CA1199834A - Rail vehicle - Google Patents
Rail vehicleInfo
- Publication number
- CA1199834A CA1199834A CA000437396A CA437396A CA1199834A CA 1199834 A CA1199834 A CA 1199834A CA 000437396 A CA000437396 A CA 000437396A CA 437396 A CA437396 A CA 437396A CA 1199834 A CA1199834 A CA 1199834A
- Authority
- CA
- Canada
- Prior art keywords
- rail vehicle
- pump
- vehicle
- valve
- pressure
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Control Of Fluid Gearings (AREA)
Abstract
"ABSTRACT"
RAIL VEHICLE"
An adhesion drive rail vehicle comprises a prime mover 1, a hydrostatic transmission 24 to power at least one driven wheel or axle of the vehicle, and a control circuit 26 to control the transmission circuit 24; the transmission circuit 24 incorporating a hydraulic motor 10 provided at the or each driven wheel or axle, a variable output pump 21 biased to a drive condition, and at least one throttle valve 3A, 3B, to control vehicle braking, located in a fluid transmission line 23, 28, of the transmission circuit 24 extending from the pump 21 to the motor(s) 10 and being operable by a disproportional area actuator 2A, the control circuit incorporating control means 6 for the variable output pump 21 and at least one driver operated speed control device 14, 15, movable in a first mode to cause acceleration of the vehicle by sending a variable pressure signal to the pump control means 6 whereby the pump 21 comes on stroke, while the driver operated speed control device 14, 15, is movable in a second mode to cause retardation of the vehicle to send a variable pressure signal to the disproportional area actuator 2A, to adjust the throttle valve 3A to induce back pressure in the return line from the motor(s) 10, a feed back loop monitoring the regenerated pressure and permitting the throttle valve 3A to continue to close as the flow through the valve 3A reduces under the influence of the actuator 2A, at a driver selected braking pressure, until the vehicle comes to rest.
RAIL VEHICLE"
An adhesion drive rail vehicle comprises a prime mover 1, a hydrostatic transmission 24 to power at least one driven wheel or axle of the vehicle, and a control circuit 26 to control the transmission circuit 24; the transmission circuit 24 incorporating a hydraulic motor 10 provided at the or each driven wheel or axle, a variable output pump 21 biased to a drive condition, and at least one throttle valve 3A, 3B, to control vehicle braking, located in a fluid transmission line 23, 28, of the transmission circuit 24 extending from the pump 21 to the motor(s) 10 and being operable by a disproportional area actuator 2A, the control circuit incorporating control means 6 for the variable output pump 21 and at least one driver operated speed control device 14, 15, movable in a first mode to cause acceleration of the vehicle by sending a variable pressure signal to the pump control means 6 whereby the pump 21 comes on stroke, while the driver operated speed control device 14, 15, is movable in a second mode to cause retardation of the vehicle to send a variable pressure signal to the disproportional area actuator 2A, to adjust the throttle valve 3A to induce back pressure in the return line from the motor(s) 10, a feed back loop monitoring the regenerated pressure and permitting the throttle valve 3A to continue to close as the flow through the valve 3A reduces under the influence of the actuator 2A, at a driver selected braking pressure, until the vehicle comes to rest.
Description
33~1 B_IL V~XCLE
.~
This invention relates to an adhesion drive rail vehicle, whether in ~he form of a fixed axle locomotive or bogie mounted locomotive, powered by prime mover (e g. a diesel engine or electric motor with or without an associated flywheel) 9 with a hydrostatic transmission to the or each driving wheel or axle. A constant problem is the avoidance of wheel slip during acceleration and retardation of the vehicle -a problem which is controllable in battery powered adhesion drive rail vehicles for instance, for selection of the current automatically selects the torque. Once slippage has occurred during retardation for example, it is virtually impossible for the driver to accelerate the wheels to match the speed of the vehicle. Furthermore, on relatively long gradients, it is difficlllt or impossible to dissipate the heat generated at con~entional disc or shoe brakes.
