Improved Mechanism for Effecting Controlled or Positive Step by Step Motion.
Year: 1899

page_text: Date of Application, 20th July, 1899-Accepted, 16th Sept., 1899
COMPLETE SPECIFICATION.
Improved Mechanism for Effecting Controlled or Positive Step
by Step Motion.
We, SIEMENS BROTHERS & Co. LIMITED, of 12, Queen Anne's Gate, West-
minster, in the County of London, Electrical Engineers, do hereby declare the
nature of this invention (as communicated to us from abroad by Rudolph Louis
Leopold Hundhausen, of Wilmersdorf, near Berlin, Germany, Chief Engineer)
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 arrangements of ratchet mechanism whereby the
actuated device is forced to follow accurately the movements of the driving
mechanism or is held stationary on its support.
The kinds of motion that result from these arrangements are shewn diagram-
matically in Fig. 1 of the accompanying drawings and in the constructions
shewn at Figs. 1" to 1'. In the latter figures A represents the driving mechanism, S
the actuating device and G the framing. A and S are parallel prismatic bars
guided in G, the part A carrying a pawl a sliding at right angles thereto
and adapted to engage with S, while the framing G carries a sliding pawl g*
also adapted to engage with S. Thus by the engagement of the one or other
pawl the bar S is locked either to A or to G.
The engagement of the pawls with the bar S can be effected in various ways,
such as by teeth or serrations, or by frictional contact; this is indicated in a
general manner in Figs. 1" to 1 and 2 by forming fine serrations on the
upper surface of the bar S and on the under surfaces of the pawls a³ and g³.
The intended step by step motion of the bar S is effected by causing the
movements of the parts A, a g* to take the place consecutively in the manner
indicated in Figs. 1 to 1 by means of arrows, and as hereinafter described
with reference to the Roman and Arabic numerals for indicating the movements
of the parts a g* and A, G, S.
Fig. 1. While the locking pawl is engaged with the bar S so that
this is held stationary in the frame G, the actuating pawl a is moved downward
in engagement with S as shewn in Fig. 1b.
1.
Fig. 1°. After the pawl is engaged with S so as to connect this to A,
the locking pawl g* is raised out of engagement.
Fig. 1. In consequence hereof, the connection between the bar S and the
frame G ceases, and S is consequently only held by the actuating bar A, so as
to move therewith, so that if A is moved to the right the bar S is carried along
thereby i.e. shifted forward.
Fig. 1°.
After this motion has been effected, the locking pawl is again
lowered into engagement (3) so that the bar S is now again held in the frame
in its new position.
Fig. 1.
In order that the actuating bar A may move back again, the
actuating pawl a* is now raised again; the bar A can then perform its idle
return motion (Iº), while the bar S remains stationary, i.e. is locked to the
framing G.
In the above described manner the six consecutive phases are repeated, these
being indicated in the diagram Fig. 1 as follows:
The several positions indicated at Figs. 1° to 1 are represented by horizontal
lines marked at each end with the letters a a to f f. The movements of the

page_text: several parts are indicated by downward extending lines, which are marked at
each end respectively with A A, a a* g g³, and S S. The main phases of
motion of the parts marked A, S, and G are indicated by Roman numerals, and
those of the parts a and g are indicated by Arabic numerals.
The movements of the actuating parts A as also those of the actuat-
ing pawl a and those of the locking pawl are reciprocating move-
ments with intervals of rest, the several phases being always shifted relatively
to each other, the movements of the bar S are step-by-step advancing ones.
As shewn in Fig. 1:
Between a and b is effected the engagement of the actuating pawl a* (1).
Between b and c, the disengagement of the locking pawl g (²).
Between and d, the forward motion of the actuating device A (I) and
consequently the forward motion of bar S (I¹).
Between and e the engagement of the locking pawl g* (3).
Between e and f the disengagement of the actuating pawl a³ (4).
Between f and a, finally, the idle return motion of the actuating device A (Iº),
while the part S is obliged to remain stationary with the frame G (II), thus
producing the locking phase (II¹).
During the intervals of time for the several parts, periods of rest occur as
follows: :-
From a to c and from d to f, the actuating device A is stationary.
From toe and from f to a, the actuating pawl a is stationary.
From e to d and from e to b the locking pawl is stationary.
From a to the connection of the bar S with the actuating device A. and
the disengaement thereof from the framing G takes place by means of corre-
sponding consecutive movements of the actuating pawl a and locking pawl g*,
namely, from a to b the engagement of a* (1) and from 6 to c the disengagement
of g (2).
