The principles of a differential chain block are indicated schematically in the figure. Determine the magnitude of force P needed to support the 800-N force. Also compute the distance x where the cable must be attached to bar AB so the bar remains horizontal. All pulleys have a radius of 60 mm

The principles of a differential chain block are indicated schematically in the figure. Determine the magnitude of force P needed to support the 800-N force. Also compute the distance x where the cable must be attached to bar AB so the bar remains horizontal. All pulleys have a radius of 60 mm

Solution

 At Left block.

Each rope on left block 800/4=200N.
Last rope also is equal 200N.

At Right block:
Same principle,
P=200/5=40N.

Let's call left block top line joint points A, B(hook point), C, D.
B=200.
Each Pulley point load is 40+40=80N.
C=80.
D=80.
sum of M(A)=0.
200 * x - 180 * 80 - 420 * 80 = 0.
200 * x = 48000.
x = 240mm.