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  • How to design a pin bushed flexible coupling?

    yadavundertaker mohit

    yadavundertaker mohit

    @yadavundertaker-0p3HBs
    Updated: Oct 25, 2024
    Views: 1.1K
    hi....

    to draw a pin bush flexible coupling the given data will be dia of shaft d to be joined in mm,power P to be transmitted in kw ,no. of revolution N in rpm,bearing pressure pb in n/mm2,allowable shear stress in shaft,keys,flange t in N/mm2 and allowable stress in pin s.


    step 1.

    find torque
    T=(P*60)/(2*3.14*N) in N-m

    cange it in N-mm by multiplying 1000.

    Check suitability of shaft dia by

    (d')3=[(16*t)/(3.14*t)]

    if d'<d then take d=d else condition fails.



    step 2.

    No. of pins n=0.02*d +5
    (n should be even)

    pin dia. d1=(0.5d)/sqrt(n)

    take standard size of d1.


    enlarged dia of pin d2= d1+2*step size(3-4) mm

    assume a brass bush t1=2-3mm and rubber bush t2= 6-8mm

    so d3 = d2+2*t1+2*t2



    step 3

    hub dia D1 = 1.75*d

    pin circle dia D2 =3d

    force per pin f= T*2/(D2*n)
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  • yadavundertaker mohit

    MemberOct 5, 2009

    step 4

    From bearing consideration

    pb=F/(l*d3)
    find l from above expression.

    shear stress in pin t= (F*4)/(3.14*d1*d1)





    step 5

    Bending moment M = F*(l/2 + e)

    select e suitably e= 3-5mm


    section modulus Z =(3.14*d1*d1*d1)/32

    bending stress = M/Z
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  • yadavundertaker mohit

    MemberOct 5, 2009

    [​IMG][​IMG]
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  • raj87verma88

    MemberOct 5, 2009

    Good job.
    Try to add some little theory also. That would make it complete.
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  • yadavundertaker mohit

    MemberOct 14, 2009

    the C program for the above pin bushed coupling...


    #include<stdio.h>
    #include<conio.h>
    #include<math.h>
    #include<string.h>
    float arr[20];
    float *am(float d1,int d,float T,float pb,float n,float ta)
    {
    int d2,t1,t2,d3,e;
    float a,d0,q,D1,k,F,l,ti,D2,D3,tp,z,M,c,qp,qb,w,t,l1;


    /* Enlarged dia of pin */

    d2=d1+2*3;
    arr[0]=d2;

    t1=2;
    t2=6;
    d3=d2+2*t1+2*t2;
    arr[1]=d3;


    /* STEP 3*/
    D1=1.75*d;
    D1 = abs(D1)+1;


    /* check suitability of hub*/

    k=d/D1;
    k=pow(k,4);
    ti=(16*T)/(3.14*D1*D1*D1);
    ti=ti/(1-k);

    if(ti<ta)
    printf("\n\n\t");
    else
    D1=2*d;

    arr[2]=D1;

    /* PIN CIRCLE DIA*/
    D2=3*d;
    arr[3]=D2;

    /* FORCE PER PIN*/

    F=2*T/(D2*n);
    arr[4]=F;

    /* STEP 4*/

    l=F/(pb*d3);
    l=abs(l)+1;
    arr[5]=l;


    /* SHEAR STRESS IN PIN*/

    tp=(4*F)/(3.14*d1*d1);
    arr[6]=tp;

    /* BENDING MOMENT
    */
    e=4;
    M=F*((l/2)+e);
    arr[7]=M;


    z=(3.14*d1*d1*d1)/32;

    arr[8]=z;
    qb=M/z;
    arr[9]=qb;
    /* PRINCIPAL STRESS IN PIN*/

    c=(qb*qb)+4*(tp*tp);
    qp=.5*(qb+sqrt(c));


