U.S. patent number 3,799,058 [Application Number 05/214,082] was granted by the patent office on 1974-03-26 for track tamping and leveling machine.
Invention is credited to Franz Plasser, Josef Theurer.
United States Patent |
3,799,058 |
Plasser , et al. |
March 26, 1974 |
TRACK TAMPING AND LEVELING MACHINE
Abstract
A track tamping and leveling machine with a track tamping unit,
a track lifting unit and a reference system for the leveling
operation comprises a continuously adjustable electrical track
level indicator. The indicator has one indicator part in constant
connection with the tensioned reference wire of the reference
system and another part in connection with the track to produce a
control signal corresponding to the track level prevailing at the
track point whereto the other indicator part is connected. A
continuously adjustable control device for the track lifting unit
drive is electrically connected to the indicator and receives the
control signals to adjust the device and correspondingly actuate
the drive for the track lifting unit.
Inventors: |
Plasser; Franz (Vienna,
OE), Theurer; Josef (Vienna, OE) |
Family
ID: |
25595902 |
Appl.
No.: |
05/214,082 |
Filed: |
December 30, 1971 |
Foreign Application Priority Data
|
|
|
|
|
Feb 19, 1971 [OE] |
|
|
1457/71 |
Aug 23, 1971 [OE] |
|
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7363/71 |
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Current U.S.
Class: |
104/7.1;
104/12 |
Current CPC
Class: |
E01B
27/17 (20130101); E01B 35/00 (20130101); E01B
2203/12 (20130101); E01B 2203/16 (20130101); E01B
2203/10 (20130101) |
Current International
Class: |
E01B
27/17 (20060101); E01B 27/00 (20060101); E01B
35/00 (20060101); E01b 027/16 () |
Field of
Search: |
;104/7R,7A,8,12
;33/60 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Sheridan; Robert G.
Assistant Examiner: Bertsch; Richard A.
Attorney, Agent or Firm: Kelman; Kurt
Claims
We claim:
1. A track tamping and leveling machine comprising
1. a machine frame mounted for mobility on the track for moving
from a previously leveled track section towards a track section to
be leveled,
2. vertically adjustable track tamping tools mounted on the machine
frame,
3. a track lifting unit mounted on the machine frame,
4. a drive for raising the track lifting unit,
5. a reference system in respect of which the track is leveled, the
reference system including
a. a tensioned reference wire extending from the leveled track
section to the track section to be leveled,
6. a continuously adjustable electrical track level indicator
having
a. two indicator parts movable in respect to each other, one of the
indicator parts being in constant connection with the tensioned
reference wire and the other indicator part being in connection
with the track whereby the indicator indicates the track level
prevailing at a track point whereto the other indicator part is
connected and produces control signals corresponding to the
indicated track level, and
7. a continuously adjustable control device for adjusting the speed
of the track lifting unit drive electrically connected to the
indicator and receiving the control signals, the control device
being adjusted in proportion to the control signals and
correspondingly controlling the speed of the drive for the track
lifting unit in proportion to the indicated track level.
2. The track tamping and leveling machine of claim 1, further
comprising a signal amplifier connected between the indicator and
the control device.
3. The track tamping and leveling machine of claim 1, further
comprising a setting control on the indicator for setting the
desired track level, and a differentiating circuit unit connected
between the indicator with its setting control and the control
device.
4. The track tamping and leveling machine of claim 3, whrein the
setting control is a potentiometer.
5. The track tamping and leveling machine of claim 1, wherein the
drive for raising the track lifting unit is a hydraulic motor
operated by a hydraulic circuit including a source of hydraulic
fluid, a fluid supply line connecting the hydraulic fluid source to
the motor and a constant-speed pump for the fluid in the supply
line, and the control device is a solenoid servo valve having a
coil electrically connected to the track level indicator.
6. The track tamping and leveling machine of claim 1, wherein the
one indicator part is a fork member having two tines wherebetween
the tensioned reference wire is constantly held, and the other
indicator part comprises a rotary potentiometer having a rotary
shaft, the fork extending radially from the potentiometer shaft,
and a measuring bogie mounted for mobility on the track and
supporting the rotary potentiometer.
