing which model actually have for the user?
THE FLAT AREA
Let’s take a simple example: suppose such a warehouse, where each pallet of goods stored requires ready access and therefore must be placed on both sides of the forklift aisle, let’s see the flat utilization rate of this warehouse using different types of forklifts, considering only the flat area.
* If the aisle width of the forklift truck used is approximately equal to the length of the carrier (1500 mm), a flat utilization rate of 66% can be achieved.
* If the aisle width of the forklift truck used is equal to twice the length of the carrier (2700mm), the floor space utilization can reach 50%.
* if the aisle width of the forklift truck used requires three times the length of the carrier (3500 mm), a flat utilization rate of 40% can be achieved.
Obviously, assuming that this warehouse needs to store goods with a flat area of 1000m2, then in the first case, 1000/0.66 = 1515m2 of land is needed. This case corresponds to a solution using overhead stacker cranes or railed stacker cranes.
In the second case, 1000/0.50 = 2000m2 of land is required. It is equivalent to the case of using a front-extension forklift.
In the third case, 1000/0.40 = 2500 m2 of land is required. It is equivalent to the case of using counterbalanced forklifts.
Therefore, choosing the right forklift can greatly save the investment in land and building, which is one of the most intuitive benefits.
CHARACTERISTICS AND APPLICABLE ENVIRONMENT OF EACH SERIES OF FORKLIFTS
Let’s take a look at the characteristics of each series of forklifts and their applicable environments
Both manual pallet trucks and electric pallet trucks are used for point-to-point transport of flat surfaces. The small and flexible size makes the manual pallet truck suitable for almost any occasion. However, because they are manually operated, they are more strenuous when moving heavy items of about 2 tons, so they are usually used for frequent operations at short distances of about 15 meters, especially in loading and unloading areas. In the future logistics links, manual pallet truck will also assume the role of linkage between various transport links, in each truck or truck equipped with a manual pallet truck, will make loading and unloading operations faster and more convenient, and not limited by the site.
When the flat transport distance is about 30 meters, the walking type electric pallet truck is undoubtedly the best choice, the driving speed is controlled by the infinitely variable speed switch on the handle, following the speed of the operator walking, which reduces the fatigue of the personnel while ensuring the safety of the operation. If the distance of the main transport route is more than 30 meters to about 70 meters, the electric pallet truck with folding pedal can be used and the driver can stand up and drive, the maximum speed can be increased by nearly 60%, taking Jungheinrich forklift as an example, its new ERE20 can reach 10 km/h unloaded.
The electric stacker is a kind of light weight lifting and stacking equipment for indoor use, with a relatively light body, and the force arm of the counterweight is lengthened by the support arm at the front of the body to balance the load. Since the pivot point is on the outside of the load’s center of gravity, the counterweight force arm is much larger than the load force arm, so a smaller counterweight can lift a larger load. Jungheinrich electric stacker crane EJC 14 for example, rated load 1.4 tons, while the weight is only 955 kg, the length, width, turning radius is also correspondingly small, Jungheinrich has its patented slow speed button device, so that in the upright brake position can also be operated at slow speed, these characteristics make it in the floor type warehouse or other small space storage environment is particularly suitable. The series load range is 1 to 1.6 tons, the maximum lifting height is 5350, 3 to 4 meters of back-to-back heavy-duty pallet racking for its most common and most effective environment, is the economic choice for small warehouses.
The use of electric stacker also has certain restrictions, because the fork needs to reach into the bottom of the pallet at the same time with the support arm to operate the pallet, so the double panel can not be used; also in the use of drive-in racking (or called the corridor racking), for balance and load-bearing considerations, usually the side of the pallet double-sided as a forklift operating surface, when the electric stacker can not be used. The design of the racks with electric stacker cranes is often to install beams at the bottom level about 100mm above the ground, with the first level of goods resting on the bottom beam instead of on the ground to facilitate forklift positioning.
In fact, we often refer to counterbalanced forklifts as forklifts, and this is one of the most widely used and used series. Since there is no support arm, it needs longer wheelbase and larger counterweight to balance the load, so regardless of three-wheeled, four-wheeled, electric or diesel, the body size and weight are large and need larger working space. At the same time, the forks fork the goods directly from the front of the front wheels without any requirement for the container; the chassis is higher and rubber tires or inflatable tires are used, so that it has strong climbing ability and ground adaptability. Therefore, counterbalanced forklifts are commonly used for loading and unloading as well as outdoor transportation.