From d to f the connection of the bar S with the framing G, and its
disengagement from the actuating device A is effected by the consecutive motions
of the pawls a* and *, namely:
From toe the engagement of 9* (3) and
From e to f the disengagement of * (4).
The movements of the actuating pawl a* (1) and (3) and the locking pawl g³ (2)
and (4) are effected consecutively in such manner that either the one or the
other, or both pawls are simultaneously engaged with the bar S, but they are
never both disengaged therefrom at the same time; consequently, the engagement
of the one always takes place before the disengagement of the other.
In the positions and e both pawls are in gear, in consequence of which
not only the bar S but also the actuating device A is prevented by their agency
from moving relatively to the framing G.
This condition also occurs for the contiguous periods from a to c and
from d to f, in the first of which the transition from locking to actuating,
and in the last the reverse transition from actuating to locking is effected.
Within these periods therefore, the actuating device A must remain stationary,
that is, the line A A describing its motion must run parallel with the vertical
straight line G G Fig. 1, indicating the stationary position of the framing G.
In the position 6 the influence of the actuating device A upon the bar S
commences while that of the framing G ceases; in the position e the reverse
takes place in the entire interval of time (made up of three parts) from 6 to e
therefore, the bar S is forced to partake of the motion of the actuating device A,
which is stationary from 6 to c and from d to e; in the other interval of time
(also made up of three parts) from e to b the bar S must remain stationary with
the frame, so that strictly speaking the locking takes place not only in the
interval from f to a, but also in the entire interval from e to b. On the other
hand, the stationary phase of the bar S occurring during the still greater
interval from d to c, must be considered, as regards its first part from d to e

page_text: and in its last part to c, not as a locking phase, but as an actuation phase,
because the bar S is not connected during these two intervals with the framing G,
but with the actuating device A, which is at those times only stationary.
As indicated in Fig. 1 by means of pairs of parallel lines I, I¹ and II, II',
the motion of the bar S may be considered as a copy, pieced together, of the
motion and stationary phases respectively of the actuating device A and the
framing G.
It will be seen from Fig. 2 and the corresponding Fig. 2, that such motion
and stationary phase may be regarded as of equal value. In this case the
locking pawl is replaced by a second actuating pawl b, which is carried
by a second actuating device B, this being arranged to slide in the framing G
in the same way as A.
If in this arrangement the two actuating devices A and B have alternately a
to and fro motion imparted to them, the pawls a and b being moved in a
manner corresponding to that described with reference to a and g, the bar S
will be made to participate alternately in the motion of the one
actuating device.
or other
Also in this case the separate movements of the two actuating devices" A
and B and the corresponding pawls a and b will take place, exactly in the same
way and sequence as before, in six consecutive phases, only in this case there
occurs, in the place of the stationary period (II) of the framing G, a reciprocating
motion with periods of rest (II), (II) of the device B, and in place of the
stationary period (II) of the bar S a second motion (II).
A somewhat different action takes place with the locking mechanism shown
at Figs. 3 to 4h. In this case it is possible that the two up and down motions,
taking place consecutively in pairs, of the actuating and locking pawls a* and g*,
may take place simultaneously, so that the four intervals of time a to b, and
b to cas also d to e and e to f are drawn together into two intervals, from
a to c and from d to f, as shewn at Fig. 3.
In this case it is assumed that with such a change of motion, the end
positions of which are for example shewn in Figs. 3" and 3°, the pawls a* and g*
are never simultaneously entirely out of gear with the bar S, so that during the
transition from the one movement to the other the medium position indicated
at Fig. 3b will occur. Otherwise the movements take place exactly in the same
way as in Figs. 1 to 2, but in this case they occur in only four consecutive
movement phases, instead of in six, the transition points of which are indicated
at Figs. 3 3 3d and 3′.
Fig. 4 and Fig. 4h shew a compound arrangement in which two actuating
devices A and B with two actuating pawls a* and * are provided, and in
addition a locking pawl * carried by the framing G, which act upon the
bar S.
It is assumed in this case that the bar S is moved step by step from c to
through two teeth divisions forwards (I¹), that it is stationary from f to g (II¹),
that it is moved backwards through a distance of one tooth division from
h to i (III) and then remains stationary from ; to a again (II).