7. The track tamping and leveling machine of claim 1, wherein the
tensioned wire has a rear end in the leveled track section and a
forward end in the track section to be leveled, and further
comprising three measuring bogies movable on the track and
supported under the machine frame for respectively supporting the
rear and forward ends of the wire and the other indicator part.
8. The track tamping and leveling machine of claim 1, wherein the
tensioned reference wire has a rear end in the leveled track
section and a forward end in the track section to be leveled, the
machine frame being of such elongation that the wire extends from
end to end within the length of the frame, and at least one of the
wire ends being affixed directly to the machine frame.
9. A track tamping and leveling machine comprising
1. a machine frame mounted for mobility on the track for moving
from a previously leveled track section towards a track section to
be leveled,
2. vertically adjustable track tamping tools mounted on the machine
frame,
3. a track lifting unit mounted on the machine frame,
4. a drive for raising the track lifting unit,
5. a reference system in respect of which the track is leveled, the
reference system including
a. two tensioned reference wires each extending from the leveled
track section to the track section to be leveled and associated
with a respective one of the track rails,
6. a measuring bogie mounted for mobility on the track section to
be leveled,
7. means for vertically adjustably supporting the forward ends of
the tensioned wires on the measuring bogie,
8. a control for adjusting the vertical positions of the forward
wire ends in respect of each other,
9. two continuously adjustable electrical track level indicators
each cooperating with a respective one of the tensioned reference
wires and each indicator having
a. two indicator parts movable in respect to each other, one of the
indicator parts being in constant connection with the tensioned
reference wire and the other indicator part being in connection
with the track whereby the indicator indicates the track level
prevailing at a track point whereto the other indicator part is
connected and produces control signals corresponding thereto,
and
10. a continuously adjustable control device for the track lifting
unit drive electrically connected to the indicator and receiving
the control signals, the control device being adjusted in response
to the control signals and correspondingly actuating the drive for
the track lifting unit.
10. The track tamping and leveling machine of claim 9, wherein the
control comprises a rotary potentiometer mounted on the measuring
bogie, the potentiometer having a rotary shaft, a pendulum mounted
on the rotary shaft for pivotal movement in a vertical plane
transverse to the track whereby the potentiometer indicates the
superelevation of the track, a superelevation selecting element for
setting a desired superelevation, and a differentiating circuit
unit electrically connected to the rotary potentiometer and the
superelevation selecting element, the means for vertically
adjustably supporting the tensioned wire ends being electrically
connected to the differentiating circuit unit for vertically
adjusting a respective one of the wire ends.
11. The track tamping and leveling machine of claim 10, wherein the
superelevation selecting element is a potentiometer.
12. The track tamping and leveling machine of claim 10, further
comprising an amplifier electrically connected between the
differentiating circuit unit and the vertical adjusting means.
13. The track tamping and leveling machine of claim 12, wherein the
vertical adjusting means is an electromotor.
14. The track tamping and leveling machine of claim 10, further
comprising an indicating device associated with the differentiating
circuit unit.
15. The track tamping and leveling machine of claim 14, wherein the
indicating device comprises a recorder.
16. The track tamping and leveling machine of 9, wherein the means
for vertically adjustably supporting the wire ends comprises an
independent drive for vertically moving each wire end, the control
actuating one of the independent drives, and further comprising a
manually operable control switch for actuating the other
independent drive.
17. A track tamping and leveling machine comprising
1. a machine frame mounted for mobility on the track for moving
from a previously leveled track section towards a track section to
be leveled,
2. vertically adjustable track tamping tools mounted on the machine
frame,
3. a track lifting unit mounted on the machine frame,
4. a drive for raising the track lifting unit,
5. a reference system in respect of which the track is leveled the
reference system including
a. a tensioned reference wire extending from the leveled track
section to the track section to be leveled,
6. a continuously adjustable electrical track level indicator
having
a. two indicator parts movable in respect to each other, one of the
indicator parts being in constant connection with the tensioned
reference wire and the other indicator part being in connection
with the track whereby the indicator indicates the track level
prevailing at a track point whereto the other indicator part is
connected and produces control signals corresponding thereto,
7. a setting control on the indicator for setting the desired track
level, the setting control comprising a shaft carrying a pointer
and a control disc carrying a scale, the disc being rotatable about
the shaft into desired angular positions and being fixable in each
of said positions, and the pointer cooperating with the scale for
setting the control,
8. a continuously adjustable control device for the track lifting
unit drive electrically connected to the indicator and receiving
the control signals, the control device being adjusted in response
to the control signals and correspondingly actuating the drive for
the track lifting unit, and
9. a differentiating circuit unit connected between the indicator
with its setting control and the control device.
