Calculation of fuel consumption rates per hour, shift, month, etc.
O. Shevtsova
According to estimates, at Russian market counterbalanced forklifts ratio of equipment to engine internal combustion and electric drive is 68%:32%. The predominance of forklifts is explained by the fact that industrialization processes (industrial and construction development) in our country are still a great incentive for the market loading equipment than the development of warehouse logistics. That is, currently the main consumers of forklifts in Russia are enterprises and companies from various industries, and not logistics, although the latter is developing at a fairly rapid pace.
Features of the operation of equipment also play a certain role: work for a significant part of the year at low temperatures on open areas, far from perfect condition coatings, etc. A diesel engine requires lower costs for purchase, maintenance, and operation - it is a reliable, easy to maintain, powerful and efficient source of energy. In addition, such machines are produced in wide range lifting capacity (up to 43 t) and with a large assortment attachments to perform various technological operations, and the exhaust gas purification system ( particulate filters), used in latest models leading manufacturers, reduces harmful emissions by 70...98%, which allows you to work indoors.
One of the characteristics of the “cost of ownership” of a diesel forklift is fuel consumption. IN pivot table technical characteristics The manufacturer often indicates specific fuel consumption in grams per unit of power measurement (hp or kW). Meanwhile, this parameter does not give an idea of how much it will “eat” in practice. this engine, how much fuel will be consumed per hour, shift, per month, etc. For this, special techniques are used, one of which we will introduce readers to.
How to calculate fuel consumption rate
Let's say a loader has already been purchased and put on the balance sheet of the enterprise. Accounting asks employees service center official dealer calculation data for fuel write-off.
They, in turn, determine the fuel consumption rate using the formula
Q = N q / (1000 R k 1),
Where Q– specific fuel consumption (data from the power characteristic curve);
N– power, hp (data from the power characteristic curve);
R– density diesel fuel(0.85 kg/dm 3);
k 1– coefficient characterizing the percentage of operating time at maximum engine speed.
Engine power and specific fuel consumption are taken from the instructions for maintenance engine that it uses official dealer, performing service maintenance. The data is entered into it in the form of a specific fuel consumption curve, which is constructed by the manufacturer’s engineers based on the results of engine testing in various modes, including on maximum speed.
In practice, in order to achieve the maximum engine speed, we squeeze the accelerator pedal all the way, literally pushing it “to the floor.” In this mode, the machine accelerates, goes uphill with a load, or lifts a load to maximum height at maximum speed. It is clear that the loader does not work this way for the entire shift, but only for some part of it. Hence the need to apply the coefficient k1. In fact, the coefficient characterizing operation at maximum speed is an indicator of the specifics of the enterprise’s technological cycle.
Let's look at two examples.
Example 1. When the enterprise operates around the clock, product shipment actually takes place twice a day for 2 hours, i.e. only 4 hours out of 24. During these “rush hours” the entire fleet of forklifts is used, all access roads are occupied, maximum number trucks. The rest of the work shift, the loaders are operated with minimal or medium intensity.
Example 2. A rented loader works unloading wagons and loading trucks almost non-stop for an 8-hour shift, but it does not overcome the slope and does not use the maximum lifting height of the forks, since the serviced areas are located at a level of 1.5...2 m from the floor. The maximum engine speed is used in in this case, when the forklift accelerates to cover the distance between the loading and unloading zones, which is approximately a third of its working time.
As you can see, the coefficient characterizing the percentage of operating time with maximum and minimum load will be greater in the second case. For precise definition its value, it is necessary to measure the time when the loader lifts maximum load when he moves against resistance road surface(acceleration, driving on a slope, etc.). By summing up these time indicators, we obtain the operating time during which the engine experiences maximum load, and subtract it from the total duration of the work shift. Ratio of operating time with minimum load (70%) to operating time with maximum load(30%) - this is the required coefficient. So, if the time spent working with maximum load was 30% of the shift duration, the coefficient will be equal to 2.3(70%:30%)=2.3.
For example, for a 4D92E engine with a power of 33.8 hp. (Komatsu AX50 series loader) operating at maximum speed for 1/3 of the working time, the calculated indicators according to the formula will be 3.49 l/moto-hour:
Q = 33.8 × 202/(1000 × 0.85 × 2.3) = 3.49 l/motor-hour.
What's in practice?
A clear and visual indicator is the amount of fuel in liters consumed per hour of equipment operation by operating enterprises and organizations. It should also be noted here that theoretical calculations of fuel consumption for a forklift will always be slightly higher than in practice, since in real conditions the load on the engine is less than in test conditions. Therefore, to determine fuel consumption for write-off, it is necessary to carry out control measurements.
