120 N R FCD (//x) Ex Ey 60 60 D C C B Bx By A P

7. The pruning mechanism of a pole saw is shown as it cuts
a branch S. For the particular position drawn, the actuating
cord is parallel to the pole and carries a tension of 120 N.
Determine the shearing force P applied to the branch by the
cutter and the total force supported by the pin at E. The
force exerted by the light return spring at C is small and may
be neglected.
Two-force member: CD
FBD of member EDF
60
FCD (//x)
o
120 N
x
y
60o
Ex
R
Ey
R2=1202+1202+2×120×120×cos40 
ME  0
 Fx  0
 Fy  0
R=225.5 N
225.5 sin 4075  150  FCD sin 6075  0 
FCD  502 N
225.5 cos 20  FCD  E x  0

E x  290 N
225.5 sin 20  E y  0

E y  77 N
E  290 2  77 2  300 N
C
FCD
D
FCD
C
FCD
Bx
By
B
x
60o
A
75o
P
MB  0
P cos 1525  FCD sin 6075  0

P  1350 N