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Shield support – general
Published in Syd S. Peng, Longwall Mining, 2019
The leg prop size ranges from 125–480 mm in diameter. There are single- and double-acting and single-, double-, and triple-stage telescopic hydraulic cylinders. In a single-acting cylinder, the piston is raised by hydraulic pressure but lowered by the weight of the structure it is supporting. Since retraction of the piston by gravity loading is very slow, the single-acting cylinder is no longer in use. On the other hand, in a double-acting cylinder, the piston is raised and lowered by hydraulic pressure such that piston retraction is much faster, thereby reducing shield cycle time. Pistons are either solid or hollow tubing to reduce shield weight.
IoT End Devices
Published in Rebecca Lee Hammons, Ronald J. Kovac, Fundamentals of Internet of Things for Non-Engineers, 2019
Hydraulic cylinder—Converts hydraulic power into linear motion. These are typically double-acting cylinders and can force movement in two directions. Hydraulic cylinders are very heavily used in industrial equipment. When you enter an elevator and press a button, this creates a control signal that forces hydraulic fluid into a cylinder and moves the elevator up to the next floor.
Hydraulic Power Deployment
Published in Qin Zhang, Basics of Hydraulic Systems, 2019
From the basic operating principle, we know that a hydraulic cylinder utilizes the flow and pressure of the inlet fluid to drive the load performing a linear motion. A typical hydraulic cylinder consists of a cylinder body, a piston, a rod, and seals(Figure 4.2). To meet the special needs for a wide range of applications, cylinders have evolved into an almost endless array of configurations, sizes, and special designs. The structural features, rod designs, actuation methods and usage are commonly used criteria for categorizing those cylinders. The most commonly used cylinder classification is based on the actuation, which sorts all hydraulic cylinders into two categories: single acting and double acting. The cylinders can also be sorted into single rod and double rod in terms of rod designs. According to their configuration features, they can be either piston cylinders, ram cylinders, or telescopic cylinders. Another way of classifying hydraulic cylinders is by their usage, normally only for some specialty cylinders. For this category, there are tandem cylinders, duplex cylinders, and many more.
Prediction of ultimate bearing capacity of circular foundation on sand layer of limited thickness using artificial neural network
Published in International Journal of Geotechnical Engineering, 2021
Barada Prasad Sethy, Chittaranjan Patra, Braja M. Das, Khaled Sobhan
Load to the foundation was applied by a special design loading unit. The loading machine consists of three units: (a) the electrical control panel, (b) hydraulic power pack, and (c) loading device. The loading device is a combination of a beam, four cylinders, four supporting columns, and a base. The hydraulic cylinder is the device that converts fluid energy to linear mechanical force and motion. It converts fluid energy to an output force in a linear direction for executing different jobs. The capacity of the hydraulic cylinder in the universal static loading set- up was 100 kN. The load could be applied to the model foundation in the range of 0–100 kN with an accuracy of 1 N. Forward and backward movement of the cylinder could change the inclination of the load. The inclination of the load remains intact throughout the testing period by the provision of check valve. Dial gauges placed on two sides of the model foundation measured the settlement along the centerline of the model foundation. The arrangement of the test set-up conducted in the laboratory is shown in Figure 4.