According to the present invention there is provided an adhesion drive rail vehicle comprising a prime mover;
a hydrostatic transmission comprising a transmission circuit to power at least one~
driven wheel or axle of the vehicle and a control circuit to control the transmission circuit;
the transmission circuit incorporating ta) an hydraulic motor provided at the or each driven wheel or axle, (b) a variable output pump biased to a drive condition, and (c) at least one throttle valve, to control vehicle braking, located in a fluid transmission line of the transmission circuit extending from the pump to the motor(s) and being operable by a disproportional area actuator;
the control circuit incorporating control means f`or the variable output pump and at least one driver operated speed control device movable in a first mode to cause acceleration of the vehicle by sending a variable presure signal to the pump oontrol means whereby the pump comes on stroke, while ~5 the driver operated speed control device is movable in a second mode to cause retardation 3~
of the vehlcle to send a variable pressure signal to the disproportional area actuator, to adjust the throttle valve to induce back-pressure in the return line from the motor(s),5 a feedback loop monitors the regenerated pressure and permits the throttle valve to continue to close as the flow through the valve reduce~ under the influence of the actuator9 at a driver selected braking pressure, until the vehicle comes to rest.
The result is that acceleration at a constant torque may be achieved by maintaining a constant pressure, while slippage during retardation is avoided or corrected by the gradually closing throttle valve. If the driver should select a control pressure which leads to wheel slip during retar~ation - a condition which is readily sensed by the driver - then returning his control device to a neutral position alters the pressure signal ._ to the actuator and consequently adjusts the throttle valve which, with the forward bias of the variable output pump, accelerates the wheelts) to rail speed~ whereupon the driver 25 ` may revert to the braking mode~ If the driver should select a control pressure which leads 33~
to wheel slip during acceleration, the driver eases his speed control device to reduce the pressure signal which permits the pump to~
stroke at a lesser rate.
The transmission circuit may incorporate two throttle valves whereby, during braking of the vehicle, in either direction of travel, pressure fluid exhausted from the motor(s) is passed through one or other of the throttle valves, before reaching the hydraulic pump.
The vehicle may take the form of a fixed axle locomotive or bogie mounted locomotive and normally at least two wheels, or a~ least one axle would be driven. It follows that in a four wheel bogie mode~ the bogie may have all four wheels drivable.
A major advantage is attainable in ~he braking mode of the vehicle if fluid is ~o extracted from the transmission circuit and passed through a cooler, whereby filtered and cooled fluid is available from tank.
If, as would normally be the case, the vehicle is required to run optionally in, both Z5 a forward direction and a reverse direction, a selector valve needs to be incorporated in the ~19~33~
control circuit to select the direction of pump output and hence the direction of wheel/axle motor(s) rotation The vehicle may:
be provided with a driver's cab at one end only, or with a driver~s cab at both ends.
In the latter case each cab incorporates a driver operable speed control device in the form of an acceleration valve and a brake valve, which may be lever operated. Indeed a single lever may be employed to operate both valves. Conveniently, the pump is of the swash plate type or bent axis type. The prime mover conveniently also drives a second pumpt which constitutes a boost pump, to boost the 15 main transmission and also to power the control circuit e.g. to provide fluid at 250 p.s.i. to the driver's control valves.
Conveniently, the boost pump is of the fixed delivery type. It is also preferred for the throttle valves to be rotary valves and the , actuators to be rotary or linear actuators.
The pump control means associated with the pu~p are preferably a pressure control device, e~g. a remote controlled relief valve, a ` 25 constant H.P. device fed by check valves, and a hydraulic stroke controller7 the latter being operable by the "direction of travel"
selector valve, whlch in effect selects the "live" cab if two cabs are provided. -The invention will now be described in greater detail, by way of example, with reference to the accompanying drawings, in which:
Figure 1 is a circuit diagram of a two cab vehicle in accordance with the invention, indicating the acceleration and constant velocity condition; and Figure 2 corresponds to Figure 1 but shows the service braking condition.
