Mane et al., International Journal of Advanced Engineering Technology E-ISSN 0976-3945 Research Paper EXPERIMENTAL STUDY OF MECHANICAL POWER ¹Prof. V.R. Gambhire , ²M.V.Mane

Address for Correspondence ¹Professor, ²ME Design second Year, Mechanical Engg Dept., T.K.I.E.T. Warananagar INDIA ABSTRACT Precise positioning and movement of heavy loads are two basic jobs for all-mechanical power amplifier. Mechanical power amplifier has a fast response. Power from its continuously rotating drums is instantaneously available. Mechanical power amplifier introduced in this experiment is used for position & force controlling. This amplifier is based on capstan principle. Experimental study is carried out to find amplification factor for amplifier. Here amplification factor for mechanical power amplifier is found out by using different rope material. Study is carried out for optimum performance of mechanical power amplifier. 1. INTRODUCTION belt friction equation, also known as Eytelwein's In many applications it is required to control a large formula relates the hold-force to the load-force, if a output load using a relatively low control force. flexible line is wound around a cylinder. Because of Applications such as load positioning, non-linear the interaction of frictional forces and tension, the broaching, hydraulic winch control etc, can be cited tension on a line wrapped around a capstan may be to describe the need of a suitable effort amplification different on either side of the capstan. A small device in the form of Mechanical power amplifier. holding force exerted on one side can carry a much The present mechanical power amplifier is designed larger loading force on the other side; this is the for a spring making machine for spring principle by which a capstan-type device operates. manufacturing industry, who manufactures various The formula is: springs such as conical springs, hook springs, hot ------(1) wound springs, special purpose springs. Where the where is the applied tension on the line, is spring is manufactured by using roller mechanism in the resulting force exerted at the other side of the which control force is applied by using manual capstan, µ is the coefficient of friction between the & cam system. In spring making machine control force is applied by using a manual lever and cam rope and capstan materials, and is the total angle system. With the present system it is very difficult to swept by all turns of the rope, measured in radians control the position and force applied by roller. (i.e., with one full turn the angle ). This problem can solve by replacing existing system with mechanical power amplifier. The position and force applied by roller is to be controlled by using the ‘Power amplifier’ mechanism. 2. CURRENT PRACTICES Philip K. Budge[1] has carried out the work on improvement in precision motive devices and improved mechanical driving mechanisms of inexpensive manufacture and high power capacity in which mechanical power amplifier is used for the regulation of powered output movements under command of control signals of low power level. Fig.1 Schematic diagram of capstan friction equation J.M. Harries[2] has worked on the mechanical power 3. ASSEMBLY OF MECHANICAL POWER amplifier based on the principle of a capstan force AMPLIFIER multiplier which is sensitive, bi-directional, with little back lash & very little inherent inertia. Mechanical power amplifier used as a multi- stage amplifier or a general control & instrument amplifier. Starkey, Michael M. [3] studied the capstan principle & used it to control the output. As amplifier control the output force, the amplifier is used for lifting load. When a tension is applied to the end of the cord pointing in the direction of the capstan’s rotation, friction will be transferred to the cord and the tension will effectively be amplified. He found out amplification factor for different angle of swept & plot graph of amplification factor vs input & compare amplification factor for different angle of swept. Capstan diameter, rotational of drum & diameter of rope does not affect the amplification factor. 2.1 Principle of mechanical power amplifier

The mechanical power amplifier is based on the Fig 2: Schematic diagram of assembly of Mechanical capstan principle. The capstan friction equation or Power Amplifier Int J Adv Engg Tech/Vol. V/Issue II/April-June,2014/55-57 Mane et al., International Journal of Advanced Engineering Technology E-ISSN 0976-3945 Component of mechanical power amplifier shown in Above fig are listed in below table.

