Forklift is the main tool for material transportation, with a wide variety of specifications. Each type of forklift has its applicable environment. Wrong selection will lead to low efficiency and accidents in storage operation. This paper systematically introduces 8 types of forklifts commonly used at present, such as manual pallet truck, electric pallet truck, balance weight forklift and forward extension forklift, and analyzes the characteristics of each type and its applicable environment. At the same time, the test and calculation methods of forklift transportation capacity are exemplified to obtain the quantity requirements of various types of forklifts needed to maintain the normal operation of the warehouse. There are many factors affecting the choice of forklift, including floor, warehousing frequency and so on, which are also described in the article C
Key words: manual hydraulic pallet truck, electric pallet truck, electric stacker, counterweight forklift, forward forklift, overhead stacker, picking truck, working cycle time
With the development and progress of socialized production, the professional division of labor and machinery is becoming more and more detailed. The matching and connection of various professional equipment makes the operation of the whole logistics system orderly and the efficiency doubled.
In the traditional storage system, because there are no more choices, all transportation, stacking and loading and unloading may be completely solved by a balanced weight forklift, which is reflected in the warehouse, which shows the disadvantages of large area, low space utilization, large number of people, scattered stacking of goods, slow delivery, vehicle queuing in high peak periods and so on. Nowadays, a complete set of warehousing, shelving, picking, distribution and delivery processes can be handled by a variety of professional equipment such as balance weight forklift, various indoor transportation machinery or automatic unmanned transportation equipment, conveyor belt and automatic sorting equipment. Commands and connections between various equipment can be completed through electronic form or wireless transmission. A warehouse environment as bright, clean, fast, effective and orderly as the office can be realized at any time.
Since the invention and use of pallets and container transportation, forklifts (including indoor and outdoor forklifts) have been the main tools for material transportation. Forklifts that continue to realize functional innovation and higher and higher degree of automation will still occupy a dominant position in the transportation field for a long time in the future. In the following, we will discuss how to select appropriate trucks according to the environment and some influencing factors to be considered in the selection of forklifts.
First, let's take a look at the classification of cars.
According to the service environment of forklifts, they can generally be divided into indoor and outdoor forklifts. Outdoor forklifts are usually large tonnage diesel, gasoline or liquefied gas forklifts, such as container forklifts and cranes used in docks or container transfer stations. Indoor forklifts are basically battery cars. Now the world's major forklift manufacturers can provide hundreds of specifications of products. We usually divide these different specifications into several series. Take Germany's JUNGHEINRICH and Sweden's BT, which rank the top three in the world and the first and second in indoor equipment, for example, their main products can be roughly divided into eight series:
*Hand pallet trucks
● electric pallet trucks
It can also be divided into self-propelled type, standing driving type and sitting driving type
*Electric stacker (supportarm stacker) can be divided into self-propelled type, station driven type and seat driven type
, electric counterbalance truck
It can also be divided into three and four wheels, rear wheel drive and front wheel drive
*Diesel / LPG counterbalance truck
Forward extension forklift
● high rackstacker
It can also be divided into superior style and non superior style
*Order pickers
It can also be divided into plane picking and high-level picking
Each of the above series has its most suitable occasions and environments, and there are overlapping parts in some functions, such as balance weight forklift, front secondary truck and overhead stacker, which can access the shelf area. So what benefits does it have for users to choose which model?
Take a simple example: suppose such a warehouse, each pallet of goods stored in it is required to be accessible at any time, so it must be placed on both sides of the vehicle passage. On the premise of considering only the plane area, let's take a look at the plane utilization of different types of forklifts in this warehouse.
If the channel width of the vehicle used is roughly equal to the length of the carrier (1500mm), the plane utilization rate can reach 66%;
If the channel width of the forklift is equal to twice the length of the carrier (270{) nm~), the plane utilization string can reach 50%;
If the channel width of the used vehicle needs three times the length of the carrier (3500mm) ", the utilization rate of J ten sides can reach 50%;
Obviously, assuming that the plane area of goods to be stored in this warehouse is 1000m2, in the first case, 1000 / 0.66 = 1515m2 land is required. This situation is equivalent to the scheme of using elevated stacker or rail stacker.
In the second case, 1000 / 0.50 = 2000m2 of land is required. Extended forklift.