In the drawings, a prime mover, e.g. a 5~ diesel engine, is indicated at 1, which drives via shaft 20 a variable output hydraulic pump 21 and via shaft 22 a boost pump 12. The variable output hydraulic pump 21 is of the swash plate type or bent axis type and the , 20 swash plate angle is adjusted by a stroke controller 6 e.g. a spring loaded, - double-ended piston, mounted on the pump 21. Also - mounted on the pump 21 are a constant H.P.
device 5 - basically comprising a spring - 25 loaded valve and a pressure control device 4 constituted by a remote controlled relief 3~
valve. A transmission circuit comprises basically the pump 219 an output/return line 23 extending from the pump 21 to a first-throttle valve 3A, e.g. of the rotary type, which throttle valve 3A is infinitely adjustable between closed and maximum open positions by ~ disproportional area actuator 2A, connected to the valves 3A by any suitable means, e.g~ a chain engaging a sprocket wheel ?0 of the throttle valve if the latter are rotary valves. From the first throttle valve 3A
extends an output/return line 24, two hydraulic motors 10, one drivably connected to each of two flanged rail wheels(not shown) of the vehiole~ From each motor 10 extends a return/output line 25 to a second throttle valve 3B also controlled by a disproportional i;.. . :
~ area actuator 2B, the clrcuit being completed by a return/output line 28 from the valve 3B
to the pump 21.
Control of the transmission circuit is effected by a control circuit powered by the boost pump 12 subject to driver operated controls for acceleration, constant speed and ; 25 retardation, and the drawings illustrate a cirauit for a vehicle with two cabs identified ~L9~33~
as cab A and cab B. Each cab incorporates an acceleration valve 14 (0-200 p.s.i.) and a brake valve 15 (0-200 p.s~i.) both man~ally operable by the driver via control levers and forming part of the control circuit. The desired direction of trave1 of the vehicle dictates which cab controls shall be live and for this purpose a cab selector valve 16 and a control pressure selector ~alve 17 are incorporated in the control circuit.
It is arranged that, in a stationery condition of the vehicleg the engine 1 is running as is the pump 21 but no fluid delivery is taking place because of the .. . .
neutral position of its swash plate. The boost pump 12 is also running and delivering pressure flu1d at 250 p.s.i. to the control clrcuit. -In practice, the engine is arranged to produce approximately half its power so that coupling, uncoupling operations etc., can be easily effe ted. Hence, the boost pump 12 . . , .-supplies pressure fluid alon~ line 50 via the cab selector valve 16 to the acceleration and brake valves 14 and 15 of cab B, but as both valves 14 and 15 are in a neutnal position9 no boost pressure is supplied to either the acceleration line 52 or the brake line 53 of the control circuit. From line 50 extends a first branch 5:1 by which filtered cooled hydraulic fluid enters the system by a low pressure selector 9 comprising two one way valves and hence boost pressure is supplied along lines 54 and 55 to lines 24 and 25 of the transmission circuit, and hence the whole of the latter is at boost pressure, including, through directional valve 18, line 56 by which hot, contaminated hydraulic fluid leaves the system via relief valve 11 (250 p.s.i.) and thereafter a cooler 13 for the hydraulic fluid. A second branch 57 from line 50 .. " . . ........ .
conveys boost pressure to the stroke controller 6, and a thircl branch 58~conveys boost pressure to contro]L pressure selector . ~ valve 17. Fr;om the transmission circuit and via high pressure selector valve 8 (4000 p.s.i.) boost pressure passes along branch 59 to the pressure control device 4. However, the pump 21 cannot stroke until acceleration valve 14 is opened to supply a pressure signal along line 52 through valve 17, along line 60 25 and along branch 61 to the control valve 4, while a branch 26 extends to the engine fuel 13~
pump 19. The control valve 4 is thereby displaced and the engine 1 accelerated.
