Sometimes, in making a comparison of receiving openings, it is helpful to make a scale drawing of both openings, superimposing one upon the other. The rectangular jaw opening is simple and easy to layout. To draw the gyratory opening, it is necessary to know the top diameter of the crushing head; to make a complete sketch, the diameter of the spider hub and the width of the spider arms should also be known, but this information is not absolutely essential in making the comparison. Taking half the top diameter of the head as a radius, draw the circle which represents the top of the head; then, increasing the radius by the actual opening between head and concaves at their tops, draw the circle representing the concave ring at the top of the crushing chamber. Then superimpose the diagram of the jaw crusher opening, laying it in tangent to the head circle.
Gyratory Jaw
20-in. 36- x 24-in. 30-in. 42- x 30-in. or 42- x 40-in: 36-in. 48- x 36-in. or 42- x 40-in. 42-in. 60- x 48-in. or 48- x 42-in. 50-in. 84- x 56-in. 54-in. 84- x 60-in. 60-in. 84- x 60-in.
To facilitate this work for the line of Superior McCully gyratory crushers, we list in the following table the top diameters of the heads, and openings between head and concaves for straight-face, and non-choking, concaves.
Laying in the plan view of the spider hub and arms will, of course, give a more complete picture of the gyratory crusher receiving openings, but the picture is likely to be a little misleading unless it is borne in mind that the maximum diameter of the spider hub is some distance above the upper rim of the
crushing- chamber, and therefore does not restrict the receiving opening- as much as the plan view indicates. The true effective receiving opening can only be shown in its proper proportions by tilting the plan view; that is, by an angular projection normal to a plane which is tangent to the bulge of the spider hub, and to the top of the crushing head. To draw such a view requires more information-and usually more drafting skill-than the average man has at his disposal. The circle method described in the second preceding paragraph is sufficiently close for all practical purposes.