In the third case, 1000 / 0.40-2500m2 of land is required. The situation of counterweight forklift.
Therefore, the selection of appropriate vehicles can greatly save an income from land and construction investment.
Let's take a look at the characteristics of each series of forklifts and their applicable environment.
Both manual pallet truck and electric pallet truck are tools for plane point-to-point transportation. C the small and flexible size makes the manual pallet truck suitable for almost any occasion. However, due to manual operation, it is difficult to transport heavy items of about 2 tons. Therefore, it is usually used for short-distance and frequent operations of about 15 meters, especially in the loading and unloading area. In all links of logistics in the future, the manual pallet truck will also play a connecting role between various transportation links. Each truck or truck is equipped with a manual pallet truck, which will make the loading and unloading operation faster and more convenient, and will not be limited by the site.
When the transportation distance of dry noodles is about 30 meters, the walking electric pallet truck is undoubtedly the best choice. The driving speed is controlled by the stepless speed change switch on the handle to follow the walking speed of the operator, which not only reduces the fatigue of personnel, but also ensures the safety of operation. C for example, when the distance of the main transportation route is more than 30 meters to about 70 meters, the electric pallet truck with folding pedal can be used, and driver I stands and drives, The maximum speed can be increased by nearly 60%. Taking yonghengli forklift as an example, its per201 can reach no-load 10km / h.
The following figure shows the transportation distance corresponding to different forklifts:
The electric stacker is a light indoor lifting and stacking equipment. The body is relatively light. The force arm of the counterweight is extended through the support arm in the front of the body to balance the load. Since the fulcrum is outside the load center of gravity, the weight arm is much larger than the load arm, so a smaller weight can lift a larger load. Taking yonghengli electric stacker jcl4 as an example, with a rated load of 1.4 tons and a self weight of only 955 kg, the length, width and turning radius of the vehicle are correspondingly small. Yonghengli has its patented slow button device, which can also operate slowly in the upright braking position. These characteristics make it particularly suitable for floor warehouses or other storage environments with small space. This series has a load range of 11.6 tons and a maximum lifting height of 5350. The back-to-back heavy pallet shelf of 34 meters is the most commonly used environment and can give full play to its benefits. It is an economic choice for small warehouses.
There are certain restrictions on the use of electric stacker. Because the fork needs to extend into the bottom of the pallet at the same time with the support arm, the pallet can be operated, so the double panel cannot be used; Similarly, when using the drive in shelf (or corridor shelf), for the consideration of balance and load-bearing, the side on both sides of the pallet is usually used as the operation surface of the forklift, and the electric stacker cannot be used at this time. With the shelf design of electric stacker, the beam is often installed on the bottom layer about 100mm above the ground, and the goods on the first layer are placed on the bottom beam instead of the ground to facilitate the positioning of forklift.
In fact, we often call the counterweight forklift a forklift, which is also the most widely used and used series. Because there is no support arm, it needs a long wheelbase and a large counterweight to balance the load. Therefore, regardless of three wheels, four wheels, electric and diesel, the body size and weight are very large, which requires a large working space. At the same time, the fork takes the goods directly from the front of the front wheel, without any requirements for the container; The chassis is high, and the rubber tire or pneumatic tire is used to make it have strong climbing ability and ground adaptability. Therefore, dry weight forklifts are widely used for loading and unloading and outdoor transportation.
In the electric counterweight forklift, it can also be divided into three and four wheels, front wheel drive and rear wheel drive. Both steering and driving are rear wheels, which are called rear wheel drive. The advantage is that the cost is low and it is easier to locate than front wheel drive. The disadvantage is that when walking on a smooth floor and slope, the pressure of the driving wheel will be reduced when the load is increased, and the driving wheel may slip. Now most electric counterweight forklifts use dual motor front wheel drive. Compared with the four-wheel counterweight forklift, the three wheel counterweight forklift has small turning radius and is more flexible. It is most suitable for the unloading operation inside the container. Now, yonghengli company takes the lead in applying AC technology to electric balance weight forklift, which greatly improves the overall performance of forklift and greatly reduces the later maintenance cost. This technology is called the future technology of forklift.