In the intermediate intervals of time from d to f from to h, from i to j,
from a to c, during which also the bar S is stationary, the reversal of the
positions of the actuating and locking pawls a and b and g takes place in
the manner indicated on the drawing and in the sequence 1, 2, 3, 4, 5, 6, 7, 8.
The idle return motion of the actuating device A (I°) must take place during
the interval of time from f to a, and the idle return motion of the actuating
device B (III) during the interval from to g.
It will be seen from the above that variously otherwise combined movements
can be carried out according to this invention; it should be specially mentioned
that these motions can take place not only in rectilinear direction or in a
circular direction backwards and forwards, but also either in a plane or in
space at right angles to each other, or in any other relative direction.

page_text: The prescribed positive motion of the locking and actuating pawls above
described with reference to Figs. 1 to 4 is of considerable importance as also
the relation as to time intervals between these motions and those of the actuating
or driving device, by means of which the bar S or part actuated is uninterruptedly
moved or is held stationary on the framing the said motion is however subject
to the condition that in different intervals of time alternately consecutive to
and fro motions and stationary phases of the several devices must take place
as is clearly shown from the above description, and drawings.
The special case should be mentioned that in the direct transition of the bar S
from the moving influence of an actuating device A into that of another actuating
device B, it is not necessary that all three should remain stationary together,
but that they may also all three move together; it is only a'necessary condition
that at the time of transition they should not have any motion relative to each
other.
We will now describe the manner in which the above laws of motion can be
practically applied to various mechanisms, referring for this purpose to Figs. 5
to 15 of the drawings.
Fig. 5 shews a construction in which the system described with reference to
Figs. 1 to 1 is carried out in connection with a mechanism with frictional
locking devices, in which a bar S carried in a framing G has to be advanced
with a step by step motion and held stationary, this being effected by a
mechanism the driving of which is chiefly effected by a revolving shaft. On
such shaft are mounted three cam groove drums K A, Ka*, Kg, which work the
actuating bar A, the actuating pawl a, and the locking pawl g by means of
levers A a¹ g¹ and connecting devices.
The lines A A a* a* and g* g³, Fig. 1, are here carried out as cylindrical
curves and give the required positive controlled motion as clearly seen from the
Roman and Arabic numerals and letters a, b, c, in Fig. 5. For further elucida-
tion, diagram figures are given at Figs. 5" and 5b, of which Fig. 5b clearly
shews the consecutive phases of motion.
Fig. 6 shews the system described with reference to Figs. 3 to 3f as carried
out by a step-by-step mechanism with toothed locking gear, the part S being in
this case in the form of a spur wheel.
The working is here effected by means of a cam groove disc Ķ revolving on
a shaft mounted in the framing G, there being two cam grooves in one and the
same plane, that represent polar projections of the lines A A and a* a Fig. 3,
and the outer one of which serves for actuating the pawl lever A mounted con-
centrically with the ratchet wheel S, while the inner one works the actuating
pawl a by means of the three-armed lever c* a¹ g².
The time intervals are in this case so disposed that for the engagement of the
actuating pawl a* (1) and the simultaneously effected disengagement of the
locking pawl g (2) from a to an angle of 60° is employed; for the useful
motion (I) from c to d an angle of 180°, for the engagement of the locking
pawl (3) and the simultaneous disengagement of the actuating pawl a³ (4)
from d to f again an angle of 60°, and for the idle return motion of the actuating
lever A (I) from f to a also an angle of 60°.
Figs. 7 and 8 shew, like the foregoing, special constructions of step by step
mechanisms with pin tooth gear, in which reference is more particularly made to
the kinematic arrangement of the connection between the actuating and locking
pawls, the actuating mechanism being only indicated by two broken coupling
rods A and c. The actuating lever A is in this, as also in all the following
cases, mounted so as to turn in the frame G concentrically with the ratchet
wheel S.
The ratchet wheel S is shewn in Fig. 7 in the form of a disc with laterally
projecting cylindrical pins; in Fig. 8 it is in the form of a ring with internal
notches as teeth, while in Figs. 9 to 911 it is in the form of a disc with peripheral
notches.

page_text: In Fig. 7 the actuating and locking pawls a³ g³ are pivotted respectively to
the lever A and to the framing G.
With the pawl gare rigidly connected both the lever to which the actuating
rod c is attached, and the lever a¹ whose free end is connected with the actuating
pawla by a link . By this means the two pawls are caused to come into
and out of gear with the ratchet wheel S alternately.
