Belt Drive Laboratory Exercise

Belt Drive Laboratory ExerciseAn investigation into the descent amidst strains in a slipping engine block and comparison of observational and theoretic results1. SummaryThe transmission of exponent across machines and systems in manufacture is vit eachy important and fringe drives enkindle provide this in a cheap but efficient form. In this experiment, a savorlesscar bash was attached around a auction block at quadruple recognize come home burdens and the tensions both before and after the city block were recorded as the mass was changed to investigate the crash tension balance and qualification of the closure, and how this comp ard to theoretical results. The experimental and predicted results were lay out to be very similar, confirming the expectation that an increase in contact angle would cause an increase in rush tension ratio. Also, a peak cleverness of 67.95% was measured which was signifi locoweedtly start than the average modern day efficiency o f 95%.2. List of symbolizationsSymbolMeaningcoefficient of friction between boot and pulleyhalf vee belt angleangle of contact between belt and pulleyT1tension after pulleyT2tension before pulleymmmillimetresNnewtonsVvoltsAampsggramsrotational speed uprpmrevs per minuteefficiencyPOUToutput power bowling pininput powerTtortuosityNmnewton metres3. cosmosBelt drives are a cost effective, easy to use devices knowing for power transmission between machines or shafts. The origins of traction devices croup be traced back as far as the Babylonians and Assyrians with flat belts, made of leather, change state the main source of power transmission in factories during the industrial revolution. Although flat belts are still used today, the introduction of vee belts by John supply in 1917 revolutionised short distance power transmission, creation adequate to(p) to feed more power than a flat belt for a pulley of certain diameter. Modern belt drives are able to transmit power at an eff iciency of 90-98%, averaging 95% 1.Vee belts provided the opportunity for continuously variable transmission with their ability to work on pulleys of variable diameters, a helpful advantage over other forms of transmission. However, the main disadvantage is the slip between belt and pulley which can limit the efficiency of the drive the factors contributing to this are the belt profile, the friction and the amount of contortion. This report investigates the relationship between the tensions in a stationary flat belt pulley and subsequently the crookedness and efficiency, comparing the experimental results with expected determine cypher using the hypothesis out direct contrastd below.4. TheoryGiven the coefficient of friction , vee belt angle 2 and angle of contact (rad), the relationship between higher(prenominal) tension and overthrow tension in a slipping pulley, known as the belt tension ratio, is given by the following equation 2 (equation 1)Given for a flat belt = 9 0 and knowing sin (90) = 1, this equation can be rewritten (equation 2)It is this theoretical equation which the experimental results will be compared against in order to analyse the relationship between the belt tension ratio and coefficient of friction.5. Method5.1 ApparatusBelt drive system pose up as shown above in excogitation 1, with the central pulley of spoke 50mm and a load cell quantity with an uncertainty of 0.005N.DC voltaic travel to provide initial rotational movement of the central pulley, measuring voltage (V) with an uncertainty of 0.05V and current (I) with an uncertainty of 0.005A.Masses, 100g severally, to vary the load use at the allay end of the drawstringHand held visual tachometer capable of measuring rotational speed () of the pulley with an accuracy of 0.5rpm.5.2 resultThe free end of the string was placed accordingly to ensure the angle of contact, , between the belt and pulley was /2. The motor supply voltage was set to 10V and it was made sur e that the pulley was rotating in the correct direction by checking T2 T1. The take form balance was zeroed before the minimum load, 100g, was placed on the free end of the string and a measurement for T1 recorded off the spring balance. 100g masses were consequently added individually until a utmost mass was apply and the value on the spring balance after the addition of each mass was recorded. These masses were then removed, the angle of contact changed, and the experiment then repeated for angles of , 3/2 and 2. The maximum mass was achieved when the motor was close to stalling but the voltage value still ask 10V.When performing the experiment at the 3/2 angle of contact, values for current and pulley rotational speed were also measured after the addition of each 100g mass. The current (I) was measured by the digital multimeter small-arm the rotational speed of the pulley () was measured using the hand held optical tachometer.6. ResultsThe tension after the pulley (T1) and the mass added to the free end of the string were recorded and collected in a table, which can be found in Appendix A. The values for the mass were converted from kg to N to give