Table 1: List of Component

Fig 4: Torque Vs. Speed

Fig 5 : Power Vs. Speed

Fig 3: Fabricated mechanical power amplifier Working of mechanical power amplifier Flywheel motor drives the train using belt pulley arrangements. The left hand gear train, drives left hand drum in clockwise direction whereas the right hand gear train drives, the right hand drum in counter clockwise direction. Both the drums are rotated in exactly opposite direction but at the same speed. Fig 6: Efficiency vs. Speed Graph Input arm & output arm are connected together by Torque Vs. Speed: Torque is decreases with band A & band B. Band A drives the output when increasing speed. Initially speed is high & torque is input arm is rotated in clockwise direction whereas less hence amplification factor for amplifier is low. band B drives the output when input arm is rotated in As load on output shaft increases, speed decreases, counter clockwise direction. When the load is applied torque increases, hence amplification factor of on the output arm; assuming that input arm is rotated amplifier increases. in clockwise, band A tightened on left hand drum & Power Vs. Speed: Power is decreases with absorb kinetic energy from drum & multiply it by increasing speed. As load on output shaft increases, number of turn & deliver it to output shaft. As input speed decreases & power increases. & output shaft are engaged they rotated at the same Efficiency vs. Speed: Efficiency decreases with speed; hence the same power that is applied to input increasing speed. Initially speed is high hence arm will be multiply as per number of turn & efficiency is less. As speed decreases, efficiency is delivered to the output shaft. Output load depends increases. upon the coefficient of friction between drum & band By using testing data, graph of amplification factor (rope) and the number of turns of rope. Vs input torque is found out for rope material leather, 4. TESTING ON MECHANICAL POWER woven cotton & steel & formula for amplification AMPLIFIER factor is found out & comparison of amplification For testing purpose power supply to system by factor is carried out. electric motor. At input shaft power is supply by using another motor, whose power is to be amplified. Various loads are applied on the output shaft, output speed for particular load is measured & output torque, power is found out. In order to conduct trial, a dynobrake pulley cord, weight pan are provided on the output shaft. Testing is carried out for different rope material like leather, woven cotton, steel & with each material amplification factor is found & performance characteristics for the observations which are obtained used to plot the graphs. Fig 7: Amplification factor Vs. input torque Graph

Int J Adv Engg Tech/Vol. V/Issue II/April-June,2014/55-57 Mane et al., International Journal of Advanced Engineering Technology E-ISSN 0976-3945 To model the slow region, an appropriate curve needed to be chosen as a model Curve to fit to the data. A basic exponential decay function, was used since the shape of the function resembles the curves made from the data. Hence equation for amplification factor for number of turns of rope three is f (x)= x + q Amplification factor = T1 + q 5. CONCLUSION In this experimental work, testing is done with the view to comment on the utility of the designed drive for given application. The following conclusions are drawn from the results of experiment. • The amplification factor provided by mechanical power amplifier depend upon co-efficient of friction between rope material, no of turns of rope wound round drum. The diameter of rope wound round drum, diameter of drum & rotation speed of drum does not affect the amplification factor. • With keeping optimum number of turns of rope three, the value of amplification factor for leather & woven cotton material is more than steel rope material. Maximum amplification factor with leather & woven cotton is 2.5 & that with steel material is 1.8 REFERENCES 1. Philip K. Budge. 1965 NOV. 2. “Mechanical power amplifier”, United States patents US 3,214,988. 2. J.M. Harries. 1970 Jan 20. “Mechanical amplifier”, United States patents US 3,491,603 3. Starkey, Michael M. "Investigation of capstan friction and its potential use as a mechanical amplifier." Master's Thesis, Ohio University , 2010 4. Attaway, Stephen W. "The Mechanics of Friction in Rope Rescue." International Rescue Symposium. 1999. 5. Smallridge, B.1992 Mar. 3. “Double capstan winch drive”, United States patents US 5,092,646 6. W.S.Miller.1963 Jan.1,“Mechanical power amplifier”, United States patents US 3,071,021 7. Robert L. William “Capstan as a mechanical amplifier”, Ohio University, 2011. 8. Capstans Gray C. Thomas, Clayton C, “Controllable, High Ratio Force Amplification Using Constrained Elastic Cable”, Olin College of Engineer in Needham, 2012 9. Juvinall, R., Marshek, K., 2006, Fundamentals of Machine Component Design. 3rd ed. John Wiley & Sons, pp. 712. 10. D. Pisla eds.,M.Ceccarelli eds., M. Husty eds., B. Corves eds, “New Trends in Mechanism Science Analysis and Design” ,Springer, pp. 345-352. 11. “Design of Machine Elements” by V. B. Bhandari, 2009 Revised

Int J Adv Engg Tech/Vol. V/Issue II/April-June,2014/55-57