When a piston moves inside an engine, it exerts a force on the connecting rod, which in turn exerts a force on the crank pin. The force exerted by the connecting rod on the crank pin can be resolved into rectangular forces at the crank pin. In this article, we will discuss how to resolve forces on the crank pin and calculate the rectangular forces.


The force exerted by the connecting rod on the crank pin is given as 2225N. We need to calculate the rectangular forces at the crank pin.


To calculate the rectangular forces, we first need to calculate the angle between the connecting rod and the crankshaft. This angle is given by the formula:

sinθ = r / L

Where θ is the angle between the connecting rod and the crankshaft, r is the radius of the crank pin (254mm), and L is the distance between the piston and the center of the rotating engine (508mm).

sinθ = 254 / 508
θ = sin-1 (0.5)
θ = 30°


Once we have calculated the angle θ, we can calculate the rectangular forces at the crank pin using the following equations:

Fy = F * sinθ
Fx = F * cosθ

Where F is the force exerted by the connecting rod (2225N), Fy is the force in the y-direction (perpendicular to the crankshaft), and Fx is the force in the x-direction (parallel to the crankshaft).

Fy = 2225 * sin30°
Fy = 1112.5N

Fx = 2225 * cos30°
Fx = 1927.8N

Therefore, the rectangular forces at the crank pin are Fx = 1927.8N and Fy = 1112.5N.


In conclusion, we can resolve the force exerted by the connecting rod on the crank pin into rectangular forces at the crank pin. We first calculate the angle between the connecting rod and the crankshaft, and then use this angle to calculate the rectangular forces. These rectangular forces are useful in analyzing the stresses on the crankshaft and designing the engine components accordingly.