In the electric counterbalanced forklift truck, it can also be divided into three wheels and four wheels, front wheel drive and rear wheel drive. The advantage is that the cost is lower and it is easier to position compared with the front wheel drive. The disadvantage is that when walking on smooth floor and slope, the pressure of the drive wheel will be reduced when the load is lifted and the drive wheel may slip, nowadays most of the electric counterbalanced forklifts adopt dual motor front wheel drive. Compared with four-wheel counterbalanced forklifts, three-wheel counterbalanced forklifts have small turning radius and are more flexible, which are most suitable for container internal hollowing operation. Now, Jungheinrich has used AC technology for electric counterbalanced forklifts, which makes the overall performance of the forklifts greatly improved while the post maintenance cost is greatly reduced. This technology is called the future technology of forklifts.
There are also two types of diesel and LPG forklift trucks according to different transmission methods, hydro-mechanical transmission type and hydrostatic transmission type. The hydro-mechanical transmission is a more traditional transmission method with lower cost, but the torque converter has low transmission efficiency, high energy consumption and high post-maintenance cost. The hydrostatic transmission is the most ideal and advanced transmission method of internal combustion forklift, with the main features of soft start, infinitely variable speed, rapid direction change, simple maintenance and high reliability. The efficiency of the internal combustion forklift truck with hydrostatic transmission is obviously improved when it is used to transport to and from the outdoor short distance frequently.
Since 1953, when Dr. Jungheinrich invented the front reach truck, this series of equipment has gradually become the main tool for indoor elevated access, and its stable load lifting performance has made the three-dimensional warehouse break through the 6.5m limit in height for the first time. Nowadays, the maximum lifting height of reach trucks has reached 11.5 meters and the load range is from 1 ton to 2.5 tons, and special purpose products such as multi reach trucks for accessing long and tubular pipes and universal reach trucks for indoor and outdoor use have been developed.
The reach truck combines the advantages of electric stacker crane with supporting arm and counterbalanced forklift without supporting arm. When the door frame (mostly door frame reach forward in European design and fork reach forward in American design) reaches the top, the load center of gravity falls on the outside of the pivot point, which is equivalent to counterbalanced forklift; when the door frame is fully retracted, the load center of gravity falls on the inside of the pivot point, which is equivalent to electric stacker crane. The combination of these two performances makes it possible to ensure operational flexibility and high load performance without increasing the volume and dead weight to a great extent, thus maximizing the saving of operating space.
The most effective operating height of the front reach forklift is 6m to 8m, which is equivalent to the building height of about 10m, and this height is also the most common building height of the stores, distribution centers, logistics centers and enterprise center warehouses. In this height range, the operator’s line of sight can be reached, positioning fast and high efficiency. When the operation height is greater than 8 meters, the use of front reach forklift needs to be slow and careful when forking and positioning, and usually auxiliary devices such as height indicator, height selector or camera can be added.
If the warehouse area is small and the height is high, and a large storage capacity and high efficiency are needed, the overhead stacker is the only and the best choice if you do not want to spend a huge investment on an automatic warehouse. The main feature of the VNA series is that the forks can be rotated in three directions or fork the goods directly from both sides, without turning in the aisle, so the required aisle space is minimal. It is commonly used in the pharmaceutical industry and the electronic and electrical industry.
The cockpit as the main lift rises at the same time with the gantry and is called the manned type, which has the advantage that the horizontal line of sight can be maintained at any height to ensure the best view and improve operational safety. It can also be used for both picking and inventory operations, as the operator can reach the goods at any position on the shelf.
In order to keep the overhead stacker in a straight line at all times in the aisle, there are two types of guidance: magnetic and mechanical. Magnetic guidance is the most used at present because it is necessary to cut and bury the magnetic wire in the center of the aisle, which can easily damage the floor and is not easy to relocate and adjust. The mechanical guidance needs to cooperate with the rack, install rails on both sides of the aisle, introduce the aisle through the body guide wheel and other auxiliary devices and drive along the straight line.
VNA series forklift trucks are also called system trucks, and there are more cooperation and influencing factors to be considered in all aspects, so each case needs to be designed separately, so we will not repeat them here.