18. A track tamping and leveling machine comprising
1. a machine frame mounted for mobility on the track for moving
from a previously leveled track section towards a track section to
be leveled,
2. vertically adjustable track tamping tools mounted on the machine
frame,
3. a track lifting unit mounted on the machine frame,
4. a drive for raising the track lifting unit,
5. a reference system in respect of which the track is leveled, the
reference system including
a. a tensioned reference wire extending from a rear end in the
leveled track section to a forward end in the track section to be
leveled,
b. the machine frame being of such elongation that the wire extends
from end to end within the length of the frame, and
c. at least one of the wire ends being affixed directly to the
machine frame,
6. a tension spring affixing the one wire end to the machine
frame,
7. a continuously adjustable electrical track level indicator
having
a. two indicator parts movable in respect to each other, one of the
indicator parts being in constant connection with the tensioned
reference wire and the other indicator part being in connection
with the track whereby the indicator indicates the track level
prevailing at a track point whereto the other indicator part is
connected and produces control signals corresponding thereto,
8. a continuously adjustable control device for the track lifting
unit drive electrically connected to the indicator and receiving
the control signals, the control device being adjusted in response
to the control signals and correspondingly actuating the drive for
the track lifting unit.
19. A track tamping and leveling machine comprising
1. a machine frame mounted for mobility on the track for moving
from a previously leveled track section towards a track section to
be leveled,
2. vertically adjustable track tamping tools mounted on the machine
frame,
3. a track lifting unit mounted on the machine frame,
4. a drive for raising the track lifting unit,
5. a reference system in respect of which the track is leveled, the
reference system including
a. a tensioned reference wire extending from the leveled track
section to the track section to be leveled,
6. a continuously adjustable electrical track level indicator
having
a. two indicator parts movable in respect to each other, one of the
indicator parts being in constant connection with the tensioned
reference wire and the other indicator part being in connection
with the track whereby the indicator indicates the track level
prevailing at a track point whereto the other indicator part is
connected and produces control signals corresponding thereto,
7. a setting control on the indicator for setting the desired track
level,
8. a continuously adjustable control device for the track lifting
unit drive electrically connected to the indicator and receiving
the control signals, the control device being adjusted in response
to the control signals and correspondingly actuating the drive for
the track lifting unit,
9. a differentiating circuit unit connected between the indicator
with its setting control and the control device, and
10. an indicating device associated with the differentiating
circuit unit.
20. The track tamping and leveling machine of claim 19, wherein the
indicating device comprises a recorder.
Description
The present invention relates to a track tamping and leveling
machine which comprises a machine frame mounted for mobility on the
track for moving from a previously leveled track section towards a
track section to be leveled, vertically adjustable track tamping
tools and a track lifting unit mounted on the machine frame, a
drive for raising the track lifting unit, and a reference system in
respect of which the track is leveled, the reference system
including a tensioned reference wire extending from the leveled
track section to the track section to be leveled.
Known machines of this type have a sensor which, upon contact with
the reference wire, actuates an electrical control circuit
operating the drive for the track lifting unit so that the lifting
stroke is terminated upon this contact which indicates the desired
level of the track. The speed of the lifting unit drive is constant
throughout the lifting stroke until the same is terminated.
However, there is a certain lag between the time the sensor
contacts the reference wire and the drive is stopped so that the
track is usually raised above the desired level indicated by the
reference wire, requiring additional track correction which is
usually effectuated manually and is time-consuming. Furthermore,
the sudden impact of the sensor on the wire upon contact therewith
causes a lifting of the tensioned wire, which additionally distorts
the track correction. Accuracy may be increased if the drive for
the lifting unit moves very slowly so as to reduce inertia to a
minimum. This, however, reduces the efficiency of teh machine below
commercially acceptable limits.
