<p>The clearance between the crosshead and the guide plates in the power end of a fracturing pump is a critical factor affecting its dynamic characteristics. The crosshead moves reciprocating between the upper and lower guide plates, forming a moving pair that operates in a semi-contact state. This condition results in continuous impacts and collisions between the crosshead and the guide plates, leading to wear and deformation of both components. Consequently, this wear significantly reduces the service life of the fracturing pump and poses potential risks to the safety of fracturing operations. This paper establishes a motion model for the crosshead based on a clearance-link modeling approach applied to crank–slider mechanisms. By analyzing the dynamic characteristics of the crosshead and guide plates, the study investigates the influence of contact pressure during the “contact–departure–collision–contact” process of the moving pair. The research findings indicate that when the crosshead changes direction, the contact pressure between the crosshead and the guide plates increases significantly due to the presence of clearance in the moving pair. When the clearance is 1&#xa0;mm, the contact pressure between the crosshead and the guide plates reaches 1.5 × 10⁵ N. Considering the material properties and the load-bearing area of the crosshead, this contact pressure approaches the compressive strength limit of the base material. Due to the extremely brief duration of this effect, it manifests as a violent impact force exerted by the crosshead on the guide plates, which is consistent with the observed deformation and fracture of components caused by excessive impact loads in field tests.</p>