In order to solve the problems of incomplete balance equation, inaccurate balance equation and large error of cam contour caused by the influence of piston deflection on cam dynamic moment in existing cam construction of pedal brake unit, the structure of pedal brake cam and output force stability were studied. Firstly, the concept of optimum compensation angle is introduced, and the rotating moment of the thrust caused by piston deflection in two directions to the cam articulation point is included in the new balance equation, which makes the balance equation more complete, accurate and has less error. Based on this, a new cam mechanism is designed and constructed. Then, on the pedal brake unit routine tester, a comparative experiment is carried out on the stability of output force value between the original cam mechanism and the newly constructed cam mechanism with optimized compensation angle. Finally, the above data and the curves of action travel and output force are comprehensively compared and analyzed. The results show that the output force value stability of cam with compensation angle is better than that of cam without compensation angle. In actual operating stroke, the maximum difference of output force between two times is (-0.8, +0.6) kN with compensation angle cam error, and (-1.2, +1.2) kN without compensation angle cam error. The error with compensation angle cam is also less than that without compensation angle cam error.

tread brake  /  equilibrium equation  /  cams  /  output force  /  stability