There are also two types of diesel and liquefied gas forklifts according to different transmission modes, hydro mechanical transmission type and hydrostatic transmission type. Hydro mechanical transmission is a traditional transmission mode with low cost, but the transmission efficiency of the torque converter is low, the energy consumption is large, and the later maintenance cost is high. At present, hydrostatic transmission is the most ideal and advanced transmission mode of internal combustion forklift. Its main characteristics are soft start, stepless speed change, rapid reversing, simple maintenance and high reliability.
The efficiency of static pressure driven internal combustion forklift is significantly improved when it is used for frequent round-trip transportation in short distance outdoors.
Since Dr. JUNGHEINRICH of Germany invented reach truck in 1953, this series of equipment has gradually become the main tool for indoor elevated access. Its stable load improvement performance makes the three-dimensional warehouse break through the limit of 65 meters in height for the first time. Now, the maximum lifting height of the front extension forklift has reached 115m, and the load range is from 1t to 25t. It has developed multi-directional front extension forklift for accessing long and pipe fittings, indoor and outdoor general-purpose front extension forklift and other special-purpose products.
The forward extended forklift combines the advantages of the electric stacker with support arm and the counterweight forklift without support arm. When the gantry (mostly the gantry in European design and the fork in American design) reaches the top, the load center of gravity falls outside the fulcrum, which is equivalent to a thousand balance forklift; When the gantry is fully retracted, the load center of gravity falls on the inner side of the fulcrum, which is equivalent to an electric stacker. The combination of these two properties ensures that the volume and self weight will not increase much while ensuring the operation flexibility and high load performance, so as to save the working space to the greatest extent.
The most effective operation height of the forward forklift is 6m to 8m, which is equivalent to the height of the building about 10m. This height is also the most common building height of the store, distribution center, logistics center and enterprise central warehouse. Within this height range, the operator can reach the line of sight, locate quickly and have high efficiency. When the operating height is more than 8m, the front extension forklift shall be used, and the positioning shall be slow and careful. 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 requires a large storage capacity and high transportation efficiency, if you do not want to spend a huge investment in the automatic warehouse, then the overhead stacker is the only and best choice. Usually, the overhead stacker and high-level picking car are called VNA (verynar? Row aisle). Its main feature is that the fork can rotate in three directions or fork goods directly from both sides. There is no need to turn in the roadway, so the required roadway space is the smallest. The maximum lifting height of VNA series is more than 14 meters, the roadway width is usually about 1600nun, and the maximum load capacity is 15 tons. It is widely used in the pharmaceutical industry and electronic and electrical industry.
The overhead stacker can be divided into two types: accessible type and non accessible type. The cockpit, as the main lifting, rises with the gantry at the same time, which is called accessible type. The advantage is that it can maintain the horizontal operation line of sight at any height, ensure the best field of vision and improve the operation safety. At the same time, because the operator can touch the goods at any position of the shelf, it can be used for picking and counting at the same time.
In order to keep the overhead stacker running in a straight line in the channel, there are two ways: magnetic guidance and mechanical guidance. Because the magnetic conductor must be cut and buried in the center of the roadway, it is easy to damage the floor and difficult to move and adjust. Therefore, the mechanical guide is most used at present. The mechanical guidance needs to cooperate with the shelf, install steel rails on both sides of the roadway, and guide the roadway shaft along a straight line through the body guide wheel and other auxiliary devices.
VNA series forklifts, also known as system trucks, need to consider many aspects of cooperation and influencing factors. Therefore, each case is designed separately and will not be repeated here.
Picking car series are widely used in distribution centers or third-party logistics warehouses.