It is accordingly the primary object of this invention to overcome
the disadvantages indicated hereinabove and to provide a machine of
the described type which works with the greatest accuracy at high
speeds.
The above and other objects and advantages are accomplished in
accordance with the invention when the sensor is constituted by a
continuously adjustable electrical track level indicator having two
indicator parts movable in respect to each other. One indicator
part is in constant connection or engagement with the tensioned
reference wire and the other indicator part is in connection with
the track whereby the indicator indicates the track level
prevailing at a track point whereto the other indicator part is
connected and produces control signals corresponding thereto. A
continuously adjustable control device for the track lifting unit
drive is electrically connected to the indicator and receives the
control signals, the control device being adjusted in response to
the control signals and correspondingly actuating the drive for the
track lifting unit.
In this manner, the indicator part which is in constant engagement
with the reference wire at all times delivers an electrical control
signal corresponding to the desired lifting stroke to the control
device which determines the raising of the track to the desired
track level. This enables the drive for the track lifting unit and
its speed to be actuated proportionally to the extent of lifting,
i.e. a certain lifting speed corresponds to each correction
magnitude. If a considerable extent of track lifting is required to
correct the track level, the lifting unit is first driven at high
speed and, proportionally, as the error becomes smaller, the
lifting speed is gradually reduced until this speed becomes zero as
the track reaches the desired level. This practically eliminates
excess raising of the track while maintaining a high working speed
in obtaining a very accurate track leveling.
According to a preferred feature of the present invention, a
setting control cooperates with the indicator to set the desired
track level (zero adjustment), and a differentiating circuit unit
is connected between the indicator with its setting control and the
control device for the track lifting unit drive, an amplifier being
advantageously connected between the differentiating circuit unit
and the control device to amplify the control signal.
When the zero point set by the setting control of the indicator has
been reached, which indicates that the track has been lifted to the
desired level or grade, the control device will stop the lifting
unit drive so that the track is no longer raised. However, certain
track working conditions require a momentary change in the track
level. For instance, it is customary to raise the track at rail
joints a little higher than the remainder of the track, i.e. above
the desired track level (zero point) set on the indicator, to
provide a "bump" at the rail joints. This bump is gradually reduced
by the train traffic passing thereover until the track level is
even and smooth along its entire extension. This level is
maintained much longer than if the track had originally been
completely leveled, including the rail joint points, since the
train loads depress the track at the rail joints and would thus
cause depressions in the track level after a little while. To take
care of this condition, it is necessary to be able to raise the
track above the desired level at each rail joint and rapidly to
reset the control to obtain the desired level at all other track
points.
For this purpose, a preferred feature of this invention provides a
setting control with a shaft carrying a pointer and a control disc
carrying a scale. The disc is rotatable about the shaft into
desired angular positions and is fixable in each such position. The
pointer cooperates with the scale for setting the control
temporarily to points deviating from the generally desired track
level, i.e. a point on the scale other than zero, even during the
lifting. Immediately after the deviation has been set, i.e. after
the track has been raised at a rail joint above the desired level,
the pointer may be re-set to zero so as to proceed with the
correction to the desired level. The rotary adjustment of the scale
in respect of the pointer into different fixable settings makes it
possible readily to vary the settings from an original zero point
to desired deviations therefrom.
While electromotor means may be used for driving the track lifting
unit, the preferred drive for raising the unit is a hydraulic motor
operated by a hydraulic circuit including a source of hydraulic
fluid, a fluid supply line connecting the hydraulic fluid source to
the motor and a constant-speed pump for the fluid in the supply
line. In this case, the preferred control device is a solenoid
servo valve having a coil electrically connected to the track level
indicator and receiving the control signals therefrom to control
the hydraulic fluid flow in response to the control signals.
Although such a hydraulic motor control has been proposed for track
lifting, the control signals were optically derived in the
conventional apparatus by means of a reference beam of
electromagnetic radiation. In this known system, the sensor is a
stop which gradually moves into the conical light bundle which
constitutes the reference and a light receiver with a plurality of
vertically spaced photocells receives varying portions of the light
to control the servo valve. Such a control is complicated and,
therefore, subject to operational difficulties and errors.
