Ballast cleaning machine

In a self-propelled ballast cleaning machine which comprises a ballast excavating chain having an output, a hydraulic drive for moving the ballast excavating chain, a ballast screening and storing device arranged to receive the excavated ballast from the output for separating the excavated ballast into waste and cleaned ballast and for storing the cleaned ballast, and a hydraulic vibrating drive for imparting vibrations to the ballast screening and storing device, a control arrangement operates the hydraulic drives, the control arrangement including a control element having an input and an output, the input of the control element being connected to the chain moving drive and the output of the control element being connected to the vibrating drive for changing the frequency of the vibrations imparted to the ballast screening and storing device analogously to a respective setting of the control element for storing the ballast in the device.

The present invention relates to a self-propelled ballast cleaning machine 
comprising a ballast excavating chain having an output, a hydraulic drive 
for moving the ballast excavating chain, a ballast screening and storing 
device arranged to receive the excavated ballast from the output for 
separating the excavated ballast into waste and cleaned ballast and for 
storing the cleaned ballast, a hydraulic vibrating drive for imparting 
vibrations to the ballast screening and storing device, and conveyor means 
for respectively receiving the waste and the cleaned ballast from the 
ballast screening and storing device, for redistributing the cleaned 
ballast and for removing the waste. This invention also provides an 
improved ballast cleaning method. 
Our U.S. Pat. No. 4,245,703, dated Jan. 20, 1981, discloses such a machine 
wherein a housing wall of the screening device at the outlet side has a 
pivotal closure which is remotely controlled by the forward drive of the 
machine to enable the screening device housing to be used for storing the 
ballast. The closure control is also connected to the vibrating drive to 
enable the same to be stopped when the closure is pivoted closed. This 
prevents disadvantageous accumulations of stored ballast when the forward 
drive of the machine is interrupted for a short time but it requires a 
pivotal closure which is prone to malfunction. 
It is the primary object of this invention to provide a ballast cleaning 
machine of the first-indicated type with simple means for assuring a 
proper intermediate storage of the cleaned ballast in the ballast 
screening and storing device. 
The above and other objects are accomplished according to one aspect of the 
invention with a control arrangement for operating the hydraulic drives 
and which includes a control element having an input and an output, the 
input of the control element being connected to the chain moving drive and 
the output of the control element being connected to the vibrating drive 
for changing the frequency of the vibrations imparted to the ballast 
screening and storing device analogously to a respective setting of the 
control element for storing the ballast in the device. 
With this control arrangement, a simple and inexpensive control element 
couples the chain moving and vibrating drives together so that the ballast 
storage will become effective immediately upon interruption of the ballast 
delivery to the ballast screening and storing device. No special and 
additional structure is required in a conventional screening device if it 
is to be retrofitted for storing. With the control arrangement of the 
invention, the frequency of vibrations may be reduced when no excavated 
ballast is fed to the screening and storing device, thus reducing wear on 
the screening means and extending its operating life. Furthermore, the 
temporary reduction of the vibration frequency and stoppage of the chain 
movement produces a considerable energy saving and diminishes the noise. 
The direct connection of the control element to the vibrating drive also 
enables the frequency of the vibrations to be increased instantaneously as 
the movement of the excavating chain is resumed so that proper cleaning of 
the ballast is assured. 
Accordingly, the ballast is cleaned by excavating the ballast with a moving 
excavating chain, moving the excavated ballast on the moving chain to a 
ballast screening and storing device including screening means for 
separating the excavated ballast into waste and cleaned ballast and for 
storing the cleaned ballast on the screening means, vibrating the 
screening and storing means for imparting vibrations thereto, reducing the 
frequency of vibrations when the moving excavating chain is stopped for a 
short time to interrupt movement of the excavated ballast to the ballast 
and screening device whereby the ballast is stored on the screening means, 
subsequently increasing the frequency of vibrations to a maximum when the 
movement of the excavated ballast on the chain is resumed for effectively 
separating the excavated ballast into waste and cleaned ballast, and 
redistributing the cleaned ballast. 