When the actuating rod c moves to the right, the pawl g* is raised out of
gear and lever a¹ has its end moved towards the common centre of the ratchet
wheel S and actuating lever A, in consequence whereof the rod will assume a
radial position relatively thereto and the actuating pawl a is put in gear there-
with.
If the driving rod A¹ be then moved to the right the wheel S will be moved in
the same direction by the lever A by means of the pawl a³, there being then
no relative motion between the parts A, a, and S.
If by the then following motion to the left of rod c¹ the two pawls have their
positions reversed, the motion to the left of rod A' will effect the idle return
motion of the lever A, the extremity of the actuating pawl a being at the
same time moved back outside the wheel S in a curve that is not concentric with
the latter. The small relative motion which occurs between A and a* (which
is of no consequence to the desired action is avoided in the arrangement shewn
in Fig. 8 and all the following figs. to Fig. 9", as both during the operative
motion and during the idle return motion of the lever A no relative motion takes
place between this and the actuating pawl a³.
In Fig. 8 both the pawls a* and * are so connected by a ling that during the
to and fro motion of the lever A only a single relative motion takes place
between the rod and the one or the other pawl round the upper or lower
pivot of the rod 1, which always coincides with the centre of the actuating
lever A and the centre of the ratchet ring S; during the forward motion of the
latter the actuating pawl a and the rod turn together round the lower pivot
of the latter as of one piece with the lever A; during the locking phase, the
rod and the locking pawl * are stationary as of one piece with the framing G
and ratchet ring S, while the actuating pawl a turns together with the actuating
lever A round the upper pivot of the link . The two pawls a and gare
actuated by the lever pivotted on the frame G and worked by rod c¹.
C
In the Figs. 9", b, c, i, d, e, f, ", the several phases of motion or positions of
the parts are shewn, being designated in the same manner as the diagram
Fig. 3.
1
The motion of the driving rod A' when transmitted to the actuating lever A,
takes place according to line A A, while the motion of the rod by which the
pawls a and have to be actuated according to the two symmetrical lines a*a*
and has to take place according to the first line a a. This motion
is transmitted on the one hand, by the lever g by means of the link of the
elbow lever a pivotted to the actuating lever A, and the coupling rod a to
the actuating pawl a capable of sliding on the lever A, and on the other hand
it is transmitted by means of the coupling rod g¹ to the locking pawl g*
sliding on the frame G.
It wil be evident that in place of the sliding pawls a* and * actuated by elbow
lever and link, an actuating pawl a and a locking pawl may be employed,
similar to Fig 7; the former arrangement was preferred in the above case
in order to more distinctly show the peculiarities of the several phases of motion.
While with toothed ratchet mechanisms it is possible, although not absolutely
necessary, that the two pawls should be directly connected together, this is
not possible with frictional ratchet mechanisms, so that the above described
lever connection with the guide link in this case serves exclusively for working
the actuating pawla, while the actuation of the locking pawl is effected
separately by direct action.
Such a mechanism is shewn at Fig. 10, where a cam-groove dise K is rotatably

page_text: mounted on the framing G for actuating the two pawls and g and actuating
lever A. The motion of the locking pawl is effected by the inner cam
groove through the lever g connected to it. The working of the actuating
pawl is effected by means of the middle cam groove through the lever a',
guide link and double lever all.
The working of the actuating lever A is effected by means of the outer cam
groove through the coupling rod A¹ and the double lever Al Am
Fig. 11 shews an arrangement in which a variable ratio of transmission can
be introduced between the levers A¹ and A¹ whereby the angle of advance of
the ratchet wheel S can be made greater and smaller.
This figure also shews that it is, for example, possible to effect the motion
of the actuating and locking pawls by means of a special sliding cam groove c
instead of the revolving cam K, the slide having a to and fro motion imparted
to it from the cam K by means of a connecting rod and double ended
lever This figure also shews that a single revolving cam is sufficient
for effecting both the to and fro motion, with intervals, of the ratchet lever
gear A A A A¹¹, as also that of the lever cc and of the other
which effects the motion of the pawls a and g in the described manner, as
shewn on the drawing; instead of employing two cam grooves shifted relatively
to each other, the pivots of the levers A A and c¹ care in this case
shifted relatively to the cam groove.
gear
Fig. 12 shews another arrangement wherein the two frictional ratchet pawls a³
and are actuated by a single cam groove and a single lever, with the
employment of a spring connection between the levers c¹ and a¹¹.
