IMPROVEMENTS IN APPARATUS FOR OPERATING THE DUST SIEVES AND THROTTLE VALVES OF VENTILATED MILLSTONES
Year: 1879

page_text: PROVISIONAL SPECIFICATION left by William Robert Lake at the Office of
the Cominissioners of Patents on the 6th October 1879. [A communication
from abroad by Wilhelm Seck, of Bockenheim, near Frankfort on the Main.
Germany.]
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. "IMPROVEMENTS IN APPARATUS FOR OPERATING
THE DUST SIEVES AND THROTTLE VALVES OF VENTILATED MILLSTONES." [A
communication from abroad by Wilhelm Seck, of Bockenheim, near Frankfort
on the Main, Germany.]
This Invention relates to an apparatus for operating automatically, and at
determined monents, the dust sieves in ventilated millstone-cases, and for operating
the valve of the exhauster pipe.
The said apparatus is of simple construction, and provides means for dispensing
with the shaking apparatus generally inserted between a pair of millstones, and the
so called self-acting apparatus heretofore employed.
In carrying the said Invention into practice I provide each pair of ventilated
millstones with a special apparatus, which is directly fastened on the upper part
of the case, and connected with the rods and levers for shaking the dust sieves, as
well as with the valve of the exhauster-pipe.
Two shafts, which I will hereinafter designate as the upper and lower shafts, are
journallod in two cast iron plates, one of which is cast in one piece with a bottom
piece, which is fastened on the circumference of the upper part of the millstone
caso. Wheels are placed upon the upper shaft, and revolve loosely on the latter,
whereas a pinion and a cam are fixed on the lower shaft, which extends down through
the mill floor, where it is guided in a bearing, and provided with a pulley in order
to transmit rotation from the mill-spindle to said shaft by means of a belt. The
lower shaft makes about forty revolutions per minute.
Three pinions (two on the upper shaft, and one on the lower shaft) form one
piece with respective wheels rotating loosely on the said shafts, and motion is
transmitted from the first pinion herein named to the wheel which is in connection
therewith, the motion being conveyed through the train, and finally imparted to
the last wheel of the same.
Each pinion has fifteen teeth, and each wheel sixty teeth, so that the last wheel
completes a single revolution at every 256th revolution of the lower shaft.
Supposing this shaft to make forty revolutions per minute the last wheel requires
about six minutes and a half for a complete revolution.

page_text: A disc concentrically fixed on the last wheel is provided with a recess, into
which falls at every revolution of the said wheel the nose of a pawl turning around
pivots. While the pawl is engaged in the said recess the shaking of the dust-sieves
takes place, by imparting at every revolution of the lower shaft an oscillating
motion to a lever by means of the fixed cam herein before mentioned; this lever
being connected with the moving mechanism of the dust-sieves by a connecting
rod, and being constantly moved towards the lower shaft with one of its armsthe
virtue of the weight of the free hanging part of the dust-sieves, transmits by
motion imparted to it through the said connecting rod upon the dust sieves, which
are thus alternately raised and lowered.
The nose of the said pawl can only then fall into the recess after the straight
edge of a cam cast on the body of one of the wheels and one of the pinions, and
provided with a straight edge and a curved edge, has completely passed the recess
in the disc, and will be able to rest therein until it is gradually driven out of said
recess by the curved edge of the said cam. The face of the nose of the pawl then
slides on the circumference of the cam just mentioned. At the moment when the
straight edge of the latter has left the nose of the pawl the last wheel is already as
much advanced as to ensure an engagement of the pawl into the said recess being
no longer possible. The said nose will now slide on the circumference of the round
or curved part of the aforesaid disc till it meets again with the recess, which takes
place about every six and a half minutes.
As the last wheel advances while the shaking of the dust sieves is being effected,
the recess in the disc must be just of such a width that a disengagement of the
pawl is still possible without pinching at the sides of the said recess.
The duration of the engagement of the pawl in the recess in the disc depends
upon the relative number of teeth in the first named pinion on the lower shaft and
in the last wheel, as well as on the length of the arc of the last named cam.
latter is thus so arranged that at every engagement of the pawl the dust-sieves are
raised and lowered nine times.
The
While the face of the pawl's nose slides upon the circumference of the disc the
aforesaid lever cannot come in contact with the cam on the lower shaft, as a bowed
or curved part of this lover abuts against the back of the pawl, and one of the
lever arms is thereby prevented from moving towards the lower shaft.
Care is to be taken to impart rotation to the wheel on which the cam is cast only
in the proper direction, otherwise the straight edge of the cam would strike against
the face of the pawl's nose, rendering thereby a disengaging of the latter out of the
recess in the disc impossible.
This automatic or self acting apparatus is at the same time put in communication
with a valve in the exhauster pipe by a stud, which is screwed into the pivot of
the aforesaid pawl.
A tappet placed loosely on a spindle, but directly connected with it by means of
a screw bolt with thumb nut, and of a sector fixed on the said spindle, receives
thereby a partial rotation, the stroke of which may be regulated by adjusting the
screw bolt in the circular slot of the said sector.
The size of the tappet is so much smaller the less the valve has to open the
passage in the exhauster pipe, therefore the current of air may be regulated.
The closing of the valve is effected automatically, having one of its halves as
much weighted as to enable the valve to fall easily down, notwithstanding the
resistance caused by friction.
The whole of the said self-acting apparatus is completely covered by a box of
metal, which lies upon projections running around the aforesaid plates.