A kind of timing was performed for the Komatsu 3-ton diesel truck of the BX50 series (FD30T-16), operating from 12 to 21 o'clock, i.e. 9 hours daily. Technological operations: unloading trucks, moving goods into cars. Fuel consumption readings for the engine on the FD30T-16 Komatsu 4D94LE loader were 2.5 l/h.
For a number of other companies we received the following data on fuel consumption Komatsu loader:
- 1.7 l/h – loader with a lifting capacity (g/p) of 1.5...1.8 t (engine 4D92E), shift 24 hours;
- 2.5 l/h – loader with a capacity of 2...2.5 t (engine 4D94E), shift 24 hours;
- 2.2 l/h – loader with a capacity of 1.5 t (engine 4D92E), shift 8 hours;
- 2.9...2.95 l/h – loader with a capacity of 1.8 t (4D92E engine), shift 8 hours or more.
Thus, fuel consumption indicators are influenced by such parameters as engine power and specific fuel consumption, and the duration of working hours when it operates at maximum speed. Machines with high mileage or, on the contrary, new ones, but not yet run-in, show higher fuel consumption than those on which the engine is adjusted. Fuel consumption higher than usual is shown by cars during special testing when working with maximum load(for example, with the manufacturer’s declared average norm 3 l/h during the test, a 1.5-ton loader can show a flow rate of up to 5...6 l/h).
What equipment manufacturers are doing to reduce fuel consumption
By the way, low fuel consumption is not an end in itself; it is important in conjunction with high performance, the dynamics of the machine, i.e. when assessing how well and quickly the machine responds when performing work operations, how confidently it overcomes inclines, etc. What are manufacturers doing to increase the speed of technological operations while maintaining fuel consumption at the same level? For example, machines are equipped with a hydraulic system high pressure, and this allows you to increase the ascent speed. True, by increasing the speed of transmission of dynamic impact, it is necessary to ensure the tightness of the circuit (high-pressure hoses, hoses, etc.) through the use of high-quality materials. In order for forklifts of one of the economy class brands to be able to compete with more expensive cars, the manufacturer will have to use a higher quality transmitting device. Accordingly, this will lead to an increase in the price of the car, and it will lose its main competitive advantage - affordability.
Another engineering technique is to divide the hydraulic flow into steering and for lifting equipment. The latest series of Komatsu BX50 forklifts (2...3 t capacity) uses a super-lift hydraulic system: dual pumps ensure that the steering and lifting mechanism operate independently of each other. The result is a steady rise to Idling at maximum load, low fuel consumption.
New diesel forklift Still Gmbh RX70 is equipped with a hybrid drive and consumes 2.5 liters of fuel per hour (measurements were carried out on the basis of a 2.5 t model according to the new VDI 2198 criteria, i.e. after 60 operating cycles per hour). Hybrid drive technology involves installing a diesel or gas engine and an electric motor. This loader model uses a hydraulic pump that supplies oil to the hydraulic system as needed, rather than constantly, which also helps save fuel.
The creators of the Jungheinrich loaders of the DFG/TFG 316-320 g/p 1.6...2 t series, speaking about the advantages of the engine, emphasize that the used industrial engine large volume (2.5-liter diesel engine with a power of 28 kW) is already low revs develops maximum torque, which also allows for low fuel consumption. For the Perkins 404C.22 engine model DFG 16 As, the manufacturer indicates a fuel consumption of 3.1 l/h according to the VDI cycle.
Thanks to the use of a high-torque engine and a steering system with hydrostatic transmission The Linde H16D diesel forklift (VVV/ADG engine) provides a fuel consumption of 2.3 l/h according to the VDI cycle.
Among the design developments of almost all leading loader manufacturers there are models designed to work on hydrogen fuel. It is clear that high-tech models cost 20...30% more than basic ones. And yet, serious attention is paid to this area as a unique intellectual contribution to the development of the brand.
Diesel forklifts are the most popular type of warehouse equipment among Russian buyers. This is easy to explain. Engines running on diesel fuel start easily when sub-zero temperatures, differ in power and are suitable for equipment with a carrying capacity of over 4 thousand kg. Market leaders implement in their equipment innovative technologies cleaning from exhaust gases. This allows their diesel forklifts to be used indoors as well.
Another argument in favor diesel equipment- efficiency. It is significantly cheaper than loaders by gasoline engine and warehouse electrical equipment and has a low cost of ownership. Diesel forklifts owe a lot to the latter low consumption fuel. The manufacturer calculates this parameter and indicates it in the documentation supplied with the equipment as specific fuel consumption. Of course, these are average data, and they may differ from actual fuel consumption - after all, the operating conditions of the equipment are different. A special technique helps to calculate an objective indicator of fuel consumption for a certain period (work shift, month, quarter, etc.).