Applicable scope of each series of stacker truck:
Maximum lifting height of load range applicable height roadway width plane uses tandem three wheel balance weight forklift
l 252 t 6500 mm 3000 mm 3300 mm 40％
Indoor and outdoor transportation, container unloading, four-wheel counterweight forklift
L65 0t 70001ttrl2 3000mm 33500mm 30% outdoor handling electric stacker
1. 01.6t 5350tam 3000 4000 coffee 2300roan 50% floor warehouse, low warehouse, internal loading and unloading of containers, and double-sided plate front extension forklift cannot be used
1．02．5t 11510 6000 8000 mm 2800 mm 45％
Various indoor environments VNA 1251.5 t 14240 mm 1000014000 mm 1600 mm 60%
Elevated stacking, picking and distribution, warehouse with good floor condition
Each forklift has its corresponding carrying capacity, which is expressed in the number of pallets operated per hour or every day. For different use environments and different operators, this number is also different, so it is necessary to make targeted test. The following introduces a simple calculation method of forklift transportation Q9 force. T: Time required to complete a working cycle (test value) t = Ti + T2 + T3 + Th Ti: time required for a working cycle in the length direction T2: time required for a working cycle in the width direction T3: time required for a working cycle in the entry direction th: time required for a working cycle in the height direction 1. Assuming that point a to point B are a standard test distance, the test includes the following processes:
1. Drive the forklift to point a for positioning, lift the pallet and drive out of point a
2. Accelerate, drive to point B, brake
3. Drive to point B, position the tray, put down the tray and drive out of point B
4. Accelerate and return to the starting point
Take the L test result as the time required for a plane work cycle
2、 Take L / 2 of the total height of the shelf as a working cycle distance, lift the tray to this height and lower the well to the ground. The test time shall be counted from the time when the fork is inserted into the tray to the time before the fork exits the tray, that is, it does not include the fork taking time, but only the lifting time; Taking VNA overhead stacker as an example, because it only operates in the shelf area, the total cycle time includes T1, T2 and th. Take the following field as an example: the standard test distance of Ti is S2, S2 = 1 / 4 shelf area length
The standard test distance of T2 is S3, S3 = 1 / 2 of the width of the shelf area
The standard test distance of th is 1 / 2 of the shelf height
Therefore, t: Ti + T2 + Th
The hourly carrying capacity of the forklift: 3600 seconds / T
Assuming that it is a one shift operation, the operation time of one shift is 8 hours, and the forklift obtains the transportation volume that can be completed within one shift by using Zai g):
Cmax=8 x 3，600 x 60％／T=7，280／T cveles／shifr
The above calculation can get the quantity of forklifts of a certain type required by a warehouse, and determine whether to use standby batteries to maintain the normal operation of the warehouse.
The traditional warehouse design usually has buildings first, and then considers the layout planning and mechanical equipment, which often leads to investment praise. Through the analysis and expectation of production plan, select the appropriate logistics form and storage mode, and then carry out the design and planning of civil engineering, or carry out the two tongue simultaneously, so as to achieve the best investment income. Moreover, the selection of vehicles and the design of storage form are inseparable. The error of equipment selection often leads to low efficiency in actual operation or prone to accidents. In serious cases, it needs to be demolished and rebuilt. Therefore, in the initial design and equipment selection of the storage system, in addition to considering the height and roadway space applicable to each series of models as described above, other factors should be comprehensively considered in combination with their own conditions. There are many influencing factors, and the following are only examples:
Pallet: most forklifts take pallet as the operating unit, so the size and form of pallet often affect the choice of forklift form and specification. The roadway space required to operate pallets with different depths and widths is different. More importantly, if the center of gravity of the pallet and the goods carried exceeds the design load center of the factory forklift, the load capacity will be reduced. Therefore, it is generally recommended to adopt a pallet form of standard specifications. At present, the four-way fork pallet of European standard 800x1200 or 1000x1200 is widely used. It can be applied to various models.
Floor: the smoothness and flatness of the floor greatly affect the use of forklifts, especially when using high lift indoor forklifts. Assuming that the lifting height of the forklift is 10m, if there is a 10mm height difference between the left and right wheels of the forklift, it will cause an inclination of nearly 80mm at 10m, resulting in the danger of shelf use. There are usually three kinds of surface conditions of the floor. The most influential is the jagged undulating ground, which should be avoided as far as possible; If the ground is wavy and there is a certain height difference outside a certain distance, it is allowed; The best ground is a flat and smooth ground, usually a surface treated concrete floor. Factors to be considered for the floor also include bearing capacity, wheel pressure of forklift, etc.
Elevator and container height: if the forklift needs to enter and exit the elevator or operate inside the container, the population height of the elevator and container needs to be considered. There are several types of gantry available for forklift. Usually, the gantry with large free lift needs to be selected at this time.
Daily operation volume: the frequency of goods in and out of the warehouse and the daily operation volume of forklift are related to the selection of forklift battery capacity or forklift quantity, so as to ensure the normal operation of daily operation.
Other factors to be considered, such as peak period of warehouse operation, wheel material, construction restrictions, etc.