In contrast to this conventional control, the present invention
provides a very simple and robust structure which continuously
indicates the track level during the entire operation, rather than
the stepwise control attained by the several photocells of the
known optical control system, which continuous reading provides an
absolutely continuous and gradual reduction in the lifting speed
until the drive stops entirely when the desired track level has
been reached. Furthermore, the reference wire use in the present
control, instead of a beam of electromagnetic radiation, has the
advantage that this reference may also be used for controlling
other operations of the track tamping and leveling machine, such as
the tamping pressure of the tamping tools and/or the lining of the
track, which is impossible with a light beam.
In a preferred embodiment, two tensioned reference wires are
provided, each associated with a respective track rail and each
cooperating with a respective track level indicator. A measuring
bogie is mounted for mobility on the track section to be leveled
and means for adjustably supporting the forward ends of the
tensioned wires is mounted on the measuring bogie. A control
automatically adjusts the vertical positions of the forward wire
ends in respect of each other. In such a reference systen, the
desired superelevation of the track may be readily selected by
providing a control comprising a rotary potentiometer mounted on
the measuring bogie and a pendulum mounted on the rotary shaft of
the potentiometer for pivotal movement in a vertical plane
transverse to the track whereby the potentiometer indicates the
superelevation of the track. A superelevation setting element for
setting a desired superelevation at the potentiometer is connected
to a differentiating circuit unit, and the means for vertically
adjustably supporting the tensioned wire ends is electrically
connected to the differentiating circuit unit for vertically
adjusting a respective wire end.
In this arrangement, one wire end is vertically adjusted
automatically in dependence on the difference between the actual
superelevation indicated by the pendulum and the desired
superelevation so that the two wires define a reference plane
parallel to the desired track plane and in respect of which the
track may be accurately corrected.
It will be advantageous to provide an independent drive, such as an
electromotor, for vertically moving each forward wire end so that
the control actuates one of the forward wire ends while a manually
operable control switch is provided for actuating the other
independent drive. In this manner, the control switch may be
manually set for selecting the basic lifting stroke for the one
rail while the superelevation is then automatically controlled by
lifting the other rail in respect of the automatically controlled
other wire end position.
For many operations, it will be desirable to have a visual
indication for the track lifting operation by associating an
indicating device, which may include a permanent recorder, with the
differentiating circuit units in the lifting and superelevation
controls.
It will also be useful if the rear ends of the tensioned wires in
the leveled track section, the forward ends of the wires in the
track section to be leveled, and the indicator part in connection
with the track are supported on respective measuring bogies movable
on the track and supported under the machine frame, the three
measuring bogies being preferably so mounted that they may be
temporarily lifted off the track. This saves the time-consuming
preparation of the machine for operation, which has been required
in known track leveling machines wherein the forward and rear
measuring bogies are held spaced from the machine by rods and had
to be pulled out to position them properly. In the present machine,
the bogies are simply lifted off the track when not operational and
are rapidly lowered into position under the machine frame when the
machine is ready for operation.
A very advantageous structure is provided when the machine frame is
of such elongation that the wire extends from end to end within the
length of the frame, and at least one wire end is affixed directly
to the machine frame. Particularly if a tension spring affixes the
one wire end to the frame, this arrangement assures a taut
tensioning of the wire and thus avoids wire vibrations or slack as
much as possible to improve the accuracy of the reference.
The above and other objects, advantages and features of the present
invention will become more apparent from the following detailed
description of certain now preferred embodiments thereof, taken in
conjunction with the accompanying drawing wherein
FIG. 1 is a schematic side elevational view of a track tamping and
leveling machine incorporating the controls of this invention;
FIG. 1a is a control circuit diagram showing the control of the
track lifting unit;
FIG. 2 is a schematic perspective view illustrating the reference
system of the machine, with particular attention to the track
superelevation control;
FIG. 2a is a control circuit diagram showing the superelevation
control;
FIG. 3 shows a portion of the control circuit diagram of FIG. 1a
with particular attention to the setting control; and
FIG. 4 is a cross sectional view of the setting control of FIG.
3.
