Fault Causes and Solutions in Hydraulic Pumps
Fault Causes and Solutions in Hydraulic Pumps
Fault Causes and Solutions in Hydraulic Pumps
Hydraulic system and hydraulic pump maintenance is very important in order to reduce the number of failures and increase operating life in hydraulic pumps. 80% of the most encountered pump failures are due to incorrect operation and maintenance.
Today, with the developing technology, the efficiency of hydraulic pumps has increased, but their strength has decreased. The choices made by the user (oil selection, using or not using filters) and his knowledge and experience about the hydraulic system during the period from the first moment the pumps start up to the moment they break down seriously affect the service life of the pump.
Hydraulic pumps do not fail suddenly, overheating, pressure fluctuations, flow loss, etc. It often manifests itself for reasons. Hydraulic system fault finding techniques in determining faults in hydraulic circuits; More clear information can be obtained about the status of the pump, taking into account the methods of sniffing, contact, observation and listening.
Hydraulic System Fault Detection Ways
Smelling: The cause of an uncomfortable odor in the system, the dry friction at any point in the system or the burning of the oil as a result of overheating of the pump.
Contact: Pumps are the first method to be used to determine the temperature. It is not a very healthy method. It is healthier to use a heat meter, as people feel the temperature differs. Excessive temperature rise can be a sign of malfunction.
Observation: Reasons such as slowing down of system pressure and movements in the system may be symptoms of loss of flow in the pump.
Listening: Mechanical parts of hydraulic pumps create friction and muffled noises due to lubrication and air intake problems.
1. Hydraulic Pump Failure
1.2 Causes of Faults in Hydraulic Pump
Pump malfunctions can often be a symptom of another element in the system. Protection from failures will increase pump and system efficiency. Approximately 85% -95% of pump failures occur when one or more of the following reasons come together. We will examine them in order of importance.
a) Pollution
b) Cavitation
c) Incorrect oil selection
d) Assembly errors
e) Commissioning
Pollution
The main task of the oil in hydraulic pumps is to create a film layer between the working surfaces of the inner groups of the pumps (Cylinder, Distribution plate control piston, etc.). Dirty oil cannot form the desired film layer in the pump, on the contrary, it enters between two moving parts and causes wear of the parts, oil leakage and heating. Oil pollution can be in the form of solid substances or they are soft materials that occur as a result of foaming, mixing with oil with water or sludge. When it comes to oil contamination, particles between 2: -50: are meant. As an example: For hydraulic pumps, the contamination degree of the oil should be Nas 9. If the Nas is higher than 9, abrasion starts on the pump parts.
Cavitation
It is the breakage of parts on the pump parts as a result of the hydraulic pumps sucking the air together with the oil during the oil suction. In the hydraulic pump that absorbs air; When the pump is under pressure or when it is exposed to low pressure, it makes sounds like knocking or knocking.
Why hydraulic pumps suck air
1. Leaks in the suction line and pipe connections
2. Liquid returning to the tank falling from above
3. Returning liquid goes directly to the suction of the pump
4. Failure to rest hydraulic oil
5. Impurity insoluble in oil.
Incorrect Oil Selection
Oil selection is an important issue to be considered in hydraulic pumps. If the hydraulic oil is chosen incorrectly, it causes the pump to suck air and cavitation. For this reason, attention should be paid to the following issues in the selection of suitable viscosity oil for hydraulic pumps.
a) Initial working viscosity at minimum ambient temperature
b) the expected maximum operating temperature at the maximum ambient temperature
This high viscosity, which lies between the operating temperature of the hydraulic oil and the operating viscosity, should be selected in any case by looking at the shaded area given in the table. For optimum efficiency and long service life, a viscosity range of 16-36 mm2 / s should be selected. Using a high viscosity fluid other than the recommended values may cause cavitation, excessive pressure drop in the system and low efficiency. If the fluid viscosity is too low, the volumetric efficiency will decrease as leakage will increase. There will be instability in the pressure balance and control will be difficult.
Assembly Errors
During the coupling of the hydraulic pump and the electric motor, the coupling connections must be made correctly. The loads that will occur after the erroneous assembly will be placed on the shaft bearings of the pump and the electric motor, thus reducing the life of the pump. In addition, the coupling connected to the pump should never be hit. If possible, the coupling should be heated.
Deployment
Hydraulic pumps get the greatest damage at the first start. Before the pump is put into operation, oil must be added from the stain line and the electric motor must be started-stop to lubricate the inner group of the pump. It should be checked that the suction line is open. As a result of avoiding these controls and carelessness, most of the pump failures occur because of this.
Result
Pumps are an indispensable element of the hydraulic system. The above conditions. If adhered to, cost and work losses can be minimized due to malfunctions in the pumps.
resources
1. REXROTH, hydraulic catalog
2. Hydraulic Oil. Tan.mak and Using Correct Hydraulic Oil (Baha .NAN Mak. Muh. Petrol Ofis As.)
3. Failure Analysis in Hydraulic Circuits (Yasar PANCAR, H. Sevil ERGUR)