Five Driving Ways of The Crawler Mobile Crushing Plant
The crawler type mobile crushing station is a device integrating the processes of feeding, crushing, screening, iron removal and transportation, with a receiving system, a feeding system, a crushing system, a power system, a conveying system, a walking system, a hydraulic system, among which the power system is the "heart" of the mobile crushing station. This article is going to make a comparison of the five driving ways of the crawler mobile crushing station.
I. The Direct Drive and The Hydraulic Drive
The diesel engine is used as the power source, and two output terminals are separated by the transfer case. The main output is connected to a clutch or a fluid coupling to drive the machine; the other output drives the hydraulic pump aggregate to perform the functions of walking, feeding, conveying, and auxiliary device folding. The workflow is shown in Figure 2.
It currently becomes the mainstream driving method at home and abroad and many large mobile crushing station manufacturers adopt this driving way to produce their crawler type product, such as Metso, Sandvik, Kleemann, and Keestrack.
Compact and highly efficient as it is, it takes more costs than the mains drive, which is the largest constraint for the promotion of the crushing and screening equipment equipped with this driving mode.
II. The Direct Drive and The Electric Drive
This driving method also adopts the diesel engine as the power source, and three output terminals are separated through the transfer case.
The main output is connected to the clutch or the hydraulic coupler to drive the main machine; another output is connected to the pump set to drive the track to walk and other hydraulic actuators; the generator is driven by the third output and the motor performs the feeding and conveying. See Figure 3 for its working process.
There are also some enterprises adopting this driving way, such as RM and Kleemann.
This driving mode is more convenient than the first one for maintenance in late stage. However, due to the large power of the walking system, the pump unit model is so large that there is a large increase in production costs and high overall layout requirements. In addition, the diesel engines increase the cost of use.
III. The Full Hydraulic Drive
With the diesel engine as the power source, the full hydraulic drive supplies hydraulic oil for the hydraulic system through a series of pumping unit. The crushing machine is driven by a variable displacement piston pump, and the other actuators are controlled by the remaining pump and valve sets. The working process is manifested in Figure 4.
The full hydraulic drive is more mature in Metso's crawler-type mobile crushing station products.
Those products with this driving method feature low production cost, easy structural arrangement and simple control, but what really restricts their production is that the main engine will cause large torque when starting, and the rotation speed is high during normal operation. Therefore, this driving method is mostly applied to small mobile crushing stations.
IV. The Mains Drive
For those crawler type mobile crushing stations adopting the mains drive mode, the diesel engine drives the walking motor to perform the walking and the other actuators are all driven by the mains. See its workflow for Figure 5.
What makes the mains drive mode unique is low costs of use. In addition, it is credited with large structural layout and it does not need maintenance even in late time.
A majority of semi-mobile crushing plants generally uses this type of driving method; however, its constraining factor relies on small scope of application. Additionally, mining and construction waste disposal sites need to be equipped with cable lines.
V. Diesel-electric Drive
The diesel-electric drive mode uses a mains or diesel generator set as the power source. In the actuator, the motor is driven by a motor and a hydraulic pump, and the other actuators are driven by a motor. The workflow is represented in Figure 6.
The diesel-electric drive is the development direction of the crawler-type mobile crushing station just like the plug-in hybrid drive of the car. In large projects, this type of crushing station can be connected to the mains to reduce the cost of use; while the small ones can use diesel engines, which is flexible and convenient.
At present, many models of crawler-type mobile crushing plants produced by Kleemann adopt this driving method. Its main constraints are high manufacturing costs, complex equipment structure, small structural space. More importantly, it is difficult to repair machines at later stages.
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