What is the rated torque of the dredger pump? Many customers asked for this question when talking with the technical engineers of our company. Because the torque of the sand dredger pump directly affects the explosive force of the equipment and the impulse under the limit state, and the torque can guarantee the sand pumping machine stable operation under the harsh working conditions. Tai’an Ocean Pump Co.,Ltd. specializes in the development and manufacture of dredger pump for more than 20 years. We have accumulated a lot of industry experience. This article elaborates the rated torque and supporting torque calculation of the sand dredger pump and the selection ideas and methods from a professional perspective. It can also be used for reference by peers and industry customers.

Significance and Effect of the Torque of Dredger Pump Set
Significance and Effect of the Torque of Sand Pump Set

I. The Meaning of Torque in Dredger Pump and Supporting Power

Torque is the special moment that causes the object to rotate. The engine torque of the sand dredger pump refers to the torque output from the crankshaft of the power equipment. In the case of fixed power, it is inversely proportional to the speed of the power equipment. The faster the speed, the smaller the torque, and vice versa, which reflects the load capacity of the power equipment within certain range. External torque is called torsional moment or external moment of a couple, and internal torque is called internal torque or torque.

Torque is a special moment in physics. It is equal to the product of force and force arm. The international unit is Nm,  you can also see the torque unit of kg·m and lb-ft, because G = mg, when g = 9.8, the gravity of 1kg is 9.8N, so 1kg·m = 9.8N·m, and The lb-ft is a 1-inch torque unit, 1 lb = 45536 kg; 1 ft = 0.3048 m, 1 lb-ft = 0.113826 kg·m. In people’s daily expression, torque is often referred to as torsion .

Take a simple example, when a person’s body is in motion, power is like the durability of the body, the speed is the frequency of motion, and the torque is the body’s explosive power. People use a shovel to dig sand, the shovel is torque, the dig frequency of the man is speed, and the physical strength of the person is power. In the case of certain physical strength (power), using a large shovel (high torque) to excavate, the frequency is definitely low (low Speed), the frequency of the small shovel (low torque) is definitely high (high speed). The final decision is how much sand can be dug, or whether it depends on the physical strength (power) of the person.

In the sand pumping processes, when the matched power is fixed, the large particle gravel sand dredger pump and the marine sand suction pump belong to the low speed sand pumps, so the torque is larger, and the small sand pump and the submersible sand pump belong to the high speed sand dredging pumps, so the torque is smaller. But no matter what kind of sand pump, the larger torque , the effect will be much better.

Significance and Effect of the Torque of Sand Dredging Pump Set
Significance and Effect of the Torque of Sand pumping Machine Set

  II. Torque Calculation formula for supporting power of dredger pump

The torque calculation formula of the dredger pump power is T=9550*P/N.

T is the torque, 9550 is the conduction coefficient, P is the rated power of the dredger pump, and N is the rated speed of the power equipment. The formula can show that the torque and power are proportional, and inversely proportional to the speed.

Taking the marine diesel engine of Weichai 6170ZC600-4 as an example, the rated power of the sand dredger pump is 450KW, the speed is 1500rpm (see Figure 1 for the parameters), and the formula T=9550*450/1500=2865N*m is in accordance with the curve (See Figure 2).

The same calculation formula is used to calculate the motor torque. Take the YX3-90S-6 motor as an example. The rated power of the  power equipment is 0.75kw, the rated speed is 910rpm, and the applied formula is T=9550*0.75/910=7.87N*m. Consistent with the parameter list (see Figure 3). The motor with the same power, the torque with high rotation speed is small. Take the YX3-801-2 type motor as an example, the rated power of the device is also 0.75kw, but the rated rotation speed is 2840rpm, and the formula is T=9550*0.75/2840=2.52. N*m, consistent with the parameter list (see Figure 4), is also 0.75kw, the torque at 910rpm is much greater than at 2840rpm.

Performance Curve for Sand Extracting Pump
Performance Curve for Sand Sucking Pump
Performance Curve for Slurry Suction Pump
Performance Curve for River Sand Pump

III. Torque Application in Dredger Pump Design

The torque of the dredger pump will directly affect the maximum pumping capacity of the sand pump machine and the overload capacity under extreme conditions. A well-designed torque can ensure stable operation and long service life of the sand dredger pump unit under harsh working conditions. When designing the sand pump for sand extraction, the engineer will consider the actual utility of the torque during operation, and thus design large torque river sand dredger pump. According to different working conditions, to achieve the same flow head conditions, sand dredger pump design engineers increase the pump impeller outer diameter and width and reduce the rotation speed, this is not only increases the torque effect, but also can reduce the wear and tear for the over flow parts, low rotational speed and high torque can achieve sustained and efficient sand extraction for a long time. At the same time, in order to match the large torque impeller, the design of dredger pump shaft and bearing are also corresponding to increase the strength to ensure stable operation under high torque conditions.

  1. The application of torque in the assembly

In general, there are certain requirements for screws on mechanical components. Such as tightening torque and slack torque.

The torque for tightening the teeth is called the breaking torque, so the tightening torque can not exceed the breaking torque. In general, the tightening torque is 70%-80% of the slack torque, which ensures the fastening strength of the screw and does not cause the screw to slip. Slack torque is the key to ensuring the life of the screw after tightening. Depending on the material of the screw, the size of the screw is not the same and is generally less than the tightening torque.

Screws and other devices also have rated torque requirements assembly of slurry suction pumps, diesel engines or ships. According to the standardized operation, uneven pressure or loose screws can be avoided.

