Stabilizing high speed railway truck safety device

A safety device for a banking vehicle includes a pair of cylinders which extend to hold the superstructure in an upright position. The cylinders are hydraulically connected to an accumulator which provides a pressurized fluid reservoir. A valve controls flow from the accumulator to the cylinders. Upon detection of a failure in one of the vehicle systems the valve moves to a position in which fluid flows from the accumulator to extend the cylinders. A pilot operated check valve is positioned between the accumulator and the cylinders to hold the cylinders in the extended position until the failure is rectified.

This invention is concerned with a safety device for banking vehicles, such 
as railway vehicles, and especially but not exclusively for such vehicles 
intended for use in high speed railway passenger cars. 
It is a continuing requirement for railway vehicles, particularly passenger 
cars, to achieve higher speeds combined with a safe, comfortable ride, and 
to this end a number of proposals have been made hitherto to bank the cars 
by tilting about a longitudinal axis, thereby reducing the lateral force 
applied to passengers, and permitting higher speeds of operation. There 
have been disclosed in U.S. Pat. Nos. 3,628,465 and 3,704,670 issued Dec. 
21, 1971 and Dec. 5, 1972 respectively, and assigned to Dominion Foundries 
and Steel Limited, different railway truck constructions whereby a car 
body mounted thereon can be tilted under the control of fluid-operated 
motors, specifically liquid-operated motors. These constructions provide, 
as far as possible, that the structure and components used in the trucks 
are the same or very closely similar to those of previously existing 
vehicles, so that the servicing and maintenance thereof can readily be 
accomplished with existing railway equipment, shop skills and personnel. 
One problem that must be anticipated in any vehicle, and fail-safe 
arrangements provided therefor, is the partial or total failure of the 
power supplies. A special problem with a banking vehicle is that such 
failure may take place while it is in a banked condition. If the vehicle 
becomes locked in that condition problems will arise with passenger 
comfort as the vehicle continues. A dangerous condition may arise if one 
truck of a car is locked in position and the other is not. It is therefore 
desirable to provide some positive means that will always be effective to 
prevent uncontrolled tilting of the truck body upon such failure. 
In U.S. Pat. No. 3,906,869 issued Sept. 23, 1975 and assigned to Dominion 
Foundries and Steel Limited, there is disclosed a device which will be 
effective to prevent such uncontrolled tilting. A pair of abutments are 
slidably mounted on the frame are biased by a coil spring to a position in 
which they engage the bolster to prevent tilting movement relative to the 
frame. The force of the coil spring is opposed by a pair of hydraulic 
cylinders which, when pressurized, act to compress the coil spring and 
move the abutments away from the bolster. Upon loss of pressure due to 
failure of the power source or a leak, or upon detection of improper 
operation of the electrical controls, the coil spring moves the abutments 
into engagement with the bolster. 
The above arrangement has proved successful in avoiding the potentially 
hazardous situation associated with the prior art. However, since space is 
at a premium there is a continuing requirement to arrange the components 
in a simple and compact manner so that the space occupied within the truck 
is reduced to a minimum. 
According to the present invention there is provided for use in a railway 
truck assembly having a bolster tiltable relative to a frame, a control 
circuit for hydraulic motor means operable between a first condition in 
which tilting of the bolster relative to a truck frame is inhibited and a 
second condition in which the tilting is permitted, the control circuit 
comprising a pressure line connected to a source of pressurized fluid, a 
return line connected to a sump for the pressurized fluid, a pair of 
hydraulic service lines connected to opposite sides of the hydraulic motor 
means, valve means connected to the service lines and the pressure and 
return lines and operable in a first position to direct fluid from the 
pressure line to one of the service lines to move the motor means to the 
first condition and in a second position to direct fluid from the pressure 
line to an other of the service lines to cause the motor means to move to 
the second condition, control means to move the valve means between the 
first and second positions, and a pressurized fluid reservoir connected to 
the pressure line and operable to supply pressurized fluid to the valve 
means whereby, upon movement of the valve means to the first position, the 
pressurized fluid reservoir supplies fluid to the one service line to move 
the motor means to the first condition. 