Previously, a proportion of the hydraulic fluid supplied by boost pump 12 had been allowed to spill off across the valve of the stroke controller 6, with the control - valve 4 held in a balanced condition.
However, with a press~re signal supplied along line 52 from the acceleration valve 14 to the ; 10 pressure control device 4, the latter is displaced and the vehicle now accelerates for pump 21 is allowed to come on stroke thus supplying fluid at 0 - 4,000 p~s.i. to the transmission circuit, with the principle quanti~y of fluid passing along line 24 ~ through motors 10 and along line 25 back to ` the pump 21. ~ A smaller quantity of fluid passes from line 24 along branch 63, a pilot line 6~ which displa~es the spool of , , ~. .~
directional valve 18, whereby a proportion of fluid~exhausted from the motors 10 may pass . ., ~
along branch 56, to the oil cooler 13 and then back to tank.
Acceleration continues until the deslred speed has been attained whereupon the driver adjusts the acceleration valve 14, it 33~
being arranged that the pump 21 is slightly biased in the direction of travel in that it will not destroke but drives, for example, at
.~
This invention relates to an adhesion drive rail vehicle, whether in ~he form of a fixed axle locomotive or bogie mounted locomotive, powered by prime mover (e g. a diesel engine or electric motor with or without an associated flywheel) 9 with a hydrostatic transmission to the or each driving wheel or axle. A constant problem is the avoidance of wheel slip during acceleration and retardation of the vehicle -a problem which is controllable in battery powered adhesion drive rail vehicles for instance, for selection of the current automatically selects the torque. Once slippage has occurred during retardation for example, it is virtually impossible for the driver to accelerate the wheels to match the speed of the vehicle. Furthermore, on relatively long gradients, it is difficlllt or impossible to dissipate the heat generated at con~entional disc or shoe brakes.
According to the present invention there is provided an adhesion drive rail vehicle comprising a prime mover;
a hydrostatic transmission comprising a transmission circuit to power at least one~
driven wheel or axle of the vehicle and a control circuit to control the transmission circuit;
the transmission circuit incorporating ta) an hydraulic motor provided at the or each driven wheel or axle, (b) a variable output pump biased to a drive condition, and (c) at least one throttle valve, to control vehicle braking, located in a fluid transmission line of the transmission circuit extending from the pump to the motor(s) and being operable by a disproportional area actuator;
the control circuit incorporating control means f`or the variable output pump and at least one driver operated speed control device movable in a first mode to cause acceleration of the vehicle by sending a variable presure signal to the pump oontrol means whereby the pump comes on stroke, while ~5 the driver operated speed control device is movable in a second mode to cause retardation 3~
of the vehlcle to send a variable pressure signal to the disproportional area actuator, to adjust the throttle valve to induce back-pressure in the return line from the motor(s),5 a feedback loop monitors the regenerated pressure and permits the throttle valve to continue to close as the flow through the valve reduce~ under the influence of the actuator9 at a driver selected braking pressure, until the vehicle comes to rest.
The result is that acceleration at a constant torque may be achieved by maintaining a constant pressure, while slippage during retardation is avoided or corrected by the gradually closing throttle valve. If the driver should select a control pressure which leads to wheel slip during retar~ation - a condition which is readily sensed by the driver - then returning his control device to a neutral position alters the pressure signal ._ to the actuator and consequently adjusts the throttle valve which, with the forward bias of the variable output pump, accelerates the wheelts) to rail speed~ whereupon the driver 25 ` may revert to the braking mode~ If the driver should select a control pressure which leads 33~
to wheel slip during acceleration, the driver eases his speed control device to reduce the pressure signal which permits the pump to~
stroke at a lesser rate.
The transmission circuit may incorporate two throttle valves whereby, during braking of the vehicle, in either direction of travel, pressure fluid exhausted from the motor(s) is passed through one or other of the throttle valves, before reaching the hydraulic pump.
