Myth #7: High Quality Must Sacrifice Quantity
Historically, management and engineering viewed issues of high production quantity and high quality as diametrically opposed. This double-Q dilemma maintains that if product quality is paramount, then production rates ...
Myth #4: High efficiency is always good
It is well-known that a distinct frequency can exist in the hydromechanical system that arises from a load mass interacting with the combined effects of hydraulic fluid compressibility, flexure in the mounting apparatus, and fluid conductor ...
Myth #2: Cylinders Always Retract Faster than they Extend
First year students in basic hydraulics are taught that cylinders will retract faster than they extend. There is truth to that assertion, but it has significant limitations, and they can lead to misunderstanding, if not the occasional ...
A Common Myth About Hydraulic Pumps
This column will be focusing on several myths that are commonly passed around in the area of hydraulic motion control. We begin this month with the myth that pumps produce flow, not pressure.
What to look for when studying electronics
This series of articles on electronics is going to draw heavily on your knowledge of hydraulics and analogies to help demystify the electronic art. Equally important is to point out where the analogies fail to apply. In previous issues, ...
Exploring the basics of electronic control
The mechanisms that allow electrical flow compared to those that allow fluid flow are fundamentally different. However, it is not erroneous or misleading to think of the electrical current using the pool ball analogy. In fact, such visualization may help to demystify electrical current!
Summarizing two-pump control
This final discussion on the two-pump control method will cover two different configurations of this energy-saving servo system and also present a method whereby any of the configurations could be applied to manually controlled mobile equipment. ...
Defining the setup of dual-pump control
Single-rod cylinders can be actuated efficiently and accurately by using two synchronized pumps with displacements matching the rod- and cap-end volumes of the cylinder. The problem with valve control of cylinder motion ...
Exploring an alternative pump control method
This prototype circuit is identical to a typical hydrostatic transmission (HST), except is uses a symmetrical (double-rod) cylinder instead of the conventional hydraulic motor. Using a variable displacement, servo-stroked pump can ...
Pump control vs valve control: Efficiency or performance?
A flying cutoff requires accelerating a knife to the same speed of a moving workpiece, then actuating a knife to cut the moving material at a specific location. Because the work material moves at a constant speed, the process is much more ...
Results of a motor simulation
Figure 1. Motor speed at no load shows minor variation due to mechanical design. Variations become more pronounced as load increases, and, ultimately result in a stall condition that can be overcome only by increasing inlet flow or reducing ...
Developing a model for motor leakage
A simulation of hydraulic motor model was conducted on an Interdata Model 14 minicomputer. Using a consistent set of metric units, the program calculates values of shaft speed, shaft position, and motor inlet pressure, and outputs these values ...
Developing a model for motor leakage
To simulate the effects of leakage resistance on low-speed stability, a suitable mathematical model is needed. The model must be consistent with actual hardware, and it evolved from test data collected from a motor at the Fluid Power Institute, ...
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