A hand squeezes the handles of a pair of pliers with 120 N each, 140 mm from the pin O. The jaws grip a bolt 40 mm from the pin. Find the gripping force Q on the bolt.
Frames & machines worksheet with answers
The bell crank shown turns about the pin O. A vertical force of 400 N acts at A, 150 mm from O, and is balanced by a horizontal force Q at B, 75 mm above O. Find Q.
The A-frame shown stands on a pin at A and a roller at B, 2.4 m apart, with its apex pin C 4 m high and the horizontal tie DE 0.8 m above the ground. A vertical load of 2 kN acts on leg AC at K, 0.6 m (horizontally) from A. Find the tension T in the tie.
The frame shown has pins at A, B and C; A and C are fixed to the ground 6 m apart, and B is 2.5 m above the ground and 2.7 m to the right of A. A vertical load of 10 kN acts on member AB at K, 1.35 m (horizontally) from A. Find the force FBC in member BC.
The A-frame shown stands on a pin at A and a roller at B, 3 m apart, with its apex pin C 2.5 m high and the horizontal tie DE 1 m above the ground. A vertical load of 10 kN acts on leg AC at K, 0.375 m (horizontally) from A. Find the magnitude of the force C that the pin C exerts on leg BC.
A toggle press has two equal links AB and BC, each 120 mm long between pins. The joint B sits 20 mm above the line AC. Which downward force F at B produces a horizontal pressing force of 1500 N at the slider C? Neglect friction and weights.
Answer key
- 1. Q = 420 N
- 2. Q = 800 N
- 3. T = 0.1875 kN
- 4. FBC = 3.726 kN
- 5. C = 1.768 kN
- 6. F = 507.1 N
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