Hydraulic machines

Fluid System’s

Fluid Coupling• A Fluid coupling is used for transmitting power

or torque from one to another shaft with the help of oil (fluid).

• Without MECHANICAL connection of two shafts.

Construction..• It consist of two rotating

elements as a radial pump impeller and radial flow turbine runner.

• The pump impeller is mounted on driving shaft and turbine runner is mounted on a driven shaft. Both the impeller and runner are identical in shape and they are enclosed in single housing filled with oil.

• There is no direct contact between the shafts.

How it works…

• When the driving shaft with pump impeller is rotated, the oil starts moving from the inner radius to outer radius of the pump impeller by centrifugal action.

• Due to centrifugal action and the speed of impeller, the pressure and kinetic energy of oil at outer radius increases. The oil then enters the turbine runner at the outer radios of the runner and flows inwardly to the inner radios of the runner. It will exert force and make it run.

• The magnitude of the torque increases with an increases in the speed of driving shaft.

• And cycle will continue.

uses • Industrial• Rail transportation

o Fluid couplings are found in some Diesel locomotives as part of the power transmission system. Self-Changing Gears made semi-automatic transmissions for British Rail.

• Automotiveo semi-automatic transmissions and automatic transmissions. Since the

late 1940s.• Aviation

o The most prominent use of fluid couplings in aeronautical applications was in the DB 601, DB 603 and DB 605 engines where it was used as a barometrically controlled hydraulic clutch for the centrifugal compressor and the Wright turbo-compound reciprocating engine

WHAT IS HYDRAULICRAM

A hydraulic ram is a cyclic water pump powered by hydropower. It functions as a hydraulic transformer that takes in water at one " hydraulic head " (pressure) and flow-rate, and outputs water at a higher hydraulic-head and lower flow-rate.

Basic components of a hydraulic

1. Inlet — drive pipe2. Free flow at waste valve3. Outlet — delivery pipe4. Waste valve5. Delivery check valve6. Pressure vessel

usesAn alternative to the hydraulic ram is the water-powered pump. It can be used if a high flow rate at high head ratio is required. A water-powered pump unit is a hydraulic turbine coupled to a water pump. The motive power needed by the pump is generated by the hydraulic turbine from the available low head water energy.[

Torque ConverterA torque converter is generally a type of fluid coupling capable of producing torque.Replacement of clutch for automatic transmission vehicle.

Introduction

o Impeller-Connected to the flywheel and towards the gearbox

o Turbine-Facing the impeller and the main shaft of the gear box is taken from the turbine through the impeller.

o Stator-Between the impeller and turbine

Parts of a Torque converter

Stall-The prime mover is applying power to the impeller but the turbine cannot rotate. Acceleration The load is accelerating but there still is a relatively large difference between impeller and turbine speed. Under this condition, the converter will produce torque multiplication Coupling The torque converter is behaving in a manner similar to a simple fluid coupling.

Operational phases

Overheating-Continuous high levels of slippage resulting in damage to the seals that retain fluid inside the converter. 

Stator clutch seizure- The inner and outer elements of the one way stator clutch become permanently locked together, thus preventing the stator from rotating during the coupling phase.

Stator clutch breakage- A very abrupt application of power can cause shock loading of the stator clutch, resulting in breakage.

Blade deformation and fragmentation- If subjected to abrupt loading or excessive heating of the converter, pump and/or turbine blades may be deformed.

Balloning-Operating a torque converter at very high RPM may cause the shape of the converter's housing to be physically distorted due to internal pressure.

Failure Problems

HYDRAULIC PRESS

A hydraulic press is a machine that has a bed or a plate in which the metallic material is placed so that it can be crushed, straightened or moulded.It applies hydraulic mechanism for applying a large lifting force or compressive force

WORKING PRINCIPLEHydraulic press works on the basis of Pascal's Law, its working is similar to the one of the hydraulic system.In hydraulic press, there is a piston at one end of the system having a small cross-sectional area. This piston is driven by a lever. The other end of the system has small-diameter tubing. When a fluid is displaced, either of the pistons is pushed inward. Small piston displaces a smaller amount of volume than the large piston for a given distance of movement. The displaced fluid volume is proportional to the ratio of pistons' head areas.

TYPESThe range includes following types of hydraulic presses:

1-Deep drawing press2-Hydraulic punching press3-compression deep drawing press4-Hydraulic trimming press5-Hydraulic coining press6-Powder compacting press7-Hydraulic blanking press8-Compression molding press

APPLICATIONThese hydraulic presses find various applications in various industrial applications. To count a few, the applications of hydraulic presses are:

- Blanking- Clamping- Coining- Compacting- Compression Molding- Drawing- Embossing- Powder Compacting- Punching- Spotting- Stacking- Stamping

AIR LIFT PUMP

An air-lift pump is a device which is used to lift water from a well or a sump with the use of compressed air.

WORKING PRINCIPLE

It is well known that the density of water is more than the density of air. So it is obvious and evident that air floats higher than water or to understand better, water has more weight than air. So the main principle used in air-lift pumps is the density difference between water and air. Air is made to mix with the water and thus allowed to form froth. Froth here consists of mixture of water and air. So the density of this mixture is less than that of the water. It is the mixture of air which makes the density less than water. Thus a very small column of pure water can balance a very long column of air-water mixture. This is the working principle of air-lift pumps.

APPLICATION

These pumps, in spite of their poor efficiency, are commonly used in many areas where conventional pumps usage is difficult. These pumps are used in

1.Petroleum fields,2.Handling some hazardous liquids,3.Sewage plants,4.Deep sea mining,5.Recovery of archeological artifact and many more.