Search results

Looks at the potential of water hydraulics as an alternative to more traditional systems and explains the advantages and disadvantages. Provides a number of examples of where water hydraulics is replacing other systems, in particular with the use of Nessie products. Also describes other areas where the use of water hydraulics is on the increase such as oil recovery, fire‐fighting, cheese making, abattoirs and sewerage service companies.

HYDRAULIC POWER and control is being applied more and more widely in industry and is finding both general and specialised uses. Generally, hydraulics could be just another item in the designer's toolchest—another way of applying power and of exercising control. In the specialist fields hydraulics is being used as the force transmitting element in complex closed loop control systems and where the very nature of a fluid medium is to be used with advantage.

Environmental protection regulations are becoming increasingly strict. Using water instead of a hydraulic mineral or biodegradable oil in power‐control hydraulic systems is a very positive step towards complying with these regulations. Since water hydraulics has many specifics, primarily related to lower viscosity and lubricity of water compared to oil, which greatly affects the leakage, and even more the friction and wear in these systems, a dedicated test rig is required for performing research with the real‐scale components. The purpose of this paper is to present some preliminary representative results on dynamic responses of the two hydraulic circuits with and without a mass load.

The paper presents the newly developed dedicated test rig and its dynamic characteristics when used with water and oil as hydraulic fluid. Hydraulic pressures and motions of spool and piston in the two different fluids were of special interest.

The results clearly show their dependence on friction properties of selected materials in different hydraulic fluids. While the oil valve worked perfectly, water valve has some irregularity, linked with the small gap, the shape irregularity, the surface roughness and the poorer lubrication conditions in the water hydraulics compared to the oil system.

The observed irregularity of the movement of the spool in the water hydraulic valve has almost no influence on the movement of the piston rod of the water cylinder, which is a very promising result for future research on water hydraulics.

The purpose of this paper is to report an experimental study on the effects of various parameters, such as varying flow velocities of water in the pipe, insulating the water pipe, and heating the pipe, to prevent pressurized water in a water hydraulic system from freezing under sub‐zero ambient temperature environment.

An experimental test rig was designed, fabricated, and set up to conduct several experiments to investigate the time taken for water to freeze under sub‐zero ambient temperature at −20°C and with the water initially at a higher temperature than the ambient.

The experiments show that it would take about 90 min for water in the pipe to freeze completely when there is no flow, or water is flowing at slow speed, in the pipe. The results also show that the use of insulation on the pipe would delay the freezing of water inside the pipe; and if used together with heating at several locations on the pipe, freezing of water inside the pipe could be prevented completely.

This paper usefully shows that insulation and heating in a water hydraulic system can prevent freezing of water in the pipe. The promising results of the experimental work mean that water might be able to replace oil in hydraulic systems on aircraft and other low‐temperature applications.

To meet an increased production demand and to speed the development of an entirely new range of products, Marconi Avionics Limited is opening a newly‐equipped Hydraulics Facility at its Airport Works factory, Rochester, England. The facility, which is being formally opened today by Mr. C. R. Robinson, Editor of the magazine “Design Engineering”, has the skilled staff and equipment needed to compete more effectively in world markets.

A feature of the recently introduced landing gear for the 300 series of the Westland W30 helicopter is the introduction of built‐in ‘crashworthiness’ to absorb the severe overloading caused by heavy landings.

RECENT developments at Electro‐Hydraulics Ltd. are in two categories: in component design and in solutions to basic hydraulic problems. Examples shown below are selected from a number of fairly recent component design details, followed by an outline of developments in seals and a summary of fatigue tests on hydraulic tubes.

A contract to supply a British deck landing system for helicopters of the United States Coast Guard has been won by Fairey Hydraulics in co‐operation with Grumman St. Augustine of Florida, USA.