Mechanism130460119026:-Dhobi prashant 130460119038:-Kale kalesh 130460119034:-Jain suraj

Geneva

mechanism

figure of Geneva mechanism

A Geneva mechanism is commanly used mechanism for producing an intermittent rotary motion from a uniform input speed. The driven member ,or star wheel ,contains evenly spaced slots into which the roller of the driving crank slides into. The number of slotes determines the ratio between the dwell and motion periods of the driven shaft.

The mechanism requires a minimum of Three slots to function and additional slots can be added. As the drive wheel turns it enters the slots of the driven ,or star,wheel and the mechanism enters its motion period. As the pin leaves the slotes the driven wheel has been indexed and it continues to stay stationary untill the pin rotates bask around.

Geneva mechanism can come in a variety of form and sizes increasing the number of slots in the mechanisms driven wheel decreases the angular displacement by each rotation of the driving wheel. The other characteristic of geneva mechanism is the “locking” feature. That is when the driven wheel is not being turned by the driving wheel ,it is locked in place and is unable to ratate.

Watt’s

mechanism

figure of watt’s mechanism

The Watt’s Mechanism is a simple mechanism consisting of a piston

used to sense theexternal pressure. The piston is

connected to a link and the link is, in turn, connected to a V- Shapedchain. One end of the V- Shaped

Chain is connected to a point which is pivoted and fixed. The other

end of the V- Shaped Chain is free to move over a vertical scale.

The point, worth noting, in the Watt’s Mechanism is that the free link that moves over the

scale generates a straight line. This is the primary reason, why the Watt’s Mechanism is also

called as the Straight Line Mechanism.

ADVANTAGES OF THE Watt’S MECHANISM:

The measurement of altitude of an aircraft by the use of a Watt’s

Mechanism has manyadvantages, some of which are

listed below.1. Less dependence on the use of

the Pitot – Static System, the susceptibilities of which have

beensaid earlier.

2. Altitude Measurement Sensors have been replaced by the

system, which eradicates the problem of

burdening of ice.

3. The problem of fluid contamination in the Pitot –

Static System is eradicated as there is no use of

fluids in the Watt’s Mechanism.4. There are no small gaps or crevices in the Mechanism,

which makes it impossible for foreign

matter to settle on the system.

DISADVANTAGES OF Watt’s MECHANISM:

Like everything and everyone, the Watt’s Mechanism has its own kind

of disadvantageswhich have been mentioned below.

1. The process is completely composed of mechanical

components which are susceptible to sudden

failure. Constant and thorough inspection is required.

Scott russel

mechanism

Figure of scott russell mechanism

A scott russell linkage converts linear motion to linear motion in a perpendicular to the input. The linkages are often used in front wheel drive vehicles with solid rear axles to control lateral movement. The engineering design of locomotives improved over the years and by the year 1830, the linkage straight line motion finally disappeared.

It lingered on for many years with stationary engines ,especially those with vertical cylinder. The main defect of the straight line motions was their ungainly size and weight especially for fast engines compared to a compact slider mechanism.

Scott russell linkages are still used today in front wheel drive motor vehicles with solid rear axles to control lateral movement. A scott russell linkage on the rear axle of a 2002 Nissan sentra.

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