How is the normalized fuel consumption of a forklift calculated?
The company's accountants use the formula below to obtain the data necessary to write off fuel when the equipment is on the organization's balance sheet.
Q = Nq/ (1000Rk 1), where:
Q - standard fuel consumption (calculated in liters per engine hour).
N - engine power in hp. With.
q - specific fuel consumption (according to the manufacturer);
R is the density of diesel fuel (0.85 kg/dm3),
k 1 - the ratio of periods of motor operation in standard and maximum modes.
Coefficient k 1 is a specific indicator of the work process. In practice the motor forklift Only part of the work shift operates at maximum speed: when accelerating, moving at maximum speed, lifting loads to maximum height, moving up a slope with a load. Let's say the forklift operates in standard mode for 60 percent of the shift. 40 percent - with maximum load. In this case, the coefficient k 1 is calculated as the ratio of the first indicator to the second: 60/40 = 1.5. After this, it is no longer difficult to calculate the rate of fuel consumption.
Let's consider the calculation method using the example of the Chinese forklift BULLFD35. Its load capacity is 3500 kg. The loader is equipped Japanese engine ISUZUC240 with a power of 35.4 hp. With. The specific fuel consumption declared by the manufacturer is 202 g/kW per hour. 25 percent of the working time the engine operates at maximum speed. The actual fuel consumption is calculated as follows:
Q = 35.4*202 / (1000*0.85*1.5) = 5.6 l/hour.
However, the calculated data may not coincide with the actual data. For loaders without return or after long-term operation in practice, fuel consumption will be higher. Diesel fuel consumption also increases when warehouse equipment operates in emergency mode.
How manufacturers optimize diesel fuel consumption by forklifts
So, diesel fuel consumption is primarily affected by engine power, the specific indicator declared by the manufacturer, and the intensity of operation of the loader during the shift. Therefore, the buyer can approximately calculate this parameter already at the stage of purchasing equipment.
Of course, the choice is determined not only by the efficiency of the model, but also by its performance. The ultimate goal of purchasing a loader is to organize prompt and accurate loading and unloading operations with minimal financial costs. Loaders with an updated hydraulic system help solve this problem. Thus, high-pressure hydraulics increases the speed of movement of the forks with a load. Twin pump hydraulic system allows the lifting mechanism and steering of the loader to operate autonomously. Another advanced technology is a hydraulic pump with periodic supply of oil to the system.
The world's largest manufacturers of warehouse equipment update each generation of their products, improving their performance with the help of advanced engineering solutions. IN last years Chinese companies are actively gaining positions in the world market warehouse equipment. For example, Chinese diesel forklifts from BULL, manufactured in famous company Heli, in terms of fuel consumption and productivity, confidently compete with their Japanese, European and American counterparts. At the same time, their cost is significantly lower, which, of course, adds points to them in the eyes of Russian consumers.
Calculation of diesel forklift fuel consumption
When purchasing a diesel forklift, the buyer may be interested in the fuel consumption of the forklift. This is due to the fact that the loader must be put on the balance sheet, fuel must be written off according to standards, and the cost of work and goods must be calculated. Manufacturers in the technical characteristics of diesel forklifts indicate “specific fuel consumption,” which is measured in grams per unit of power (hp or kW).
N - engine power;
Q - specific fuel consumption;
Q - maximum theoretical fuel consumption in grams per 1 hour of engine operation at maximum power.
For example, if the technical specifications of a forklift included the following parameters:
Rated engine power, kW. (hp), not less: 59 (80)
Specific consumption fuel g/kw h (g/l.s.h) no more than: 265 (195)
Then in 1 hour of operation the loader would consume 265 * 59 = 15635 grams of fuel.
When calculating actual fuel consumption, two amendments need to be taken into account:
1. The forklift engine does not work all the time at maximum speed with maximum power,
2. Fuel is usually recorded in liters, not grams.
Therefore, to calculate real fuel consumption the loader should use the improved formula:
Q = Nq/(1000*R*k1),
Q - specific fuel consumption;
N - power, hp (kW);
R - density of diesel fuel (0.85 kg/dm3);
K1 - coefficient characterizing the percentage of operating time at maximum engine speed;
Q - fuel consumption in liters per hour.
