The rare large and medium excavator also usually gathers the piston pump and gear pump together to form the hydraulic pump assembly. Similarly, the main pump is usually a plunger pump (the input hydraulic oil pressure is relatively high) to supply oil to the hydraulic walking motor, hydraulic reverse rotating motor and hydraulic cylinder. Pilot pump for gear pump (input hydraulic oil pressure is small) to the distribution valve oil supply.

 

The main pump assembly

 

Gear pump:

Gear pump is to rely on two meshing gear torsion when the situation closed to move things. Gear pump is gear transmission to supply energy, gear pump is quantitative pump, mostly used for low precision in low pressure control.

 

Its important characteristic is: layout is brief, make convenient, capital is low, price is low, volume is small, weight is light, from suck function is good, to oily fluid purify insensitivity and thing reliable etc.

 

Its main fault is: flow and pressure pulsation, noise, discharge into conditioning.

 

It is widely used in various low pressure systems. Gear pump on the lowest request for oil, the earliest moment due to low pressure, is also commonly used in the low pressure system (pilot pump), now gear pump pressure can do 25MPA you, commonly used in the pressure request is not high on the machine, but his oil pulsation, can not be variable, the interest is good self-priming function.

 

 

External gear pump is commonly used in hydraulic system of loader and small excavator. Pump body has a similar modulus, similar to the number of teeth of the gear, gear on the two end face pump cover seal. Pump body, end cover and gear of the alveolus to form a sealed volume, two gear along the meshing of the closed volume space dividends oil suction cavity and oil cavity two departments, and in the matter of each other. As the gear meshing, so that the volume of the seal gradually reduced, the oil in the alveolar groove was squeezed, from the oil outlet. Gear ceaseless torsion, gear in the rodent caused by oil absorption and oil drainage cavity volume changes, to complete oil absorption cavity ceaseless oil absorption, oil pressure cavity ceaseless oil pressure.

 

Piston pump:

 

Piston pump is to rely on the piston movement to supply energy, plunger pump is a variable pump, mostly used for high-precision low-pressure control, plunger pump, things high pressure, the same thing pressure is usually 20 ~ 40MPa, up to 1000MPa; Compact layout; High efficiency and flow conditioning convenience and other advantages.

 

Plunger pump high pressure, stable function, high cost, minimum pulsation, variable, commonly used in low-pressure systems and engineering machinery. But he's the worst at self-absorption.

 

When the engine mobilizes the drive shaft to migrate and transform (the left end of the figure above), the connecting rod propelling plunger moves in and out of the cylinder block, while the front mobilizing piston of the connecting rod twists together with the cylinder block, and the oil distribution plate is fixed.

 

 

Under the influence of the CAM and the plunger spring, the plunger can be repeatedly moved to complete the oil pumping duty. When the CAM protrusion department turned the past, under the influence of plunger spring, plunger downward movement, part of the space on the plunger is the pump oil chamber vacuum, this moment on the plunger end plunger sleeve on the oil inlet will close, the hydraulic oil on the oil channel of the pump through the oil inlet hole into the pump oil chamber, plunger activity to the top, the end of the oil.

 

When the camshaft turns to the CAM protrusion part to jacking up the rotating body, the plunger spring is compressed, the plunger moves upward, the hydraulic oil is compressed, and one part flows back to the upper body oil cavity through the oil hole. When the top surface of the plunger covers the oil inlet hole, the oil distribution chamber on the top of the plunger becomes a sealed space due to the small common clearance between the plunger and the cylinder liner. The plunger continues to rise, and the oil pressure in the pump oil chamber decreases rapidly. When the oil pressure of the pump is greater than the oil spring, the hydraulic pump is pushed out, and the low pressure liquid enters the oil cylinder through the main control valve.

 

When the plunger oil supply, and the plunger chute and cylinder liner on the oil return hole to think, pump oil chamber low pressure oil and the plunger head hole and chute to think, oil pressure reduction, oil valve closed under the influence of the spring end oil supply. Plunger inherited downward, when the CAM highlight department turned past, under the influence of the spring, plunger and downward beginning of the next cycle.

The above: ZHANGFA HYDRAULIC manufacturing HYDRAULIC gear pump best-selling throughout the country