The vehicle may take the form of a fixed axle locomotive or bogie mounted locomotive and normally at least two wheels, or a~ least one axle would be driven. It follows that in a four wheel bogie mode~ the bogie may have all four wheels drivable.
A major advantage is attainable in ~he braking mode of the vehicle if fluid is ~o extracted from the transmission circuit and passed through a cooler, whereby filtered and cooled fluid is available from tank.
If, as would normally be the case, the vehicle is required to run optionally in, both Z5 a forward direction and a reverse direction, a selector valve needs to be incorporated in the ~19~33~
control circuit to select the direction of pump output and hence the direction of wheel/axle motor(s) rotation The vehicle may:
be provided with a driver's cab at one end only, or with a driver~s cab at both ends.
In the latter case each cab incorporates a driver operable speed control device in the form of an acceleration valve and a brake valve, which may be lever operated. Indeed a single lever may be employed to operate both valves. Conveniently, the pump is of the swash plate type or bent axis type. The prime mover conveniently also drives a second pumpt which constitutes a boost pump, to boost the 15 main transmission and also to power the control circuit e.g. to provide fluid at 250 p.s.i. to the driver's control valves.
Conveniently, the boost pump is of the fixed delivery type. It is also preferred for the throttle valves to be rotary valves and the , actuators to be rotary or linear actuators.
The pump control means associated with the pu~p are preferably a pressure control device, e~g. a remote controlled relief valve, a ` 25 constant H.P. device fed by check valves, and a hydraulic stroke controller7 the latter being operable by the "direction of travel"
selector valve, whlch in effect selects the "live" cab if two cabs are provided. -The invention will now be described in greater detail, by way of example, with reference to the accompanying drawings, in which:
Figure 1 is a circuit diagram of a two cab vehicle in accordance with the invention, indicating the acceleration and constant velocity condition; and Figure 2 corresponds to Figure 1 but shows the service braking condition.
In the drawings, a prime mover, e.g. a 5~ diesel engine, is indicated at 1, which drives via shaft 20 a variable output hydraulic pump 21 and via shaft 22 a boost pump 12. The variable output hydraulic pump 21 is of the swash plate type or bent axis type and the , 20 swash plate angle is adjusted by a stroke controller 6 e.g. a spring loaded, - double-ended piston, mounted on the pump 21. Also - mounted on the pump 21 are a constant H.P.
device 5 - basically comprising a spring - 25 loaded valve and a pressure control device 4 constituted by a remote controlled relief 3~
valve. A transmission circuit comprises basically the pump 219 an output/return line 23 extending from the pump 21 to a first-throttle valve 3A, e.g. of the rotary type, which throttle valve 3A is infinitely adjustable between closed and maximum open positions by ~ disproportional area actuator 2A, connected to the valves 3A by any suitable means, e.g~ a chain engaging a sprocket wheel ?0 of the throttle valve if the latter are rotary valves. From the first throttle valve 3A
extends an output/return line 24, two hydraulic motors 10, one drivably connected to each of two flanged rail wheels(not shown) of the vehiole~ From each motor 10 extends a return/output line 25 to a second throttle valve 3B also controlled by a disproportional i;.. . :
~ area actuator 2B, the clrcuit being completed by a return/output line 28 from the valve 3B
to the pump 21.
Control of the transmission circuit is effected by a control circuit powered by the boost pump 12 subject to driver operated controls for acceleration, constant speed and ; 25 retardation, and the drawings illustrate a cirauit for a vehicle with two cabs identified ~L9~33~
as cab A and cab B. Each cab incorporates an acceleration valve 14 (0-200 p.s.i.) and a brake valve 15 (0-200 p.s~i.) both man~ally operable by the driver via control levers and forming part of the control circuit. The desired direction of trave1 of the vehicle dictates which cab controls shall be live and for this purpose a cab selector valve 16 and a control pressure selector ~alve 17 are incorporated in the control circuit.