Referring now to the drawing, wherein like reference numerals
designate like parts functioning in an equivalent manner in all
figures, FIG. 1 illustrates a track tamping and leveling machine
with an elongated machine frame 3 mounted for mobility on the track
7 for moving in the direction of arrow A from a previously leveled
track section, wherein the machine frame is supported on rear
running gear 1, towards a track section to be leveled, wherein the
machine frame is supported on front running gear 2. Mounted on the
frame between the running gears are generally conventional
vertically adjustable tamping tools 4 and a generally conventional
track lifting unit 5. The tamping tool unit 4, which is illustrated
as being of the general type shown in our U. S. Pat. No. 3,429,276,
dated Feb. 25, 1969, is mounted immediately adjacent the rear
running gear 1 so that the tamping tools may tamp the ballast
underneath the ties and thus fix the track in the graded position
after it has been raised to the desired track level by the track
lifting unit 5 mounted forwardly of the tamping unit. The unit 5 is
also conventional and includes a hydraulic drive motor 24 mounted
on the frame 3 and having a vertically movable piston rod connected
to a bracket supporting rail gripping rollers and glidably mounted
on a vertical guide rail on the frame. As is also known, a track
lining unit 6 is combined with the track lifting unit so that the
track may be lined at the same time that it is graded. All of these
structures are well known and may be substituted, of course, by
other suitable tamping and track lifting means. Measuring bogies 8,
9 and 10 are vertically movably mounted on the machine frame and
run on the track under the frame during operation of the machine
while they may be lifted off the track when desired. The measuring
bogies have respective vertical support rods 11, 12 and 13, the
rear bogie 10 supporting the rear ends 18 of tensioned reference
wires 14, 14 (see FIG. 2), the front bogie 8 supporting the front
ends 15 of the wires, and the intermediate bogie 9 within the range
of the tamping unit supporting the track level indicator 20. The
ends of the track level reference wires 14, 14 are trained over
guide rollers 16 and 19, respectively, which are mounted on support
rods 11 and 13, respectively, the front ends being fixed to the
rollers 16 while the rear ends are guided by rollers 19 to tension
springs 17, 17 which affix the rear ends of the tensioned wires to
frame 3 so that the wires are tautly held on the frame. Instead of
tension springs 17, the rear ends of the wires could be attached to
pressure fluid operated tensioning cylinders, with an equivalent
result.
For the sake of clarity and since it forms no part of the present
invention, the reference system for the lining unit 6 has been
omitted from the drawing.
As best shown in FIG. 2, the track leveling reference system
comprises two tensioned wires 14, 14 each associated with a
respective track rail 7 and each cooperating with a respective
track level indicator 20. The forward ends 16 of the wires are
vertically adjustably supported on the rods 11 of measuring bogie 8
to control the superelevation of the track in a manner to be
described hereinafter. First, however, the track leveling control
of the present invention will be described with reference to FIGS.
1a, 3 and 4.
As shown in FIGS. 1 and 2, the support rods 12, 12 carry the
two-part track level indicators which are shown as comprising one
part consisting of a fork member 22 (see FIG. 1a) having two tines
wherebetween the tensioned reference wire 14 is constantly held,
and another part consisting of a rotary potentiometer 20 having a
rotary shaft 21 whence the fork member 22 extends radially, the two
indicator parts thus being movable in respect to each other. Each
change in the vertical position of the track rail 7 in respect of
the associated reference wire 14 automatically causes a movement of
the radial fork member and a corresponding adjustment of the
potentiometer, the changed resistance in the potentiometer
producing a control signal corresponding and responsive to the
change in the vertical track rail position. This control signal is
used to operate a servo valve 23 in the manner illustrated in FIG.
1a.
As shown, the drive for raising the track lifting unit 5 is
hydraulic motor 24 operated by a hydraulic circuit including a
source of hydraulic fluid constituted by sump 32, a fluid supply
line 32' connecting the hydraulic fluid sump to the motor 24, a
fluid return line 33, and a constant-speed pump 31 for the fluid in
the supply line 32'. The control device is solenoid servo valve 23
in the supply line. The coil 26 of the valve is electrically
connected to the track level indicator by the control circuit
illustrated in FIG. 1a.