  1. The application of torque in dredger pump and related power equipment

The diesel engine is characterized by large torque, strong explosive force, and more powerful under extreme conditions. Generally, it is a low-speed machine, and small wear, and long service life. Low and medium speed engines such as Brand WEICHAI, Zichai, and Yuchai are commonly used. When matching the gear box, adding a gearbox is equivalent to reducing the output speed of the engine and increasing the engine output torque. Gear power loss is extremely small and can be ignored.

The role of torque in the motor is as the same as the diesel engine. If a pulley belt is required , it is recommended to use a low-speed machine, ie 10 poles > 8 poles > 6 poles > 4 poles > 2 poles.

The greater the torque in the dredger pump, the more powerful, the better the power, the large particles or high concentration conditions can be opened instantly, the greater the supporting power torque under the same power, the better.

Significance and Effect of the Torque of Sand Suction Pump Set
Significance and Effect of the Torque of Sand Mining Pump Set

IV. How to Match the Diesel Engine and Gear Box to Ensure the Maximum Torque of the Dredger Pump Unit

  1. Aalculate the shaft power of the dredger pump by calculation, and determine the coefficient according to the specific gravity of the medium and the applicable working conditions. In the past, the shaft power was multiplied by a factor of 1.2-1.3, and the diesel engine was multiplied by a factor of 1.2-1.3.
  2. According to the speedof the dredger pump, the diesel engine is matched. The domestic brand engine, we take 80% of the engine rotation speed as the economy speed, and the imported brand engine takes the rated speed, if the dredger pump does not match the matching gear box or pulley.
  3. The power speed of dredger pump is determined well. Basically, the rated torque of the diesel engine or motor is greaterthan the torque of dredger pump. If using pulley belt, the torque loss is large and the horsepower needs to be increased.
  4. Pay attention to rotation direction of the dredger pumpand diesel engine . the general selection of gearboxes are hydraulic control forward retrogression, so the forward or reversal gear has no loss for the diesel engine power, and has no impact on the life of the gearbox.
Diesel Engine for Marine Sand Suction Pump
Hydraulic Gear Box for Marine Sadn Pump

Tai’an Ocean Pump Co., Ltd. pays more attention to the entire production process of the dredger pump. When matching the dredger pump impellers and dredger pump bearings , high torque dredger pump under different working conditions are designed to achieve continuous and stable transportation of long-distance delivery sand and mud with high concentration and large flow rate; the bolts are installed in strict accordance with the fixed torque to ensure uniform stress. In the process of continuous work, it is firmly assembled and not slipped off. In the process of supporting power, high cost-effective power equipment of international and domestic first-line brands are selected to ensure the maximum torque of the diesel engine or motor; the deep cooperation with auxiliary equipment manufacturers such as gear box factory, etc. Low rotation speed ratio gearbox suitable for sand dredger pump construction to ensure that the power and torque curves of the diesel engine and sand mining pump that are matched.

V. The Torque Design Application of Fredger Pump

One domestic customer from jiangxi province choose the 450GN-40 marine sand dredger pump for sand pumping in the offshore. our technical engineers conducted field surveys. Considering that the local sand is relatively loose, high concentration pumping sand, and the pipe plugging is extremely prone to occur. Therefore, when designing the project, match high torque diesel engine and gear box. 450GN-40 type marine sand dredger pump with flow capacity 3100m3/h, head 40m, rotation speed 550rpm, calculated shaft power 441.6kw, through the torque calculation can get the rated torque T=9550*441.6/550=7667.8N*m, engineers choose Jichai 12V190 type 1200 horsepower/1350rpm engine, and Hangzhou gear box 1260 type with reduction ratio 2:1, through the torque calculation T=9550*900/675=12733.3N*m, the bearing torque is far greater than the sand pump, in the actual pumping sand project, there was a high concentration situation. The amount of sand reached 1,000 cubic meters per hour, and the dredger pump torque was as high as 11,000 N*m. Since the diesel engine had a large torque margin, the dredger pump was very easy to run and the user was very satisfied.

Ocean Pump (Tai’an Ocean Pump Co., Ltd) is the New Hi-tech Enterprise certificated by the Government and the leading sand pump and sand dredger manufacturers, suppliers and exporters since 1996. We have more than 30 talented technical experts and 15,000 square meters factory. More than 4 series 20 kinds of sand pumps, slurry pumps, sand dredgers and related parts had been manufactured to satisfy your pumping requirements. Product innovation, quality assurance and customer satisfaction are our continuous commitment to all our partners.Certifications had our witnessed continuous efforts and achieved results, they are our long term promises to all our customers and ourselves. The goal of Ocean Pump is to delivery finest quality sand pump, slurry pump, gravel pump and sand dredgers to worldwide customers. In recent years, we had been continuously investing in technological innovation and manufacturing facilities to ensure the leading technology and high quality products. Our 30 talented garment design experts and their experiences are our real wealth and competence that can make our honors and certificates much valuable.

Tai’an Ocean Pump specializes in R&D, production and sales of simple sand pump, sand pump, dredging pump, mud pump, slurry pump, etc., and has extensive experience in dredging, sand mining and embankment construction. Currently occupying most of the market, it is the customer’s first choice. We focus on the dredger pump for 20 years, not only providing high-quality products and overall solutions for the industry, but also providing on-site installation services. Please contact us at any time for program design and equipment issues related to dredging and pumping.