Browse Topic: Hydraulic drives
This ARP delineates requirements for system cleanliness, test gas supply system, test stand design, environmental chamber definition, instrumentation, dynamic test equipment and testing procedures.
A new method for driving the hydraulic free piston engine is proposed. This method achieves the compression stroke automatically rather than special recovery system. Principle of hydraulic differential drive free-piston engine is analyzed and the control strategy of this novel hydraulic driving engine is also introduced. Then energy balance method is used to design the main parameters of the novel engine. High pressure and secondary high pressure of the hydraulic system are constrained by the combustion parameters and therefore parameters are analyzed. In order to verify the effectiveness of energy balance method, the mathematical model is established based on the piston force analysis and engine working principle. The transient results of dynamics are obtained through simulation. In addition, the effectiveness of the simulation is proofed by dimensionless analysis. It indicates that energy balance method realizes the basic performance of hydraulic free piston engine.
The heavy duty trucks have large engine power and drive continuously in mountainous area, so the heat dissipation of engine is very important. In the traditional cooling system with fixed transmission ratio fan, the cooling capacity is insufficient and the engine is easy to be over-heated when the engine is working in low speed and heavy load conditions. Owning to the bigger size of electric motor compared to the hydraulic motor, it is not suitably applied to the heavy duty trucks. Contrasted with the electric motor, the hydraulic drive cooling system is widely applied in heavy duty trucks due to smaller size, larger power, continuous speed modulation and flexible installation location. However, the low transmission efficiency of the pump-motor system results in high power consumption of the cooling system. In this paper, the mathematical and simulation model of hydraulic-driven fan cooling system is established for the specific engine. The study applies the digital PID controller of
The tracked vehicle with a fully hydraulic driving system, which has a strong traveling performance of passing and mobility ability in the complex terrain, is a typical system of mechanical-electrical-hydraulic integration. At the same time, for the good low-speed stability of the hydraulic system, this vehicle is widely applied in most engineering projects. However, for the complexity and unpredictability of the motion state in the complex environment and the power matching of the driving system, the driving path of the tracked vehicle with hydraulic driving is difficult to control. Moreover, for the complicated interaction between mechanics, the establishment of the mathematical model is much more complex, and the traditional mechanics-control and hydraulic-control co-simulation can not accurately simulate this physical phenomenon. The kinematic and dynamics characteristics of the tracked vehicle are studied firstly, and the dynamics model is built. Meanwhile, the hydraulic system is
The hydraulic free piston engine is a complex mechanical-electro-liquid system, in order to simplify the complex system of the single hydraulic free piston engine, a new method for the driving of hydraulic free piston engine is proposed. Hydraulic differential drive achieves the compression stroke automatically rather than special recovery system. The structure and principle of hydraulic differential drive free-piston engine are analyzed and the mathematical model is established based on the piston force analysis and the hydraulic system working principle. In addition, the control strategy of this novel hydraulic driving engine is also introduced. Finally, the transient results of dynamics are obtained through simulation. Then we compare our results to the ones from the hydraulic free piston engine made by the company Innas. The results show that: 1) the simplified engine can achieve the similar performance of the Innas BV concept. 2) The maximum frequency and the maximum power of the
The use of multiple hydraulic pumps can satisfy the needs of various circuits in off-highway equipment. With fuel prices continually on the rise, it is critical to maximize the operating efficiency of off-highway equipment. Southwest Research Institute (SwRI) continues to develop advanced electrohydraulic systems that improve vehicle efficiency. New efforts are focusing on improving the efficiency of the powertrain, the hydraulic systems, and the engine accessories that all consume significant energy during vehicle operation. Motive power is produced by powertrains to ascend grades, overcome rolling resistance, pull plows, push blades, or move harvesters through fields. Powertrain efficiency improvement is being pursued through continuously variable transmissions (CVTs), including hydraulic CVTs, to produce the maximum desired travel speed while minimizing the fuel consumed by the engine.
The pressurization system design considerations presented in this AIR deal with human physiological requirements, characteristics of pressurization air sources, methods of controlling cabin pressure, cabin leakage control, leakage calculation methods, and methods of emergency cabin pressure release.
