DOI Seite / Zitierlink:
https://doi.org/10.11588/diglit.25888#0066
50
ENGINEER AND MACHINIST’S DRAWING-BOOK.
three of them are supposed to be removed, to show the
size of the holes and thickness of metal round them. The
bolt holes in the sole of the pillow-block are made oblong
longitudinally, to admit of accurate adjustment within
certain small limits in this direction, so as to compen-
sate for inaccuracies of workmanship, affecting the posi-
tion of the centre. When properly adjusted, the whole
is usually rendered immovable by employing, in addition
to the holding-down bolts, keys of wood or iron, driven
firmly between the ends of the sole and suitable snugs cast
upon the sole-plate.
In drawing the pillow-block, the ground line A B is
first drawn; then the centre line, S T, of the plans may be
drawn, and the vertical centre lines, F G, H I, of the
figures. The height of the centre of the bearing, C, is
next set off, and a horizontal line drawn through it. On
the centre C, circles are described to show the diameter of
the journal, and the thickness of the bush which is circular,
and also to show the thickness and contour, i k, of the
cover. In the plan, Fig. 2, the breadths of the upper and
lower parts of the block, x y, x' y, are set off, and parallels
drawn through the points. The length of the sole is also
set off, and, in Fig. 4, the inside width of the bush, 0 0, the
thickness of the bush, and the width apart, 9 inches of the
jaws of the block. The centre-lines K L, M N, 0 P, QR,
of the cover bolts, and the centre lines l, to, of the sole
bolts, are then laid down, and an inspection of the draw-
ing will show the succeeding steps to be taken for the
completion of the drawing.
When the section is taken through a bolt-hole, as in
Fig. 3, the bolt, if shown at all, should be left in full,
unsectioned, as at d. The same recommendation applies
in all similar cases, where a central core, as it were, is laid
bare. The effect is good, and the method of illustration
adds to the distinctness of the drawing.
Projections of a Standard and of a Hanging
Bracket.—Plate XIII.
The standard is simply a modification of the pillow-
block, being employed for the support of horizontal shafts
situated at a considerable distance above the foundation
plate or sole, to which the part destined for the reception
of the journal is joined by limbs whose forms and dimen-
sions vary according to the relative positions of the sole
and axis, the strain to which it is to be subjected and the
characteristic forms of the adjacent parts. Its use is
confined mostly to the lighter description of machinery.
Fig. 1 is a front elevation, Fig. 2 a plan, and Fig. 3 an
end elevation of a piece of machinery such as we now refer
to; the mode of its attachment to the foundation-plate (a
portion of which is represented in dotted lines in Fig. 1),
is precisely the same as that of an ordinary pillow-block.
Fig. 4 is a plan of the body of the standard, with the
cover removed. Having laid down the directing lines of
the drawing, and arranged the positions of the figures, as
already explained, let A B represent the plan of the under
surface of the standard, and upon the vertical centre line
.C D set off above A B the distance (17 inches) from the
sole to the centre; then draw the circle of the bearing and
the outlines of the brasses, in the manner indicated in the
preceding plate. Now, set off, and represent by appro-
priate lines, the axes of the cover bolts, the thickness of
metal round their holes, as also that of the cover itself
above the upper brass; the plane a i against which the
nuts of the bolts F and G bear, and the outlines c h and
dg of the body of the cover, which, it may be observed,
coincide in all cases with the axes of the cover bolts.
Then having drawn the horizontal line e f, mark off
according to the measurement indicated, the points e and
/, at equal distance on either side of the centre line C D,
and through these points respectively draw quadrants of
circles tangents to e f and to the lines c h and d g.
The length and thickness of the sole being now marked
off and delineated, the only remaining feature in the front
elevation worthy of special notice is the determination of
the curvature of the exterior limbs of the standard. This
is a point on which the designer is at liberty to exercise
his taste; the ordinary form given to these parts, how-
ever, is that of circular arcs. In the example now before
us the curvature of the external outline is obtained by
taking a radius of 16 inches, and from the points e and k,
f and l, as centres, describing arcs whose intersections
give the centres of the circular arcs required. The lines
representing the thickness of metal are, of course, drawn
from the same centres ; and are to be united to the hori-
zontal lines representing the upper surface of the sole and
lower surface of the body of the standard by small circu-
lar arcs whose radius may be taken at pleasure. The
central limb is rectilinear and vertical, and its outlines
are terminated by arcs of the same radius.
In constructing the front elevation of this object, the
learner should, at the same time be careful to mark off
upon Figs. 2 and 3 the outlines of all such parts as are
immediately transferable by the help of the square and
compasses from the one figure to the other.
Passing to the end elevation, we have first to determine
the centre of the circular arc e k, which forms the an-
terior outline of the limbs of the standard. The centre
of this arc is upon the line e f produced, and that radius
is determined by the condition that it should be such as
to touch the line c e and pass through the point k. To
find the projection of this arc upon the plan, Fig. 2, draw
through any points to and n, taken at pleasure upon the
arc e k (Fig. 3), the horizontals mm, n n; and through
to and n (Fig. 1), draw to to, and n n, parallel to CD;
then set off the distances 0 m and p n (Fig. 3) to the cor-
responding points on the lower side of the centre fine M N
(Fig. 2); by this means the curve fmnl will be deter-
mined. By a similar method the curve d to' to', will be
obtained; as also the projections of all such arcs as are
denoted by r g (Fig. 3).