the corresponding tensions (T2). A graph of T2 against T1 (figure 2) was then drawn for all four angles of contact .This experimental value was calculated from figure 3 to be 0.3269. Using this value and equation 1 for all four angles, a theoretical plot of the belt tension ratio was able to be produced and compared with the experimental results achieved at the four points, shown done figure 4.7. handlingIt was expected that as the angle of contact increased, the value of T1 would decrease and therefrom the value of the belt tension ratio would increase. It can clearly be seen from the experimental data points produced in figure 4 that the results from this experiment were as expected.Also from figure 4, an analysis of the experimental data points and the theoretical line of best fit shows a clear corre lation between the two calculations, confirming the theory discussed during section 3 of the report. The slight differences found between these two forms of data, particularly at =3/2 where the largest error is found, can be accredited to systematic errors due to the measurements from the load cell.Observing figure 6, the motor efficiency shows a generally increasing trend though the curve begins to flatten out as T2 reaches 9.810N. This shows the relationship between torque and efficiency not to be linear but instead parabolic, demonstrating the whim of a peak efficiency at each contact angle. By differentiating the equation of the line of best fit we can calculate that the maximum efficiency is achieved at a torque of 1.627 Nm with this efficiency being 67.95%. This efficiency is significantly smaller than the modern day average of 95% stated in the introduction this difference in values can be attributed to various factors affecting the calculations. Firstly, it was assumed tha t the motor driving the pulley was 100% efficient in reality this would not be the oddball as there would be energy lost internally through friction, cooling systems and core losses. Secondly, this experiment was conducted using a constantly slipping flat belt as opposed to a more ordinarily used form of transmission such as a vee belt, where higher efficiencies would be anticipated.8. ConclusionTo conclude, the experiment outlined in this report was useful in demonstrating the relationship between tensions in a slipping pulley, successfully validating the theory from section 3 that belt tension ratio is related to angle of contact as tends towards 2, the belt tension ratio tends towards a maximum due to an increased area of contact and consequently larger friction.In the experiment, a maximum efficiency of 67.95% was calculated at a torque of 1.627 Nm. The graph of efficiency against torque analysed in section 5 demonstrates a need to find the optimum torque of a system in order to achieve maximum efficiency from it.The findings from this experiment are statistically insignificant as the nature of the pulley does not correspond to common industry types. However, the experiment was useful in showing the basic relationships between angles of contact, belt tension ratio and efficiency found in belt drives and the effect slipping can select on the output of these systems.Appendix A Raw Data/23/22Weight (kg)T2 (N)T1 (N)Current (A)Speed (revs/min)T1(N)T1(N)T1 (N)1.09.8105.803.812183.401.700.98.8295.203.512393.051.501.150.87.8484.603.212562.701.351.000.76.8674.002.912802.401.150.900.65.8863.452.613082.050.950.750.54.9052.852.313401.700.800.600.43.9242.252.013701.350.600.450.32.9431.651.713991.000.400.350.21.9621.151.314290.650.250.250.10.9810.51.014700.300.100.101Carlisle world-beater Transmission products, Inc., Energy loss and belt efficiency, Online. getable http//www.clark-transmission.com/images/pdf/carlisle/energy_loss_and_belt_efficiency.pdf. Accessed 9 February 2016.2J. Darling, ME 10010 unfaltering mechanics 2 Belt Drive Labratory Exercise, University of Bath, 2016.3University of Geulph, Department of Physics, What is torque?, Online. Available https//www.physics.uoguelph.ca/tutorials/torque/Q.torque.intro.html. Accessed 16 February 2016.1PIX Transmissions Limited, Belts Brief history and types, Online. Available http//www.pixtrans.com/blog/belts%E2%80%93brief-history-and-types.html. Accessed 9 February 2016.2Groschopp, Efficiency and losses in electric motors, 24 March 2015. Online. Available http//www.groschopp.com/efficiency-and-losses-in-electric-motors/. Accessed 10 February 2016.3Habatec, Introduction to the power transmission flat belt drive, 2011. Online. Available http//www.habatec.net/HNet/HabaTEC.nsf/vwWebContent/FF5800BDAD1854E0C12571CA0028442B?OpenDocument. Accessed 10 Feb 2016.4IHS Engineering360, Flat belt pulleys, Online. Available http//www.globalspec.com/learnmore/motion_controls/power_transmission/flat_bel t_pulleys. Accessed 15 February 2016.5J. Darling, ME 10010 Solid mechanics 2 Belt Drive Labratory Exercise, University of Bath, 2016.6V. R. Chennu, Belt drives types, advantages, disadvantages, 31 October 2015. Online. Available http//me-mechanicalengineering.com/belt-drives-types-advantages-disadvantages/. Accessed 15 February 2016.