The design of a digitally controlled hydraulic fan drive from Denison Hydraulics is said to help diesel engines run leaner and cleaner. One of the keys to properly and efficiently controlling emissions from diesel powered on- and off-highway machinery is maintaining the engine's optimum operating temperature. That fact plus a very important secondary benefit, reducing fuel usage, can be achieved by using an infinitely variable hydraulic fan drive. A recent solution to reducing emissions, adapted by a majority of engine suppliers to both the on- and off-highway market, has been the introduction of an electronic gas-recirculation (EGR) system. While relatively effective at reducing emissions, the EGR solution also causes considerable parasitic power loss on the engine, resulting in higher fuel consumption. As an on-highway example, an EGR system adds $5000 to $7000 per Class-8 truck application. These costs include such items as variable geometry turbochargers, additional intercoolers
This SAE Standard describes a uniform method to calculate and specify travel performance characteristics of hydraulic excavators, material handlers, knuckle boom log loaders, delimbers, feller bunchers, harvesters, processors, and other knuckle boom material handlers. It establishes definitions and specifies machine conditions for calculations and tests. This document applies to crawler mounted machines such as hydraulic excavators as defined in SAE J/ISO 6165 and ISO 7135, and knuckle boom log loaders as defined in SAE J1209 and SAE J2055. This document also applies to certain forestry equipment defined in SAE J1209 and ISO 6814 that have crawler mountings such as delimbers, feller bunchers, harvesters, and processors. Included in the definition of hydraulic excavators are also front shovel, clamshell, and telescoping boom excavators.
Researchers from Johannes Kepler University believe agricultural machinery can be improved by further advances in motion generation. Proper adjustment of plow geometry is a challenging handling operation for the operator of plowing and hay-harvesting machines. The optimal values depend on the actual ground situation, which may vary. To adapt the parameters to the ground optimally, adjustment is necessary rather frequently, which realistically can be done only via remote control, or, even better, with automatic control. Current practice is to adjust manually by spindles and to use some complex kinematic mechanism to get an uncoupled relation between the position of the spindles and the relevant functional plow parameters. With full automatic control, easier operation and optimal results-both with respect to quality and performance-can be achieved. The mechanical performance characteristics of modern hay harvesters and tractors allow operation speeds of about 30 km/h (18.6 mph). At such
The following system of symbols is recommended for use in technical papers and engineering reports dealing with hydrodynamic drives.
This AIR provides a description of representative state-of-the-art, fly-by-wire (FBW) actuation systems used in flight control systems of manned aircraft. It presents the basic characteristics, hardware descriptions, redundancy concepts, functional schematics, and discussions of the servo controls, failure monitoring, and fault tolerance. All existing FBW actuation systems are not described herein; however, those most representing the latest designs are included. While this AIR is intended as a reference source of information for future aircraft actuation system designs, the exclusion or omission of any other appropriate actuation system or subsystem should not limit consideration of their use on future aircraft.
This SAE Standard describes a uniform method to calculate and specify travel performance characteristics of hydraulic excavators, material handlers, knuckle boom log loaders, delimbers, feller bunchers, harvesters, processors, and other knuckle boom material handlers. It establishes definitions and specifies machine conditions for calculations and tests. This document applies to crawler mounted machines such as hydraulic excavators as defined in SAE J1057 and ISO 7135, and knuckle boom log loaders as defined in SAE J1209 and SAE J2055. This document also applies to certain forestry equipment defined in SAE J1209 and ISO 6814 that have crawler mountings such as delimbers, feller bunchers, harvesters, and processors. Included in the definition of hydraulic excavators are also front shovel, clamshell, and telescoping boom excavators.
This SAE Standard provides a uniform method for calculating and specifying travel performance characteristics of hydrostatically driven crawler mounted hydraulic excavators as defined in SAE J1057.
This recommended practice applies to hydraulic excavators as defined in SAE Standard J1057, which are crawler mounted. It describes the methods for calculating and specifying travel performance characteristics. It does not apply to wheel mounted excavators.
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