Mechanics of Machines 2 Lab Report (2012)

4047 Words Jul 1st, 2013 17 Pages


Friction is to be avoided in some parts of machines, but is wanted in such items as clutches, brakes and belt-driven pulley systems. The apparatus used for this experiment is a simulation of a clutch, the pressure being provided by vertical weight on a plate. In engaging a clutch between a running engine and a stationary machine there is bound to be some wear, and it is evident that the wear must be uniform on the surface of the friction plate. As wear is proportional to both load and travel it follows that for uniform wear the product of plate pressure and radius from the axis is a constant which depends on the materials.
The substitution of the consequence of assumed uniform wear
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* The mass of the turntable was given to be 4.89kg and the mean diameter at which the torsion was applied was found to be 250mm. Therefore, the radius of the turntable Rtt = 0.125m.

* The internal and outer diameters of each of the friction plates were given. * With the turntable removed the friction plates were in turn positioned on the bottom plate on its location pins. * The turntable was then replaced in position with the torque cords taken over their diametrically opposed pulleys and the load hangers hooked. * Initially a 2kg mass was placed on top of the turntable and equal value masses added to the load hangers until with a slight start the turntable very slowly revolves at a constant speed. * The load per hanger and also the mass on top were recorded in a table. * The procedure was repeated by adding increments of 2kg masses onto the turntable up to 10kg. * The turntable was unloaded and removed to exchange the friction plate for the next larger one and the aforementioned procedure was repeated.

* Finally, the largest friction plate was used in a similar way. * At the end of the experiment all three friction plates were positioned on the stationary plate and the turntable replaced.


i. Given Data & Calculations:

* Mass of turntable (top plate) M = 4.89kg * Radius of turntable Rtt = 12.5cm = (12.5/100) m = 0.125m * Plate 1:

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