abutments 94 and 96 it cannot rotate in a counterclockwise direction fig5 but with swing arm 14 in the extreme position shown latch arm 124 128 is not in abutment with arcuate camming surface 130 hence ski 70a and pivotal mount 22 can rotate in a clockwise direction extended spring 110 is resisting such rotation at this particular position of the apparatus reffering now to fig6 as the ski is pulled a few inches forward latch arm 124 is brought into abutment with arcuate camming surface 130 thereby preventing clockwise rotation of ski 70a this movement is provided by the practicing skiers pulling on tow handle 34 and applying pressure against the ski 70a with his legs as further effort is extended by the practicing skier to move the ski forward extended spring 108 collapses and opposing spring 110 begins to exert a pulling force in this phase of the operating cycle air shock 34 is compressed but is pushing in a straight vertical direction as swing arm 14a has rotated to a position where end portion 14b is directly aligned with fixed arm 26 no work is required to hold ski 78 in this center position between the two extreme positions of the swing arms rotation when using the machine the momentum of the practicing skier 39 s weight and.