The provision of a pressurized fluid reservoir, which is preferably a 
variable volume accumulator, ensures that pressurized fluid is available 
to move the motor means upon failure of the pressure source. The 
accumulator therefore acts as a selectively operable biasing means which 
is controlled by the valve means. Locking of the motor means in the first 
position may be achieved by a check valve located in the one service line 
which prevents flow out of the motor. Pilot operation of the check valve 
is utilized to permit such flow when it is desired to move the motor means 
to the second position.

Referring now to FIGS. 1 to 5 a railway car 8 is supported on a pair of 
spaced trucks 9 each having four wheels and intended for use at high 
speeds. Each truck 9 includes a frame comprising two parallel side frame 
members 10 and 12. The members have their centre portions depressed, and 
are connected to one another intermediate their ends by a single central 
massive transom 14. The truck 9 runs on two similar wheel and axle 
assemblies, each constituted by a respective axle 16 and pair of wheels 
18. The truck is of course provided with conventional brakes (which are 
not shown) and may be a motorized unit, in which case each axle will, for 
example, be driven by a respective electric motor and gear unit (not 
illustrated) mounted on the frame and operatively connected to the 
respective axle. The manner in which such motor and gear units (when 
provided) and the brake units can be mounted in the frame will be apparent 
to those skilled in the art. 
Each axle 16 is rotatably mounted in the frame by a respective pair of 
journals 20, each of which is mounted and guided for the necessary 
generally vertical movement by two resilient suspension units 22. The car 
body that is to be mounted on the truck is indicated diagrammatically as a 
floor member 24 (FIGS. 3 and 5), having downwardly extending bracket 
members (FIG. 3) fastened to the underside thereof on either side adjacent 
each truck. Bolster means for mounting the body on the truck frame 
comprise lower and upper bolster members 28 and 30 respectively, the lower 
bolster member 28 being connected to the side frames by a link suspension 
system, while the upper bolster member 30 is pivotally connected to the 
lower bolster member and in turn supports the vehicle body 24 via massive 
laterally-spaced air springs 32. 
In this particular embodiment the means pivotally connecting the two 
bolster members comprise four resilient suspension units 34, disposed at 
the four corners of a rectangle with their longitudinal compression axes 
generally vertical. The center portion of the lower bolster is provided 
with an upwardly extending spigot 36 that extends into an aperture 38 in 
the upper bolster 30. In some embodiments it may be preferred to mount the 
spigot 36 on the upper bolster and have it enter into a corresponding 
aperture in the lower bolster. The spigot 36 is mounted in the aperture 38 
by two opposed longitudinally spaced resilient suspension units 40; stop 
members 42 are provided and are engaged by the spigot upon its extreme 
transverse motion. 
Each end of the lower member 28 is connected to the respective truck side 
frame by an articulated linkage comprising a generally Y-shaped link 
member 44, which is operative as a bell-crank lever and is pivoted to 
upstanding lugs 46 on the frame about its crank pivot axis by a pivot axis 
by a pivot rod 48. The end of one crank arm of the link member 44 is 
connected by a pivot rod 50 to the adjacent ends of a bifurcated link 52, 
the other ends of the link 52 being connected by a pivot 54 to lugs 56 
extending from the bolster member 28. The ends of the other crank arms of 
the Y link members 44 are connected by pivot rods 58 to the respective 
ends of a connecting link 60. The articulated linkage is completed by a 
depending link 62 (FIG. 2a) fixed rigidly at its upper end to the central 
portion of bolster member 28 and pivoted at its lower end by a rod 64 to 
one end of a short transverse link 66 that is disposed generally parallel 
to the connecting link 60 and is accomodated in a recess therein. The 
other end of the transverse link 66 is connected to the link 60 by a pivot 
rod 68. 
The required rolling or tilting motion of the two bolster parts relative to 
the frame is produced under the control of first motor means 70 comprising 
two double acting hydraulic units 70a, 70b which are disposed one on each 
side of the bolster. Each unit 70a, 70b is pivotally connected at 72 to 
the frame and at 74 to the lower member 28. Solid links 76 (FIG. 2) are 
connected by spherical rubber bushings to the upper bolster 30 and to the 
brackets 26 fastened to the car floor, while damper units 78 are pivotally 
connected between the two bolster members. 
