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Used Excavator On The External Factors Affecting The Service Life Of The Hydraulic Pump

Oct 20, 2016

Many factors influencing the service life of hydraulic pumps, in addition to pumping their own design and manufacturing factors and some pump-related elements (such as coupling, oil filters, etc) of the selected test runs in the process also work with. Awareness of this paper presents itself.

Relevant component analysis 

1 coupling 

(1) selection of the coupling

Hydraulic pump drive shaft cannot withstand the radial and axial forces and therefore does not allow installation directly in the shaft end pulleys, gears, sprockets, usually with the coupling drive shaft and pump shaft. For manufacturing reasons, excessive pump shaft with coupling, and bias when it is assembled, with the speed of pump centrifugal force to increase coupling deformation, deformation and the centrifugal force increases, creating a vicious circle, which produce vibration and noise, thereby affecting the service life of the pump. In addition, such as loose coupling pin when not fastening, rubber ring worn without the timely replacement and other factors.

(2) coupling Assembly

Rigid coupling of two axes coaxial error 0.05mm;

Flexible coupling of two axes coaxial error 0.1mm;

Two-axis angle <1 °;

Distance between drive shaft and pump should remain 5~10MM. 

2 hydraulic tank, 

(1) the selection of hydraulic oil tank

Hydraulic oil tank in the main role of hydraulic system for oil storage, thermal, separation and eliminate the air bubble contained in the oil. Selection tank first to consider its capacity, General mobile type equipment take pump maximum flow of 2~3 times, fixed type equipment take 3~4 times; second consider tank oil bit, dang system all hydraulic oil cylinder out Hou tank oil surface shall not below minimum oil bit, dang oil cylinder back shrink yihou oil surface shall not above highest oil bit; last consider tank structure, traditional tank within of clapboard does not can up precipitation dirty real of role, should along tank longitudinal axis installation a vertical clapboard, this clapboard end and tank end Board Zhijian left has vacancy makes clapboard on both sides space connected, Hydraulic pump oil inlet and outlet arrangement at the unconnected end of both sides of the diaphragm, into the farthest distance between the oil and return oil, hydraulic oil tank up some cooling effect.

(2) hydraulic oil tank installation

In the installation location can be divided into upper, side and bottom mount.

Upper fuel tank has good hydraulic pumps and other devices installed in the stiffness of the cover, its structure is compact, the most widely used. Also cast in the tank shell fins, enhance the cooling effect, namely, to increase the service life of the hydraulic pump.

Side-mounted hydraulic pumps and other devices are installed in the tank next to the fuel tank, covers an area as big as is convenient in installation and repair, used to flow in the system and the fuel tank capacity is often greater, especially when a tank for hydraulic pumps for oil use. Side-mounted oil level above the pump suction port, it has good suction effect.

Mounted under the fuel tank was placed under the tank hydraulic pump, not only easy to install and repair, hydraulic pump and suction capability is greatly improved. 

3 oil filters, 

(1) selection of oil filters

General size of less than 10 μ m less obvious impact of pollutants on the pump, and greater than 10 μ m, especially in the more than 40 μ m has obvious effect on the service life of the pump. Hydraulic oil solid contaminant particles in relative motion of the parts within the pump surface can be easily aggravated, oil filter needs to be installed to reduce oil pollution. Filtration precision: axial piston pumps 10~15 μ m, 25 μ m vane pump, gear pump is 40 µ m. Pollution and wear of the pump can be controlled within the allowed range. High precision oil filter is widely used at present, you can greatly extend the service life of hydraulic pumps.

(2) oil filter installation

Points following 3 species situation: ① sucking oil filter oil device structure simple, its role is prevent sucking oil Shi will larger of particles pollutants inhalation pump within, General used low precision filter, highest filter precision not over 30~50 μ m, to easy maintenance should be will filter oil device installation in tank top Department or side Department, also should consider its circulation capacity should in hydraulic pump maximum flow twice times above, case pump will sucking empty; II pressure oil filter oil device loaded in hydraulic pump downstream pressure pipeline, to hydraulic system conveying clean pressure oil, usually selection high precision filter oil device, 3~20 μ m filter precision, its flow capacity shall be not less than the pressure oil flow c oil filter installation after the total return line, will the outside world to break into the system and system-generated pollutants filter NET, often also use high-precision oil filter. According to a recent pollution control system theory, should the oil in the tank reaches a certain level of cleanliness, as well as to prevent filter oil filter before and after the excess pressure due to the plug, you should install cartridge jam sent letters in order to replace the filter in a timely manner.

4 globe valve, 

When removing hydraulic pump and tubing, oil will go back in the system. Parking also cause hydraulic pump hydraulic pump with load reversal, makes the suction pipe of the pump to produce a partial vacuum, dissolved in oil came out of the air on the Plaza until the next time the system will mix with the air, generate noise, cavitation, shorten pump life, usually in the hydraulic pump oil drain port not far from the installation of a globe valve. Should also set up a show that valve in the valve open signal switch and hydraulic pump only when the valve is fully open to start a chain of devices to ensure the hydraulic pump does not suck air when driving. 

5 heat exchanger, 

Oil temperature of hydraulic system allows for 15~80℃, the best temperature is 25~55℃. Hydraulic system inevitably produces mechanical loss, pressure and volume losses, these losses are all converted into heat, some heat through the tank, most of the space around the pipe into heat the tank temperature. For excessive oil temperature in the oil can go bad and precipitation of asphalt and other debris, the viscosity of the oil, hydraulic pump leak inside and outside increases, poor lubricating oil film fragile, relative sliding wear of parts within the pump and shorten the service life of the pump, the system must be set at the high temperature oil cooler. Cooler consists of air-cooled, water-cooled, and cold, lane choice.

Conversely, if the oil temperature is too low, the oil viscosity, friction resistance increase, the hydraulic pump to start and suction difficulties, affecting the use of pumps. 0 ℃ the following areas before starting the pump oil should be heated to 15 ° c above and into the pump body until the temperature rises above 15 c to start the pump, set for the bottom level in the tank can also be a heater to ensure always soaked in oil. 

6 operation notes, 

(1) before running

① the hydraulic pump is installed is accurate and reliable, and screws are tighten couplings installation in accordance with the requirements;

Second, the pump is filled with oil;

③ the direction is consistent with the oil inlet and outlet of the pump;

II safety valves of the hydraulic system is adjusted to the required pressure value. 

(2) operation

Starting is not sharp at full speed when starting, should move under the system of unloading continuous no-load running motor switch several times before in order to exclude as much as possible of the air in the pipe cleaner, no-load running 1~2min no abnormal phenomenon gradually after loaded, the loading process should be no abnormal vibration, noise and leak, or immediately stop check analysis, troubleshooting. 

(3) run after the

If pump pump oil should not be released for a long time, low acid value oil liquid filling, exposed machined surface-coating antirust oil, the oil port screw plug seal against dirt.

Can be seen from the above analysis, the hydraulic pump using a length of life was governed by its own internal parts damage, wear and decided, but the internal parts damage, wear and direct influence from the external components used, so a reasonable selection of hydraulic pump external components, correct operation using hydraulic pump can greatly improve the life of the pump.

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