The 4DOF Trebuchet with Moving Cart
The 4DOF trebuchet with moving cart is shown in the figure above. This has all the features of the traditional 3DOF trebuchet but adds a moving cart to help the counterweight move straight downward. When designed correctly, the forward velocity of the cart adds to the launch velocity of the projectile, and results in a very efficient trebuchet.
The required dimensions are the same as for the 3DOF trebuchet, with the addition of the cart mass. The height of the pivot, H, must be less than the arm length L2 plus the sling length L3 or the trebuchet won't have a valid starting angle.
