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Pivot Arm Toggle Formulae and Calculator

Pivot Arm Toggle Mechanism Design Formula and Calculator

Pivot Arm clamp design with forces applied and reaction forces calculator. Force is applied at Q and maintained by the spring between the pivot arm and stop collar.

Eq. 1
Q = P [ ( ( l + l1 ) + ( ( l + l1 ) / l1 - 1 ) r · fo / ( l1 - h · f1 ) ]

Eq. 2
P = Q / [ ( ( l + l1 ) + ( ( l + l1 ) / l1 - 1 ) r · fo / ( l1 - h · f1 ) ]

When n is designated

Eq. 3
Q = P [ ( l + l1 ) / l1 ] ( 1 / n )

Eq. 4
P = Q / [ ( l + l1 ) / l1 ] ( 1 / n )

Figure 1
Pivot Arm Toggle Mechanism

Where:

Q = force applied to handle. lbf, (N)
P = clamping force, lbf. (N)
fo = coefficient of friction (axles and pivot pins) = 0.1 to 0.15
f1 = coefficient of friction of pin contact surface = 0.1 to 0.15
n = efficiency coefficient, 0.98 to 0.84
l, l1 = length as indicated. in, (mm)
h = distance as indicated. in, (mm)
r = radius of pivot hole. in, (mm)

Reference:

Handbook of Machining and Metalworking Calculations
Ron A. Walsh
2001

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