Since in practice the forklift is not loaded to its maximum during the shift, the forklift engine does not operate at its maximum power all the time, but the power varies depending on the load. Hence the need arises to apply a coefficient that would take into account the ratio of the engine operating time at maximum speed to the engine operating time at minimum speed. If there is no reliable data on the operation of the loader, it is assumed that out of 100% of the working time, only 30% of the machine operates at maximum speed, therefore k1 will be equal to 70%:30% = 2.33.
An example of calculating fuel consumption in liters per hour for the D3900 engine.
Q=265 g/kWh;
R -0.85 kg/dm3;
Q = N*q/(1000*R*k1) = 59*265:(1000*0.85*2.33)=7.9 l/hour.
In reality, theoretical calculations of diesel fuel consumption will always be slightly higher than in practice, since in real conditions the loader works less and the load on the engine is correspondingly less than in test conditions.
According to our statistics, fuel consumption for the D3900 engine ranges from 4.5 l/hour to 7.5 l/hour, depending on the load.
As statistics show, the Russian forklift market is dominated by models with internal combustion engines, which are significantly larger than their counterparts that run on electricity. This technique is used in harsh conditions, requiring large resources. That is why one of the most important parameters The thing you need to pay attention to is the fuel consumption of the forklift.
The cost of goods and work performed is directly calculated based on the fuel and lubricants used. The problem is that fuel consumption is front loaders much more difficult to determine than for normal vehicle, because for this equipment the standard for a mileage of 100 km has not been determined.
Key Features
Fuel consumption, which in most cases is indicated by manufacturers, is as follows: number of grams / unit of power. That is why there is a rather strong discrepancy in the numbers, which creates even more confusion not only for the average person, but also for experienced drivers.
The fuel consumption indicated by the company that manufactures the equipment does not give any understanding of how much a particular engine will actually consume. It is not clear what the norm will be for an hour, a work shift or a whole month of operation. In this case, it is impossible to do without the use of certain theoretical knowledge and calculations.
How to calculate fuel consumption rate
The fuel consumption rate for forklifts is determined by the following formula:
Q = (N*q)/(1000*R*k), where
N is an indicator of the power of specific diesel engines, which is set to a certain model, for which the calculation is carried out.
q is the nominal fuel consumption, which is specified in the relevant documentation for the engine.
R is an indicator of the density of the diesel fuel used. This parameter is known initially, according to the approved standard (840 kg/m 3 - for winter and 860 kg/m 3 - for summer). For convenience, the general indicator is set to 0.85 kg/dm 3 .
k is a certain coefficient that reflects the time period in percentage when the front loader was operated in normal mode and the amount of time when it was used at maximum crankshaft speed.
Practical nuances
From the above information we see that almost all parameters when determining the fuel consumption of a forklift are known in advance, which cannot be said about the last coefficient (k).
To understand the situation, consider two examples:
- The equipment works at the railway station, loading and unloading railway cars. The shift is about 8 hours without a break. Workers are located on a platform that is located higher than the level of the special equipment, so the front loader forks do not rise to the height of the maximum boom reach. Limit rotation crankshaft engine operation occurs only when the operator presses the pedal all the way, covering the distance between two certain points.
- The warehouse is open 24 hours a day. During the entire working day, there are two arrivals of trucks, which are unloaded in a few hours using the available equipment. It is at these moments that peak engine loads occur, but the rest of the time the crankshaft speed decreases, because the units perform warehouse work inside the warehouse without excessive intensity.
If we compare these two situations, then in the first case, the coefficient will be higher. This parameter takes into account peak loads - acceleration, downhill movement and lifting, during which the greatest use of equipment resources occurs. The calculation of fuel consumption for a front loader is determined based on the duration of its operation at peak crankshaft speeds from the total operating time (shift).
Specific examples
In order to have a rough idea of all the nuances of the calculation, we will determine the fuel consumption for Chinese forklifts. All information is taken from the data provided by the manufacturer and technical parameters, so there is no reason not to trust her. As for the coefficient (k), we will take the default indicator 2.3, based on the fact that the equipment operates at maximum speed for about 30% of the total operating time.
First, let's determine the fuel consumption for the Chinese SDLG LG936 loader with an engine power of 125 hp. With. The parameter specified by the manufacturer is 220 g/kWh. According to the formula, the norm will be as follows:
(125 * 220)/(1000 * 0.85 * 2.3) = 14 liters.
Now let's determine the fuel consumption for the XCMG ZL50G loader. Its engine power is 215 hp. With. Fuel consumption - 240 g/kWh. We count:
(215 * 240)/(1000 * 0.85 * 2.3) = 26 liters.