The last point to be attended to in the construction of
these projections is the mode of drawing correctly upon
Fig. 3, the curve s t h, which is the line of penetration of
two cylinders. To insure accuracy, it is proper, in such
cases, to transfer the operations to another part of the
ENGINEER AND MACHINIST’S DRAWING-BOOK.
three of them are supposed to be removed, to show the
size of the holes and thickness of metal round them. The
bolt holes in the sole of the pillow-block are made oblong
longitudinally, to admit of accurate adjustment within
certain small limits in this direction, so as to compen-
sate for inaccuracies of workmanship, affecting the posi-
tion of the centre. When properly adjusted, the whole
is usually rendered immovable by employing, in addition
to the holding-down bolts, keys of wood or iron, driven
firmly between the ends of the sole and suitable snugs cast
upon the sole-plate.
In drawing the pillow-block, the ground line A B is
first drawn; then the centre line, S T, of the plans may be
drawn, and the vertical centre lines, F G, H I, of the
figures. The height of the centre of the bearing, C, is
next set off, and a horizontal line drawn through it. On
the centre C, circles are described to show the diameter of
the journal, and the thickness of the bush which is circular,
and also to show the thickness and contour, i k, of the
cover. In the plan, Fig. 2, the breadths of the upper and
lower parts of the block, x y, x' y, are set off, and parallels
drawn through the points. The length of the sole is also
set off, and, in Fig. 4, the inside width of the bush, 0 0, the
thickness of the bush, and the width apart, 9 inches of the
jaws of the block. The centre-lines K L, M N, 0 P, QR,
of the cover bolts, and the centre lines l, to, of the sole
bolts, are then laid down, and an inspection of the draw-
ing will show the succeeding steps to be taken for the
completion of the drawing.
When the section is taken through a bolt-hole, as in
Fig. 3, the bolt, if shown at all, should be left in full,
unsectioned, as at d. The same recommendation applies
in all similar cases, where a central core, as it were, is laid
bare. The effect is good, and the method of illustration
adds to the distinctness of the drawing.
Projections of a Standard and of a Hanging
Bracket.—Plate XIII.
The standard is simply a modification of the pillow-
block, being employed for the support of horizontal shafts
situated at a considerable distance above the foundation
plate or sole, to which the part destined for the reception
of the journal is joined by limbs whose forms and dimen-
sions vary according to the relative positions of the sole
and axis, the strain to which it is to be subjected and the
characteristic forms of the adjacent parts. Its use is
confined mostly to the lighter description of machinery.
Fig. 1 is a front elevation, Fig. 2 a plan, and Fig. 3 an
end elevation of a piece of machinery such as we now refer
to; the mode of its attachment to the foundation-plate (a
portion of which is represented in dotted lines in Fig. 1),
is precisely the same as that of an ordinary pillow-block.
Fig. 4 is a plan of the body of the standard, with the
cover removed. Having laid down the directing lines of
the drawing, and arranged the positions of the figures, as
already explained, let A B represent the plan of the under
surface of the standard, and upon the vertical centre line
.C D set off above A B the distance (17 inches) from the
sole to the centre; then draw the circle of the bearing and
the outlines of the brasses, in the manner indicated in the
preceding plate. Now, set off, and represent by appro-
priate lines, the axes of the cover bolts, the thickness of
metal round their holes, as also that of the cover itself
above the upper brass; the plane a i against which the
nuts of the bolts F and G bear, and the outlines c h and
dg of the body of the cover, which, it may be observed,
coincide in all cases with the axes of the cover bolts.
Then having drawn the horizontal line e f, mark off
according to the measurement indicated, the points e and
/, at equal distance on either side of the centre line C D,
and through these points respectively draw quadrants of
circles tangents to e f and to the lines c h and d g.
The length and thickness of the sole being now marked
off and delineated, the only remaining feature in the front
elevation worthy of special notice is the determination of
the curvature of the exterior limbs of the standard. This
is a point on which the designer is at liberty to exercise
his taste; the ordinary form given to these parts, how-
ever, is that of circular arcs. In the example now before
us the curvature of the external outline is obtained by
taking a radius of 16 inches, and from the points e and k,
f and l, as centres, describing arcs whose intersections
give the centres of the circular arcs required. The lines
representing the thickness of metal are, of course, drawn
from the same centres ; and are to be united to the hori-
zontal lines representing the upper surface of the sole and
lower surface of the body of the standard by small circu-
lar arcs whose radius may be taken at pleasure. The
central limb is rectilinear and vertical, and its outlines
are terminated by arcs of the same radius.
In constructing the front elevation of this object, the
learner should, at the same time be careful to mark off
upon Figs. 2 and 3 the outlines of all such parts as are
immediately transferable by the help of the square and
compasses from the one figure to the other.
Passing to the end elevation, we have first to determine
the centre of the circular arc e k, which forms the an-
terior outline of the limbs of the standard. The centre
of this arc is upon the line e f produced, and that radius
is determined by the condition that it should be such as
to touch the line c e and pass through the point k. To
find the projection of this arc upon the plan, Fig. 2, draw
through any points to and n, taken at pleasure upon the
arc e k (Fig. 3), the horizontals mm, n n; and through
to and n (Fig. 1), draw to to, and n n, parallel to CD;
then set off the distances 0 m and p n (Fig. 3) to the cor-
responding points on the lower side of the centre fine M N
(Fig. 2); by this means the curve fmnl will be deter-
mined. By a similar method the curve d to' to', will be
obtained; as also the projections of all such arcs as are
denoted by r g (Fig. 3).
The last point to be attended to in the construction of
these projections is the mode of drawing correctly upon
Fig. 3, the curve s t h, which is the line of penetration of
two cylinders. To insure accuracy, it is proper, in such
cases, to transfer the operations to another part of the