Improvements in Automatic Belt Shifting Gear.
Year: 1898

page_text: Date of Application, 20th July, 1898-Accepted, 27th Aug., 1898
COMPLETE SPECIFICATION.
Improvements in Automatic Belt Shifting Gear.
I, ALFRED EUGENE MATHEWSON, of Atlantic Works, Broadheath, in the County
of Chester, Engineer, do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement:-
The object of this invention is to provide means for automatically shifting the
belts of machinery in general, but the invention relates more particularly to belt
driven fluid compressors.
In that class of fluid compressors where the consumption of the compressed
fluid is irregular, it is desirable to have means for automatically throwing the
belt off and on the fast and loose pulley, as the pressure increases or decreases
beyond that required to carry on the operations for which the compressed fluid
is to be employed.
In the accompanying drawings,
Fig. 1 is a side elevation of an air compressor, with the invention applied
thereto.
Fig. 2 is a plan view of the same.
Fig. 3 is a side elevation, partly in section, and on an enlarged scale, of the
belt shipper arrangement; and
Fig. 4 is a plan view thereof.
Referring now to Figs. 1 and 2, A is the compressor, which is operated by the
crank shaft B, on which are' mounted a fly wheel C and a fast and loose pulley C¹ C³.
The pulleys C¹ C³ are driven by belt from the engine, or in any other convenient
manner.
When the pressure in the compressed fluid reservoir exceeds a certain amount,
the belt is shifted from the fast pulley C¹ to the loose pulley C³, and the com-
pressor is thus stopped working, but as soon as the pressure is decreased below,
the requirement, then the belt is shifted back again onto the fast pulley, and
the compresser is again started.
The belt-shipper is carried by a bed plate D, mounted on brackets D¹ bolted
to the main frame of the compressor.
Referring now to Figs. 3 and 4, the belt shipper consists of three parts, namely,
an operating mechanism E, a regulating mechanism F, and the belt shipper
proper G, all of which are secured to the bed plate D.
The operating mechanism consists of a frame or standard E, in which a shaft E¹
is mounted. This shaft is continuously driven from an overhead shaft (not shown),
through a band round the pulley E2 on the end of the shaft E¹. Upon the shaft
is mounted loosely, between two discs E³, set at an inclination a strap a, provided
with a projecting pin b, which enters a recess in, and (with a motion like what
is known as a drunken saw motion) gives a rectilinear reciprocating movement
to a bar c, which slides in guides in the standards E. This bar c has an up-
wardly-turned arm d, and a guide, rod e.

page_text: The regulator consists of a cylinder F, in connection, by the pipe f, with the
compressed fluid receiver. F¹ is a piston or plunger which carries, at its upper
end, a sleeve or pierced boss F2, in which slides a bar F3. This bar carries, at
one end, a socket F4, in which the turned-up part d of the operating bar c loosely
enters. F5 is a guide, and above this guide the piston or plunger, or its rod, is
loaded with weights F6, corresponding to the pressure it is desired to sustain in
the receiver.
If the pressure is greater than required, the piston F¹ is forced upwards. If
the pressure is lower, the piston descends, under the influence of the weights.
As the bar c of the operating mechanism is caused to reciprocate, so the bar F3
with which it is connected will also reciprocate, for a purpose to be explained.
The belt-shipper proper consists of the frame G, which carries the bearings for
a sliding rod G¹, on which the shifting prongs G2 are secured.
His a shaft mounted in suitable bearings, and having at about the centre of its
length a pinion H¹. Mounted on the end of this shaft H is a crank arm H2, the
pin of which enters a slot in an arm H³ keyed on the sliding rod G¹.
As this pinion rotates in one direction, as will be presently described, the crank
arm is rocked from one side to the other, and, through the rod G¹, the prongs G2
are shifted laterally, to move the belt onto or off the fast pulley C¹.
The movement of the pinion H¹ is effected by means of the racks J J', which are
kept in contact with the pinion in any convenient manner.
The position of the parts, as shown on the drawing, is that which they will
assume when the belt is on the fast pulley.
In this position, the bar F3, in its reciprocations, has forced the rack J' to the
left, and it is kept in that position by the bar F3 striking it at each reciprocation..
When the pressure increases in the receiver,, the piston F1 of the regulator is
raised, and with it the sleeve F2 and bar F. This bar, in its reciprocations, will
now strike against the rack J, which will thus be forced to the left, the rack J¹
coming to the right. This movement of the bar J will throw the crank arm H²
over to the left, and thus move the sliding rod Ġ in the same direction, shifting
the belt onto the loose pulley C2, and arresting the action of the compressor.
When the pressure decreases, the piston F1 will descend, and the bar F3 will
be brought against rack J, reversing again the position of the crank arm H³, and
bringing the belt on to the fast pulley C', thus starting the compressor again.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is
1. The automatic belt shipping or shifting mechanism as herein shown and
described.
2. In an automatic belt shipper operated by fluid pressure conveyed to a cylinder,
the use of a weighted piston or plunger having a sleeve or pierced boss, and a
reciprocating bar to which motion is communicated in any suitable manner, as
and for the purpose set forth.
.
3. In an automatic belt shipper the combination of two racks or bars moving
in opposite directions, a pinion, a crank arm on the pinion axle, and a pronged
shifting bar, all substantially as herein shown and described, and operated as set
forth.