attached to a mounting bracket 13 which is to be attached by welding or otherwise fixed to the frame 110 the mounting bracket can be attached to the bottom of the frame the side of the frame or the top of the frame the base of the bracket 13 aligns with the frame 110 and the pin 12 is projecting at an angle to the inclined surface of the bracket 13 the inclined surface is oriented at an angle u03b8 relative to the frame 110 as illustrated in fig9 a 9 b and 9 c the angle u03b8 should be equal to the tangent slope of the sprocket nest 101 as shown in fig9 a 9 b and 9 c the angle u03b8 was 30 degrees the angled guide arm 11 fits over the pin 12 and is rotatable about the pin 12 while it translates back and forth to line up with the sprockets in the nest 101 and thus the guide arm 11 rotates forward and translates sideways as shown in fig1 one embodiment includes the mounting plate disposed along a plane generally orthogonal to the axis of the roller sprockets the angled guide arm 11 as shown has a projecting tab 9 with a hole 15 for securing the gear shifting rod or.