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Патент USA US2127909

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Aug. 23, 1938.
F. FREITAG
AUTOMATIC RETURN DEVICE FOR CONTROL MEMBERS
Filed Feb. 3, 1938
2,127,909
Patented Aug. 23, 1938
‘
2,127,909
UNITED STATES PATENT OFFICE
2,127,909
AUTOMATIC RETURN DEVICE FOR CON
TROL MlElVIBERS
Friedrich‘ Freitag, Wallstadt, Germany, assignor
to Zellsto?fabrik Waldhof, Mannheim-Wald
hof, Germany, a joint-stock company of Ger
many
Application February 3, 1938, Serial No. 188,591
In Germany March 28, 1936
1 Claim. (Cl. 74-501)
This application corresponds to the application
A construction of the invention is shown by
of Zellsto?fabrik Waldhof, Serial No. Z.23108, way of example in the accompanying ?gure.
which was ?led in Germany on 28th March, 1936.
For allowing starters or control switches for
5 electric motors and the like devices (for example,
valves in gas and liquid conveying conduits and
the like) , which are adapted to be moved in either
direction out of a zero position by means of two
oppositely acting pull members to return auto10 matically into the zero position again on releasing the pull members, spiral leaf springs have
generally been employed. In this case two
springs are necessary, namely a spring for the
return of the starter from each direction, the
15 tension produced in said spring by the pulling
being liberated on release and the apparatus being automatically returned into its centre position.
Automatic return by means of spiral springs
20 has, however, considerable disadvantages. The
springs which are encased in a housing are not
easily accessible, are troublesome to clean, foul
and stick easily and require frequent repairs,
while fracture of the springs is comparatively
25 frequent, the entire apparatus being thereby put
out of operation.
>
According to the invention, these disadvantages
At A is shown the starting pulley of an electric
motor. By exerting a pull on one of the cables
or chains B1 and B2, the pulley can be rotated to 01
the left or to the right out of the zero position, a
motor being thereby switched for lifting or lower
ing. For example, if the chain B1 is pulled, the
chain B2 passing through the bore G2 is raised
and its lifter C2 carries the weight D2 with it, the 10
latter being guided in a tube E2. Instead of ex
ternal guide tubes E2, guide rails or internal guide
tubes may be used. Upon releasing B1, the
weight B2 by bearing on the lifter C2 presses the
chain B2 downwardly until it has returned into 15
its inoperative position F2. The starting pulley
A is thereby turned back and the starter returns
to its zero position. Further running down of
the chain 132 is prevented by abutment of the
lifter C1 of the chain B1 against the weight D1 20
which has remained in the inoperative position
F1.
Upon pulling the chain B2, the same cycle
occurs in respect of the weight D1 moving in
the guide E1 and provided with a bore G1.
25
I claim:
In mechanism for effecting return to a neutral
are obviated and a satisfactory return of the
device into the central position and hence a re30 liable and undisturbed operation of the apparatuses may be ensured by arranging on each
pull member a weight which is raised upon a
position of a control device displaceable in either
direction from such position, the combination
with a pulley operatively connected to the con- 30
trol device, a ?exible member passing over said
pulley and having generally vertical runs, an
pull being exerted on the opposite member, and
upon release returns into the stationary inoper35 ative position.
If the apparatus is in its central position, the
two weights also occupy their inoperative positions by resting for example on a stationary support or being suspended from a stationary device.
‘10 In order that the weights will be able to .move
up and down within certain limits de?ned by
lifters or the like'mounted on the pull members,
each of said weights is provided with a preferably
central bore, through which the pull member
4-.5 passes. In order to ensure satisfactory sliding
of the weights, it is expedient to allow them to
run in guides, for example on vertical rails or
in tubes.
abutment connected to each of said runs, a
weight supported for engagement by each of said
abutments, each of said weights being positioned
for engagement by the associated abutment on
initiation of movement of the flexible member
in a direction to- raise such abutment and the
weight engaged thereby, whereby on release of
the ?exible member, the weight thus raised will
return the ?exible member and the pulley to the
initial position thereof, and stationary means
cooperating with each of said weights to guide
the latter in the direction of the associated runs
of said flexible member.
FRIEDRICH FREITAG.
35
110
45
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