Shaft′ing.
（
Machinery.) The principal means in a machine-shop for the transmission of power.
It serves to convey the force which is generated in the engine to the different working-machines, for which purpose it is provided with drums and belts, or else cog-wheels firmly keyed on.
Horizontal shafts are known as
lying; vertical, as
upright.
Their
stiffness resists
flexure and
torsion; their
strength resists
fracture. The
stress is the power tending to break them.
A,
Fig. 4899, represents a portion of a line of shafting attached to beams of a ceiling.
The hangers
a are secured to the beams by bolts, and are provided with swivel-boxes
b, facilitating adjustment and keeping of the shafting in line.
These are adjustable in hight by bolts and nuts.
c are oil-drip cups,
d a pulley, and
e the coupling which unites two lengths of the shaft.
These are shown in contact, but disconnected.
at
B. C C are inside and outside views of the coupling proper
D, one half of the coupling, with its appendages complete.
E E are the
thimbles, and
F F the securing nuts.
The cylindrical interior of the coupling is bored with a
shim between the two sections, so as to allow something for compression or hug. These are placed over the butting ends of the shaft-sections, and secured thereto by pins, if desirable; the thimbles or cone-rings are slipped over them, and the nuts
F F screwed on with a spanner, binding the whole together.
In
Fig. 4900,
A shows another pattern of shafting, with hangers and appurtenances.
The journal-box
a is held between two pintles or stems
b c, the ends of which are concave, those of the
[
2129]
box bearing being convex, so as to form a species of ball and socket joint, and allow the box to adjust itself to the alignment of the shaft.
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Shafting. |
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Shafting. |
The box is self-lubricating; the oil, after being drawn up from a reservoir below by the rotation of the shaft, and performing its office, is again returned to the reservoir, the drip-cup being dispensed with.
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Plummer-block. |
Fig. 4901 is a cast-iron plummer-block; it is lined with gunmetal or
Babbitt metal, and supported on a wall-plate having snugs between which the block fits, and is adjusted in line with the shaft by cotters driven between its ends and the snugs.
Fig. 4902 is a form of flexible shafting, avoiding the use of gearing.
See also flexible coupling, page 882.
It sometimes becomes necessary to take down a section of shafting, drive out keys, and remove couplings, merely to slip on a pulley.
To obviate this necessity, pulleys have been made in sections, to be keyed together on the shafting.
Preferable to this is an arrangement by which a small section of hub and rim are made removable.
In
Wheeler's (
C, Fig. 4900), one or more of the arms of the pulley are enlarged, or divided, admitting a piece shown at
a, a casting separate from the pulley, and easily fitted to the latter by the file.
This supplementary piece has a section of the hub embracing one half of the shaft.
It engages with the rim of the pulley by a parallel cut, divided in the center at right angles.
This form of division, however, is not material.
The piece is held in place by a bar
b, passing through the true arms of the pulley and the false arms of the segment, and held in place securely by a set-screw
c. Instead of this arrangement the bar may be a single key without set-screw.
There is no set-screw to mar the shaft, and no key in the hub of the pulley or keyway on the shaft to be cut. Most of the fitting required is at the rim, as the hub portion may be cast accurately enough and the key may be forged to fit.
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Universal shafting. |
