Practically all are electrically propelled, either by cables, sheave and counterweight, by a winding-drum mechanism (still used in many low-rise freight elevators), or by an electro-hydraulic combination.
This is achieved by using a specially developed hydraulic cylinder in combination with a hydraulic motor.
The compact hydraulic dimensions, in combination with the low number of parts, lead to a cost-effective manufacturing process and to a reduction in product and inventory costs.
A combination hydraulic-fluid-and-air suspension system has been developed in which the elastic medium is a sealed-in, fixed mass of air, and no air compressor is required.
Using a dual actuator hydraulic testing machine, combinations of axial and transverse loading are applied to the specimens.
In the previous work in this area, the micro-heterogeneity effects on the Pc S Kr relationships have been analysed in a number of contexts, e.g., uniformly distributed heterogeneities (simplified cases), various binary sand combinations, hydraulic parameters (e.g., entry pressure, permeability), boundary conditions, etc.
So far the natural gas industry has drilled about 6,000 Marcellus wells using a combination of hydraulic fracturing and horizontal drilling.
At the same time, a technological revolution in drilling — the combination of hydraulic fracturing and horizontal drilling of shale rock — has opened up new gas and oil fields throughout the state.
What's new is the combination of hydraulic fracturing and horizontal drilling in the rich gas deposit known as the Marcellus Shale, which runs roughly 600 miles — including in parts of Virginia, West Virginia, Ohio, Pennsylvania and New York.
Conformance fracturing, a combination of hydraulic fracturing and water control, has proven to be an effective conformance control technique.
