Appliance for Automatically Varying the Speed of Mechanism Driven by a Crank Shaft during the Motion thereof.
Year: 1896

page_text: Date of Application, 25th Jan., 1896-Accepted, 29th Feb., 1896
COMPLETE SPECIFICATION.
Appliance for Automatically Varying the Speed of Mechanism
Driven by a Crank Shaft during the Motion thereof.
I, JOHANNES GRIMME of Baarestrasse No. 3 Bochum, Germany, 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 :-
This invention relates to a mechanism, actuated by the machinery with which it
is connected, which enables the speed of moving parts actuated from a crank shaft
to be varied at will, or to enable them to be stopped altogether, without in any
way interfering with the motion of the crank shaft itself.
Figure 1 of the accompanying drawings shews the mechanism in combination
with one of the well known reciprocating driving gears, of which Figure 2 shews
a vertical section;
Figure 3 shews a front view of the mechanism for varying the speed;
Figures 4 and 5 shew side views of modifications of the construction shewn at
Figure 2.
The crank a of the shaft revolving in the bearings k carries a guide in
which a slide carrying the crank pin b can be shifted by means of a screw spindle c.
This screw spindle c carries at the end next the shaft a bevil pinion gearing
with two other bevil pinions d and e, Figure 3.
The latter two are fixed on shafts
situated concentrically within the crank shaft, with their other ends projecting
Over these
from the latter, and on these ends are fixed the friction discs f and g.
discs is situated a T headed lever pivoted to a fixed support at i, the longer arm
of which lever serves as a hand lever while the two short arms carry brake
blocks fg, pivoted thereto in such manner that on moving over the lever h
to the one side or the other, either the friction disc f is held stationary by the
block for the friction disc g is held stationary by the block g. From this
arrangement it will be seen that by the rotation of the crank shaft driven by a belt
pulley t, or otherwise, the two pinions d e and consequently the discs f g will also
be carried round thereby. If however by moving over the lever h one of the two
discs and g and consequently the pinion fixed to its shaft be held stationary,
the pinion e fixed on the screw spindle e will be caused to roll round upon the
stationary pinion, and consequently the crank pin b will be shifted towards or from
the crank shaft.
According as the stroke of the crank is lengthened or shortened by such shifting
of the crank pin, the peripheral speed of the latter will be increased or decreased,
and in consequence hereof the mechanisms which are actuated by the crank pin
will be made to move with a corresponding increased or decreased speed. The
adjustment of the crank pin b is so arranged that the speed can be reduced to zero,
by bringing the centre of the crank pin in the axial line of the shaft.
In this position all movement of the driving gear connected to the crank will
cease, although the crank shaft continues to rotate at its original speed.
In the drawing the above described mechanism is combined with an arrangement
which admits of a reversal of the motion, independly of the change of speed.
This arrangement consists, as shown at Figures 1 and 2, of a lever m mounted
loose on the shaft o, the free end of which lever is connected by a connecting rod
with the crank pin b.

page_text: By the rotation of the crank shaft a the lever m will receive a reciprocating
motion the extent of such motion depending upon the stroke, for the time being of
the crank a.
On the lever m are mounted two opposite pawls p and q pivoted to m at r, of
which pawls, for example, p is shewn in the drawing gearing with the V sbaped
groove of a friction disc n fixed on the shaft o, so that at each stroke of lever m
to the left hand the friction disc n and shaft o will be rotated through a
corresponding angle, while on the movement of m to the right, the pawl p will
slide over the disc n.
By making the pawl 9 gear with the friction dise n in place of pawl p, the
direction of rotation of the shaft will be reversed.
For producing a uniform rotary motion of shaft o, this is provided with a fly-wheel s.
When greater power has to be transmitted, the friction ratchet device can be
replaced by a toothed ratchet mechanism as shewn at Figure 4, and in place
of transmitting the motion by a connecting rod and lever, it may be effected by a
toothed rack and spur wheel as shewn at Figure 5.
As by the alteration of the stroke of the crank a, the stroke of the lever mis
also altered, while the speed of the crank shaft remains the same, there will of
course result a change of speed of the shaft o as the lever m must perform its
larger strokes in the same time as its smaller strokes.
It will be evident that in place of the friction discs ƒ and g and their brake
blocks fg, any equivalent known mechanism, such as ratchet wheels and
pawls may be employed.
Having now particularly described and ascertained the nature of this inven
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. Appliance for automatically varying the speed or stopping the motion of
mechanism actuated by a crank shaft, consisting in a crank pin, whose position
can be varied on the crank, for varying its stroke, by means of a screw spindle c
carrying a bevel pinion cl which is made to roll upon one or other of two opposite
bevel pinions d or e, such pinion being at the time held stationary by means of a
brake disc g or f, or equivalent device, substantially as described.
2. In combination with the appliance referred to in the first claim, the use of a
lever m receiving reciprocating motion from the crank a by a connecting rod 1,
which lever carries two oppositely working pawls p and q which can be alternately
made to engage with a friction disc nor a ratchet wheel u substantially as
described.
Dated this 25th day of January 1896.
ABEL & IMRAY,
Agents for the Applicant.