on the beam 11 by means of rollers not shown the length of the board is greater than one half the length of the beam as depicted in fig1 and 7 an exerciser manipulates a rope and pulley system while he is positioned on the board 27 to move the board up and down the system is described later on for a given exercise and often for a given exerciser the beam 11 has to be positioned at a given angle to the floor on which the bars 14 and 16 rest to change the angle of the beam 11 the knob 26 is pulled and the bracket 24 is moved along the length of the leg 10 until the beam 11 has the desired inclination the knob 26 is released for the plunger to enter an appropriate hole in the leg 10 in the process of changing the inclination of the beam 11 the inclination of the leg 10 relatively to the floor also changes effectively the lower end of the beam pivots about the pins 19 while the lower end of the leg 10 pivots about the centres of the ball heads 21 the geometry is such that in use the leg 10 always forms an angle of less than 90 u00b0 with the floor however low down on the leg 10 there is a hole 31 for the plunger in.