Material picker series are widely used in distribution centers or third party logistics warehouses.
Each type of forklift has its own capacity, expressed as the number of pallets operated per hour or per day. This quantity varies for different environments and different operators, and therefore requires specific testing.
THE FOLLOWING IS A SIMPLE METHOD OF CALCULATING FORKLIFT CAPACITY
T: Time required to complete a work cycle (test value)
T = T1+T2+T3+Th
T1: Time required for one work cycle in the length direction
T2: time required for one work cycle in the width direction
T3: time required for one work cycle in the entry direction
Th: height direction a work cycle time required
I. Assuming that point A to point B is a standard test distance, the test of one working cycle time includes the following process.
1、Forklift truck drive to point A and position, lift the pallet, drive out of point A
2、Accelerate, drive to point B, brake
3、Driving into point B, positioning the pallet, putting down the pallet, driving out of point B
4、Accelerate, return to the starting point
The above test result is the time required for a flat working cycle
Second, 1/2 of the total height of the rack as a working cycle distance, lift the pallet to this height and lower to the ground, this test time should be from the fork inserted into the pallet until the fork exit the pallet, that is, not including fork picking time, only counting the lifting time.
In the case of the VNA overhead stacker, for example, the total cycle time includes T1, T2 and Th, since it operates only in the racking area.
The standard test distance for T1 is S2, S2=1/4 the length of the shelf area
The standard test distance for T2 is S3, S3=1/2 shelf area width
Th’s standard test distance 1/2 shelf height
The forklift’s hourly transport capacity = 3600 seconds/T
Assuming that the operation is on one shift, the operation time of one shift is 8 hours, and the utilization rate of forklift is 60%, then we can get the transport volume that can be completed in one working time.
The above calculation can be used to obtain the number of forklifts of a certain type required for a warehouse, or to decide whether to use a backup battery to maintain the normal operation of the warehouse.
The traditional warehouse design is usually to have a building first and then consider the layout and mechanical equipment in it, which often results in wasted investment. Through the analysis of the production plan and expectations, choose the appropriate form of logistics storage, and then the design and planning of civil engineering, or both simultaneously, in order to achieve the best return on investment. The choice of forklift and the design of storage form are inseparable. The mistake of equipment selection often causes inefficiency or accident easily in actual operation, and serious cases need to be demolished and rebuilt. Therefore, in the initial design of storage system and equipment selection, in addition to considering the applicable height and aisle space of each series of models as mentioned above, we must also combine our own conditions and make comprehensive consideration of other factors.
There are many influencing factors, the following are just some examples
Pallets: Most of the forklifts are operated by pallets, so the size and form of pallets often affect the choice of forklift forms and specifications. Different pallets with different depths and widths require different aisle space to operate, and more importantly, if the center of gravity of the pallet and its cargo exceeds the designed load center of the forklift, the load capacity will be reduced. Therefore, it is usually recommended to adopt a pallet form with standard specifications. At present, the more commonly used pallet is the European standard 800×1200 or 1000×1200 four-way fork pallet. It can be applied to various models.
Flooring: The smoothness and flatness of the flooring greatly affect the use of forklift, especially when using high lift indoor forklift. Suppose the lifting height of forklift is 10m, if there is 10mm height difference between the left and right wheels of forklift, it will cause nearly 80mm tilt at 10m, which will cause the danger of racking use. The surface condition of the flooring usually has three conditions, the most influential is the jagged undulating ground, which should be avoided as much as possible; if the ground is undulating, a certain height difference outside a certain distance is permissible; the best ground is a flat and smooth ground, usually a concrete floor with surface treatment. Factors to be considered for flooring also include load-bearing capacity, forklift wheel pressure, etc.
Elevator, container height, etc.: If the forklift needs to enter and exit the elevator or to work inside the container, the entrance height of the elevator and container needs to be considered. There are several types of gantries for forklifts to choose from, and usually at this time you need to choose the gantries with large free lift.
Daily operation volume: the frequency of incoming and outgoing goods in the warehouse and the daily operation volume of forklifts are related to the choice of forklift battery capacity or forklift quantity to ensure the normal daily operation.
Other things to be considered such as warehouse operation spikes, wheel material, building restrictions, etc.