In the illustrated control circuit, the potentiometer 20 is
electrically connected to the solenoid valve coil 26 via a
differentiating circuit unit 27 and a signal amplifier 25. The
voltage changes automatically occurring in the potentiometer 20
during raising of the track are thus transmitted to the servo valve
to change the hydraulic fluid supply to motor 24 correspondingly so
that the motor speed is reduced proportionally to the rise of the
track towards the desired track level until it stops entirely when
this level has been reached. This control operates continuously
rather than stepwise. The control would operate functionally
identically if the hydraulic motor 24 were replaced by an
electromotor, for instance, since it would reduce the electric
power for the motor proportionally to the rise of the track with
which the potentiometer 20 is connected and with which it
rises.
While the electrical conductor from potentiometer 20 forms one
input of the differentiating circuit unit 27, an electrical
conductor from a setting control 28, also constituted by a rotary
potentiometer, forms the other input of the differentiating circuit
unit, the potentiometer 28 serving to set the zero point for the
control, i.e. the point when the desired track level has been
reached.
After the front end 15 of wire 14 in the track section to be
leveled has been set, any voltage differences in differentiating
circuit unit 27, which are due to differences in the vertical
position of wire 14 and shaft 21 of indicator potentiometer 20, may
be balanced or equalized by means of setting potentiometer 28
forming the second input of unit 27 so that the track lifting unit
will always stop at the desired track level. This setting control
will be further explained hereinbelow in connection with FIGS. 3
and 4. If desired, the potentiometer 28 may be manually operated to
provide a manual control of servo valve 23.
The output of the differentiating circuit unit 27 is connected to
signal amplifier 25 whose output feeds the amplified signal to
servo valve coil 26 as well as to branch conductors leading to
indicating devices 29 and 30. The indicating device 30 is a
visually accessible meter whose scale shows the status of the
lifting operation while indicating device 30 is a recorder wherein
a stylus operated by the control signal permanently records the
track level on a moving tape. If desired, meter 30 may be used for
setting the potentiometer 28, i.e. the potentiometer pointer is
moved until the pointer on meter 30 registers with zero on the
scale of the meter.
The control circuit 34 for adjusting the vertical positions of the
forward wire ends 16 in respect of each other is shown in FIG. 2a
but it should be noted that the track lifting control according to
the invention may be used also with a track level reference system
comprising only a single tensioned reference wire running, for
instance, centrally between the rails. However, when two wires each
associated with a respective rail are used, as herein described, an
automatic control can be provided not only for the track level but
also for the superelevation of the track.
For this purpose, and as mentioned hereinabove, the front ends 16
of the two reference wires 14 are vertically adjustably mounted on
support rods 11. For instance, the support rods may consist of two
telescoping tubes, with the upper tubes carrying the guide rollers
15 to which the wire ends 16 are affixed. These upper tubes are
vertically moved by respective electromotors 35a, 35b whose
respective output shaft is coupled to the upper tube by a gear
transmission. A transverse carrier beam 36 is affixed to the two
supports rods 11, 11 and a rotary potentiometer 37 is mounted on
the carrier beam to control the operation of the lift motors 35a,
35b. The rotary shaft 38 of control potentiometer 37 mounts a
pendulum 39 for pivotal movement in a vertical plane tranverse to
the track in the directions of the double-headed arrow shown in
FIG. 2a. The rotary shaft 38 is freely rotatable by the swinging
movement of the pendulum to indicate the actual superelevation of
the track. A superelevation selecting element for setting the
desired superelevation, which is embodied herein by another rotary
potentiometer 40, provides one input for differentiating circuit
unit 41 while the other input thereof is provided by potentiometer
37, both potentiometers being electrically connected to the unit 41
whose output provides a control signal to amplifier 42. The
amplified control signal is fed to the electromotor lifting the
wire end to be adjusted (in the illustrated embodiment motor 35a),
the end of the wire associated with the grade rail having been
previously set by manually operable switch 43 connected in the
illustrated embodiment to the motor 35b by electrical conductor
43'. Of course, a switch (not shown) is provided to change the
electrical connections to electromotors 35a, 35b when the grade
rail is changed, i.e. when a change in the direction of the track
curve occurs, so that electromotor 35a is connected to manual
switch 43 and electromotor 35b is connected to control circuit
34.
Also, the amplified control signal in circuit 34 is fed by a branch
conductor to indicating devices 44 and 45 which are identical to
devices 29 and 30 so that they require no further description.
