German Knoll pump Knoll model Knoll price

Knoll pumps are an important component in hydraulic systems. They rely on the reciprocating motion of plungers within the cylinder block to change the volume of the sealed working chamber, thereby achieving oil suction and discharge. Plunger pumps offer advantages such as high rated pressure, compact structure, high efficiency, and convenient flow regulation. Plunger pumps are widely used in applications requiring high pressure, large flow rates, and flow adjustment, such as hydraulic presses, construction machinery, and ships.

Knoll pump usage instructions

For plunger pump cylinder blocks fitted with copper bushings, installation can be performed by replacing the copper bushings. First, trim the outer diameters of a set of plunger rods to a uniform size, then polish the outer diameter using sandpaper of 1000# grit or higher. Three methods for installing copper bushings in the cylinder block: a) Heating the cylinder block for hot assembly or cryogenic compression of the copper bushing for interference fit; b) Adhesive assembly using Loctite adhesive; this method requires grooves on the outer surface of the copper sleeve; c) Tapping the cylinder bore and machining threads on the outer diameter of the copper bushing, then applying Loctite adhesive and screwing it in for assembly. Installation methods for cylinder blocks and copper bushings joined by sintering are as follows: a) Use a honing rod to manually or mechanically hone and repair the cylinder bore; b) Use a coordinate boring machine to re-bore the cylinder block holes; c) Use a reamer to repair the cylinder block holes. Methods using "surface engineering technology" are as follows: a) Electroplating technology: Plate a layer of hard chrome on the plunger surface; b) Brush plating technology: Brush plate wear-resistant materials on the plunger surface; c) Thermal spraying, arc spraying, or electric spraying: Spray high-carbon martensitic wear-resistant materials; d) Laser cladding: Clad high-hardness wear-resistant alloy powder on the plunger surface. e) For cylinder blocks without copper bushings, the material is mostly ductile iron, with an amorphous film or coating prepared on the inner wall of the cylinder block. Because of this special material on the inner wall of the cylinder bore, a hard-to-hard friction pair can be formed.

Knoll pump classification

Plunger pumps are generally classified into single plunger pumps, horizontal plunger pumps, axial plunger pumps, and radial plunger pumps. 1) Single plunger pump: The main structural components include an eccentric wheel, plunger, spring, cylinder block, and two check valves. A sealed volume is formed between the plunger and the cylinder bore. One rotation of the eccentric wheel causes the plunger to reciprocate once, sucking oil during downward motion and discharging oil during upward motion. The volume of oil discharged per revolution of the pump is called displacement, which depends only on the structural parameters of the pump. 2) Horizontal plunger pump: Horizontal plunger pumps consist of several plungers (generally 3 or 6) installed in parallel. A 1 crankshaft drives the plungers to reciprocate via connecting rod sliders or directly via an eccentric shaft, achieving hydraulic pumping for suction and discharge of liquids. They all use valve-type distribution devices and are mostly fixed-displacement pumps. Emulsion pumps in coal mine hydraulic support systems are generally horizontal plunger pumps. Emulsion pumps are used at coal mining faces to provide emulsion for hydraulic supports. Their working principle relies on the rotation of the crankshaft to drive the Piston to reciprocate, achieving liquid suction and discharge. 3) Axial type: Axial plunger pumps (English name: Piston pump) are plunger pumps where the reciprocating motion direction of the piston or plunger is parallel to the central axis of the cylinder block. Axial plunger pumps operate by utilizing the volume change generated by the reciprocating motion of plungers parallel to the drive shaft within the plunger bores. Since both the plunger and the plunger bore are circular parts, they can achieve very high precision fits, resulting in high volumetric efficiency. 4) Straight-axis swashplate type: Straight-axis swashplate plunger pumps are divided into pressure-supply type and self-priming type. Pressure-supply hydraulic pumps mostly use pressurized tanks. For hydraulic tanks relying on air pressure for supply, after each machine start-up, operation must wait until the hydraulic tank reaches the required operating pressure. If the machine is started when the air pressure in the hydraulic tank is insufficient, it will cause detachment of the slipper shoes inside the hydraulic pump, leading to abnormal wear between the return plate and the pressure plate in the pump body. 5) Radial type: Radial plunger pumps can be divided into two categories: valve distribution and shaft distribution. Valve-distribution radial plunger pumps have disadvantages such as high failure rates and low efficiency. Shaft-distribution radial plunger pumps developed in the 70s and 80s internationally have overcome the shortcomings of valve-distribution radial plunger pumps. Due to the structural characteristics of radial pumps, shaft-distribution radial plunger pumps are more impact-resistant, have longer service lives, and offer higher control precision than axial plunger pumps. The variable displacement of short-stroke variable pumps is achieved by changing the eccentricity of the stator under the action of the variable plunger and limit plunger. The maximum eccentricity of the stator is 5–9mm (depending on the displacement size), resulting in a very short variable stroke. Furthermore, the variable mechanism is designed for high-pressure operation and controlled by a control valve, giving the pump a fast response speed. The radial structural design overcomes problems such as uneven slipper shoe wear found in axial plunger pumps, significantly improving its impact resistance. 6) Hydraulic type: Hydraulic plunger pumps rely on pressurized hydraulic tanks. After each machine start-up, operation must wait until the hydraulic tank reaches the required operating pressure. Straight-axis swashplate plunger pumps are divided into pressure-supply type and self-priming type. Pressure-supply hydraulic pumps mostly use pressurized tanks, while some hydraulic pumps have a built-in charge pump to provide pressure oil to the inlet of the hydraulic pump. Self-priming hydraulic pumps have strong self-priming capabilities and do not require external oil supply.