The action of the connecting linkage is permitting tilting of the bolster 
member and of the vehicle body mounted thereon will be apparent to those 
skilled in the art. A detailed description appears in the above identified 
U.S. patents, the teachings of which are incorporated herein by reference. 
However, to ensure a full and complete understanding of the present 
invention the operation of the connecting linkage will be briefly 
described, assuming that the body is to be tilted counter clockwise with 
respect to the frame 12 when viewed in FIG. 3. Pressure fluid is directed 
to the first motor means 7a, 70b by a control circuit described below to 
cause extension of hydraulic unit 70a and retraction of hydraulic unit 
70b. The lower member 28 moves to the right to exert a lateral force 
through transverse link 66 to the connecting link 60. The Y-shaped links 
44 will rotate counter clockwise about the pivot pins 48 and act through 
respective links 52 to rotate the lower member 28 counter clockwise. Since 
the bolster member 30 is carried by the four pads 34, it will also tilt 
counter clockwise and move the car body into a banked condition. The body 
will be held in this condition until flow to the motor means is reversed 
to move the lower member 28 to the left so that the linkage operates to 
move the car back to an upright condition. 
The tilting of the car body is controlled by the electrical and hydraulic 
circuit shown in FIG. 6. An electrically driven motor 80 drives a variable 
displacement hydraulic pump 82 which receives fluid from a sump 84 and 
delivers it to a pressure line 86. A pressure sensing device 88 is 
connected in the pressure line 86 to sense the pressure delivered by the 
pump 82 and generate an electrical signal should the pressure drop below a 
predetermined value. Accumulators 87 are also hydraulically connected to 
the pressure line 86 to provide a reservoir of pressurized hydraulic fluid 
and reduce pressure surges in the circuit. The pressure line 86 is 
connected through a check valve 90 to a pair of branch conduits 92,93 
which respectively supply a pair of manifolds 94, 95. Hydraulic fluid from 
the manifolds 94, 95 is returned to the sump 84 through conduits 101, 103 
and return conduit 96 which includes a filter assembly 98. Each of the 
manifolds 94, 95 includes identical hydraulic components and each is 
associated with a respective one of the trucks 9. Since the manifolds 94, 
95 are identical only one has been shown in detail and will be described 
herein. The manifold 94 includes a tilt circuit 97 and a safety circuit 99 
which are connected in parallel to the branch conduit 92 and conduit 101. 
To service the tilt circuit, the branch conduit 92 and conduit 101 are 
connected respectively to an inlet port 100a and return port 100b of an 
electro-hydraulic proportional servo valve 102. The valve 102 has a pair 
of outlet ports 104, 106 to which are connected tilt lines 108, 110 
respectively. The tilt line 108 is connected to the head end of the 
hydraulic unit 70a and rod end of hydraulic unit 70b. The tilt line 110 is 
connected to the rod end of the hydraulic means 70a and the head end of 
unit 70b. If the valve 102 is maintained in a neutral position the tilt 
lines are sealed so that the motor means 70a and 70b are fixed. The valve 
102 may be moved to a first position in which the branch conduit 92 is 
connected to the tilt line 108 and the conduit 101 connected to the 
conduit 110. The hydraulic unit 70a will thus extend and cause 
anti-clockwise tilting of the car body 24 in the manner described above. 
Similarly, the valve 102 may be moved to a second position to connect the 
branch conduit 92 to the tilt line 110 and the conduit 101 to the tilt 
line 108 to produce clockwise tilting of the body. The valve 102 is 
controlled by a servo device 112 which is regulated by an accelerometer 
control 114. The accelerometer senses lateral acceleration of the railway 
car 8 and generates a signal to the servo 112. The servo device 112 
responds to move the valve 102 in the desired tilting direction and in 
proportion to the magnitude of the signal received from the accelerometer 
114. The movement of the valve 102 is thus proportional to the lateral 
acceleration to produce a proportional tilting of the car 8. 