It is arranged that, in a stationery condition of the vehicleg the engine 1 is running as is the pump 21 but no fluid delivery is taking place because of the .. . .
neutral position of its swash plate. The boost pump 12 is also running and delivering pressure flu1d at 250 p.s.i. to the control clrcuit. -In practice, the engine is arranged to produce approximately half its power so that coupling, uncoupling operations etc., can be easily effe ted. Hence, the boost pump 12 . . , .-supplies pressure fluid alon~ line 50 via the cab selector valve 16 to the acceleration and brake valves 14 and 15 of cab B, but as both valves 14 and 15 are in a neutnal position9 no boost pressure is supplied to either the acceleration line 52 or the brake line 53 of the control circuit. From line 50 extends a first branch 5:1 by which filtered cooled hydraulic fluid enters the system by a low pressure selector 9 comprising two one way valves and hence boost pressure is supplied along lines 54 and 55 to lines 24 and 25 of the transmission circuit, and hence the whole of the latter is at boost pressure, including, through directional valve 18, line 56 by which hot, contaminated hydraulic fluid leaves the system via relief valve 11 (250 p.s.i.) and thereafter a cooler 13 for the hydraulic fluid. A second branch 57 from line 50 .. " . . ........ .
conveys boost pressure to the stroke controller 6, and a thircl branch 58~conveys boost pressure to contro]L pressure selector . ~ valve 17. Fr;om the transmission circuit and via high pressure selector valve 8 (4000 p.s.i.) boost pressure passes along branch 59 to the pressure control device 4. However, the pump 21 cannot stroke until acceleration valve 14 is opened to supply a pressure signal along line 52 through valve 17, along line 60 25 and along branch 61 to the control valve 4, while a branch 26 extends to the engine fuel 13~
pump 19. The control valve 4 is thereby displaced and the engine 1 accelerated.
Previously, a proportion of the hydraulic fluid supplied by boost pump 12 had been allowed to spill off across the valve of the stroke controller 6, with the control - valve 4 held in a balanced condition.
However, with a press~re signal supplied along line 52 from the acceleration valve 14 to the ; 10 pressure control device 4, the latter is displaced and the vehicle now accelerates for pump 21 is allowed to come on stroke thus supplying fluid at 0 - 4,000 p~s.i. to the transmission circuit, with the principle quanti~y of fluid passing along line 24 ~ through motors 10 and along line 25 back to ` the pump 21. ~ A smaller quantity of fluid passes from line 24 along branch 63, a pilot line 6~ which displa~es the spool of , , ~. .~
directional valve 18, whereby a proportion of fluid~exhausted from the motors 10 may pass . ., ~
along branch 56, to the oil cooler 13 and then back to tank.
Acceleration continues until the deslred speed has been attained whereupon the driver adjusts the acceleration valve 14, it 33~
being arranged that the pump 21 is slightly biased in the direction of travel in that it will not destroke but drives, for example, at
2 H~P. at full engine revolutions, the aim ;
being to match rolling friction etc.
When it is desired to retard the - vehicle, the driver opens brake valve 15, thereby activating line 53, which provides control pressure to the opposite side of the actuator 2A associated with the return line 24.
The disproportional area actuator 2A may have a ratio of 22.5 : 1. The valve 3B associated with the line 25 is gradually closed by movement o~ the actuator 2B, wlth a reduced quantIty of fluid supplied to the pump 1 from the valve 3B ~(0-4500 p.s.i.) ~ , ~ or ease of understanding the mode of operation, the various c:ircuits have been dicated by differing line styles in the 20. Figure9. ~ Thus, in Figure 1 t the control pressure circuit is shown in chain dotted ., , ~ :
.: ~ line, the boost :pressure circuit in long-dotted line, and the transmission pressure circuit in ùeavy line; while in Figure 2, the control pressure circuit (0-200 p.s.i.) is ~` again shown in chain-dotted line, the boost ~L99~33~
pressure circuit (250 p.s.i.) is again shown in long-dotted line, while the regenerative braking pressure circuit (0-4000 p.s.i.) is shown in short-dotted line. '-, ~
~ : -
being to match rolling friction etc.