This method assures a continuously homogenous cleaned ballast bed, 
regardless of operational interruptions, stoppages from time to time or 
different forward speeds of the machine. By storing the cleaned ballast 
directly in the screening device, this storage can be assured 
automatically in immediate response to any interruption of the delivery of 
the excavated ballast and totally independently of the experience and/or 
attention of the machine operator. Furthermore, when the excavating chain 
movement is resumed and without any time lapse, the ballast is immediately 
and forcefully screened and the cleaned ballast is received from the 
screening and storing device by the conveyor means for redistribution so 
that the operation will proceed automatically without requiring the 
attention of an operator.

Referring now to the drawing and first to FIG. 1, there is shown 
self-propelled ballast cleaning machine 1 comprising frame 3 mounted on 
two swivel trucks on which the machine is moved along track 2 in an 
operating direction indicated by arrow 4. As is conventional, a track 
lifting unit is mounted on machine frame 3 for raising the track where the 
ballast is to be excavated by endless ballast excavating chain 6 which is 
moved by hydraulic drive 5 for excavating the ballast under the track and 
delivering the excavated ballast to ballast screening and storing device 8 
arranged to receive the excavated ballast from an output at the apex of 
the excavating chain for separating the excavated ballast into waste and 
cleaned ballast and for storing the cleaned ballast. Hydraulic vibrating 
drive 7 imparts vibrations to the ballast screening and storing device. 
Four heavy coil springs mount ballast screening and storing device 8 for 
free vibration on support frame 9 which is mounted on machine frame 3 and 
the ballast screening and storing device is pivotal with respect to the 
machine frame about an axis extending in the direction of track 
elongation. This enables heavy ballast screening and storing device 8 to 
be adjusted into a horizontal position at a point of track superelevation. 
Vibrating drive 7 has eccentric balancing weights rotating in opposite 
directions for imparting linear oscillations to device 8. The ballast 
screening and storing device has ballast screening means illustrated as 
three superposed screens 10 comprised of tensioned rubber sieves of 
different mesh sizes for separating the excavated ballast into waste and 
cleaned ballast and for storing the cleaned ballast. Outlet chutes 11 are 
arranged at each side of the ballast screening and storing device. 
Conveyor means is arranged on the machine for respectively receiving the 
waste and the cleaned ballast from the ballast screening and storing 
device, for redistributing the cleaned ballast and for removing the waste. 
The illustrated conveyor means comprises a respective conveyor band 12 
having an input end under a repective outlet chute 11 for receiving the 
cleaned ballast therefrom. Each conveyor band is mounted on machine frame 
3 for pivoting about a vertical axis so as to sweep the output end of the 
conveyor band opposite to the input end over substantially half of the 
track area for redistributing the cleaned ballast near the point of 
excavation. The conveyor means further comprises conveyor 14 having an 
input end below ballast screening and storing device 8 for receiving the 
waste therefrom. Conveyor 14 extends partially between conveyor bands 12 
associated with the respective rails of the track and rises to an output 
end thereof whence the waste is thrown into a hopper for further disposal 
or to the shoulders of the track, all in a conventional manner. 
Furthermore, a conventional ballast planing device is shown to be mounted 
on machine frame 3 rearwardly of the output ends of conveyor bands 12 for 
smoothing the redistributed cleaned ballast. 