    /* KEY DIMENSIONS*/

    w=d/4;
    w=abs(w)+1;
    t=d/6;
    t=abs(t)+1;
    l1=1.5*d;
    l1=abs(l1)+1;
    printf("\n\n\t principle stress in pin =\t%fN/mm2",qp);
    arr[10]=qp;
    printf("\n\n\t n=%f",n);
    printf("\n\n\t d1=\%fmm",d1);
    printf("\n\n\t D1=\%fmm",D1);
    printf("\n\n\t ti=\t%fN/mm2",ti);
    printf("\n\n\t Hub is safe");
    printf("\n\n\t d2=%dmm",d2);
    printf("\n\n\t d3=\t%dmm",d3);
    printf("\n\n\t D2=\t%f",D2);
    printf("\n\n\t Force per pin =\%fN",F);
    printf("\n\n\t l=\%fmm",l);
    printf("\n\n\t shear stress in pin =\t%fN/mm2",tp);
    printf("\n\n\t bending moment =\t%fN-mm",M);
    printf("\n\n\t section modulus =\t%fmm3",z);
    printf("\n\n\t STRESS =\t%fN/mm2",qb);
    printf("\n\n\t width of key =%fmm",w);
    printf("\n\n\t thickness of key =\t%fmm",t);
    printf("\n\n\t length of key =\t%fmm",l1);
    printf("\n\n\n");
    return arr;

    }
    main()
    {
    clrscr();
    float farr[20];
    int d,p,N,b,d2,t1,t2,d3,e,i;
    float T,n,d1,a,d0,pb,ta,q,D1,k,F,l,ti,D2,D3,tp,z,M,c,qp,qb;
    printf("\n\n\t\t DESIGN OF PIN BUSHED FLEXIBLE COUPLING");
    printf("\n\n\n\t enter the dia of pipe to be joined in mm=\t");
    scanf("%d",&d);
    printf("\n\n\t enter the power to be transmitted in kw=\t");
    scanf("%d",&p);
    printf("\n\n\t enter the rpm of the shaft =\t");
    scanf("%d",&N);
    printf("\n\n\t enter the bearing pressure in N/mm2=\t");
    scanf("%f",&pb);
    printf("\n\n\t enter the allowable shear stress in shaft,keys ,flange =\t");
    scanf("%f",&ta);
    printf("\n\n\t enter the allowable stress in pin =\t");
    scanf("%f",&q);

    /* To find the torque*/
    T=(p*60000)/(2*3.14*N);
    T=(T*1000);
    printf("\n\n\t torque produced =\t%fN-mm",T);

    /* Suitability of shaft dia*/
    a=(16*T)/(3.14*ta);
    d0=pow(a,.33333);

    d0=fabs(d0)+1;
    if (d0<d)
    {
    d0=d;
    printf("\n\n\t d0=%fmm",d0);
    }
    else
    printf("\n\n\t Dia is not secure");

    /* No. of pins */
    n=(0.02*d)+5;
    if(abs(n)-n==0)
    i=abs(n);
    else
    {
    n=abs(n)+1;
    i=abs(n)+1;
    }
    if(i%2==0)
    n=n;
    else
    n=n+1;
    printf("\n\n\t no. of pins =\t%f",n);

    /* Pin dia*/
    d1=(0.5*d)/sqrt(n);
    b=abs(d1)+1;
    d1=abs(d1)+1;
    if(b<10)
    printf("\n\n\t The value of d1 is =\t%fmm",d1);
    else {
    if(b%2==0)
    printf("\n\n\t The value of d1 is =\t%fmm",d1);
    else
    {
    d1=d1+1;
    printf("\n\n\t The value of d1 is =\t%dmm",d1);

    }
    }
    qp=0;

    //farr[20] = am(d1,d,T,pb,n,ta);
    memcpy(farr,am(d1,d,T,pb,n,ta),sizeof(am(d1,d,T,pb,n,ta)));
    if (arr[10] > q)
    {
    for(int i=0;arr[10]>q;i++)
    {
    printf("\n\n*********************************************************");
    printf("\n\n*********************************************************");
    printf("\n\n\t ITERATION NO.%d",i+1);
    d1=d1+2;
    memcpy(farr,am(d1,d,T,pb,n,ta),sizeof(am(d1,d,T,pb,n,ta)));

    }
    }
    getch();
    return 0;
    }
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