Knoll pump mechanical maintenance

For plunger pumps supplied with oil by a charge pump, after 3000h of use, operators must inspect the plunger pump 1-2 times daily to check if the hydraulic pump operating noise is normal. If a decrease in hydraulic cylinder speed or stalling is observed, the charge pump should be disassembled for inspection to check for scoring on the impeller edges and whether the internal gear pump clearance is excessive. For self-priming plunger pumps, the oil level in the hydraulic tank must not fall below the lower limit of the oil gauge; sufficient hydraulic oil must be maintained. The higher the cleanliness of the hydraulic oil, the longer the service life of the hydraulic pump. The most important component of a plunger pump is the bearing. If bearing clearance occurs, the normal clearance of the three friction pairs inside the hydraulic pump cannot be guaranteed, and the thickness of the static hydrostatic support oil film of each friction pair will be compromised, reducing the service life of the plunger pump bearings. According to data provided by hydraulic pump manufacturers, the average service life of bearings is 10000h; beyond this value, new bearings need to be replaced. Removed bearings cannot be tested for clearance without professional detection instruments; only visual inspection is possible. If scratches or discoloration are found on the roller surfaces, they must be replaced. When replacing bearings, note the English letters and model numbers of the original bearings. Plunger pump bearings mostly use high-load capacity bearings. Purchase products from the original manufacturer with original specifications. If switching to another brand, consult personnel experienced with bearings to check tables for equivalents, aiming to maintain the bearing's precision grade and load capacity. The service life of a plunger pump is related to routine maintenance, the quantity and quality of hydraulic oil, and oil cleanliness. Avoiding wear on the plunger pump friction pairs caused by particles in the oil is also an effective way to extend plunger pump life. During maintenance, try to use original manufacturer parts when replacing components. These parts may sometimes be more expensive than other counterfeit parts, but their quality and stability are better. Purchasing cheap counterfeit parts may seem to save costs in the short term, but it brings hidden dangers and may cause greater harm to the use of the plunger pump. Distribution plates come in two forms: flat distribution and spherical distribution. For spherical distribution friction pairs, if scratches on the cylinder block distribution surface are shallow, they can be repaired by grinding. If the grooves on the cylinder block distribution surface are deep, "surface engineering technology" should first be used to fill the grooves before grinding. Blind grinding should be avoided to prevent thinning of the copper layer or exposing the steel base, which could lead to oil leakage. Plunger pumps can also use frequency converters to save energy. Engineers from Shanghai Zhengyi point out that in actual production processes, plunger pumps usually regulate their operating status by pressure or flow. When the actual pressure exceeds the required pressure, relief valves are used to regulate it, maintaining stable working pressure by releasing the excess through the relief valve. However, the motor continues to run at full speed with repeated actions, and power consumption remains unchanged. When using overflow to regulate pressure and flow, some surplus flows back to the original system, resulting in useless power in the plunger pump and low work efficiency. If a Chuangjie energy-saving frequency converter is used, the relief valve can be set to close, and the energy-saving frequency converter automatically adjusts the working pressure, maintains stable working pressure, and automatically tracks the equipment pressure. This achieves automated control, thereby saving energy consumption. The greatest advantage of this regulation method is that it can reduce the operating energy consumption of the plunger pump, with power savings reaching over 30%.

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