When it is desired to retard the - vehicle, the driver opens brake valve 15, thereby activating line 53, which provides control pressure to the opposite side of the actuator 2A associated with the return line 24.
The disproportional area actuator 2A may have a ratio of 22.5 : 1. The valve 3B associated with the line 25 is gradually closed by movement o~ the actuator 2B, wlth a reduced quantIty of fluid supplied to the pump 1 from the valve 3B ~(0-4500 p.s.i.) ~ , ~ or ease of understanding the mode of operation, the various c:ircuits have been dicated by differing line styles in the 20. Figure9. ~ Thus, in Figure 1 t the control pressure circuit is shown in chain dotted ., , ~ :
.: ~ line, the boost :pressure circuit in long-dotted line, and the transmission pressure circuit in ùeavy line; while in Figure 2, the control pressure circuit (0-200 p.s.i.) is ~` again shown in chain-dotted line, the boost ~L99~33~
pressure circuit (250 p.s.i.) is again shown in long-dotted line, while the regenerative braking pressure circuit (0-4000 p.s.i.) is shown in short-dotted line. '-, ~
~ : -
Claims (24)
1. An adhesion drive rail vehicle comprising a prime mover;
a hydrostatic transmission comprising a transmission circuit to power at least one driven wheel or axle of the vehicle and a control circuit to control the transmission circuit;
the transmission circuit incorporating (a) an hydraulic motor provided at the or each driven wheel or axle, (b) a variable output pump biased to a drive condition, and (c) at least one throttle valve, to control vehicle braking, located in a fluid transmission line of the transmission circuit extending from the pump to the motor(s) and being operable by a disproportional area actuator;
the control circuit incorporating control means for the variable output pump and at least one driver operated speed control device movable in a first mode to cause acceleration of the vehicle by sending a variable presure signal to the pump control means whereby the pump comes on stroke, while the driver operated speed control device is movable in a second mode to cause retardation of the vehicle to send a variable pressure signal to the disproportional area actuator, to adjust the throttle valve to induce back pressure in the return line from the motor(s), a feedback loop monitors the regenerated pressure and permits the throttle valve to continue to close as the flow through the valve reduces under the influence of the actuator, at a driver selected braking pressure, until the vehicle comes to rest.
a hydrostatic transmission comprising a transmission circuit to power at least one driven wheel or axle of the vehicle and a control circuit to control the transmission circuit;
the transmission circuit incorporating (a) an hydraulic motor provided at the or each driven wheel or axle, (b) a variable output pump biased to a drive condition, and (c) at least one throttle valve, to control vehicle braking, located in a fluid transmission line of the transmission circuit extending from the pump to the motor(s) and being operable by a disproportional area actuator;
the control circuit incorporating control means for the variable output pump and at least one driver operated speed control device movable in a first mode to cause acceleration of the vehicle by sending a variable presure signal to the pump control means whereby the pump comes on stroke, while the driver operated speed control device is movable in a second mode to cause retardation of the vehicle to send a variable pressure signal to the disproportional area actuator, to adjust the throttle valve to induce back pressure in the return line from the motor(s), a feedback loop monitors the regenerated pressure and permits the throttle valve to continue to close as the flow through the valve reduces under the influence of the actuator, at a driver selected braking pressure, until the vehicle comes to rest.
2. A rail vehicle as claimed in Claim 1, wherein the transmission circuit incorporates two throttle valves whereby during braking of the vehicle, in either direction of travel, pressure fluid exhausted from the motor(s) is passed through one or other of the throttle valves, before reaching the hydraulic pump.