As illustrated in FIG. 2, it is also possible to associate further
indicators 46 with each tensioned reference wire to produce
additional control signals for other operations, such as the
regulation of the tamping pressure or the lateral movement of the
track, in which case operating motors for the tamping tools and/or
the lateral track moving unit 6 are controlled by the additional
control signals.
The operation of the machine will be apparent from the above
description of its structure and will be summarized hereinbelow for
a ready understanding of the invention.
First, one of the rails 7 is selected as the grade rail and the
front end 15 of the tensioned reference wire 14 associated with the
grade rail is vertically adjusted to the desired level by manual
operation of switch 43. Secondly, the desired superelevation is
selected by operating selecting potentiometer 40 which has digital
indicators to show the selected parameters. When the machine
operates in a straight track section, the potentiometer 40 will be
set at zero, of course.
The differentiating circuit unit 41 receives its input from the
potentiometer 40 set to indicate the desired superelevation and
from potentiometer 37 which indicates the actual superelevation of
the track. If unit 41 detects a voltage difference between these
two inputs, it produces an output signal which operates lift motor
35a so as to raise the front end 15 of the reference wire 14
associated with the other rail to a level producing the desired
superelevation. This automatic adjustment may be visually observed
and recorded on instruments 45 and 44.
After the relative positions of the front ends of the reference
wires have been thus adjusted, they define a reference plane in
respect of which the track is to be leveled. As the machine
advances in the direction of arrow A, the lifting of the track by
unit 5 is continuously and automatically controlled in accordance
with the zero setting of potentiometer 28, the speed of drive 24
for each track lifting unit 5 being controlled by servo valve 23
which, in turn, is adjusted in dependence on the angular position
of indicator part 22 in respect of control potentiometer 20. The
voltage received from potentiometer 20 will be at a maximum at the
beginning of the lifting stroke so that the resultant control
signal will fully open the servo valve to supply a maximum amount
of hydraulic fluid to motor 24, thus operating it at maximum speed.
As the track is raised towards the reference, the wire engaging the
fork 22 will move the fork in respect of the potentiometer, thus
increasing the resistance and decreasing the voltage. The resultant
control signal will proportionally close the valve gradually to
reduce the lifting speed of motor 24 until the valve will be
entirely closed to stop the motor when the desired track level has
been reached and without causing the track to be raised beyond this
point.
As illustrated in FIGS. 3 and 4, the setting control 28 may be used
to set deviations from the generally desired track level, for
instance at rail joints where it is useful to raise the track
initially above the grade of the remainder of the track. To enable
such a temporary deviation from the desired track level determined
by the reference system to be set, the setting potentiometer 28
comprises a rotary shaft 49 carrying a pointer 48 on a manually
operably knurled knob 49a and a control disc 50 carrying a scale
47. The disc is rotatably journaled on potentiometer shaft 49 for
rotary movement into desired angular positions and may be fixed by
a set screw 51 in each such angular position, the pointer 48
cooperating with the scale 47 for setting the control.
The scale 47 may be calibrated in millimeters, for instance, FIG. 3
showing merely by way of example a lifting stroke deviation of .+-.
20 mm although a larger range up to 100 mm may be encompassed, if
desired. Also, the minus range, i.e. a setting below the desired
track level, may be reduced or eliminated in favor of a larger plus
range on the scale. Of course, the respective resistance values of
the potentiometer must correspong to the values marked on the scale
so as to produce corresponding control signals.
Since, as explained hereinabove, the setting potentiometer 28 also
serves for setting the zero point, i.e. for balancing the voltage
in differentiating circuit unit 27 after the grade rail reference
wire 14 has been set, it may occur that the pointer 48 does not
register with the zero point on scale 47 when the potentiometer is
set for the desired track level. This makes a setting for a
deviation from the desired track level difficult because the
operator must then add the required difference to the value with
which the set pointer 48 has registered for the desired track
level, and the pointer must then be turned to the calculated value.
Furthermore, the operator must remember the original value so that
the pointer can be turned back to it after the machine has passed
the point of track level deviation. All this is avoided by the
illustrated construction wherein the rotatable disc 50, which
carries the scale, can be rotated into temporarily fixed different
angular positions and rotated back into their normal position for
normal operation.
* * * * *