The control arrangement of this invention is shown in the enlarged diagram 
of FIG. 2. As schematically illustrated, a hydraulic fluid supply source 
15 for chain moving drive 5 and vibrating drive 7 is connected to the 
drives, this source comprising a hydraulic fluid sump and a fluid delivery 
pump connected in the hydraulic circuit to supply hydraulic fluid from the 
sump to chain moving drive 5. Control arrangement 16 is arranged in the 
hydraulic circuit between the fluid delivery pump and drives 5 and 7, and 
this arrangement comprises two-way valve 17 mounted in the supply conduit 
delivering the hydraulic fluid from the pump to drive 5. The two-way valve 
is operated by control lever 18 and this lever is connected to control 
element 19 mounted in the supply conduit delivering the hydraulic fluid to 
drive 7. The control element has input 20 and output 21. The illustrated 
control element is a steplessly adjustable pump controlling the flow of 
hydraulic fluid from a sump to the vibrating drive. The pump may be a 
rotary pump having 1150-1350 rpm. Such a steplessly adjustable pump will 
provide a particularly simple and stepless control particularly suitable 
for conventional vibrating drives for steplessly changing the rotary speed 
of the vibrating drive and, thus, the frequency of vibrations imparted 
thereby. As shown, input 20 of control element 19 is connected to chain 
moving drive 5 by way of its actuating valve and output 21 is connected to 
vibrating drive 7 for changing the frequency of the vibrations imparted to 
the ballast screening and storing device analogously to a respective 
setting of the control element for storing the ballast in device 8. When 
control element 19 is arranged to reduce the frequency of the vibrations 
to at least about one third of a maximum frequency of vibrations when 
chain moving drive 5 is operated to stop movement of the chain, the 
frequency range of vibrations will enable the ballast deposited on screens 
10 to follow the vibrations without being displaced and thus to be stored 
thereon. On the other hand, the frequency of the vibrations is still 
sufficient to enable the very heavy screening and storing device to 
overcome the inertia of its great mass rapidly and to be much more rapidly 
vibrated immediately upon resumption of the excavating chain movement so 
that the stored excavated ballast may be efficiently cleaned on the screen 
vibrated at a high frequency for separating the waste from the cleaned 
ballast. 
Ballast cleaning machine 1 may be operated in the following manner for 
cleaning the ballast: 
During normal operation, the machine is continuously advanced along track 2 
in operating direction 4 and hydraulic drive 5 is operated to move 
excavating chain 6 to excavate the ballast while vibrating drive 7 imparts 
a maximum frequency of vibrations to ballast screening and storing device 
8 which oscillates on its coil springs in the direction of the 
longitudinal extension of the machine. The excavated ballast is moved on 
the moving chain to ballast screening and storing device 8 and thrown from 
the excavating chain onto uppermost screen 10, ballast of a size exceeding 
the mesh size of this screen is retained thereon while the vibrations 
imparted to the screen cause material below this size to fall through the 
openings in the screen to intermediate screen 10 therebelow. This 
operation is repeated there and material below the size of the openings in 
the intermediate screen falls onto the lowest screen 10. The waste 
separated from the cleaned ballast on the lowest screen passes through 
outlet chutes 13 to removal conveyor 14 while the cleaned ballast passes 
through outlet chutes 11 to redistributing conveyor bands 12. 
When the operator throws operating lever 18 into the position shown in FIG. 
2 in broken lines, two-way valve 17 is actuated to interrupt the flow of 
hydraulic fluid to chain moving drive 5 so as to stop movement of ballast 
excavating chain 6. This may be required, for example, when the forward 
movement of the machine has to be temporarily discontinued. As the 
operating lever is thus moved by the operator, input 20 of control element 
19 is also moved into the position shown in broken lines. This causes the 
rotary speed of control pump to be reduced, for instance by about two 
thirds, so that the output of vibrating drive 7 is correspondingly reduced 
to reduce the frequency of vibrations imparted to the ballast screening 
and storing device, causing the ballast in this device to be stored on the 
screening means because it is no longer shaken through the openings in 
screens 10. Thus, as soon as excavating chain 6 stops moving, the ballast 
is stored in device 8. This avoids any accumulation of cleaned ballast in 
the range of the output end of conveyor bands 12 during a temporary halt 
in the ballast excavating operation. Any ballast falling through the large 
openings of the upper screen 10 will be stored on the screen therebelow, 
which has smaller openings. In other words, when the movement of the 
excavated ballast is interrupted for a short time, the frequency of 
vibrations imparted to device 8 is reduced sufficiently to permit the 
ballast in the device to be stored therein. Subsequently, when the 
movement of the excavated ballast on chain 6 is resumed, i.e. operating 
lever 18 is thrown back into the position shown in full lines, the 
frequency of vibrations is increased to a maximum for effectively 
separating the excavated ballast into waste and cleaned ballast, and to 
enable the cleaned ballast coming from screening and storing device 8 to 
be redistributed by conveyor bands 12.