3. A rail vehicle as claimed in Claim 1 in the form of a fixed axle locomotive.
4. A rail vehicle as claimed in Claim 1 in the form of a bogie mounted locomotive.
5. A rail vehicle as claimed in Claim 3, wherein at least one axle is driven.
6. A rail vehicle as claimed in Claim 4, wherein at least two wheels are driven.
7. A rail vehicle as claimed in Claim 4 or Claim 6, in a four wheel bogie mode, with all four wheels drivable.
8. A rail vehicle as claimed in Claim 1 or 2, wherein fluid is extracted from the transmission circuit and passed through a cooler, whereby filtered and cooled fluid is available from tank.
9. A rail vehicle as claimed in Claim 1 or 2, wherein a selector valve is incorporated in the control circuit to select the direction of pump output and hence the direction of wheel/axle motor(s) rotation.
10. A rail vehicle as claimed in Claim 1 or 2, provided with a driver's cab at one end only.
11. A rail vehicle as claimed in Claim 1, provided with a driver's cab at both ends.
12. A rail vehicle as claimed in Claim 11, wherein each cab incorporates a driver operable speed control device in the form of an acceleration valve and a brake valve.
13. A rail vehicle as claimed in Claim 12, wherein the speed control device is lever operated.
14. A rail vehicle as claimed in Claim 12 or Claim 13, wherein a single lever is employed to operate both valves.
15. A rail vehicle as claimed in Claim 1 or 2, wherein the pump is of the swash plate type.
16. A rail vehicle as claimed in Claim 1 or 2, wherein the pump is of the bent axis type.
17. A rail vehicle as claimed in Claim 1, wherein the prime mover also drives a second pump, which constitutes a boost pump, to boost the main transmission and also to power the control circuit.
18. A rail vehicle as claimed in Claim 17, wherein the boost pump is of the fixed delivery type.
19. A rail vehicle as claimed in Claim 1 or 2, wherein each throttle valve is a rotary valve.
20. A rail vehicle as claimed in Claim 1 or 2, wherein the actuators are rotary actuators.
21. A rail vehicle as claimed in Claim 1 or 2 wherein the actuators are linear actuators.
22. A rail vehicle as claimed in Claim 1, wherein the pump control means associated with the pump are a pressure control device, a constant H.P. device fed by cheek valves, and a hydraulic stroke controller.
23. A rail vehicle as claimed in Claim 22, wherein the pressure control device is a remote controlled relief valve.
24. A rail vehicle as claimed in Claim 22 or Claim 23, wherein a selector valve is incorporated in the control circuit to select the direction of pump output and hence the direction of wheel/axle motor(s) rotation, the hydraulic
24. A rail vehicle as claimed in Claim 22 or Claim 23, wherein a selector valve is incorporated in the control circuit to select the direction of pump output and hence the direction of wheel/axle motor(s) rotation, the hydraulic
Claim 24 - cont'd ...
stroke controller being operable by the direction of travel selector valve.
stroke controller being operable by the direction of travel selector valve.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8227742 | 1982-09-29 | ||
| GB8227742 | 1982-09-29 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1199834A true CA1199834A (en) | 1986-01-28 |
Family
ID=10533239
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000437396A Expired CA1199834A (en) | 1982-09-29 | 1983-09-23 | Rail vehicle |
Country Status (3)
| Country | Link |
|---|---|
| AU (1) | AU1954583A (en) |
| CA (1) | CA1199834A (en) |
| ZA (1) | ZA837036B (en) |
-
1983
- 1983-09-21 ZA ZA837036A patent/ZA837036B/en unknown
- 1983-09-23 CA CA000437396A patent/CA1199834A/en not_active Expired
- 1983-09-26 AU AU19545/83A patent/AU1954583A/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| AU1954583A (en) | 1984-04-05 |
| ZA837036B (en) | 1984-05-30 |
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| Date | Code | Title | Description |
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| MKEX | Expiry |