Figs. 13 to 15 shew ratchet gear with toothed ratchet devices. Fig. 13
shews the arrangement for varying the ratio of transmission between the levers A
and A as in Fig. 11; it will be seen that by means of the positive motion
the angle of advance of the ratchet wheel S can be readily made to vary one
or more teeth divisions.
The angular division of the cam disc K for the several movement phases
is in this case arranged as at Fig. 6 so as to produce as slow an acceleration
and retardation as possible in the forward motion of the ratchet wheel S, while
in the idle return motion of the ratchet. lever gear A, A¹ A" as also in the
actuation of the pawl mechanism a aa", gc c¹ c¹¹, as comparatively small
masses have to be dealt with, the to and fro motion can take place in a shorter
interval of time.
Fig. 14 shews an arrangement with positive double motion of toothed ratchet
gear. In this case there are two actuating pawls a and e which are both
worked by the common driving rod c¹¹ by means of the levers a and c rigidly
'connected thereto, and the two guide links and 1°, while the driving rod
receives its to and fro motion with intervals of rest by means of the cam c
revolving between the two rollers c c carried in cl, the periphery of the cam
being made with such curves as to fit and fill."
"6
The two actuating levers A and E are simultaneously worked by the connect-
ing rods AE pivoted to the looped crosshead in which works a rectangular
slide C containing a revolving triangular cam C.
The two cams and c are fixed rigidly on the same shaft which revolves
in bearings in the frame G.
This arrangement shews that the to and fro movements at intervals can
also be obtained by other means than by the ordinary cam action of the previously
described constructions.
Fig. 15 finally shows an arrangement in which the ratchet disc S is made in
the form of a dividing plate of the form commonly used in machine tools, the
disc being provided with a number of circular rows of cylindrical holes bored
parallel to the axis.
The actuating lever A is rotatably and adjustably mounted in the framing G:
it receives its rotation from the upper curve of the cam drum K by means of

page_text: the lever A adjustably fixed thereto, by means of the connecting bar A guided
in the framing G and by means of the rocking lever Al pivoted to the
framing G, the cam drum being rotated by the crank K'.
The lower cam groove effects by means of the elbow lever g¹¹ not only the
motion of the locking pawl g' sliding in the framing G, and which engages
with the division plate by means of the locking pin 9 but it also effects the
to and fro motion of the actuating lever A by means of the double ended lever a¹
pivoted to the framing, the lever A together with its axis adjustable in the
framing and the devices combined therewith operates as the actuating pawl
and engages by means of its pin a with the holes of the dividing plate."
By means of the guides provided on the lever A and on the corresponding
part of the framing provision is made for varying the angle of advance, in order
to enable the plate to be turned through a varying number of divisions by means
of one and the same cam disc.
The above described improved mechanism for obtaining a controlled positive
step by step motion can be applied with advantage in a variety of cases and in
particular in those where it is necessary to obtain a rapid and reliable forward
motion of ratchet devices, such as in machines for stamping the grooves in
sheet iron for the armatures of dynamos, on account of its absolutely accurate
action at high speeds.
Having now prticularly described and ascertained the nature of this inven-
tion, and in what manner the same is to be performed, we declare that what
we claim is :-
1. Mechanism for effecting step by step motion by toothed or frictional devices
wherein the part which receives the step by step motion is always in locked
engagement either with the actuating device or pawl, or with a fixed part or
framing substantially as described.
2. In mechanism such as is referred to in the first claim the arrangement
wherein an actuating device moveably carried by the framing is so arranged
in positive connection with an actuating pawl that the latter can have a position
motion imparted to it in any desired manner while during the forward motion
of the actuated part the pawl has no motion relatively to the latter, substantially
as described.
3. In mechanism such as is referred to in the first claim, in particular where
toothed devices are employed, the arrangement wherein the actuating device
referred to in the second claim is in positive connection with the locking pawl,
for the purpose of simultaneously actuating the locking pawl and the actuating
pawl, substantially as described.
4. In mechanism such as is referred to in the preceding claims, in particular
for a revolving ratchet wheel or disc, the arrangement wherein the positive
connection is obtained by means of a guide link so arranged that either only
during the forward motion or also during the idle return motion of the actuating
lever one of its pivot joints coincides with the axis of the ratchet wheel,
substantially as described.
5. Mechanism for effecting step by step motion by toothed or frictional devices,
arranged and operating as herein described with reference to the accompanying
drawings.
ABEL & IMRAY,
Agents for the Applicants.