The tilt lines 108, 110 are protected against excessive pressure and 
cavitation by crossover relief and check valve assembly 116 which includes 
four check valves 117, 118, 119, 120 and a pressure relief valve 122. The 
check valves 117, 118 permit flow from the lines 108, 110 to the relief 
valve through a choke 121 whereas the valves 119, 120 permit flow to the 
tilt lines 108, 110 from a relief line 124 connected to the conduit 101 
and the return conduit 96. In this manner, whichever of the lines 108, 110 
is at the higher pressure is serviced through one of the check valves 117, 
118 by the relief valve 122 and any flow through the relief valve 122 is 
directed through relief line 124 and one of the other check valves 119, 
120 to the opposite side of the first motor means 70a and 70b. 
The setting of the relief valve 122 is regulated by a two position control 
valve 156 which forms part of the safety circuit 99. The control valve 156 
controls flow through a drain line 158 connected between the valve 122 and 
the drain line 101. The valve 156 is biased by a spring 160 to a first 
position in which flow through the valve 156 is permitted. In this 
position, the relief valve 122 will open at a very low nominal pressure so 
that there is free flow across the first motor means units 70a and 70b 
through the crossover relief and check valve assembly 116. This permits 
the car 8 to tilt freely relative to the truck 9. A solenoid 162 operates 
when energized to move the valve 156 against the spring 160 to a second 
position in which flow through the line 158 is prevented. When the valve 
156 is in the second position fluid trapped between the valve 122 and 
valve 156 acts to set the relief valve 122 at a higher pressure, typically 
in the order of 2,300 p.s.i. In this condition under normal operating 
conditions, flow between the tilt lines 108, 110 is prevented. 
The safety circuit includes a two position directional valve 132 which 
controls flow from the branch conduit 92 through pressure conduit 126 to a 
pair of safety cylinders 134, 135. The cylinders 134, 135 are connected to 
the valve 132 by service lines 136, 137 so that when the valve 132 is in a 
first position it connects the pressure conduit 126 to the service line 
136 to cause extension of the cylinders 134, 135. In this first position 
flow from the cylinders 134, 135 is returned to sump 84 through service 
line 137 which is connected by valve 132 to a drain line 128 communicating 
with conduit 101 and return line 96. 
As can best be seen in FIGS. 2 to 5, the cylinders 134, 135 are mounted on 
the frame 12 in alignment with lugs 56 on the lower member 28. With the 
cylinders 134, 135 retracted, a clearance is provided between the lugs 56 
and the frame 12 to permit the desired tilting action. The stroke of the 
cylinders 134, 135 is chosen so that when extended, as shown in FIG. 5, 
pads 134a, 135a are positioned to engage the lugs 56 when the lower member 
is in a generally horizontal position. 
The valve 132 is biased to the first position by a spring 138 and is moved 
by a solenoid 139 to a second position in which the pressure conduit 126 
is connected to service line 137 and drain line 128 is connected to 
service line 137. The service line 136 includes a check valve 140 which 
normally prevents flow from the head end of cylinders 134, 135. In order 
to permit the cylinders 134, 135 to be retracted when the valve 132 is in 
the second position, a pilot line 142 is connected between the service 
line 137 and the check valve 140 so that pressurized fluid in the line 137 
will open the check valve and allow fluid to flow to drain conduit 128. 
The line 136 also includes a relief valve 144 between the check valve 140 
and the cylinders 134, 135 to relieve excessive pressures in the head end 
of the cylinders. 
An accumulator 150 is connected by a conduit 152 to the pressure conduit 
126 intermediate the check valve 146 and throttle 148 and serves as a 
pressurized fluid reservoir. The accumulator 150 is precharged with 
nitrogen gas and constitutes a variable volume reservoir. Delivery of 
pressurized hydraulic fluid through the conduit 152 will compress the gas 
in the accumulator and increase the volume of hydraulic fluid stored by 
the accumulator. Similarly a reduction of hydraulic pressure will allow 
the gas to expand and expel hydraulic fluid from the accumulator. 