From these data it becomes obvious that what more powerful engine, the higher the fuel consumption rate for the loader. Of course, real practice may differ significantly from the above theoretical calculations, because the specifics of the operation of Chinese loaders and other equipment may be different. The shift may last longer, the platform may be higher or lower, etc.
To others important nuance is the fact that a recently purchased unit that has not yet been properly run-in, as well as one that has a decent mileage - they are all characterized by increased consumption fuel. In this case, it is necessary to carry out computational activities over several days of operation.
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One of the most important questions that any owner of this equipment faces. Sometimes the manufacturer clearly indicates fuel consumption per unit of power measurement ( horsepower or kilowatts) in grams. You can find this information in the loader specifications table. However, for all its usefulness, it does not give a clear idea of how much fuel is required for operation.
How to determine the consumption rate for 1 engine hour?
It is calculated as follows:
Q = Nq/(1000Rk1) , where:
- N is the power of the power unit;
- q - indicator of specific fuel consumption of the loader;
- R - density of fuel (diesel). Usually taken at the level of 0.85 kg/dm3;
- k1 is the percentage ratio of the operating time at maximum crankshaft speed.
The power of the power unit, as well as the specific fuel consumption, can be found in the maintenance instructions. The data is included in it in the form of a graph. It is built by specialists from the manufacturing plant. The basis for this is the test results in different modes. In practice, achieving the maximum speed of the power unit is very simple - press the gas pedal all the way. As a result, the loader accelerates, overcomes the rise with the load, lifts it to its maximum permissible height and all this, mind you, at maximum speed. Of course, in this mode the loader will only work for part of the shift. Therefore, it is necessary to use a coefficient designated as k1: it characterizes operation at maximum speed. It can be called an individual indicator of the specifics of the loader’s operation.
Calculation example
Let's assume that a diesel forklift was rented to load trucks and unload wagons. It works for the entire shift (8 hours), without overcoming slopes and without using the maximum fork lift height, since the sites it serves are located at a height of only 1,500-2,000 mm. The maximum engine speed is only used when the unit is accelerating to cover the distance between the loading and unloading areas. This operation takes approximately 30% of working time.
But it may be so. The company operates 24 hours a day. But shipment of materials (products) during this time is carried out only 2 times for 2 hours. The remaining time the loader is operated with minimal or medium intensity.
Accordingly, the coefficient characterizing the ratio of operating time with load (maximum/minimum) is lower in the second case. Its value can be accurately determined by measuring the time during which the loader overcomes the resistance of the surface (road) and lifts loads maximum weight. Summing up the indicators, we obtain the operating time during which maximum loads are applied to the unit. And it is this time that needs to be subtracted from the duration of the (total) one shift.
The required coefficient is the ratio of operating time with minimum and maximum load (70% and 30%, respectively). Therefore, if the forklift was used with a maximum load of 30%, then the value of the coefficient is found by dividing 70% by 30% (that is, the value is 2.3).
For example, famous model AX50 loader from Komatsu is equipped with power unit 4D92E. Its power is 33.8 hp. With. In the event that 30% of the entire work shift is operated at maximum speed, then the fuel consumption for 1 engine hour will be: 33.8x202/(1000x0.85x2.3) = 3.49 liters.
On the practical aspects of fuel consumption rates
Of course, there are certain differences between theoretical calculations and practice. Fuel consumption is affected not only by the duration of operation at maximum speed, but also by the power of the power unit and specific fuel consumption.
Equipment that has not been run-in and loaders with an impressive mileage demonstrate more high consumption fuel than those whose engines have been adjusted. Excessive consumption can also be detected during special testing in the case of operation at maximum load. For example, a one and a half ton car can show consumption from 5 to 6 liters per hour, although average value this indicator is 3 liters per hour.
It should also be noted that in real conditions the power unit is subject to less load than during test trials. To determine fuel consumption for write-off, you need to carry out a series of control measurements.
As an example, let's take the timing of the BX50 forklift from Komatsu (power unit - FD30T-16, load capacity - 3,000 kilograms). Type of work operations - unloading trucks, as well as placing cargo in cars. The work is performed for 9 hours every day. Fuel consumption is 2.5 liters per hour of operation.
With the 4D92E power unit, with a shift duration of 24 hours, the fuel consumption of the equipment is:
- for loaders with a lifting capacity from 1,500 to 1,800 kilograms - 1.7 liters per hour;
- for loaders with a lifting capacity from 2,000 to 2,500 kilograms - 2.5 liters per hour.
During an eight-hour shift, the consumption of a loader with a lifting capacity 1,500 kilograms is 2.2 liters, and the carrying capacity 1,800 kilograms - up to 2.95 liters per hour.
