In order to compare loaders and discuss them with customers, MPD has developed a system for describing a loader's variable dimensions. We use four measurements,
A = the setback of the leading edge from the front of the mount pad. B = the depth of the leading edge from the mount pad.
C = the length of the ramp.
D = the distance from the roof of the intake to the ramp, at a reference point in a fixture. The fixture simulates a suction piece on an intake adapter and the reference line is located on the roof, 14 inches back from the front of the mount pad.
A and B give us the position of the leading edge of the ramp in the inlet tract. C tells us how far the ramp carries the water into the inlet before releasing it. D tells the approximate aiming point of the ramps (aims the water high or low on the impeller).
A typical "Open Center River Racer" type loader would have dimensions like this:
Blockers are described by length and type (flat, V, etc). Most are installed at an angle of 13-14 degrees to the mount pad. This is usually parallel to the keel-shoe line.