The pressure conduit 126 incorporates a check valve 146 to prevent flow 
from the accumulator 150 to the branch conduit 92 and a throttle 148 to 
regulate the rate of flow through the valve 132 to the cylinders 134 and 
135. 
A control centre 154 controls electrical power supply to the motor 80, the 
servo device 112, and the solenoids 139, 162 in accordance with signals 
received from a number of sensors. These sensors include the pressure 
sensing device 88, a pressure differential sensing device to detect 
variations in pressure in the first motor means units 70a and 70b of the 
trucks 9, and a thermostat to detect abnormal temperatures, an electric 
power supply monitor although additional sensors may be utilized if 
desired. 
Under normal operating conditions, the control centre 154 directs power to 
the motor 80, the servo device 112 and the solenoids 139, 162. The pump 82 
thus supplies pressurized fluid to the tilt and safety circuits and the 
valve 156 is moved to set the relief valve 122 to the higher relief 
pressure. The valve 132 is moved by the solenoid 139 to its second 
position so that pressurized fluid is directed to the line 137 to open the 
check valve 140 and retract the cylinders 134, 135. The pilot operation of 
the check valve 140 ensures that pressurized fluid is available before 
flow out of the head end of the cylinders 134, 135 is permitted. The 
accelerometer 114 will thus control movement of the proportional servo 
valve 102 and direct fluid as required to produce the desired tilting 
movement. 
Upon detection of an abnormal condition by one of the sensors, for example, 
a pressure loss detected by the sensor 88, the control centre will cut the 
power supply to the motor 80, servo device 112 and solenoids 139, 162. The 
valve 156 will be moved by the spring 160 to its first position to open 
the conduit 158 and reduce the pressure setting of the relief valve 122. 
Hydraulic fluid is free to move across the motor means units 70a and 70b 
through the cross over relief and check valve assembly 116 to permit 
movement of the car relative to the truck 9. The choke 121 controls the 
rate of such morement. 
At the same time, the valve 132 will be moved by the spring 138 to connect 
the conduit 126 with the service line 136. Fluid will be expelled from the 
accumulator 150 through the line 152 and into the head end of the 
cylinders 134, 135. The check valve 146 prevents flow from the accumulator 
150 to the sump so that the cylinders 134, 135 extend at a rate controlled 
by the throttle 148. 
If the lower member 28 is in a tilted condition, e.g. moved to the right as 
viewed in FIG. 2, one of the cylinders, in this case cylinder 135, will 
fully extend to the position shown in FIG. 5, in which its pad 135a is 
spaced from the adjacent pad 56. The other cylinder 134 will extend until 
the pad 134a abuts the respective lug 56. The suspension of the railway 
car 8 on the truck 9 is such that there is a tendency for the body to 
return to an upright position. As the car 8 returns to the upright 
position, the pad 134a will follow the lug 56 until the lower member is 
horizontal and the pad 135a abuts the respective lug 56. The check valve 
140 prevents flow of fluid from the head end of the cylinders 134, 135 so 
that they act as rigid struts and hold the lower member 28 in a horizontal 
position. 
The cylinders 134, 135 will remain in the extended locking condition until 
the condition detected by the sensor is normalized and pressure again 
exists in line 137 to retract the cylinders. 
It will be seen, therefore, that a simple effective arrangement is provided 
which ensures that the car 8 is maintained in a stable condition upon 
detection of a fault. It will be appreciated that the safety circuit also 
operates when the car is taken out of service, resulting in a loss of 
electric power supply, and ensures that pressure has built up in the 
tilting circuit and accumulator 150 before the check valve 140 opens to 
retract the cylinders 134, 135. 
Whilst a solenoid operated valve has been shown to control the safety 
circuit it is possible to utilize a pilot pressure operated valve which is 
connected directly to a suitable tap point in the tilt circuit such as the 
feed to the relief valve 122. 
It will be seen therefore that a simple compact arrangement is achieved 
which reduces the space required by the safety device on the frame of the 
truck and operates in an efficient, simple manner.